Friction最新文献_第2页

Friction behaviour of graphene edges within carbon surface

IF 6.8 1区工程技术

Friction Pub Date : 2025-02-28 DOI: 10.26599/frict.2025.9441086

Kun Sun, Mingjun Sun, Ri Pan, Meijie Yin, Kai Qi, Dongju Chen, Jinwei Fan, Dongfeng Diao

{"title":"Friction behaviour of graphene edges within carbon surface","authors":"Kun Sun, Mingjun Sun, Ri Pan, Meijie Yin, Kai Qi, Dongju Chen, Jinwei Fan, Dongfeng Diao","doi":"10.26599/frict.2025.9441086","DOIUrl":"https://doi.org/10.26599/frict.2025.9441086","url":null,"abstract":"We reported a friction behaviour of graphene edges within carbon film, encompassing the structures ranged from amorphous carbon (a-C) to graphene nanocrystalline carbon (GNC). Structural characterization revealed that vertical-growing graphene nanocrystallites implanted into a-C structure, exposing high-density layer edges on the film surface. AFM nanofriction test highlighted the nature of graphene edge friction. Firstly, the edge friction of GNC films was tested at a critical-contact state, and the results showed that graphene edges exhibited lower friction forces compared to a-C edges. Secondly, the surface friction of GNC films was investigated at a full-contact state, revealing that the edge friction of graphene nanocrystallites regulated the surface friction of GNC films. As the edge density of graphene nanocrystallites increased, the nanofriction force of GNC films decreased. Finally, the mechanism of the regulated friction bahaviour was attributed to the amount of the edges of graphene nanocrystallites, which provided plentiful sp2 C dangling-bonds with weak bonding interactions and edge quantum wells with low surface potentials for lowing the friction. This finding shed light on the significance of graphene-related materials and their high-density edges in the structural design and nanofriction application of carbon films.","PeriodicalId":12442,"journal":{"name":"Friction","volume":"190 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Brittle-plastic synergistic removal mechanism and grain wear in ultrasonic grinding of anisotropic fiber-reinforced MMCs

IF 6.8 1区工程技术

Friction Pub Date : 2025-02-28 DOI: 10.26599/frict.2025.9441087

Tao Chen, Biao Zhao, Wenfeng Ding, Ning Qian, Jiuhua Xu, Yumin Wang

{"title":"Brittle-plastic synergistic removal mechanism and grain wear in ultrasonic grinding of anisotropic fiber-reinforced MMCs","authors":"Tao Chen, Biao Zhao, Wenfeng Ding, Ning Qian, Jiuhua Xu, Yumin Wang","doi":"10.26599/frict.2025.9441087","DOIUrl":"https://doi.org/10.26599/frict.2025.9441087","url":null,"abstract":"Continuous fiber reinforced metal matrix composites (CFMMCs) are increasingly utilized in high-performance aerospace engines due to their exceptional strength along the fiber axis. Unlike particle-reinforced metal matrix composites (PMMCs), CFMMCs exhibit significant anisotropic properties, which complicate their machining processes. While extensive studies have focused on tool wear in PMMCs, a notable research gap exists regarding the grinding removal mechanisms and grain wear behaviors in CFMMCs, particularly in the context of ultrasonic vibration-assisted grinding (UVAG). This study addresses this gap by investigating grain wear along different fiber orientations—perpendicular fiber (PF), transverse fiber (TF), and longitudinal fiber (LF)—through single grain grinding experiments on SiC fiber-reinforced TC17 matrix composites (SiCf/TC17). A detailed analysis of surface morphologies within the grinding scratches was conducted, revealing significant differences in CBN grain wear patterns under different fiber orientations, particularly when comparing UVAG with conventional grinding (CG). The results indicate that ultrasonic vibration effectively mitigates fiber fracture and grain wear, with the most severe grain wear and adhesion occurring when grinding along the LF orientation. This research not only advances the understanding of CFMMC grinding mechanisms but also contributes to enhancing the machinability of CFMMCs, thereby facilitating their broader application in aerospace and other high-performance industries.","PeriodicalId":12442,"journal":{"name":"Friction","volume":"85 2 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigation of the influence of substrate hardness on the tribological performance of graphene oxide solid lubricant coatings

IF 6.8 1区工程技术

Friction Pub Date : 2025-02-28 DOI: 10.26599/frict.2025.9441085

Yuzhen Liu, Hui Chen, Wenli Wang, Kai Le, Guoqing Wang, Yong Luo, Xiaoming Gao, Xu Zhao, Xingnan Liu, Shusheng Xu, Dae-Eun Kim, Weimin Liu

{"title":"Investigation of the influence of substrate hardness on the tribological performance of graphene oxide solid lubricant coatings","authors":"Yuzhen Liu, Hui Chen, Wenli Wang, Kai Le, Guoqing Wang, Yong Luo, Xiaoming Gao, Xu Zhao, Xingnan Liu, Shusheng Xu, Dae-Eun Kim, Weimin Liu","doi":"10.26599/frict.2025.9441085","DOIUrl":"https://doi.org/10.26599/frict.2025.9441085","url":null,"abstract":"This study explores the impact of substrate hardness on the tribological properties of graphene oxide (GO) solid lubricant coatings on NiP alloy layers coated Q235 steel. Through the adjustment of electroless plating parameters, NiP alloy layers with varying hardness levels were produced to investigate their effect on the wear resistance and friction performance of GO coatings. The methodology included substrate preparation, electroless NiP alloy plating, electrophoresis deposition of GO, and detailed analysis of the structural, mechanical, and tribological characteristics of the coatings. The findings underscore the crucial role of substrate hardness in the tribological efficiency of GO coatings. A specific hardness level emerged as optimal, significantly enhancing the distribution and effectiveness of the GO tribofilm. This uniform and continuous tribofilm presence led to notable improvements in wear resistance and a reduction in friction coefficients. Moreover, this optimal hardness ensured continuous lubrication and superior load-bearing capabilities, substantially prolonging the lifespan of the coatings. The substrates with either too high or too low hardness levels were observed to hinder the maintenance of a consistent tribofilm, thereby negatively impacting the tribological performance of the coating. Conclusively, this research highlights the significance of achieving an optimal substrate hardness to enhance the tribological performance of solid lubricant coatings. By optimizing the balance between substrate hardness and the integrity of the tribofilm, the study paves the way for developing more efficient, durable, and environmentally sustainable mechanical components, offering new insights into tribological science and materials engineering.","PeriodicalId":12442,"journal":{"name":"Friction","volume":"41 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantifying cross-country ski–snow friction using real-time kinematic positioning 利用实时运动定位量化越野滑雪与雪地之间的摩擦力

IF 6.8 1区工程技术

Friction Pub Date : 2025-02-27 DOI: 10.26599/frict.2025.9441011

Kalle Kalliorinne, Joakim Sandberg, Gustav Hindér, Hans-Christer Holmberg, Matej Supej, Roland Larsson, Andreas Almqvist

{"title":"Quantifying cross-country ski–snow friction using real-time kinematic positioning","authors":"Kalle Kalliorinne, Joakim Sandberg, Gustav Hindér, Hans-Christer Holmberg, Matej Supej, Roland Larsson, Andreas Almqvist","doi":"10.26599/frict.2025.9441011","DOIUrl":"https://doi.org/10.26599/frict.2025.9441011","url":null,"abstract":"In cross-country skiing, athletes expend large amounts of energy to overcome friction as their skis interact with snow. Even minor reductions in the friction can significantly influence race outcomes. Over the years, researchers have found many ways of quantifying ski–snow friction, but there are only a few methods that consider the glide of real-sized skis under natural conditions during both accelerating and decelerating movements. This study introduces a novel experimental setup, consisting of a sled equipped with authentic cross-country skis and a base station that uses satellite receivers to communicate via radio, constituting a real-time kinematic positioning system with centimetre accuracy. While the sled was running on a classic ski track with natural height variations, altitude and velocity data were recorded for quantification of the coefficient of friction (COF), both for accelerating and decelerating motion, employing a model based on Newton’s second law. The results show that the COF during acceleration was more than 20% higher than during deceleration, demonstrating dynamic changes in the frictional behaviour between these phases. This finding is crucial for the execution of all types of cross-country skiing techniques, where the athlete either accelerates or decelerates while moving forward. The ability of the current experimental set-up to distinguish between the COF during acceleration and deceleration has considerable implications for further developments.","PeriodicalId":12442,"journal":{"name":"Friction","volume":"29 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A “bricks-and-mortar” structured graphene oxide/polyvinyl alcohol coating: enhanced water interfacial lubrication and durability 砖墙 "结构氧化石墨烯/聚乙烯醇涂层：增强水界面润滑性和耐久性

IF 6.8 1区工程技术

Friction Pub Date : 2024-09-27 DOI: 10.1007/s40544-024-0902-7

Hanglin Li, Lin Ding, Jingchun Zhang, Zhaoyang Guo, Yazhuo Shang, Honglai Liu, Xiangqiong Zeng, Jiusheng Li

{"title":"A “bricks-and-mortar” structured graphene oxide/polyvinyl alcohol coating: enhanced water interfacial lubrication and durability","authors":"Hanglin Li, Lin Ding, Jingchun Zhang, Zhaoyang Guo, Yazhuo Shang, Honglai Liu, Xiangqiong Zeng, Jiusheng Li","doi":"10.1007/s40544-024-0902-7","DOIUrl":"https://doi.org/10.1007/s40544-024-0902-7","url":null,"abstract":"Coatings serve as ideal protective films for mechanical systems, providing dependable as well as efficient lubrication because of their unique structure along with outstanding tribological characteristics. Inspired by the “bricks-and-mortar” structure, we prepared layered graphene oxide (GO) composite finishes strengthened with polyvinyl alcohol (PVA) and borax. Our study demonstrates that the tribological properties of the GO-based coating on 304 stainless steel (SS304) are potentially greatly affected through PVA, GO, and annealing. By optimizing the composition, we achieved the PVA40 wt%/GO0.01 wt%/borax composite coating, which exhibited the lowest average coefficient of friction (COF) of 0.021±0.003 (a 97.86% reduction compared to control SS304) with minimal wear and abrasion even in a water environment. We found that the enhanced mechanical characteristics as well as elastic recovery within the coating were attributed to the hydrogen bonds and cross-linking between PVA and borax, which led to stress distribution. Reduced friction was further aided by the formation of a hydrated layer at the friction interface. As a result, the coating demonstrated remarkable durability, maintaining a low COF during long sliding distances (576 m, 28,800 cycles, significantly longer than previously reported) without breaking.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"6 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142325121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lubrication antagonism mechanism of nano-MoS2 and soot particles in ester base oil 酯类基础油中纳米 MoS2 和烟尘颗粒的润滑拮抗机制

IF 6.8 1区工程技术

Friction Pub Date : 2024-09-25 DOI: 10.1007/s40544-024-0904-5

Chonglong Zhong, Kunhong Hu, Yong Xu, Enzhu Hu, Xianguo Hu

{"title":"Lubrication antagonism mechanism of nano-MoS2 and soot particles in ester base oil","authors":"Chonglong Zhong, Kunhong Hu, Yong Xu, Enzhu Hu, Xianguo Hu","doi":"10.1007/s40544-024-0904-5","DOIUrl":"https://doi.org/10.1007/s40544-024-0904-5","url":null,"abstract":"Spherical nano-MoS2 (S-MoS2) has excellent lubricating properties and potential application value in engine oil additives. Engine soot can enter the engine oil, so the tribological interaction between S-MoS2 and diesel combustion soot (DCS) should be investigated. In this study, DCS was used to simulate engine soot. The interaction was investigated in dioctyl sebacate (DOS), and the interaction mechanism was full characterized. Results showed that S-MoS2 and DCS had obvious antagonism effects on lubrication. The 0.5% S-MoS2 exhibited good lubricating properties in DOS, which could reduce friction by ∼22% and wear by ∼54%. However, after 0.5% S-MoS2 was added to the 0.5% DCS contaminated DOS, the lubrication performance was not improved and was even worse than that without S-MoS2. When S-MoS2 was added for DOS lubrication, a tribofilm containing MoS2 formed on the friction surface, but simultaneously adding 0.5% DCS resulted in the disappearance of the MoS2 tribofilm. Moreover, under the action of friction heat, DCS and S-MoS2 could form hard MoxCy, thereby increasing abrasive wear. Finally, a preliminary deantagonism method was provided. After 2.0% zinc isooctyl dithiophosphate was added to the above antagonistic system, the friction coefficient did not show visible changes, but the wear recovered to a level close to that when only S-MoS2 was added. The antiantagonism method is not very satisfactory and some more efficient methods need to be further explored.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"47 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Excellent lubricating hydrogels with rapid photothermal sterilization for medical catheters coating 用于医用导管涂层的具有快速光热灭菌功能的优质润滑水凝胶

IF 6.8 1区工程技术

Friction Pub Date : 2024-09-18 DOI: 10.1007/s40544-024-0903-6

Yue Sun, Zhenling Shang, Chenghao Li, Jinglun Guo, Zhuo Chen, Nan Zhao, Guoqiang Liu, Feng Zhou, Weimin Liu

{"title":"Excellent lubricating hydrogels with rapid photothermal sterilization for medical catheters coating","authors":"Yue Sun, Zhenling Shang, Chenghao Li, Jinglun Guo, Zhuo Chen, Nan Zhao, Guoqiang Liu, Feng Zhou, Weimin Liu","doi":"10.1007/s40544-024-0903-6","DOIUrl":"https://doi.org/10.1007/s40544-024-0903-6","url":null,"abstract":"Bacterial infection and tissue damage caused by friction are two major threats to patients’ health in medical catheter implantation. Hydrogels with antibacterial and lubrication effects are competitive candidates for catheter coating materials. Photothermal therapy (PTT) is a highly efficient bactericidal method. Here, a composite hydrogel containing MXene nanosheets and hydrophilic 3-sulfopropyl methacrylate potassium salt (SPMK) is reported, which is synthesized through the one-pot method and heat-initiated polymerization. The hydrogel shows excellent antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in 3 min in the air or 20 min in the water environment under near-infrared light (NIR; 808 nm) irradiation. The friction coefficient of the hydrogel is about 0.11, which is 48% lower than that without SPMK. The rapid photothermal sterilization is attributed to the outstanding antibacterial ability and thermal effect of photoactivated MXene. The ultra-low friction is the result of the hydration lubrication mechanism. This study provides a potential strategy for the surface coatings of biomedical catheters, which enables rapid sterilization and extremely low interface resistance between catheters and biological tissues.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"98 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A robust low-friction triple network hydrogel based on multiple synergistic enhancement mechanisms 基于多重协同增强机制的稳健低摩擦三重网络水凝胶

IF 6.8 1区工程技术

Friction Pub Date : 2024-09-18 DOI: 10.1007/s40544-024-0907-2

Xinyue Zhang, Qin Chen, Kai Chen, Cunao Feng, Haiyan Feng, Xiaowei Li, Dekun Zhang

{"title":"A robust low-friction triple network hydrogel based on multiple synergistic enhancement mechanisms","authors":"Xinyue Zhang, Qin Chen, Kai Chen, Cunao Feng, Haiyan Feng, Xiaowei Li, Dekun Zhang","doi":"10.1007/s40544-024-0907-2","DOIUrl":"https://doi.org/10.1007/s40544-024-0907-2","url":null,"abstract":"Hydrogels exhibit promising applications, particularly due to their high water content and excellent biocompatibility. Despite notable progress in hydrogel technology, the concurrent enhancement of water content, mechanical strength, and low friction poses substantial challenges to practical utilization. In this study, employing molecular and network design guided based on multiple synergistic enhancement mechanisms, we have developed a robust polyvinyl alcohol (PVA)–polyacrylic acid (PAA)–polyacrylamide (PAAm) three-network (TN) hydrogel exhibiting high water content, enhanced strength, low friction, and fatigue resistance. The hydrogel manifests a water content of 63.7%, compression strength of 6.3 MPa, compression modulus of 2.68 MPa, tensile strength reaching 7.3 MPa, and a tensile modulus of 10.27 MPa. Remarkably, even after one million cycles of dynamic loading, the hydrogel exhibits no signs of fatigue failure, with a minimal strain difference of only 1.15%. Furthermore, it boasts a low sliding coefficient of friction (COF) of 0.043 and excellent biocompatibility. This advancement extends the applications of hydrogels in emerging fields within biomedicine and soft bio-devices, including load-bearing artificial tissues, artificial blood vessels, tissue scaffolds, robust hydrogel coatings for medical devices, and joint parts of soft robots.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"23 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Tribological behavior of TiN, AlTiN, and AlTiCrN coatings in atmospheric and vacuum environments TiN、AlTiN 和 AlTiCrN 涂层在大气和真空环境中的摩擦学行为

IF 6.8 1区工程技术

Friction Pub Date : 2024-08-29 DOI: 10.1007/s40544-024-0930-3

Youn-Hoo Hwang, Kuk-Jin Seo, Tae-Hyeong Kim, You Jin Min, Yuzhen Liu, Dae-Eun Kim

{"title":"Tribological behavior of TiN, AlTiN, and AlTiCrN coatings in atmospheric and vacuum environments","authors":"Youn-Hoo Hwang, Kuk-Jin Seo, Tae-Hyeong Kim, You Jin Min, Yuzhen Liu, Dae-Eun Kim","doi":"10.1007/s40544-024-0930-3","DOIUrl":"https://doi.org/10.1007/s40544-024-0930-3","url":null,"abstract":"In this study, the tribological characteristics of TiN, AlTiN, and AlTiCrN coatings sliding against a SUS420J1 stainless steel pin were investigated in atmospheric and vacuum environments. The coatings were deposited on SUS440C substrates using the arc-physical vapor deposition technique. The friction and wear behavior of the coatings were evaluated based on the systematic analyses of the friction coefficient data as well as the physical and chemical state of the wear track. The results revealed that the friction coefficients of the SUS440C specimen and AlTiCrN coatings increased, whereas those of the TiN and AlTiN coatings decreased when the environment was changed from atmospheric to vacuum. It was confirmed that the formation of an oxide layer and adsorption of oxides on the surface were dominant factors that influenced the tribological behavior in the atmospheric environment. On the other hand, the compatibility, oxidation inhibition, and droplets of the surface mainly affected the frictional characteristics in the vacuum environment. The results of this work are expected to aid in the selection of proper coating materials for tribological systems operating in a vacuum.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"29 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142090177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modeling static friction behavior of elastic–plastic spherical adhesive microcontact in full-stick condition 全粘状态下弹塑性球形粘合剂微接触静摩擦行为建模

IF 6.8 1区工程技术

Friction Pub Date : 2024-08-29 DOI: 10.1007/s40544-024-0929-9

Guo Xiang, Roman Goltsberg, Izhak Etsion

引用次数: 0