熟妇熟女乱妇乱女网站_噼里啪啦免费高清看_av中文字幕一区二区_欧美日韩国产激情_热久久国产_另类视频在线观看_人人爱人人澡_一本黄色片_精品一区电影_亚洲第四页_爱情岛亚洲首页论坛小巨_婷婷丁香色_中文字幕一二区_麻豆传媒一区二区_国产在线网址

2023 Vol. 44, No. 4

Separating and Extracting of Vanadium and Titanium
Study on migration and transformation behavior of elements during vanadium extraction by calcification
Liu Xi, Pu Yuwen, Xu Zongyuan, Tang Kang, Zheng Guocan, Chen Yan, Liu Zuohua, Du Jun, Peng Yi, Tao Changyuan
2023, 44(4): 1-9. doi: 10.7513/j.issn.1004-7638.2023.04.001
Abstract(550) HTML (192) PDF(50)
Abstract:
Combined with XRD, XPS, SEM-EDS and ICP-OES characterizations, the phase composition and morphology of acid ammonium salt precipitation vanadium products under different pH values were studied; also the migration and transformation behavior of V, Fe and Mn were analyzed when the pH value of vanadium precipitation was 2.20. The results show that the pH value of vanadium precipitation significantly affects the composition and morphology of the product. The filter cake of vanadium precipitation is amorphous at low pH value, and the crystal form is gradually determined with the increase of pH value. V exists in the form of CaV2O6 in vanadium extraction tailings, polyvanadate in filter cake, and V2O5 in the final product. The main forms of Fe in tailings are Fe2O3 and Fe2TiO5, which are less abundant in vanadium filter cake and final product. Mn exists in the form of MnSO4 in the tailings, and mainly enters the supernatant during vanadium precipitation, while MnV2O6·4H2O exists in the filter cake and with 0.210% in the final product.
Study on the preparation of spherical TiC nanopowder by molten salt method
Li Wenjing, Guo Yun, Yang Yadong, Liu Bo, Xin Yanan
2023, 44(4): 10-17. doi: 10.7513/j.issn.1004-7638.2023.04.002
Abstract(584) HTML (219) PDF(26)
Abstract:
In combination with the national strategic deployment of the 14th Five-Year Plan, based on the enterprise resource background and the downstream market demand, this paper proposes to prepare spherical titanium carbide (TiC) nanopowder through the short process of molten salt method. The process does not use flammable and explosive reducing agent, and has high safety factor. The process produces products with high quality, controllable output, short production cycle and environmental protection, which has certain industrial popularization. The selection and proportion of titanium source and carbon source, the proportion of molten salt, the calcination temperature of nanoparticles, and the effect of holding time on the morphology and quality of nanoparticles were studied. The phase composition and microstructure of the particles were characterized by XRD and SEM. The results show that when the molar ratio of NaCl-KCl mixed salt is 1∶1, the reactants in the ratio of Ti/C molar ratio of 1∶1, and TiC begins to form when the temperature is kept at 700 ℃ for 2 h. With the increase of temperature, the purity of the target product in the product gradually increases. The temperature of holding at 900 ℃ for 2 h can obtain the pure target product, without the formation of other by-products. The morphology is spherical, and the particle size is about 80 nm. If the holding time is changed, when the holding time is 5 h, the pure target product can be obtained at 850 ℃, but the particle size will be moderately increased to 100 nm. From the perspective of reducing raw material costs, when the titanium source ratio is Ti∶TiO2=9∶1, impurity free titanium carbide nanoparticles can be obtained at 900 ℃, with spherical morphology and particle size ranging from 50 to 65 nm.
Research on the leaching characteristics of Ca, Mg, Al elements in high titanium blast furnace slag
Huangfu Lin, Jiang Yang, Qiu Zhengqiu, Wang Kui
2023, 44(4): 18-24. doi: 10.7513/j.issn.1004-7638.2023.04.003
Abstract(517) HTML (145) PDF(25)
Abstract:
To make full use of the valuable elements in high titanium blast furnace slag, the physical and chemical properties were analyzed. The method of hydrochloric acid hydrothermal leaching was proposed to separate Ca and Mg elements from high titanium blast furnace slag. And the influence of reaction condition parameters on the leaching characteristics of elements in high titanium blast furnace slag was studied. The results reveal that with the increase of hydrochloric acid concentration, hydrochloric acid amount, reaction temperature and reaction time, the leaching efficiency of Ca, Mg and Al elements in high titanium blast furnace slag all increase. Among them, the leaching efficiency of Mg and Al remain stable when they are higher than 95%, while the leaching efficiency of Ca can raise to nearly 100%. The Ca and Mg elements in high titanium blast furnace slag can be entirely dissociated when the concentration of hydrochloric acid is 4 mol/L, the amount of hydrochloric acid is 1.5 times of theoretical acid amount required for the entire dissolution of Ca, Mg and Al elements in high titanium blast furnace slag, the reaction temperature is 150 ℃, the reaction time is 10 h. Meanwhile, the amounts of both MgO and CaO in the leaching residue are all below 1%, and the aggregate amounts of TiO2, SiO2 and Al2O3 are higher than 95%, which can fulfill the requirements of preparing porous adsorption materials. The results of this research are anticipated to provide data support for the efficient utilization of high titanium blast furnace slag.
Study on the effect and mechanism of Al3+ during the calcination of metatitanic acid
Lu Ruifang, Yang Fang, Liu Chan, Hao Lin
2023, 44(4): 25-32. doi: 10.7513/j.issn.1004-7638.2023.04.004
Abstract(432) HTML (198) PDF(21)
Abstract:
In the production of titanium dioxide by sulfate process, obtaining rutile titanium dioxide with suitable particle size through different salt treatments and high-temperature calcination of metatitanic acid is the basis for preparing titanium pigments. Aluminum salt treatment is currently one of the commonly used salt treatment systems, but the mechanism of aluminum salt in the calcination process is still unclear. In this study, the intermediate material in the production of titanium dioxide by sulfate process, metatitanic acid after second washing, was used as raw material, and only aluminum sulfate was used as salt treatment agent. The material was calcined in a muffle furnace at a temperature of 800-950 ℃. The effects of Al3+on the crystal transformation and particle growth of TiO2 during the calcination process were studied using XRD, SEM, HRTEM, and other analytical methods. The results show that different amounts of aluminum salts and calcination temperatures have significant effects on the crystal transformation, particle growth, and existence form of Al3+ in TiO2. When the amount of aluminum salt is low, Al3+ is doped into the TiO2 lattice in a substitution mode, displacing Ti4+, reducing the crystal cell volume and shortening the internal bond length of the crystal, which is not conducive to the atomic rearrangement and bond breaking processes, leading to a decrease in the crystalline transformation rate. And with the increase of the amount of aluminum salt added, excessive Al3+ exists as Al2O3 on the TiO2 surface. At the same time, with the increase of the amount of aluminum salt added, the particle size of anatase or rutile TiO2 obtained at the same calcination temperature decreases.
Research progress in vanadium extraction from stone coal vanadium ore by roasting
Song Changxu, Ye Guohua, Kang Xuanxiong, Zhang Yun, Rong Yiyang, Xiang Xinyue
2023, 44(4): 33-40. doi: 10.7513/j.issn.1004-7638.2023.04.005
Abstract(937) HTML (257) PDF(75)
Abstract:
The research progress of vanadium extraction from stone coal vanadium ore by roasting was reviewed. The possible application scenarios of roasting process were discussed. The advantages and disadvantages of different roasting processes were discussed through examples. The development status and industry difficulties of vanadium extraction from stone coal vanadium ore by roasting were summarized and prospected. Vanadium in stone coal vanadium ore mainly exists in the form of isomorphism, and roasting is the key to extracting vanadium. Traditional roasting processes include sodium roasting, calcification roasting, composite additive roasting and salt-free roasting. These processes are relatively mature but need to control pollution. The newly proposed roasting processes include microwave roasting, alkali fusion roasting, chlorination roasting and low-temperature sulfation roasting. The concept of microwave roasting was proposed earlier, but obvious theoretical and practical progress has been made recently. Alkali fusion roasting has a good effect in improving vanadium valence. Chlorination roasting and low-temperature sulfation roasting are in line with the development concept of green and low-carbon, and can obtain ideal vanadium extraction indicators.
Effect of glucose content on the lithium storage performance of Li3V2(PO4)3/C cathode materials prepared by sol-gel combustion method
Li Nali, Zhang Renjie
2023, 44(4): 41-47. doi: 10.7513/j.issn.1004-7638.2023.04.006
Abstract(354) HTML (128) PDF(11)
Abstract:
In this paper, submicrometer porous Li3V2(PO4)3 (LVP)/C composites with different carbon contents were successfully prepared by a modified sol-gel combustion method by changing the amount of glucose added. The effects of glucose addition on the structure, morphology and electrochemical properties of LVP were systematically studied. Although the addition of glucose did not change the crystal structure and lattice parameters of LVP, nanoneedle-like particles appeared in the samples with glucose, which were beneficial to electron transport and Li+ diffusion. With the increase of glucose content, the volume fraction of nanoneedle-like particles increased, thus improving the rate performance of LVP/C cathode materials. The amorphous carbon generated by carbonization of glucose is evenly coated on the surface of LVP particles, which improves the conductivity of the composites. The conductivity increases with the increase of glucose content. However, excessive glucose addition will lead to too thick carbon coating, which is not conducive to the transmission of Li+. Benefiting from the appropriate amount of glucose addition, nanoneedle-like particles and porous structure, LVP/C-G15% sample has excellent lithium storage performance. It can still provide a discharge specific capacity of 75.1 mAh/g after 200 cycles at a high rate of 10 C, and the capacity retention rate is as high as 89.0%.
Application of Vanadium and Titanium
Study on the microstructure and properties of the transition region of IN625/TC4 bimetallic structure by laser melting deposition with Cu interlayer
Wang Wenbo, Xu Nuo, Xu Guojian, Jing Zhicheng, Zhang Guoyu, Zhao Xue, Xiang Zhuo
2023, 44(4): 48-54. doi: 10.7513/j.issn.1004-7638.2023.04.007
Abstract(475) HTML (206) PDF(25)
Abstract:
The bimetallic structure composed of IN625 nickel-based high-temperature alloy with excellent high-temperature properties and lightweight and high-strength TC4 titanium alloy has broad application prospects in the aerospace field. However, due to the large differences in physical and chemical properties of the two metals, the direct fabrication of IN625/TC4 bimetallic structure inevitably results in the formation of metallurgical defects such as cracks in the transition region, so the effective connection of IN625/TC4 bimetallic structure has been a hot spot and a difficult area of research in the industry. In this work, laser melting deposition technology was used to prepare IN625/TC4 bimetallic structure without cracks and other metallurgical defects by adding Cu interlayer, and studied the microstructure and mechanical properties of the transition region. The results show that the phase composition inside the transition region of the IN625/TC4 bimetallic structure deposited by laser melting with Cu interlayer is mainly γ-Ni, γ-Cu, (Cr, Mo), Ti2Cu, TiCu, TiNi3, α-Ti and β-Ti. Tensile results at room temperature indicate that the tensile strength of the IN625/TC4 bimetallic structure with Cu interlayer is about 228.9 MPa. The fracture location is near the Cu/IN625 transition region, and the fracture morphology shows quasi-dissociative fracture characteristics.
Effect of self-induced magnetic field on liquid flow and segregation during VAR process for titanium alloys
Huang Liqing, Wu Jingyang, Guo Jie, Fan Kai, Li Chao, Li Zhihong, Li Junjie, Wang Jincheng
2023, 44(4): 55-61. doi: 10.7513/j.issn.1004-7638.2023.04.008
Abstract(458) HTML (292) PDF(42)
Abstract:
A continuum model for alloy solidification was used to simulate the temperature evolution, solute distribution, liquid flow, and self-induced magnetic field during VAR process for titanium alloys. The work reveals the influence of self-induced magnetic force and/or buoyancy force on the melt flow and solute segregation by contrastively exerting the forces. When a small melting current of 0.3 kA is used, the melt flow is dominantly driven by the buoyancy force that the melt flows downward at the side of the melt pool and upward in the center of the melt pool. When a large melting current of 0.73 kA is used, the melt flow is dominantly driven by the self-induced magnetic force and the melt flows adversely, and the maximum velocity reaches 0.036 m/s. When a medium current of 0.45 kA is applied, both the two forces act evidently, forming two regions in the pool where the melt flow directions are opposite, and the maximum flow rate in the pool can reach a minimum value of 0.004 m/s due to their competition. With increasing the current, the total segregation of the ingot rises at begin, has a reduction stage after a peak, but then increase continuously again. The extreme values of the three stages are 0.54%, 0.39% and 0.57%, correspondingly. The minimum segregation can be obtained when the self-induced magnetic force and buoyancy force act equally.
Effect of ball milling time on the microstructure and mechanical properties of porous Ti-5Cu alloys
Mai Ping
2023, 44(4): 62-67. doi: 10.7513/j.issn.1004-7638.2023.04.009
Abstract(380) HTML (121) PDF(9)
Abstract:
Biomedical porous Ti-5Cu alloys were prepared by mechanical ball milling and space holder method through vacuum sintering. The metal powders ball milled with different time were analyzed by scanning electron microscopy, X-ray diffractometer and laser particle size analyzer, and the effects of ball milling time on the microstructure and mechanical properties of the porous Ti-5Cu alloy were investigated. The results showed that the morphology of Ti-5Cu powder became flat and its average particle size decreased significantly after 2 h ball milling. Further increasing the milling time only slightly reduced the average particle size of the powder. With the increase of ball milling time, the porosity of the porous Ti-5Cu alloy with anisotropic pore structure simulating human bone gradually decreased, and its elastic modulus and compressive strength first increased and then decreased. At the time point of ball milling, the elastic modulus and compressive strength of porous Ti-5Cu alloy prepared by ball milling for 2 h achieved the highest values, which were 3.79 GPa and 89.00 MPa, respectively.
Effect of compression deformation on the microstructure and properties of TA18 titanium alloy
Huo Sihan, Lv Xiao
2023, 44(4): 68-72. doi: 10.7513/j.issn.1004-7638.2023.04.010
Abstract(913) HTML (219) PDF(20)
Abstract:
In the present study, the compression experiments with compression deformation of 10%, 20%, 30%, 50% and 70% were carried out for the nearly α type TA18 titanium alloy bars after radial precision forging and hot rolling. The bars were subsequently annealed for 2 hours at 510 ℃. The influence of compression deformation on the microstructure and mechanical properties was investigated by metallographic microscopy. It is found that the radial precision forged and hot rolled TA18 alloy bars can achieve uniform microstructure after compress experiments with compression deformation of 10%, 20%, 30%. The mechanical properties of the alloy bars after radial precision forging and hot rolling keep basically consistent and the compressive strength gets a maximum value at the compression deformation of 30%. The grain size and distribution of the compressed alloy bars are still relatively uniform after annealing at 510 ℃ for 2 hours. After annealing, the microstructure of the compressed radial precision forging bar is more uniform.
Preparation and properties of lithium titanate anode materials with different titanium sources
Jiang Xinyu, Ma Guangqiang, Zhu Qinmei, Tian Congxue
2023, 44(4): 73-77. doi: 10.7513/j.issn.1004-7638.2023.04.011
Abstract(385) HTML (420) PDF(18)
Abstract:
Spherical Li4Ti5O12 anode materials were prepared by high temperature solid phase method, and the effects of different titanium sources on the properties of Li4Ti5O12 anode materials were investigated. The structure and morphology of the prepared materials were characterized by XRD and SEM, and the synthesized materials were tested by electrochemical method. The results show that the discharge specific capacities of t-LTO, h-LTO and f-LTO prepared with nano TiO2(P40), industrial H2TiO3 and industrial H2TiO3 containing iron are 170.0, 156.3 and 150.7 mAh/g at lower charge/discharge rate of 0.2 C, respectively. And the discharge specific capacities at the higher rate of 5 C are 91.9, 93.0 and 26.7 mAh/g, respectively. After 100 cycles of charging and discharging at 1 C, the capacity retention rates are 97.4%, 97.3% and 94.6%, respectively. Li4Ti5O12 prepared with nano TiO2 and industrial H2TiO3 has good electrochemical performance, so relatively pure industrial H2TiO3 can be used as a substitute for expensive TiO2 to prepare Li4Ti5O12 anode materials.
Study on electrical removal of aluminum from Ti-Al alloys in low-temperature molten salt
Xu Peidong, Tan Min, Li Tao, Gao Aimin, Xin Zhaoyang, Liu Wei, Gu Shaopeng
2023, 44(4): 78-84. doi: 10.7513/j.issn.1004-7638.2023.04.012
Abstract(455) HTML (217) PDF(17)
Abstract:
In order to realize the secondary recycling and separation of Al-Ti alloys, the dealloying of Al-Ti alloys was studied with 1-butyl-3-methyl imidazolium chloride (BMIC)-aluminum chloride (AlCl3) as the electrolyte and Ti-Al alloys as the sacrificial anode. Cyclic voltammetry, potentiodynamic polarization method, and potentiostatic polarization method were performed to analyze the dealloying behavior during electrolysis. SEM-EDS was used to characterize the micromorphology of the samples before and after electrolysis. The Al content in the Ti-Al alloy samples was quantified by ICP-AES. The results showed that the dealloying reaction of Ti-Al alloy in BMIC-AlCl3 is quasi-reversible. The current remains stable during the long-time electrolysis, indicating that the electrolytic dealloying could be achieved continuously. The cathodic deposition layer was found to be metallic aluminum with high purity and porous structure by scanning electron microscopy. The content of Al in titanium aluminum alloy after electrolysis decreased by 10.67% compared with that before electrolysis based on the ICP-AES analysis.
Study on long time corrosion resistance of titanium welded tube
Li Haiming, Hu Xingguang, Li Junzhao, Liu Wenzheng, Yang Weijun
2023, 44(4): 85-88. doi: 10.7513/j.issn.1004-7638.2023.04.013
Abstract(369) HTML (136) PDF(7)
Abstract:
Simulating different operating conditions the corrosion resistance of titanium welded pipe in tap water, 5% magnesium chloride aqueous solution, seawater and 10% sulfuric acid solution soaked for a long time was studied through macro-size detection, metallographic analysis and mechanical properties test. The results show that there is almost no evident corrosion of titanium welded pipe after long-term immersion in tap water, 5% magnesium chloride aqueous solution and seawater. The corrosion rate is 0.333, 0.466 μm /year and 0.466 μm/year, respectively, representing a predominant corrosion resistance of titanium welded pipe. The titanium welded pipe can be corroded after a long-term immersion in 10% sulfuric acid solution. The wall of titanium welded pipe becomes thinned with a reduction rate of 2% . The corrosion rate is 1.398 μm/year, and the corrosion resistance is worse than the other three solutions. This research is of great significance to the application of titanium welded pipe in domestic water, salt making, ocean engineering and seawater desalination.
Resources Environment and Energy Saving
Experimental research on the recycling of valuable metal elements with the extracted-vanadium residues reduced by biomass
Gao Yang, Xie Huaqing, Zhou Mi, Guo Rui, Qin Mengxin, Wang Zhengyu, Dai Bing
2023, 44(4): 89-95. doi: 10.7513/j.issn.1004-7638.2023.04.014
Abstract(438) HTML (184) PDF(16)
Abstract:
In order to solve the problems of land resources waste and environmental pollution caused by accumulation of vanadium extraction tailings, two kinds of vanadium extraction tailings were studied in this paper. Biomass was used as reducing agent for high temperature reduction experiment, and the component analysis and phase analysis of reduction products were carried out to explore the influences of oxygen absorption ratio, time and temperature on metallization rate of reduction products. The results show that the iron metallization rate can reach 58.67% when the oxygen absorption ratio is 4, the reduction temperature is 1450 ℃ and the reduction time is 2 h. The chromium metallization rate of vanadium-precipitated waste slag can reach 99.19% when the oxygen absorption ratio is 1.75, the reduction temperature is 1550 ℃ and the reduction time is 4 h. Two kinds of vanadium extracting tailings were mixed to prepare ferrochromium alloy by high temperature reduction of biomass. The preliminary experiment proved that the reduction product was melted under the condition of oxygen absorption ratio of 4, reduction time of 3 hours and reaction temperature of 1550 ℃. The content of chromium in the alloy was 61.51%, the content of iron was 31.05%, and the content of elements met the national standard requirements of FeCr65C4.0 alloy.
Research on properties of air-quenched steel slag abrasives with different particle sizes
Li Shuo, Xing Hongwei, Liu Chao, Lin Wenlong, Zhang Wei, Gu Shaopeng, Wang Hui, Pei Jingjing
2023, 44(4): 96-102. doi: 10.7513/j.issn.1004-7638.2023.04.015
Abstract(351) HTML (131) PDF(11)
Abstract:
Using solid steel slag as raw material, steel slag with different particle sizes was prepared by air quenching after high-temperature remelting in an electric arc furnace. the differences and similarities of air-quenched steel slag with different particle sizes in terms of phase composition, microstructure, apparent density, morphological characteristics and hardness were compared, and the feasibility of using air-quenched steel slag as sandblasting abrasive was analyzed. The air-quenched steel slag with better abrasive properties was selected for sandblasting experiment. The results show that the phase composition of air-quenched steel slag is similar, mainly calcium silicate phase and cubic magnesite. The apparent density decreases with the increase of particle size, which conforms to the density standard of nonmetallic abrasives. The average Vickers hardness of the five particle sizes of air-quenched steel slag is more than 588, which is suitable for abrasive blasting. Considering the performance and blasting effect of different particle sizes of air-quenched steel slag, 0.5~1.0 mm air-quenched steel slag is the most suitable for abrasive blasting.
Study on hydration reaction of titanium gypsum–titanium slag low clinker cement
Jiang Yong, Su Yaobin, Gao Rui, Wu Maojie, Jiang Yun, Jiao Xiaofei
2023, 44(4): 103-111. doi: 10.7513/j.issn.1004-7638.2023.04.016
Abstract(556) HTML (167) PDF(13)
Abstract:
In order to explore the feasibility of using titanium gypsum and titanium slag to prepare low clinker cement and study its hydration characteristics, 10 groups of cement were prepared with titanium gypsum, titanium slag and cement clinker as the main raw materials and sodium silicate as the activator. The compressive strength, softening coefficient and shrinkage rate of each group were tested. The hydration process and hydration products were studied by hydration thermal analysis, TG-DSC, XRD and SEM. The results show that appropriate increase of titanium slag or clinker content can improve the compressive strength and softening coefficient of cement, and reduce the shrinkage of cement. Sodium silicate can significantly activate the hydration reactivity of cement, and promote the generation of more C-S(A)-H, AFt and CH, so as to improve the compressive strength and softening coefficient, but excessive incorporation of sodium silicate will cause an increase in shrinkage rate. With the ratio of titanium gypsum, titanium slag, clinker and sodium silicate of 30∶55∶15∶8, the compressive strength reached 51.3 MPa of 56 days after curing and the softening coefficient was 0.74, showing good mechanical properties and water resistance.
Laboratory study on improving recovery rate of pyrite concentrate in titanium separation process in Panxi region
Wang Hongbin, Shi Zhangliang, Zhao Kaile, Yang Yaohui, Luo Rongfei
2023, 44(4): 112-116. doi: 10.7513/j.issn.1004-7638.2023.04.017
Abstract(358) HTML (139) PDF(13)
Abstract:
In the case of sanding of a titanium flotation inclined plate in Panxi area, the conventional process of “first floating sulfur and then enriching cobalt sulphide” and the recovery of sulphides with the conventional reagent “Butyl xanthate +2# oil” were adopted, the low recovery of cobalt sulphide is unfavorable to the subsequent flotation separation of cobalt sulphide, the flotation process of “one roughing, two sweeping and three refining” was optimized by adding high efficient auxiliary collector EMC-50, foaming agent EMP-02 and inhibitor EM515.The results showed that sulfur concentrate with yield of 2.00% , S grade of 36.37% , Co grade of 0.36% and S recovery of 83.53% could be obtained by adding new reagent, the recovery of pyrite concentrate is 3.21% higher than that of conventional reagent, and the reagent cost per unit pyrite concentrate is 111 yuan/t lower. The use of new reagents will be beneficial to improve the comprehensive utilization value of Panxi pyrite concentrate.
Ferrous Metallurgy and Materials
Effect of preformed calcium ferrite addition on sintering behavior of vanadium titanomagnetite
Xie Hao, Li Gang, Lv Xuewei, Sun Xiaodong, He Haixi
2023, 44(4): 117-124. doi: 10.7513/j.issn.1004-7638.2023.04.018
Abstract(515) HTML (194) PDF(17)
Abstract:
In view of the problems of low yield, poor strength and high energy consumption in the sintering process of vanadium titanomagnetite, a new sintering technology of preformed calcium ferrite is proposed in this paper, and its feasibility and theoretical basis are revealed through the tablet sintering and thermal analysis test. The results show that with the increase of substitution ratio (preformed calcium ferrite to partially substitute CaO), the microstructure of roasted products changes from granular structure to melting corrosion structure, the content of SFCA increases, while perovskite content decreases. In addition, the quantity of melts increases, the coalesce of sintering bubbles is promoted, the average porosity decreases from 42.9% to 36.2%, and the densification of the matrix is promoted. The formation of calcium ferrite melts in the heating process can be divided into three reactions, according to the formation temperature from low to high, it is the eutectic reaction of CF+CF2 → L, the melting of SFCA-I and SFCA, respectively; the addition of preformed calcium ferrite can reduce the generation temperature of initial melts, and increase the total sintering melts by about 9 %; promote the melting of iron oxides into the initial melts, increase the content of calcium ferrite, and promote solid-liquid assimilation reaction.
Investigation of multiphase transport behaviors in a FTSR mold during electromagnetic continuous casting process
Xu Lin, Pei Qunwu, Li Yang, Han Zefeng, Yang Shuo, Wang Jianyu
2023, 44(4): 125-134. doi: 10.7513/j.issn.1004-7638.2023.04.019
Abstract(422) HTML (146) PDF(6)
Abstract:
For the research object of flexible thin slab rolling (FTSR) funnel-shaped mold, a three-dimensional (3-D) multi-field coupling mathematical model was established for describing the electromagnetic braking (EMBr) continuous casting process. To investigate the metallurgical effect of Ruler-EMBr device, the effects of various electromagnetic parameters on the behaviors of molten steel flow, heat transfer, solidification, and inclusions motion in the FTSR mold were discussed. The results indicate that the application of Ruler-EMBr can improve the uniformity of molten steel temperature distribution and reduce the penetration depth of downward backflow in the FTSR mold. This is beneficial to the floating removal of inclusions entrained in the downward backflow. Moreover, it is also conducive to the upward backflow to transport more heat to the meniscus region, avoiding slag solidification and slag rim formation. The parametric study also shows that the molten steel surface velocity can be reduced and the surface fluctuation at the upper ports of submerged entry nozzle (SEN) can be controlled with the increase of magnetic flux density appropriately. When the magnetic flux density reaches to 0.3 T, the maximum molten steel surface velocity decreases to 0.27 m/s, and the surface peak value at the upper ports of SEN decreases to 7.3 mm.
High temperature mechanical properties and hot working properties of high magnetic orientation silicon steel
Shi Pengzhao, Li Jiangbo, Qiao Jialong, Guo Feihu, Qiu Shengtao
2023, 44(4): 135-141. doi: 10.7513/j.issn.1004-7638.2023.04.020
Abstract(490) HTML (197) PDF(14)
Abstract:
In this paper, Gleeble3800 thermal simulation test machine was used to conduct high temperature tensile and high temperature compression experiments on high magnetic induction oriented silicon steel billets. The influence of temperature on high temperature mechanical properties (tensile strength and section shrinkage) of high magnetic induction oriented silicon steel, and the hot working properties of high magnetic induction oriented silicon steel were studied. The results showed that the temperature of the first brittle zone of high magnetic orientation silicon steel was around the melting point ~1200 ℃, and the temperature of the third brittle zone was about 750 ℃, and there was no second brittle zone. The fracture mechanism of the sample at 750 ℃ is intergranular brittle fracture, and there are Al, Si and other oxidation inclusions at the fracture surface. When the shape variable and temperature are constant, the deformation resistance of the specimen increases with the increase of strain rate.
Research on microstructure evolution of GH5188 alloy during plastic processing
Guo Xulong, Jiang Shichuan, Qi Huilin, Fu Jianhui
2023, 44(4): 142-148. doi: 10.7513/j.issn.1004-7638.2023.04.021
Abstract(475) HTML (164) PDF(16)
Abstract:
The Gleeble-3800 thermal simulation testing machine was used to investigate the thermal deformation behavior and structure transfer law of GH5188 superalloy. In the isothermal compression test, the relevant data of stress in the range of deformation temperature of 980~1230 ℃, strain rate of 0.01~10 s?1, and the deformation amount of 10%~70% was obtained. And the effect of different temperatures and rates on the stress of GH5188 superalloywas discussed. Furthermore, the constitutive relation model of GH5188 alloy was established, and the optimized forging process parameters were proposed. Deformation behaviors show that the flow stress decrease with the increase of deformation temperature, but increase with the increase of flow stress. Microstructural observation indicates that the as-cast structure can be broken and refined when the deformation of the alloy does not exceed 70% and the forging temperature exceed 1230 ℃. When the upsetting is performed multiple times in the temperature range of 1080~1180 ℃, it is easier for the alloy to reach a fully recrystallized state and the recrystallized grain size refines during the heat preservation process as the amount of deformation increases, while the size of recrystallized grains will grow significantly as the holding time increases.
Effect of different vanadium and nitrogen contents on microstructure and properties of Nb-V microalloyed high-strength seismic reinforcement
Lu Jie, Su Qixiang, Huang Jixiang, Zhang Huanhuan, Lei Ting, Yin Shubiao, Ma Zhenghong
2023, 44(4): 149-157. doi: 10.7513/j.issn.1004-7638.2023.04.022
Abstract(604) HTML (165) PDF(24)
Abstract:
Vanadium and nitrogen can effectively improve the comprehensive performance of Nb-V microalloyed high strength seismic reinforcement. The microstructure of three kinds of Nb-V microalloyed high-strength seismic reinforcement bars with different vanadium and nitrogen contents was characterized and tested by metallographic microscope, scanning electron microscope, transmission electron microscope and mechanical testing machine. The results show that the final microstructure of the three test steels is composed of ferrite, pearlite and small amount of bainite. As vanadium and nitrogen contents in test steel increases, the ferrite grain size is reduced, pearlite lamellar spacing is gradually thinning. With the increase of vanadium and nitrogen contents in precipitated phase NbV (C, N), the volume fraction of precipitated second phase particles increases and the particle size decreases. The fracture morphology of the tested steels is dimple fracture, and the dimple deepens and the diameter increases with the increase of vanadium and nitrogen contents. In terms of mechanical properties, tensile strength increases, yield strength and hardness slightly decrease and then increases.
Research progress of biodegradable iron-based materials for vascular stents
Xu Yanan, Wang Weiqiang, Yang Shuaikang, Wang Yinong
2023, 44(4): 158-166. doi: 10.7513/j.issn.1004-7638.2023.04.023
Abstract(997) HTML (183) PDF(72)
Abstract:
Iron-based biodegradable metal material is one of the most potential materials to replace permanent vascular stents. The slow degradation rate is the main problem hindering its development. Many researchers optimized its biocompatibility, corrosion and degradation behaviors, mechanical properties and magnetic properties by adjusting its microstructure, surface treatment, alloying, and "composite" material design, aiming for the ideal iron-based biodegradable stent materials. Although the pure iron compatibility can be ensured by microstructure adjustment, its degradability improvement is limited. While, it is hard to optimize the corrosion resistance properties of pure iron matrix, despite the fact that the corrosion rate of the close-to-surface regions can be enhanced by specific surface treatments. Among these ways, the comprehensive properties of materials were optimized via "composite" materials designed by alloying. However, a great improvement is still required for the alloying materials to satisfy the properties of ideal stents. This work summarized the researches of iron-based biodegradable stent materials from the above aspects and suggestions on the future research directions were also proposed.
Development and application of high strength complex phase steel HR680/800CP for automobile chassis
Tan Daqing, Zhou Li, Jia Guoxiang, Cao Xiao’en, Wen Caijun, Xue Renjie
2023, 44(4): 167-172. doi: 10.7513/j.issn.1004-7638.2023.04.024
Abstract(477) HTML (169) PDF(14)
Abstract:
Considering lightweight requirement and forming process characteristics of chassis structural parts, a complex alloying system of C-Si-Mn-Nb-Ti-Mo elements had been designed in order to achieve a better performance of weldability, second phase precipitation and bainite transformation at intermediate temperature. Based on theoretically calculation, a TMCP process where FET and CT are set at 890 ℃ and 570 ℃ and uses laminar cooling mode front 3/4, had been developed. During the TMCP process stable rolling steps were within austenite phase zone, and ferrite and bainite transformation occurred upon cooling period during and after laminar process. As a result HR680/800CP was produced which is featured with well flanging and hole expansion property. Microstructure mainly consists of Ferrite/Bainite, and mechanical properties reaches yield strength 769 MPa, tensile strength 840 MPa, elongation 17.92%, hole expansion ratio up to 110%. This product has been successfully used for structure parts of chassis control arm and battery pack bracket in new energy automobile.
Study on deformation behavior and microstructure evolution at elevated temperatures of nickel based superalloy GH4065A
Shui Lang, Fu Jianhui
2023, 44(4): 173-182. doi: 10.7513/j.issn.1004-7638.2023.04.025
Abstract(536) HTML (189) PDF(33)
Abstract:
This paper performs thermal compression studies on GH4065A samples from a sample disk that is obtained from an industrial plant and has undergone VIM+ESR+VAR and homogenization. This study reveals the impact of thermal compression parameters such as deformation temperature, strain rate and engineering strain on the flow stress of GH4065A, and constructs constitutive equations of GH4065A at the 50% engineering strain. Based on experimental data, the thermal processing map and instability criterion map of GH4065A are proposed, by which the stable processing zones of GH4065A can be identified. This paper also studies the microstructure evolution of GH4065A, and the results reveal the precipitation range of γ’ phase, non-recrystallization processing range, partial recrystallization processing range, and full recrystallization processing range of GH4065A, by which the recrystallization map is proposed.
Study on the composite inclusions of MnS-Al2O3 in wheel steel
Ding Xiaoming, Li Tao, Guo Xiaopei, Zhuang Qianyu, Liu Kai
2023, 44(4): 183-189. doi: 10.7513/j.issn.1004-7638.2023.04.026
Abstract(378) HTML (237) PDF(22)
Abstract:
The composite inclusions of MnS-Al2O3 in high-speed railway wheel steel can reduce the effect of Al2O3 on fatigue properties of wheel steel. In this study, the types of inclusions in wheel steel were determined as MnS, Al2O3 and MnS-Al2O3 composite inclusions by testing wheel steel prepared in laboratory. The inclusions of Al2O3 were extracted by acid dissolution method. XRD results showed that crystal texture of Al2O3 inclusion in steel was α-Al2O3. The composite inclusion in steel was extracted by non-aqueous electrolysis method, and the morphology of MnS-Al2O3 composite inclusion was detected. Based on the thermodynamic calculation of steel composition, the relationship between the solidus and liquidus temperatures of experimental steel and the precipitation temperature of inclusions was analyzed. The results show that Al2O3 inclusions in wheel steel can provide nucleation sites for the precipitation of MnS. It was clarified that the surface of (100) of MnS can precipitate on the Al2O3 (0001) through the calculation of the mismatch between the two phases of MnS and Al2O3. This works provides a theoretical basis for the formation of MnS-Al2O3 composite inclusions in steel and the reduction of the damage of Al2O3 inclusions.
Microstructure and properties of vanadium microalloyed cast magnesium alloy for automobile
Gao Yanan, Zheng Lei, Zhang Quanyu
2023, 44(4): 190-195. doi: 10.7513/j.issn.1004-7638.2023.04.027
Abstract(350) HTML (134) PDF(10)
Abstract:
In order to study the microstructure, wear resistance and corrosion resistance of vanadium microalloyed cast magnesium alloy for automobile, different contents of alloy element vanadium were added into the cast Mg-9Al-1Zn magnesium alloy, and the microstructure, wear resistance and corrosion resistance of the test alloy were tested and compared. The results show that the alloy element vanadium can effectively refine the internal structure of the alloy and improve the wear resistance and corrosion resistance of the alloy. With the gradual increase of vanadium content from 0 to 0.4%, both the wear resistance and corrosion resistance of the test alloy have been improved. Further increasing vanadium content to 0.5% will reduce the wear and corrosion resistance. Compared with Mg-9Al-1Zn magnesium alloy without vanadium, when 0.4% alloy element vanadium is added to Mg-9Al-1Zn magnesium alloy, the wear volume of the alloy is reduced by 12.7×10?3 mm3 or 29.8%, and the positive shift of corrosion potential reaches by 0.107 V or 12.2%. The tensile strength, yield strength and elongation of the alloy are increased by 58, 58 MPa and 3.3% respectively, with relative increasing amplitude of 20.9%, 36.0% and 40.2%, respectively. The alloy element vanadium content for Mg-9Al-1Zn-V magnesium alloy is preferably at 0.4%.
Research on prediction accuracy of the flow stress of 0Cr17Ni4Cu4Nb stainless steel based on machine learning
Zhao Lidong, Zhang Youming, Zhang Jilin, Dou Jianming, Yao Jiabao
2023, 44(4): 196-204. doi: 10.7513/j.issn.1004-7638.2023.04.028
Abstract(385) HTML (176) PDF(8)
Abstract:
A new model for predicting rheological stresses based on particle swarm optimization BP neural network is proposed for 0Cr17Ni4Cu4Nb stainless steel as an example. Based on the quasi-static (0.001 s?1) compression testing data at room temperature and the impact testing data at four temperatures (25, 350, 500 and 300 ℃) and six strain rates (750, 1500, 2000, 2600, 3500 and 4500 s?1), a random forest prediction model for rheological stress of 0Cr17Ni4Cu4Nb stainless steel, a Particle Swarm Optimized Random Forest prediction model, a Back Propagation (BP) neural network, and a Particle Swarm Optimized BP neural network are constructed. Four indicators including the statistical coefficient of determination (R2), mean absolute error (MAE), mean square error (MSE) and root mean square error (RMSE) are used to analyze and evaluate the four models mentioned above. The comprehensive performance of the prediction models is in sequence of particle swarm optimization BP neural network model, BP neural network model, particle swarm optimization random forest model, and the random forest model. The coefficient of determination R2=0.9997, mean absolute error MAE=1.5773, mean squared error MSE=5.5053 and root mean squared error RMSE=2.3463 are determined for the particle swarm optimized BP neural network model, which can predict the rheological stress of 0Cr17Ni4Cu4Nb stainless steel very well.
很黄很污的网站 | 97精产国品一二三产区 | 爆操白丝美女 | 午夜免费在线 | 91短视全免费 | 日本性视频网站 | 男人操女人的视频 | 欧美jizz欧美性大全 | 精品视频一区二区三区四区 | 白又丰满大屁股bbbbb | 日本在线三级 | 伊人久久国产 | 91人妻一区二区 | 亚洲综合区 | 欧美黑人一级片 | 五月开心网 | 亚洲网站在线 | 久久三级视频 | 免费色网址 | 女女les互磨高潮国产精品 | 女人做爰全过程免费观看美女 | 善良的女朋友在线观看 | 亚洲成成品网站 | 午夜免费在线 | 国产激情久久久久久熟女老人av | 日韩经典一区二区 | 欧美黄在线 | 韩国一区二区三区在线观看 | 草民午夜理伦三级 | 婷婷免费| 国产成人精品片 | 国产精品久久网站 | 国产亚洲色婷婷久久99精品91 | 看特级毛片 | 久久国产小视频 | 中文字幕自拍偷拍 | 亚洲啊v | 少妇综合| 成人做爰视频www | 美女靠逼app | 日本人体视频 | 日本成人一级片 | 手机在线观看毛片 | 免费一级片视频 | 超碰免费av | 欧美一区二区三区不卡 | 黄色av网站免费 | 九九视频在线免费观看 | 好大好舒服视频 | 特黄aaaaaaaaa真人毛片 | 99在线视频精品 | 欧美综合激情网 | 人妻丰满熟妇av无码区hd | 做爰视频 | 免费色网址 | 国产成人精品片 | 免费三片在线观看网站v888 | 92国产精品| 天天干天天干天天干 | 免费看日韩毛片 | 99re国产| 国产在线精品视频 | 午夜精品久久久久久久久久 | 美女爱爱视频 | 人人爽人人插 | 男人天堂中文字幕 | 国产又大又黄的视频 | 无码人妻aⅴ一区二区三区玉蒲团 | 懂色av一区二区三区免费观看 | 调教在线观看 | 中文字幕不卡在线观看 | 操操干干| 韩国一区二区在线观看 | 亚洲第一免费 | 在线观看国产黄色 | www.在线播放 | 香蕉视频免费看 | www.伊人网| 在线观看免费黄色 | 91桃色在线观看 | 国产中文字字幕乱码无限 | 亚洲综合中文字幕在线 | 人成在线 | 毛茸茸的中国女bbw 国产午夜精品久久久 | 色婷婷小说 | 久久久96人妻无码精品 | 欧美春色| 国产精品tv | 成人午夜淫片免费观看 | 篠田优在线 | 国产欧美在线看 | 偷拍亚洲视频 | 日韩av一区二区三区在线观看 | 欧美亚洲国产一区二区三区 | 三级av电影 | mm131美女视频 | 欧美亚洲国产一区二区三区 | 欧洲精品一区二区三区 | 黄色h视频 | 999国产精品视频 | 国产卡一卡二 | h片在线免费看 | 男人操女人网站 | 冲田杏梨 在线 | 91久久国产 | 污污内射久久一区二区欧美日韩 | 国产青青青 | 和黑帮大佬的365 | 少妇扒开粉嫩小泬视频 | 在线免费看av片 | 久久大香 | 成人在线综合 | 特大黑人巨交吊性xxxx视频 | 爆操欧美美女 | 91成人在线免费视频 | 日本亚洲在线 | 国产在线小视频 | 日韩精品视频在线免费观看 | 高h喷水荡肉少妇爽多p视频 | 久久午夜视频 | 丁香婷婷久久久综合精品国产 | 亚洲在线电影 | 成人丁香婷婷 | 黄污视频在线观看 | 女女les互磨高潮国产精品 | 午夜国产精品视频 | 欧美尻逼| 国产美女视频免费观看下载软件 | 久久99亚洲精品 | gogo人体做爰大胆视频 | 日韩视频一区在线观看 | 亚洲精品色午夜无码专区日韩 | 爆操巨乳 | 国产精品91久久 | 超碰在线人人 | 国产精品精品国产 | 天天综合影院 | 国产一区二区欧美 | 欧美午夜精品一区二区 | 亚洲综合中文字幕在线 | 四虎影视永久免费观看 | 精品无码人妻一区二区三区品 | 欧美精品中文 | 中文字幕一区二区人妻电影 | 国产在线小视频 | 美女一区 | 青青青国产在线 | 女人洗澡一级特黄毛片 | 日日夜操 | 女女les互磨高潮国产精品 | 国产激情网址 | 日皮视频免费观看 | 国产精品1024 | 91超碰免费在线 | 成人h在线观看 | 亚洲一区二区三区免费视频 | 在线观看黄色网页 | 91视频在线网站 | 国产精品探花视频 | 欧美熟妇精品一区二区蜜桃视频 | 成人丁香婷婷 | 在线观看黄色网页 | 综合激情久久 | 成人黄网免费观看视频 | 日韩av一二三 | 熟女一区二区三区四区 | 一区二区免费 | 不卡在线播放 | 性爱一级视频 | 99re视频这里只有精品 | 九九视频在线免费观看 | 国产片一区二区三区 | 欧美国产片 | 日韩美女网 | 少妇全黄性生交片 | 日韩理论片在线观看 | 好吊操视频这里只有精品 | 亚洲精品v| 男人操女人的视频 | av中文网站 | 啪啪网站免费看 | 国产91小视频 | 国产白丝在线观看 | 午夜免费播放观看在线视频 | 欧美性猛交xxxx乱大交俱乐部 | 40到50岁中老年妇女毛片 | 西西人体大胆4444www | 欧美黑人xxxx | 91麻豆精品国产91久久久久久 | 综合久久久久 | 波多野吉衣一二三区乱码 | 97超碰成人 | 精品国内自产拍在线观看视频 | 修仙淫交(高h)h文 | 在线不卡中文字幕 | 久久色婷婷| 免费黄色网址大全 | 波多野结衣中文字幕在线 | 欧美精品亚洲精品 | 白又丰满大屁股bbbbb | 黄桃av | 国产精品av一区 | 西西444www无码大胆 | 99re视频这里只有精品 | 爱情岛亚洲论坛入口福利 | 五月开心婷婷 | 就去吻亚洲 | 青娱乐超碰在线 | 婷婷欧美 | 日韩性视频 | 国产乱人 | 天天干视频在线观看 | 91久久国产 | 一本不卡| 日韩一区二区三区四区五区六区 | 三上悠亚 在线观看 | 黑夜传说1| 欧美bbbbbbbbbbbb精品 | 91大尺度| 青青草青青操 | 免费网站观看www在线观 | 男人都懂的网站 | 中文字幕一级 | 亚洲三级精品 | 黄色1级视频 | 日本亚洲色大成网站www久久 | 永久免费在线 | 欧美国产片 | 1024国产在线 | 亚洲国产成人精品女人久久久 | 亚洲视频国产精品 | 久草网在线视频 | 97在线视频免费 | 少妇扒开粉嫩小泬视频 | 亚洲一区色 | av在线免费电影 | 无码人妻aⅴ一区二区三区玉蒲团 | 日本少妇xxxxx | 91嫩草视频在线观看 | 中文字幕观看 | 色图一区 | 男女瑟瑟网站 | 樱桃香蕉视频 | 色噜噜狠狠狠综合曰曰曰 | 黄色av中文字幕 | 国产精品1024 | 免费观看毛片视频 | 国产精品高清无码在线观看 | av在线免费电影 | 在线精品观看 | 日韩在线观看视频网站 | 9.1人网站| 在线免费看污视频 | 亚洲理论片| 国产一区二区欧美 | www.一区二区 | 污网站视频| 天堂在线一区 | 人妻丰满熟妇av无码区hd | 免费爱爱视频网站 | 秘密基地动漫在线观看免费 | 岛国av大片 | 国产视频资源 | 福利电影网 | 91人人爽| 国产精品吴梦梦 | 91色国产 | 野花视频免费在线观看 | 殴美一级黄色片 | 国产18在线| 在线观看成人网 | 精品国产不卡 | 日韩高清一区 | 国产呦小j女精品视频 | 国产片一区二区三区 | 日本精品一区二区三区视频 | 91黄色免费视频 | 手机在线免费看av | 51 吃瓜网 | 中文字幕自拍偷拍 | 久久国产免费视频 | 男人都懂的网站 | 蜜桃成人网| 久久久久久亚洲av无码专区 | 天天毛片 | 麻豆成人免费 | 国产熟女高潮一区二区三区 | 国产美女网站 | 亚洲女优在线观看 | 欧美日韩h | 五月天婷婷综合网 | 日韩影音 | 四虎影库在线播放 | 怡红院最新网址 | 亚洲日本中文 | 污污网站在线免费观看 | 久久手机视频 | 国产美女网站 | 久久精品一区 | 韩国三级与黑人 | 日本少妇xxxx软件 | 午夜国产精品视频 | 免费看黄色a级片 | 日韩精品久久久久久久 | 欧美丰满熟妇bbbbbb | 不良视频在线观看 | 日韩精品一区在线观看 | 免费看一级大片 | 欧美成人黄色片 | 日日夜夜影院 | 欧洲一区二区在线 | 樱桃av| 黄污视频在线观看 | 懂色av蜜臀av粉嫩av分享 | 精品无码久久久久久久久 | 老司机午夜电影 | 日皮视频免费观看 | 免费麻豆视频 | 亚洲国产成人精品女人久久久 | 草民午夜理伦三级 | 亚洲色图19p | 丁香婷婷久久久综合精品国产 | 国产在线精品一区二区 | 久久大陆| 青娱乐导航| 亚洲欧洲视频 | 亚洲精品一二区 | 亚洲天堂一区二区三区 | 色屋在线| 色鬼艳魔大战1春荡女淫 | 蜜桃91视频 | 亚洲免费福利视频 | 污污网站在线免费观看 | 欧美亚洲另类小说 | 国产美女网站 | 国产又爽又黄视频 | 国语对白永久免费 | 玖玖国产| 欧美福利一区 | 亚洲九九 | 久久久久久一区二区三区 | 九九视频在线免费观看 | 国产午夜在线视频 | 亚洲欧美日韩综合在线 | 亚洲区一区二区三区 | 国产又大又黄的视频 | 黑人性高潮 | 亚洲自拍偷拍网站 | 精品九九九九 | 想要视频在线观看 | 秘密的基地| 激情开心网站 | 久久亚洲精品小早川怜子 | 狠狠干狠狠插 | 午夜免费小视频 | 日韩三级黄色 | 永久91嫩草亚洲精品人人 | 传媒av在线 | 强睡邻居人妻中文字幕 | 人妻精品久久久久中文字幕 | 一道本av | 欧美成人三区 | 开心激情播播 | 国产精品免费一区二区三区 | 欧美自拍视频 | www.欧美在线 | 欧美婷婷| 337p亚洲精品色噜噜狠狠 | 善良的女朋友在线观看 | 色哟哟精品一区 | 操到喷水 | 日韩精品视频在线免费观看 | 成人av电影免费观看 | 婷婷精品在线 | 亚洲一区二区三区免费视频 | 欧美激情性做爰免费视频 | 久久久久极品 | 婷婷中文 | 成人av网站在线 | 欧美一级生活片 | 超碰青青操 | 国产视频大全 | 亚洲国产成人久久 | 午夜精品亚洲 | 一二三区视频 | 国产亚洲精品女人久久久久久 | 日韩五码 | 灌篮高手全国大赛电影 | 国产精品偷拍 | 日韩av一区二区三区在线观看 | 男女网站免费 | 乱色视频 | 中文字幕在线免费看 | 亚洲精品777 | 可以看的毛片 | 想要视频在线观看 | 国产在线看片 | av老女人| 日本中文字幕免费 | 青青草视频免费 | 香蕉视频黄色 | 超碰在线国产 | 国精品一区 | 成年人精品 | 美女扒开双腿 | 天天射天天射 | 中文字幕丰满乱子伦无码专区 | 人妻少妇精品视频一区二区三区 | 国产麻豆精品久久一二三 | 中文字幕观看 | 北条麻妃av在线 | 国产免费久久 | 成人免费毛片果冻 | 欧美毛片基地 | 99激情网 | 国产三级在线观看视频 | 好大好舒服视频 | 福利视频免费 | 狠狠干2023 | 精品人妻午夜一区二区三区四区 | 综合导航| 亚洲av无码国产综合专区 | 亚洲一区二区欧美 | 色愁久久 | 色哟哟一区 | 一区二区免费在线观看 | 高清久久久 | 高清久久久 | 蜜桃成人网| 传媒av在线 | 91桃色在线观看 | 午夜精品久久久久久久爽 | 久久大香 | 中文天堂网 | 欧美亚洲另类小说 | a天堂在线视频 | 日韩在线免费av | 暖暖日本在线视频 | 国产69av| 国产日批视频 | 在线观看黄色片 | 中文字幕一区二 | 日韩精品一区在线观看 | 欧美9999 | 99热这里只有精品在线观看 | 91成人在线免费视频 | 尤物av在线| 日本一级一片免费视频 | 国精品一区 | 三级av片 | 国内自拍av | 美女一区| 免费a视频在线观看 | 午夜看毛片 | 艳母日本动漫在线观看 | 性生活免费网站 | 成人啪啪漫画羞羞漫画 | 美女一区| 中文天堂网 | 黄色1级视频 | 国产又爽又黄视频 | 艳母日本动漫在线观看 | 午夜肉体高潮免费毛片 | 欧美大片免费 | 亚洲三级图片 | 在线97| 成人高清在线 | 国产1区2区在线观看 | 99久久久无码国产精品免费蜜柚 | 欧美九九 | 天天干在线观看 | 天天操天天操天天操 | 久久精品9| 成人看片泡妞 | 精品无码人妻一区二区三区品 | av在线电影网 | 少妇被躁爽到高潮无码人狍大战 | 国产精品v欧美精品v日韩 | 日韩一区二区三区四区五区六区 | 秋霞午夜| 人人妻人人澡人人爽精品日本 | 久久99久久99精品免观看软件 | 天堂在线一区 | 亚洲综合一区二区三区 | 亚洲欧美日韩综合在线 | 另类日韩| 男人天堂一区 | av不卡网站 | 99激情网| 日日碰 | 日本美女一区二区 | 草久影院 | 免费在线国产视频 | 91大神久久 | 久久精品一区 | 色噜噜在线观看 | 香港黄色网 | 日韩在线观看一区 | 蜜桃av噜噜一区二区三区麻豆 | 亚洲成年人影院 | 91成人在线观看喷潮动漫 | 九九视频在线免费观看 | 操到喷水 | 91免费影片| 特黄aaaaaaaaa毛片免费视频 | 黄色片在线观看视频 | 天天摸夜夜添狠狠添婷婷 | 欧美区一区二 | 久久久久久av无码免费网站 | 青春草视频 | 中文字字幕在线中文乱码电影 | 亚洲三级图片 | 日韩精品一区二区三区免费视频 | 草莓视频免费在线观看 | 黄黄的网站 | 老年人毛片 | 星铁乱淫h侵犯h文 | 五月婷婷小说 | 爱搞国产 | 少妇久久久久 | 久久99视频 | 少妇扒开粉嫩小泬视频 | 波多在线观看 | 中文字幕观看 | 超大量吹潮系列合集 | 色屋在线| 国产福利在线观看 | 男女日批视频 | 成人h在线观看 | 91久久久久久久久久久 | 欧美成人黄色片 | 少妇高潮惨叫久久久久久 | 免费特级毛片 | 亚洲三级精品 | 四虎影视库 | 日韩高清不卡 | 好看的h文| 91免费影片| 精品久久二区 | 久草久热 | 五月天狠狠干 | 久久久久久av无码免费网站 | 中文字幕亚洲区 | 麻豆做爰免费观看 | 专干老肥女人88av | 亚洲欧洲日本在线 | 色综合中文字幕 | 欧美日韩一区二区三 | 日本精品一区二区三区视频 | 久久精品9 | 国产精品久久一区二区三区 | 三级黄在线观看 | 亚洲免费福利视频 | 精品国产欧美一区二区三区成人 | 一本不卡| 免费国产一区 | 色哟哟一区 | 青青青青操 | www.色多多 | 打屁股调教视频 | 年代下乡啪啪h文 | 女同vk| 精品无码人妻一区二区三区品 | 福利电影网 | 3p在线观看 | 成年人免费网站在线观看 | 五月婷婷激情四射 | 国产69av| 高h喷水荡肉少妇爽多p视频 | 911精品国产一区二区在线 | 色情毛片 | 欧洲一区二区在线 | 久久99亚洲精品 | gogo人体做爰大胆视频 | 91久久电影 | 日本一区二区在线 | 日韩在线观看一区 | 国产一区二区毛片 | 九一网站在线观看 | 国产在线97| 久久久久久亚洲av无码专区 | 国产一区二区视频在线 | 久久久久9999 | 国产亚洲一区二区三区在线观看 | 性史性dvd影片农村毛片 | 国产午夜电影 | 午夜免费播放观看在线视频 | 一级片手机在线观看 | 人人草人人爽 | 午夜院线 | 国产精品探花在线观看 | 久久国产精品免费视频 | 午夜在线观看视频 | 99综合| 欧美性猛交xxxx乱大交退制版 | 四虎网址在线观看 | 成人免费在线播放 | 国产一区免费视频 | 日本乳汁视频 | 五月婷婷开心中文字幕 | 亚洲乱码视频 | 前所未有的深入 | yy6080午夜 | 欧美丰满熟妇bbbbbb | a一级黄色 | 精品人妻午夜一区二区三区四区 | 日韩少妇| 人妻精品久久久久中文 | 久久久久久av无码免费网站 | 色人阁视频 | 黄色av网站免费 | 美女吞精视频 | 在线97 | 欧美va视频 | 可以免费看的av网站 | 日本五十路女优 | 黄色h视频 | 51国产偷自视频区视频 | 亚洲黄视频 | 欧美日韩专区 | 久操视频免费观看 | 国产高清免费在线播放 | 国产精品天天干 | 欧美成人激情在线 | 午夜美女福利 | 99久久久无码国产精品免费蜜柚 | 自拍偷拍专区 | 成人免费毛片男人用品 | 男人操女人的视频 | 日韩一级黄色大片 | 天天干天天草天天射 | 韩国一区二区三区在线观看 | 免费的一级片 | 久久精品大片 | 蜜桃精品视频在线 | 亚洲日日夜夜 | 五月精品 | 亚洲精品在线观看视频 | 美女娇喘 | 欧美黄在线| 日日碰| 久久久99精品免费观看 | 欧美va视频| 男女网站免费 | 激情小说亚洲图片 | 中文字幕一区二区三区人妻不卡 | 日韩精品久 | 潘金莲一级淫片免费放动漫 | 国产精品v欧美精品v日韩 | 欧美亚洲在线视频 | 九九热九九 | 久久国产精品免费视频 | 91嫩草在线| 好吊操视频这里只有精品 | 色鬼艳魔大战1春荡女淫 | 久久成年人视频 | 激情综合激情五月 | 麻豆视频在线观看 | 成年人性生活视频 | 视频一区在线播放 | 日本精品视频在线播放 | 91日本在线 | 草莓视频免费在线观看 | 黑人极品ⅴideos精品欧美棵 | 国产97在线观看 | 久久久久影视 | 久久午夜视频 | 午夜精品一区二区三区在线视频 | 中文字幕亚洲精品 | 最新国产露脸在线观看 | 碧蓝之海动漫在线观看免费高清 | 欧美mv日韩mv国产网站app | 火影忍者羞羞漫画 | a天堂在线视频 | 中文字幕av久久爽一区 | 人妻少妇偷人精品视频 | 久章草影院 | 中文字幕最新 | 91成人在线观看喷潮动漫 | 97在线公开视频 | 欧美福利视频导航 | 成人高清在线 | 久操视频免费观看 | 日本一区精品 | 91片看 | 日韩午夜一区 | 日韩和欧美的一区二区 | 国产又粗又大又爽视频 | 在线无限看免费粉色视频 | 今天高清视频在线观看播放 | 打屁股调教视频 | 欧美丰满熟妇bbbbbb | 国产1区2区在线观看 | 欧美综合一区 | 成人在线激情视频 | 精品伦精品一区二区三区视频密桃 | 开心激情播播 | 日本精品一区二区三区视频 | 在线观看国产精品入口男同 | 性生活免费网站 | 中日一级片 | 黄色av中文字幕 | av无限看 | 久久国产免费 | 免费观看毛片视频 | 日本天堂网在线观看 | 亚洲精品白浆高清久久久久久 | 懂色av一区二区三区免费观看 | 日本黄色网址大全 | 成人xx视频| 华丽的外出在线 | 小早川怜子一区二区三区 | 日韩av高清| 黄页网站在线播放 | 国产免费成人 | 欧美老熟妇xb水多毛多 | aaaa一级片 | 超碰97人人草 | 岛国av大片| 9.1人网站| 国产黄色一级大片 | 欧美日韩性视频 | 另类日韩| 人妖一区 | 狠狠干.com| 日本中文字幕一区 | 80日本xxxxxxxxx96 国产超级av | 亚洲熟妇色自偷自拍另类 | 免费久久视频 | 久热只有精品 | 日本在线视频免费观看 | 日韩久久成人 | 99热日韩 | a级片免费在线观看 | 免费av播放 | 久久国产免费视频 | 国产尻逼视频 | 黄色aaa视频| 奶妈的诱惑 | 五月婷婷久久久 | 狠狠干狠狠插 | 中文久久精品 | 91短视全免费 | 国产一区二区欧美 | 日韩一区二区三区四区五区六区 | 麻豆av一区二区 | 久久久96人妻无码精品 | 人人草人人射 | 性综艺节目av在线播放 | 国产亚洲一区二区三区在线观看 | 欧美一卡二卡三卡 | 在线看福利影 | 蜜桃av噜噜一区二区三区麻豆 | 黄色国产视频 | 久久成人免费视频 | 国产乱码精品一区二区三区中文 | 91日本在线| 亚洲天堂av网站 | 在线观看毛片网站 | 天堂影视在线观看 | 欧美20p| 99re视频这里只有精品 | 国产精品视频在线观看 | av中文网 | 精品伦精品一区二区三区视频密桃 | 欧美日韩一区二区三 | 黄色av中文字幕 | 三上悠亚 在线观看 | 好大好舒服视频 | 中文字幕亚洲欧美日韩高清 | 又粗又大又深又硬又爽 | 日韩成人一区二区 | 欧美日韩精品久久久 | 成人自拍av | 操操干干 | 国产性色av| 秋霞一区 | www.在线播放 | 黄色一级图片 | 欧美在线专区 | 欧美骚少妇 | 国产精品天天干 | 欧美视频久久久 | 四虎影视库| 久久精品一区 | 91国产高清| 91视频在线网站 | 欧美亚洲另类小说 | 色悠悠视频 | 碧蓝之海动漫在线观看免费高清 | 亚洲精品97 | 亚洲熟妇色自偷自拍另类 | 图片区偷拍区小说区 | 美女爆乳18禁www久久久久久 | 开心激情播播 | 欧美精品一线 | 自拍偷拍第五页 | 亚洲性事 | 91视频污| 久久综合狠狠综合久久综合88 | 小早川怜子一区二区三区 | 中文字幕第九页 | 国产美女视频免费观看下载软件 | 精品无码久久久久久久久 | www.色婷婷| 午夜视频在线免费 | 张柏芝亚洲一区二区三区 | 欧美日韩专区 | 91精品人妻一区二区三区 | 免费午夜影院 | 婷婷五月综合久久中文字幕 | 伊人99热 | 原神女裸体看个够无遮挡 | 在线观看国产精品入口男同 | 男人天堂一区 | 特黄aaaaaaaaa真人毛片 | 精品国产欧美一区二区三区成人 | 五月丁香久久婷婷 | 久久免费在线视频 | 欧美又粗又深又猛又爽啪啪九色 | 中文字幕一区二区人妻电影 | 潘金莲一级淫片免费放动漫 | 熟妇高潮一区二区三区 | 欧美高清免费 | 亚洲欧美另类图片 | 黄网在线免费观看 | 日本伊人久久 | 99精品视频在线 | 中文字幕 自拍偷拍 | 亚洲美女视频 | 欧美又粗又深又猛又爽啪啪九色 | 午夜影视在线观看 | 韩国一区二区在线观看 | 久久久在线 | 狂野欧美 | 欧美一级爱爱 | 蜜桃视频在线观看www | 三级黄在线观看 | 污污视频免费观看 | 国产无套精品一区二区三区 | 亚洲女优在线观看 | 中文字幕一区二区三区精华液 | 国产成人av一区 | 成年人视频免费在线观看 | 国产一区二区中文字幕 | 性视频播放免费视频 | 4438x在线观看| 看片网站在线观看 | 年代下乡啪啪h文 | 超碰伊人| 色小说在线 | 欧洲激情网 | 少妇久久久久 | 久久手机视频 | 日韩av一二三 | 今天高清视频在线观看播放 | 日韩久久成人 | 色噜噜在线观看 | 和黑帮大佬的365 | 超碰人人干 | 亚洲午夜精品一区二区三区 | 超大量吹潮系列合集 | 阿娇全套94张未删图久久 | 91欧美精品 | 小宝贝真紧h军人h | 亚洲国产一区在线观看 | 图片区偷拍区小说区 | 午夜激情网站 | 在线观看xxxx| 国产亚洲精品女人久久久久久 | 亚洲免费观看高清 | 日韩黄色在线 | 午夜欧美激情 | 性高潮视频在线观看 | 日本黄色网址大全 | 久久久久噜噜噜亚洲熟女综合 | 不卡av在线| 涩人阁| 日韩精品在线一区 | 西西44rtwww国产精品 | 1024国产在线 | 中文字幕一区二 | 婷婷av一区二区三区 | 国产精品第三页 | 亚洲青青草 | 欧美亚洲中文精品字幕 | 亚洲涩综合 | 999视频 | 成人片免费视频 | 亚洲成成品网站 | 青青草激情视频 | 夜夜操夜夜爱 | 一级片手机在线观看 | 成人性生交大片免费 | 国内精品久久久久久 | 黄色片在线观看视频 | 天天摸夜夜添狠狠添婷婷 | 亚洲精品中文字幕 | 91香蕉国产 | 国产一区二区欧美 | 爱情岛亚洲论坛入口福利 | 中文字幕丰满乱子伦无码专区 | 欧美九九 | 五月婷婷,六月丁香 | 国产亚洲一区二区三区在线观看 | 2019中文字幕在线观看 | 久久国产精品久久久 | 国产青青草视频 | 色婷婷777777仙踪林 | 51国产视频| 青青免费在线视频 | 秘密基地动漫在线观看免费 | 超碰免费av | 国产精品久久网站 | 免费久久视频 | 传媒av在线 | 日本一级一片免费视频 | 日韩在线免费av | 四虎影视永久免费观看 | 五月婷婷,六月丁香 | 香港黄色网 | 捆绑无遮挡打光屁股 | 青青青草视频在线 | 韩国一区二区在线观看 | 91黄色免费视频 | 怡红院av| 丁香花电影免费播放电影 | 国产精品自拍偷拍 | 欧美熟妇精品一区二区蜜桃视频 | 成人午夜视频在线 | 秋霞av鲁丝片一区二区 | 青青草国产成人99久久 | 亚洲精品一二区 | 青青草国产成人99久久 | 卡一卡二卡三 | 男人天堂一区 | 91亚洲欧美| 亚洲天堂一区二区三区 | 麻豆午夜 | 校园春色综合网 | 成人在线一区二区三区 | av综合在线观看 | 国产伦精品一区 | 国产a国产 | 日本国产一区 | 亚洲成人精品久久 | 久久久久久久精 | 98在线视频 | 人人草在线 | 国产a电影 | 婷婷免费| 亚洲专区在线播放 | 人妻少妇偷人精品视频 | 亚洲天堂午夜 | 成人免费在线播放 | 亚洲少妇一区二区 | 在线视频 日韩 | 2019毛片| 久久久久久一区二区三区 | 视频在线观看免费大片 | 欧美黄色片免费看 | 福利电影网 | 狂野欧美| 国产一区二区av | 久久久久影视 | 成年人毛片| 黄色在线| 强睡邻居人妻中文字幕 | 淫欲的美女理论电影完整版 | 一道本av | 伊人色网 | 91麻豆精品国产91久久久久久 | 日日夜夜影院 | 女人免费视频 | 久久99亚洲精品 | heyzo在线播放 | 在线播放第一页 | 一区二区免费 | 日本一级淫片色费放 | 欧美性猛交xxxx乱大交退制版 | 成人黄网免费观看视频 | 中文久久精品 | 日韩啊啊啊 | 亚洲午夜激情 | 国产一区精品在线观看 | 高潮呻吟videoshd | 中文字幕女同女同女同 | 日韩毛毛片 | 污视频网站在线看 | 男女视频免费 | 亚洲一区二区三区免费视频 | 亚洲美女视频 | 成人在线综合 | 国产精品久久久一区 | 国产第8页| 亚洲自拍偷拍网站 | 欧美福利一区 | 特色黄色片 | 柠檬福利第一导航在线 | 午夜视频免费看 | 欧美熟妇精品一区二区蜜桃视频 | 久久tv| 天天射天天射 | 熟女一区二区三区四区 | 成人教育av| aaaaa黄色片 日韩电影院 | 淫欲的美女理论电影完整版 | 欧美成人精品激情在线视频 | 在线观看网页视频 | 天天插天天射 | 国产黄色影视 | 中国女人内谢69xxxx | 免费的一级片 | 午夜免费小视频 | 伊人色网 | 黄漫在线免费观看 | 一区二区免费在线观看 | 日日夜操| 天天干在线观看 | 日韩免费 | 国产亚洲精品成人a | 欧美黄在线 | 神马久久久久久久久 | 91日本在线 | 日韩videos| 国产亚洲色婷婷久久99精品91 | 熟妇高潮一区二区三区 | 男18无遮挡脱了内裤 | 少妇久久久久 | 国产超级av | 免费看黄色a级片 | 亚色中文| 五月精品 | 国产无套精品一区二区三区 | 操操操操操操操操操 | 久久久观看| 日本少妇色 | 国产又粗又猛视频免费 | 在线观看三级电影 | 米奇影视777 | 年代下乡啪啪h文 | 99久久99久久精品国产片果冻 | 91桃色在线观看 | 一区二区免费 | 特黄aaaaaaaaa真人毛片 | 亚洲最新中文字幕 | 欧美一级成人 | 久草青青草 | 亚洲国产成人久久 | 亚洲精品色午夜无码专区日韩 | 香蕉视频久久 | www.在线播放 | 亚洲视频在线观看一区二区 | 免费看毛片的网站 | 另类日韩 | 日本黄色网址大全 | 欧美大片免费 | 另类日韩 | ass亚洲肉体欣赏pics | 欧美一级色片 | 日本少妇xxxxx | 国产精品久久影视 | 国产精品免费久久 | 香蕉视频免费看 | 亚洲美女一区二区三区 | 久久看看 | 亚洲女成人图区 | 日韩av一二三 | 国产片91| 中文字幕首页 | 久草网在线视频 | 欧美成人高清视频 | 草莓视频app18在线视频 | 欧美激情第五页 | 国产97视频 | 欧美第一页| 成人精品影院 | 国产精品精品软件视频 | 想要视频在线观看 | 国产一区二区毛片 | 午夜av网站 | 欧美激情自拍偷拍 | 殴美一级黄色片 | 成年网站在线视频网站 | 欧美mv日韩mv国产网站app | 91丝袜在线| 特黄色一级片 | 亚洲精品v| 性色av蜜臀av浪潮av老女人 | 人妻一区二区在线 | 3p在线观看 | 91久久国产综合久久91精品网站 | 成人亚洲 | 欧美成人小视频 | 超碰人人干 | 爆操巨乳| 99激情网 | av免费一区 | 碧蓝之海动漫在线观看免费高清 | 黄色aaa视频 | 影音先锋毛片 | 国产视频黄 | 久久在线看 | 麻豆av在线播放 | 免费看毛片的网站 | 波多野结衣av无码 | 国产在线小视频 | 欧美毛片基地 | 蜜桃av噜噜一区二区三区麻豆 | 日日夜夜爽爽 | 1769在线视频| 久久久96人妻无码精品 | 日韩欧美国产高清 | 九九视屏 | 日韩美女网 | 可以免费看的av网站 | 精品伦精品一区二区三区视频密桃 | 免费日b视频 | 久久久久久中文字幕 | 欧美日韩在线观看一区二区 | 玖玖国产| 泰剧19禁啪啪无遮挡 | 日韩一级黄色大片 | 国模在线| 亚洲天堂午夜 | 亚洲视频在线观看一区二区 | 免费特级毛片 | 中文字幕不卡在线观看 | 欧美大片高清免费观看 | 欧美又粗又大aaa片 亚洲欧洲视频 | 国产精品2 | 色婷婷777777仙踪林 | 欧美伦乱 | 欧美夜夜| 久久精品9 | 天天干视频在线观看 | 婷婷中文 | 色蝌蚪 | 泰剧19禁啪啪无遮挡 | 久久精品成人 | 天天天天天操 | 怡红院av | av免费网站 | 男女瑟瑟网站 | 天天射天天射 | 欧美精品亚洲精品 | 免费在线国产视频 | 九九热视频在线播放 | 成人教育av | 91亚洲欧美 | 韩国一区二区在线观看 | 亚洲午夜精品一区二区三区 | 精品午夜久久 | 九九热视频在线播放 | 国产97在线观看 | 中国一级黄色 | 嘿咻免费视频 | www.五月激情 | 男女瑟瑟网站 | 欧日韩一区二区三区 | 特黄色一级片 | 亚洲天堂av在线播放 | 91免费短视频 | 欧美色图在线播放 | av影院在线观看 | 一级做a视频 | 一级片手机在线观看 | av视屏| 美女又爽又黄网站泳装 | 亚洲视频综合 | 日韩免费| 依人在线 | 神马久久久久久久久 | 国产精品久久久久久吹潮 | 日本精品在线播放 | 中文字幕观看 | 亚洲色成人www永久网站 | 色视频网 | 亚洲三级免费 | 在线观看免费黄色 | 伊人网免费视频 | www.伊人网 | 国产免费不卡 | 国产精品视频入口 | 色婷婷av一区二区三区之红樱桃 | 奇米影视在线播放 | 精品无码人妻一区二区三区品 | 欧美成人小视频 | 成人xx视频| 日本网站免费观看 | 男人天堂一区 | 大陆熟妇丰满多毛xxxⅹ | 涩人阁 | 深夜福利免费观看 | 欧美成人黄色片 | 国产精品1024 | 国产69av | 无码人妻久久一区二区三区 | 日韩精品久久久久久久 | 国产h视频在线观看 | 丰满少妇在线观看 | 亚洲美女视频 | 亚洲乱码视频 | 看免费毛片 | 欧美一区二区三区成人精品 | 国产乱码精品一区二区三区中文 | 免费网站观看www在线观 | 日本三级视频在线观看 | 国产做爰免费视频观看 | www.一区二区 | 欧美精品久久99 | www.夜夜骑| 日韩一区二 | 啪啪网站免费看 | 91久久一区| 在线观看黄色网页 | 99热网址 | 欧日韩一区二区三区 | 成人免费黄色网 | 成人av电影免费观看 | 亚洲精品一二三 | 亚洲手机在线观看 | 欧美区一区二 | 国产精选在线观看 | 99热日韩 | 日本妈妈9 | a视频在线| 另类日韩 | www日日日| 激情网五月| 国产黄色片在线播放 | 97看片吧| 特色黄色片| 在线观看亚洲 | 性综艺节目av在线播放 | 欧美黄色片免费看 | 精品国产乱码久久久久久郑州公司 | 久草高清视频 | 国产夜夜操| 欧美精品久久久久久 | 久久精品波多野结衣 | 国产三级久久 | 99re国产精品 | 日韩成人一区二区 | 爱情岛亚洲论坛入口福利 | 亚洲一区二区精品在线 | 国产乱人 | 图片区偷拍区小说区 | 蜜桃视频在线观看www | 国产在线无码精品 | 毛茸茸的中国女bbw 国产午夜精品久久久 | 国产午夜精品久久久 | 91久久久久国产一区二区 | 国产精品久久国产精麻豆96堂 | 99热免费 | 超碰青青操 | 久热在线| av不卡网站 | 日本三级视频在线观看 | 神马午夜国产 | 午夜久久福利 | 欧美性猛交xxxx黑人猛交 | 中文久久精品 | 亚洲啊v | 四虎影视永久免费观看 | 91超碰免费在线 | 影音先锋毛片 | 亚洲特级毛片 | 在线观看亚洲国产 | 国产视频大全 | 天天插天天狠 | 国产呦系列 | 亚洲欧美精品一区二区三区 | 亚洲最大av在线 | 黄色三级生活片 | 欧美亚洲在线视频 | 97看片吧 | 久青草视频在线观看 | 欧美成人激情在线 | 青青草青青操 | 色愁久久 | 欧美日韩中文字幕一区二区 | 蜜桃av噜噜一区二区三区麻豆 | 总裁憋尿呻吟双腿大开憋尿 | 亚洲最大av在线 | 超污视频网站 | 色av影院 | 久久极品视频 | 国产在线高清 | 懂色av一区二区三区免费观看 | 国产在线97 | 天天天天干 | 女女les互磨高潮国产精品 | 污网站视频| 久久久96人妻无码精品 | 91精品国产91久久久久久黑人 | 国产亚洲精品成人a | 久久久91| 日韩精品第二页 | 久草99 | 日韩一区二区三区四区在线 | 综合激情久久 | 国产亚洲激情 | 久久超| 丁香花电影免费播放电影 | 天天天天天操 | 成人国产网站 | 黄漫app | 黄色免费看片网站 | 综合久久久久久久 | 精品影院 | 久久久久久国产精品 | 污污网站在线免费观看 | 久久综合社区 | 久久ww | 青娱乐导航 | 欧美激情性做爰免费视频 | 国产成人高清在线 | 天天操天天操天天操 | 色情毛片 | 日韩中文欧美 | 欧美激情自拍偷拍 | 4438全国成人免费 | 2019中文字幕在线观看 | 篠田优在线| 成人黄色免费电影 | 日本性视频网站 | 久久久久噜噜噜亚洲熟女综合 | 中国极品少妇xxxx做受 | 超碰在线人人 | 亚洲精品白浆高清久久久久久 | 亚洲黄色三级 | 成年人视频免费在线观看 | 超碰三级 | 大地资源二中文在线影视观看 | 亚洲黄视频 | 人人草在线 | 国产精品999 | 久草青青草 | 在线观看黄色片 | 中文字幕一区二区三区人妻不卡 | 国产一区免费视频 | 欧美日韩h| 国产精品视频在线观看 | 国产精品白丝喷水在线观看 | 亚洲欧美另类图片 | 国产一区二区毛片 | 国产精品tv | 91成人在线观看喷潮动漫 | 日韩精品视频在线免费观看 | 国产视频一区二区在线观看 | 波多野结衣中文字幕在线 | 欧美国产片| 国产美女自慰在线观看 | 无码人妻久久一区二区三区 | 国产成人精品片 | 91精品人妻一区二区三区蜜桃欧美 | 奇米色777| 尤物av在线 | 欧美成人激情视频 | 一区二区三区欧美视频 | 久草网在线视频 | 橹图极品美女无圣光 | 一区二区三区毛片 | 欧美激情黑白配 | 久久国产精品偷 | 亚洲第一男人天堂 | 奇米色777| 国产成人精品无码片区在线 | 一区二区三区黄 | 国产激情久久久久久熟女老人av | 国产又爽又黄视频 | 九九热视频在线播放 | 久久涩视频| 人人澡人人看 | 韩国三级与黑人 | 天天综合亚洲 | 久久影视精品 | 北京富婆泄欲对白 | 92国产精品 | 亚洲综合区 | 国内精品一区二区 | 男女日批视频 | 熟妇熟女乱妇乱女网站 | 免费爱爱视频网站 | 深夜成人福利视频 | 九九九热视频 | 色图一区 | 日本在线三级 | 免费一级毛片麻豆精品 | 小早川怜子一区二区三区 | 免费一级片视频 | 九九视频在线免费观看 | 久久久久久av无码免费网站 | 亚洲一区在线视频观看 | 亚洲成年人av | 人妻少妇偷人精品视频 | a在线观看| 波多野结衣一区二区三区在线观看 | 一级黄色短视频 | 国产亚洲色婷婷久久 | 亚洲美女视频 | 日韩在线观看视频网站 | 4438x在线观看 | 337p日本欧洲亚洲大胆张筱雨 | 成人福利在线 | 久草五月 | 国产精品2| 欧美成人黄色片 | 午夜影视在线观看 | 91久久国产综合久久91精品网站 | 黄网在线免费观看 | aaaa一级片 | 日韩有码第一页 | 安装下载app | 亚洲天天干 | 999国产精品视频 | 久久久久噜噜噜亚洲熟女综合 | 精品无码免费视频 | 欧美熟妇精品一区二区蜜桃视频 | 都市激情一区 | a一级黄色 | 国产精品一级 | 高h喷水荡肉少妇爽多p视频 | 四虎成人精品永久免费av九九 | 性综艺节目av在线播放 | 艳母日本动漫在线观看 | 国产精品免费一区二区三区 | 色婷婷综合久久久中文字幕 | 波多野结衣一区二区三区在线观看 | 亚洲一区二区欧美 | av片在线观看免费 | 调教在线观看 | 日韩av无码一区二区三区 | 国产精品v欧美精品v日韩 | 亚洲在线电影 | 欧美高清hd18日本 | av中文网 | 打白嫩光屁屁女网站 | 性一交一乱一区二区洋洋av | 涩人阁 | 男人插入女人阴道视频 | 中文在线免费视频 | 97精产国品一二三产区 | 日韩午夜精品 | 毛茸茸的中国女bbw 国产午夜精品久久久 | 丰满熟妇被猛烈进入高清片 | 中文字幕在线免费看 | 日本五十肥熟交尾 | 九九热视频在线播放 | 性一交一乱一区二区洋洋av | 久久男人天堂 | 久久一二三四区 | 一区二区av在线 | 蜜桃精品视频在线 | 日本精品在线播放 | 午夜精品一区二区三区在线视频 | 国产欧美在线看 | 中国男女全黄大片 | 久久黄色大片 | 波多野结衣人妻 | 校园春色综合网 | 婷婷中文 | 日韩五码 | 女女les互磨高潮国产精品 | 亚洲精品乱码久久久久 | 国产无遮挡裸体免费视频 | 国产三级不卡 | 国产一区二区欧美 | 蜜桃av噜噜一区二区三区麻豆 | 丁香花电影免费播放电影 | 成人丁香婷婷 | 爱搞国产 | 中文字幕一区二区人妻电影 | 欧美国产片 | 日皮视频免费观看 | www.日本高清 | 久久久久久亚洲av无码专区 | 中文字幕一区二区三区5566 | 欧美有码在线 | 你懂得在线观看 | 亚洲熟妇无码久久精品 | 国产成人激情 | 欧美尻逼 | 欧美日韩在线观看一区二区 | 美女一区二区三区四区 | 国产亚洲色婷婷久久 | 91大尺度| 欧美成人不卡 | 熟睡侵犯の奶水授乳在线 | 美女又爽又黄网站泳装 | 欧美成人不卡 | 国产在线小视频 | 三级av片| 蜜桃视频中文字幕 | 国内91视频 | 国产精品精品软件视频 | 国产做爰免费视频观看 | 四虎成人精品永久免费av九九 | 能免费看av的网站 | 午夜院线 | 久久久96人妻无码精品 | 成人在线播放视频 | 午夜精品一区二区三区在线视频 | ass大乳尤物肉体pics | 国产亚洲一区二区三区在线观看 | 91黄色片| 污污内射久久一区二区欧美日韩 | a级片久久| 国产青青草视频 | 亚洲综合色在线 | 牛牛电影国产一区二区 | 美女爆乳18禁www久久久久久 | 国产精品偷拍 | 精品无码久久久久 | 亚洲第一男人天堂 | 天天干天天草天天射 | 97超碰精品 | 亚洲精品乱码久久久久 | 免费a视频在线观看 | 中文字幕女同女同女同 | 亚洲精品中文字幕 | 午夜精品亚洲 | 91嫩草视频在线观看 | 国产青草| 伊人影院av| 香港a毛片 | 想要视频在线观看 | 久久tv| 亚洲一区在线视频观看 | 99激情网 | 中文av网 | 免费一级大片 | 国产亚洲在线观看 | av蜜臀网站 | 国模在线观看 | 91视频污| 久久精品国产亚洲AV无码男同 | 欧洲精品一区二区三区 | 不卡在线播放 | 18免费网站 | 精品资源成人 | 久久精品国产亚洲AV无码男同 | 日韩av高清 | av综合在线观看 | 性史性dvd影片农村毛片 | 天天干天天草天天射 | 久久精品噜噜噜成人 | 中国极品少妇xxxx做受 | 亚洲熟妇无码久久精品 | 好吊一区二区三区 | 精品资源成人 | 黄色h视频 | 草民午夜理伦三级 | 丰满大爆乳波霸奶 | 二十四小时在线更新观看 | 欧美一级成人 | 丝袜 亚洲 另类 欧美 重口 | 日本欧美激情 | 在线免费看污视频 | 农村老妇性真猛 | 色综合中文字幕 | 色七七视频 | 中文字幕一区二区三区5566 | 久久久久极品 | 超碰在线免费 | 日本高清二区 | 韩国一区二区在线观看 | 亚洲午夜精品一区二区三区 | 日本一区二区在线 | 人妖一区| 青青草狠狠干 | 国产片一区二区三区 | 色视屏 | 欧k影视| 欧美成人小视频 | 欧美在线免费观看视频 | 欧美激情性做爰免费视频 | 奇米影视av | 国产黄色一级大片 | 亚洲一区在线视频观看 | 五月天狠狠干 | 三级黄色免费 | 久久久久性 | 青娱乐青青草 | 在线不卡一区 | 黄色精品在线观看 | 午夜免费播放观看在线视频 | 四虎精品一区二区三区 | 黄色一级图片 | 91久久久久国产一区二区 | 清纯粉嫩极品夜夜嗨av | 中文字幕一区二区三区精华液 | 可以看的毛片 | 国产精品久久久久av | 鲁一鲁在线 | 91丨九色丨黑人外教 | 日本在线视频免费观看 | 中文字幕首页 | 日本精品视频在线播放 | 国产精品99视频 | 国产精品精品国产 | 国产九九精品视频 | 欧美一级少妇 | 亚洲国产一区在线观看 | 安装下载app | 日韩和欧美的一区二区 | 欧美黄色片免费看 | 秘密基地动漫在线观看免费 | 国产精品一级 | 欧美在线中文字幕 | 日本黄色大片免费 | 国产一级二级 | 成年人免费网站在线观看 | 激情视频91 | 一级黄色短视频 | 淫欲的美女理论电影完整版 | 亚洲青青草原 | 丁香六月综合 | 国产1区2区在线观看 | 99资源在线 | 国产熟女高潮一区二区三区 | 国产精品天天狠天天看 | 丝袜 亚洲 另类 欧美 重口 | 好吊操视频这里只有精品 | 成人午夜淫片免费观看 | 亚洲黄色小说网 | 亚洲欧美精品一区二区三区 | 色吧av色av| 欧美私人影院 | 日本一级淫片色费放 | 欧美在线亚洲 | 人妻熟女一区 | 风流少妇一区二区三区91 | 波多野吉衣一二三区乱码 | 中文字幕第18页 | 国产精品v欧美精品v日韩 | 欧美bbbbbbbbbbbb精品 | 亚洲人天堂 | 久色网站 | 91好色先生 | 国产做爰免费视频观看 | 91免费短视频| 欧美a∨| 西西人体大胆4444www | 国产麻豆传媒 | 野花视频免费在线观看 | 在线观看免费黄色 | 日韩欧美大片在线观看 | 日本黄色网址大全 | 91成人在线免费视频 | 国产精品久久久久久吹潮 | 在线看片你懂得 | 性综艺节目av在线播放 | 日本一区精品 | 丰满熟妇被猛烈进入高清片 | 久久久国产一区二区三区 | 精品伦精品一区二区三区视频密桃 | 综合久久久久久久 | 艳母日本动漫在线观看 | 久章草影院| 国产视频资源 | 火影忍者羞羞漫画 | 两女双腿交缠激烈磨豆腐 | 欧美专区第一页 | 欧美春色 | 白又丰满大屁股bbbbb | 污污网站在线免费观看 | av免费一区| 青青草国产精品 | 亚洲黄色片 | 91精品国产91久久久久久黑人 | 老师让我她我爽了好久视频 | 69久久久久 | 免费三片在线观看网站v888 | 日韩在线观看视频网站 | 欧美亚洲国产一区二区三区 | 国产黄色影视 | 国产精品视频入口 | 青青草日本 | 亚洲爽爽网 | 懂色av蜜臀av粉嫩av分享 | 特级毛片在线观看 | 美国毛片网站 | 久久av电影| 一级色网站| 北条麻妃av在线 | 最新国产露脸在线观看 | 亚洲h视频在线观看 | 国产精品免费久久 | 91久久久久久久久久久 | 特黄aaaaaaaaa毛片免费视频 | 91精品国产综合久久久蜜臀粉嫩 | 超碰在线亚洲| 免费一二三区 | 久久免费看少妇高潮 | 欧美国产日韩一区二区 | 免费在线国产视频 | 日本极品丰满ⅹxxxhd | 国产三级久久 | 国产又大又黄的视频 | 92国产精品 | 强睡邻居人妻中文字幕 | 91久久国产综合久久91精品网站 | 国产超级av | 免费三级av| 神马午夜国产 | 午夜大片 | 国产中文字字幕乱码无限 | 最新国产露脸在线观看 | 丁香六月综合 | 欧美日韩国产高清 | 69精品无码成人久久久久久 | 国产精品免费一区二区三区 | 中文字幕亚洲乱码熟女1区2区 | 亚洲美女视频 | 91久久久久久 | 俄罗斯厕所偷拍 | 永久免费视频网站直接看 | 亚洲免费中文字幕 | 欧美一级少妇 | 午夜精品亚洲 | 中文字幕丰满乱子伦无码专区 | 国产白丝在线观看 | 欧美二区在线观看 | 日本黄页网 | 91在线播放视频 | 四虎影视免费永久大全 | 亚洲少妇一区二区 | 日韩av一区二区三区在线观看 | 精久久久久 | 免费一级片视频 | 狠狠干狠狠插 | 国产成人在线观看免费网站 | 神马影院午夜伦理 | 天天草夜夜 | 五月丁香久久婷婷 | 日韩在线视频看看 | 黄色av网站免费 | 中文字幕第18页 | 99久久99久久精品国产片果冻 | 国产成人a人亚洲精品无码 最近中文字幕av | 久久久久久国产精品 | 国产午夜电影 | 国产中文字字幕乱码无限 | 西欧毛片 | 无码人妻aⅴ一区二区三区玉蒲团 | 超碰麻豆 | 不良视频在线观看 | 福利免费视频 | 懂色av一区二区三区免费观看 | 免费的一级片 | 总裁憋尿呻吟双腿大开憋尿 | 成人av电影免费观看 | 欧美性猛交xxxx乱大交退制版 | 五月天狠狠干 | 午夜黄色小视频 | 打白嫩光屁屁女网站 | 欧美一区二区三区不卡 | 中文字幕女同女同女同 | 玖玖国产 | 天天干夜夜欢 | 欧美春色 | 中文字幕一级 | 成人91视频 | 二十四小时在线更新观看 | 成人午夜视频在线 | 超碰在线亚洲| 亚洲最大av在线 | 99久久久无码国产精品免费蜜柚 | 日本少妇xxxx软件 | 日批国产 | 五月婷婷,六月丁香 | 午夜在线看 | 午夜在线看 | 自拍偷拍第五页 | 成人h在线观看 | 亚洲欧洲日本在线 | 成人羞羞国产免费 | 欧美精品成人在线 | 日韩人妻无码一区二区三区99 | 白又丰满大屁股bbbbb | 国产精品欧美在线 | 欧美色激情 | 欧美午夜在线 | 米奇影视777 | 亚洲一区国产一区 | www.日本高清| 国产精品免费久久 | 性欧美sm调教 | 一级全黄裸体片 | 在线不卡| 天天干在线观看 | 成人自拍av | 激情开心网站 | 欧美日韩在线观看一区二区 | 国产福利在线观看 | 午夜免费观看视频 | 欧美福利一区 | 亚洲视频大全 | 亚洲免费资源 | 欧洲成人免费视频 | aaaa一级片 | 亚洲精品二| 污污视频免费观看 | 国产网站免费 | 亚洲av无码国产综合专区 | 欧美日韩h| av国产免费 | 欧美国产日韩一区 | 国产尻逼视频 | av无限看 | 久久99亚洲精品 | 不卡在线播放 | 日批网址 | 碧蓝之海动漫在线观看免费高清 | 老司机午夜电影 | 久久精选 | 国内视频精品 | 青娱乐青青草 | 伊人网免费视频 | 久久av在线 | 久久久国产一区二区三区 | 91中文| 日韩av一区二区三区在线观看 | 少妇被躁爽到高潮无码人狍大战 | 激情五月婷婷 | 91精品人妻一区二区三区蜜桃欧美 | 日本黄页网 | 欧美成人激情视频 | 亚洲视频在线观看一区二区 | 亚洲免费观看高清 | 一道本av| 美女一区二区三区四区 | 国产激情久久久久久熟女老人av | 麻豆av一区二区 | 求av网址 | 国语毛片| 久久免费在线视频 | 亚洲成人精品久久 | 午夜国产精品视频 | 日本一区二区在线 | 国产精品xxx在线观看 | 都市激情一区 | 樱桃香蕉视频 | 亚洲av无码国产综合专区 | 成人免费黄色网 | 欧美一区二区三区成人精品 | 2019毛片| 日韩国产欧美一区二区 | 国产在线97 | 在线看一级片 | 蜜桃av噜噜一区二区三区麻豆 | 欧美激情性做爰免费视频 | 欧美a∨| 成人在线一区二区三区 | 亚洲作爱视频 | 四虎成人在线观看 | 欧美国产日韩一区二区 | 亚洲色图另类 | 樱桃香蕉视频 | 天天操天 | 日本妈妈9 | 婷婷精品在线 | av在线播放网站 | 国产传媒一区 | 小宝贝真紧h军人h | 免费看日韩毛片 | 国产18在线 | 91久久国产综合久久91精品网站 | 久久免费播放 | 免费特级毛片 | 人人爱操| 欧美香蕉在线 | 国产黄色片在线播放 | 草草免费视频 | 欧美自拍视频 | 青娱乐超碰在线 | 奶妈的诱惑 | 午夜视频免费看 | 成人片免费视频 | 欧美日韩精品久久久 | 美女久久久 | av无限看 | 日韩精品无码一区二区三区久久久 | 成年人视频免费在线观看 | 超碰人人超碰 | 日本亚洲色大成网站www久久 | 国产精品白丝喷水在线观看 | 91嫩草视频在线观看 | 精久久久久久久 | 欧美激情黑白配 | 艳母日本动漫在线观看 | 俄罗斯特级毛片 | 超大量吹潮系列合集 | 欧美熟妇精品一区二区蜜桃视频 | www午夜 | 欧洲成人免费视频 | 毛片三级 | 中文字幕一级 | 三级黄色免费 | www.色婷婷 | 欧美日韩中文字幕一区二区 | 欧美激情自拍偷拍 | 日韩精品五区 | 禁断介护老人中文字幕 | 美女一级黄色片 | 精久久久久久久 | 精品无码免费视频 | 亚洲欧美在线看 | 乌克兰黄色片 | 亚洲熟妇色自偷自拍另类 | 久久手机视频 | www日本高清视频 | 欧美黑人一级片 | 高清日韩| 99精品视频在线 | 午夜av网站 | 波多野吉衣一二三区乱码 | 99爱在线视频 | 国产精品电影网站 | 亚洲精品在线观看视频 | 波多野结衣人妻 | 日韩在线观看视频网站 | 超碰在线亚洲| 麻豆av在线播放 | 色妞综合 | 自拍亚洲欧美 | 国产精品v欧美精品v日韩 | 日韩精品久 | 视频在线你懂的 | 日批网址| 狠狠干干 | 欧美日韩麻豆 | 二区三区视频 | 西西人体大胆4444www | 成人综合色站 | 韩国无码一区二区三区精品 | 日韩有码第一页 | 暖暖日本在线视频 | av在线免费电影 | 日韩精品一区二区三区免费视频 | 潘金莲一级淫片免费放动漫 | 韩国一区二区三区在线观看 | 欧美日韩在线观看一区二区 | 国产精品xxx在线观看 | 在线精品观看 | aa亚洲| 久久噜| 泰剧19禁啪啪无遮挡 | 国产欧美在线看 | 亚洲精品97久久 |