Friction最新文献_第4页

Experimental investigation of junction growth of rough contacts using X-ray computed tomography 利用 X 射线计算机断层扫描对粗糙触点的结生长进行实验研究

IF 6.8 1区工程技术

Friction Pub Date : 2024-08-06 DOI: 10.1007/s40544-024-0896-1

Runliang Wang, Jianhua Liu, Bo Liu, Duo Jia, Xiaoyu Ding

{"title":"Experimental investigation of junction growth of rough contacts using X-ray computed tomography","authors":"Runliang Wang, Jianhua Liu, Bo Liu, Duo Jia, Xiaoyu Ding","doi":"10.1007/s40544-024-0896-1","DOIUrl":"https://doi.org/10.1007/s40544-024-0896-1","url":null,"abstract":"The real contact area (RCA) of randomly rough contacts has received a great deal of attention because it correlates strongly with friction, lubrication, sealing, and conductivity. Simulations have revealed that the RCA associated with deterministic normal squeezing loads increases when tangential loads are also applied, in a phenomenon called junction growth. However, experimental investigations of the junction growth of randomly rough contacts are rare. Here, we used X-ray computed tomography (CT) to measure junction growth when two aluminum alloy surfaces were in contact. A high-resolution experimental setup was used to apply loads and observe contact behaviors at a resolution of 4 µm. The RCA and average contact gaps were computed using a three-dimensional (3D) geometric model constructed from gray CT images using the Otsu thresholding method. The results showed that the RCA increased as the normal load increased. The RCA increased by 22.67% after a tangential load was applied (junction growth), and the average gap decreased by 14.01% after a tangential load was applied. Thus, X-ray CT accurately measured the junction growth as a novel quantitative method.","PeriodicalId":12442,"journal":{"name":"Friction","volume":"11 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141895469","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 performance of graphene in the sliding electrical contact interface 石墨烯在滑动电接触界面中的润滑性能

IF 6.8 1区工程技术

Friction Pub Date : 2024-08-05 DOI: 10.1007/s40544-024-0910-7

Lv Wang, Qian Tang, Tao Liang, Chenxu Liu, Deen Sun, Shu Wang, Jingchuan Li, Sam Zhang, Yonggang Meng, Yuehua Huang

{"title":"Lubrication performance of graphene in the sliding electrical contact interface","authors":"Lv Wang, Qian Tang, Tao Liang, Chenxu Liu, Deen Sun, Shu Wang, Jingchuan Li, Sam Zhang, Yonggang Meng, Yuehua Huang","doi":"10.1007/s40544-024-0910-7","DOIUrl":"https://doi.org/10.1007/s40544-024-0910-7","url":null,"abstract":"Electrical contact materials are increasingly widely used, but the existing electric contact lubricants still have lots of room for improvement, such as anti-wear performance and lubrication life. Due to the excellent electrical and lubrication properties, graphene shows great potential in lubricating the sliding electrical contact interface, but there is a lack of relevant research. Some researchers have studied the lubrication performance of graphene between the gold-coated/TiN-coated friction pair at an ultra-low current. However, the lubrication performance of graphene on more widely used electrical contact materials such as copper and its alloys under larger and more commonly used current or voltage conditions has not been reported. In this paper, we study the lubrication performance of graphene in the copper and its alloys sliding electrical contact interface under usual parameters, which is explored through four aspects: different substrates—copper and brass, different test methods—constant voltage and constant current, different normal loads and durability test. The experiments demonstrate that graphene can significantly reduce the friction and wear on brass and copper under the above test methods and parameters, with low contact resistance at the same time. Our work is expected to provide a new lubricant for electrical contact materials and contribute to enriching the tribological theory of graphene.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"55 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891721","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

Fretting-corrosion mechanisms of Ti6Al4V against CoCrMo in simulated body fluid under various fretting states 不同摩擦状态下模拟体液中 Ti6Al4V 与 CoCrMo 的摩擦腐蚀机理

IF 6.8 1区工程技术

Friction Pub Date : 2024-08-05 DOI: 10.1007/s40544-024-0909-0

Jian Pu, Zupei Zhang, Yali Zhang, Xiaogang Zhang, Xinlu Yuan, Xiaoyu Zhang, Guoxian Zhang, Wen Cui, Shu Yang, Zhongmin Jin

{"title":"Fretting-corrosion mechanisms of Ti6Al4V against CoCrMo in simulated body fluid under various fretting states","authors":"Jian Pu, Zupei Zhang, Yali Zhang, Xiaogang Zhang, Xinlu Yuan, Xiaoyu Zhang, Guoxian Zhang, Wen Cui, Shu Yang, Zhongmin Jin","doi":"10.1007/s40544-024-0909-0","DOIUrl":"https://doi.org/10.1007/s40544-024-0909-0","url":null,"abstract":"Ti6Al4V alloy–CoCrMo alloy pair is commonly applied for modular head–neck interfaces for artificial hip joint. Unfortunately, the fretting corrosion damage at this interface seriously restricts its lifespan. This work studied the fretting corrosion of Ti6Al4V–CoCrMo pair in calf serum solution. We established this material pair’s running condition fretting map (RCFM) regarding load and displacement, and revealed the damage mechanism of this material pair in various fretting regimes, namely partial slip regime (PSR), mixed fretting regime (MFR), and gross slip regime (GSR). The damage mechanism of Ti6Al4V alloy was mainly abrasive wear induced by CoCrMo alloy and tribocorrosion. Adhesive wear (material transfer) also existed in MFR. The damage mechanism of CoCrMo alloy was mainly abrasive wear induced by metal oxides and tribocorrosion in GSR and MFR, while no apparent damage in PSR. Furthermore, a dense composite material layer with high hardness was formed in the middle contacting area in GSR, which reduced the corrosion and wear of Ti alloys and exacerbated damage to Co alloys. Finally, the ion concentration maps for Ti and Co ions were constructed, which displayed the transition in the amount of released Ti and Co ions under different displacements and loads.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"27 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891720","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

Topographic variation and fluid flow characteristics in rough contact interface 粗糙接触界面的地形变化和流体流动特性

IF 6.8 1区工程技术

Friction Pub Date : 2024-08-05 DOI: 10.1007/s40544-024-0911-6

Jiawei Ji, Wei Sun, Yu Du, Yongqing Zhu, Yuhang Guo, Xiaojun Liu, Yunlong Jiao, Kun Liu

{"title":"Topographic variation and fluid flow characteristics in rough contact interface","authors":"Jiawei Ji, Wei Sun, Yu Du, Yongqing Zhu, Yuhang Guo, Xiaojun Liu, Yunlong Jiao, Kun Liu","doi":"10.1007/s40544-024-0911-6","DOIUrl":"https://doi.org/10.1007/s40544-024-0911-6","url":null,"abstract":"Understanding flow characteristics of fluid near rough contact is important for the design of fluid-based lubrication and basic of tribology physics. In this study, the spreading and seepage processes of anhydrous ethanol in the interface between glass and rough PDMS are observed by a homemade optical in-situ tester. Digital image processing technology and numerical simulation software are adapted to identify and extract the topological properties of interface and thin fluid flow characteristics. Particular attention is paid to the dynamic evolution of the contact interface morphology under different stresses, the distribution of microchannels in the interface, the spreading characteristics of the fluid in contact interface, as well as the mechanical driving mechanism. Original surface morphology and the contact stress have a significant impact on the interface topography and the distribution of interfacial microchannels, which shows that the feature lengths of the microchannels, the spreading area and the spreading rate of the fluid are inversely proportional to the load. And the flow path of the fluid in the interface is mainly divided into three stages: along the wall of the island, generating liquid bridges, and moving from the tip side to the root side in the wedge-shaped channel. The main mechanical mechanism of liquid flow in the interface is the equilibrium between the capillary force that drives the liquid spreading and viscous resistance of solid wall to liquid. In addition, the phenomenon of “trapped air” occurs during the flow process due to the irregular characteristics of the microchannel. This study lays a certain theoretical foundation for the research of microscopic flow behavior of the liquid in the rough contact interface, the friction and lubrication of the mechanical system, and the sealing mechanism.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"19 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891863","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

Semi-analytical calculation model for friction of polymers on the example of POM ∣ PE-UHMW and steel ∣ PE-UHMW 以 POM ∣ PE-UHMW 和钢∣ PE-UHMW 为例的聚合物摩擦半分析计算模型

IF 6.8 1区工程技术

Friction Pub Date : 2024-07-29 DOI: 10.1007/s40544-024-0887-2

André Bergmann, Jens Sumpf, Niels Dallinger, Martin Moneke, Markus Golder

{"title":"Semi-analytical calculation model for friction of polymers on the example of POM ∣ PE-UHMW and steel ∣ PE-UHMW","authors":"André Bergmann, Jens Sumpf, Niels Dallinger, Martin Moneke, Markus Golder","doi":"10.1007/s40544-024-0887-2","DOIUrl":"https://doi.org/10.1007/s40544-024-0887-2","url":null,"abstract":"In this paper, a semi-analytical calculation model for the coefficient of friction (COF) of single spherical protrusions is presented. It allows the prediction of the deformative friction part (μdef) and adhesive friction part (μadh) of the friction pairings steel ∣ polyethylene with ultra-high molecular weight (PE-UHMW) and polyoxymethylene (POM) ∣ PE-UHMW. The experimental studies included unlubricated friction tests, which served to determine the total COF (μtot), as well as tests being lubricated with silicone oil, from which μdef is obtained. Based on the verification tests, it could be shown that both states of lubrication result in the same deformation and that the relationship between the rear angle (ω) and μdef postulated in the calculation model is valid. Therefore, friction tests with segmented spheres were carried out, which allow a specific variation of the ω.It can be concluded that for both pairings the μdef is generally of minor significance (approx. 1/3 μtot) and the influence of the μadh predominates (approx. 2/3 μtot) the friction process. Furthermore the μtot decreases with increasing contact pressure especially in the low pressure range and depends on the form of motion (continuous and discontinuous).\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"72 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141791054","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 properties of the beetle leg joints 甲虫腿关节的摩擦学特性

IF 6.8 1区工程技术

Friction Pub Date : 2024-07-24 DOI: 10.1007/s40544-024-0933-0

Konstantin Nadein, Alexander Kovalev, Stanislav N. Gorb

引用次数: 0

An inorganic-organic hybrid CQDs@PVP lubricant additive: Achieving low friction and wear in PEG and water 一种无机-有机混合 CQDs@PVP 润滑油添加剂：在 PEG 和水中实现低摩擦和低磨损

IF 6.8 1区工程技术

Friction Pub Date : 2024-07-24 DOI: 10.1007/s40544-024-0871-x

Tao Yang, Xiaozhen Wang, Huanchen Liu, Qin Zhao, Kuiliang Gong, Weimin Li, Yongmin Liang, Xiaobo Wang

{"title":"An inorganic-organic hybrid CQDs@PVP lubricant additive: Achieving low friction and wear in PEG and water","authors":"Tao Yang, Xiaozhen Wang, Huanchen Liu, Qin Zhao, Kuiliang Gong, Weimin Li, Yongmin Liang, Xiaobo Wang","doi":"10.1007/s40544-024-0871-x","DOIUrl":"https://doi.org/10.1007/s40544-024-0871-x","url":null,"abstract":"High-temperature lubrication has always been a hot topic in the lubricant and grease industry, and is also an essential concern in the high-end equipment sector to be addressed. Carbon quantum dots (CQDs) are an emerging material widely applied in the field of lubrication, owing to their exceptional lubricity and high load-bearing capacity. However, the vulnerability of CQDs to oxidation in air and reduced stability dramatically restrict their high-temperature application capability. In this study, a nanocomposite of amphiphilic polyvinyl pyrrolidone (PVP) homopolymer with excellent lubricating properties and thermal stability, which is hydrogen bonded to CQDs (CQDs@PVP), was designed to achieve low friction and wear of lubricants at high temperatures. The CQDs@PVP are consistently dispersed in both PEG400 and water, and exhibit superior lubricity compared to unmodified CQDs at high temperatures (ranging from 200–150 °C and 90.50 °C). Meanwhile, the dense carbon film on the wear surface and the chemically reactive film of iron compounds directly contribute to the enhanced lubrication performance. These analytical results demonstrate the powerful candidacy of CQDs@PVP as a lubrication additive and promote future high-temperature applications of CQDs in industrial production.","PeriodicalId":12442,"journal":{"name":"Friction","volume":"3 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764183","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

Recent developments in functional organic polymer coatings for biomedical applications in implanted devices 用于生物医学植入设备的功能性有机聚合物涂层的最新进展

IF 6.8 1区工程技术

Friction Pub Date : 2024-07-22 DOI: 10.1007/s40544-023-0850-7

Yinuo Yang, Yiran Jia, Yanran Zhao, Haimang Wang, Hongyu Zhang

{"title":"Recent developments in functional organic polymer coatings for biomedical applications in implanted devices","authors":"Yinuo Yang, Yiran Jia, Yanran Zhao, Haimang Wang, Hongyu Zhang","doi":"10.1007/s40544-023-0850-7","DOIUrl":"https://doi.org/10.1007/s40544-023-0850-7","url":null,"abstract":"Organic polymer coatings have been commonly used in biomedical field, which play an important role in achieving biological antifouling, drug delivery, and bacteriostasis. With the continuous development of polymer science, organic polymer coatings can be designed with complex and advanced functions, which is conducive to the construction of biomedical materials with different performances. According to different physical and chemical properties of materials, biomedical organic polymer coating materials are classified into zwitterionic polymers, non-ionic polymers, and biomacromolecules. The strategies of combining coatings with substrates include physical adsorption, chemical grafting, and self-adhesion. Though the coating materials and construction methods are different, many biomedical polymer coatings have been developed to achieve excellent performances, i.e., enhanced lubrication, anti-inflammation, antifouling, antibacterial, drug release, anti-encrustation, anti-thrombosis, etc. Consequently, a large number of biomedical polymer coatings have been used in artificial lungs, ureteral stent, vascular flow diverter, and artificial joints. In this review, we summarize different types, properties, construction methods, biological functions, and clinical applications of biomedical organic polymer coatings, and prospect future direction for development of organic polymer coatings in biomedical field. It is anticipated that this review can be useful for the design and synthesis of functional organic polymer coatings with various biomedical purposes.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"29 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737078","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

Nickel phosphorous trisulfide: A ternary 2D material with an ultra-low coefficient of friction 三硫化磷镍：摩擦系数超低的三元二维材料

IF 6.8 1区工程技术

Friction Pub Date : 2024-07-22 DOI: 10.1007/s40544-024-0877-4

Haoyu Deng, Tongtong Yu, Changhe Du, Ruilin Shen, Yongkang Zhao, Xinjian He, Yange Feng, Liqiang Zhang, Daoai Wang

{"title":"Nickel phosphorous trisulfide: A ternary 2D material with an ultra-low coefficient of friction","authors":"Haoyu Deng, Tongtong Yu, Changhe Du, Ruilin Shen, Yongkang Zhao, Xinjian He, Yange Feng, Liqiang Zhang, Daoai Wang","doi":"10.1007/s40544-024-0877-4","DOIUrl":"https://doi.org/10.1007/s40544-024-0877-4","url":null,"abstract":"Ultra-low friction is crucial for the anti-friction, anti-wear, and long-life operation of nanodevices. However, very few two-dimensional materials can achieve ultra-low friction, and they have some limitations in their applications. Therefore, exploring novel materials with ultra-low friction properties is greatly significant. The emergence of ternary two-dimensional materials has opened new opportunities for nanoscale ultra-low friction. This study introduced nickel phosphorous trisulfide (NiPS3, referred to as NPS), a novel two-dimensional ternary material capable of achieving ultralow friction in a vacuum, into the large nanotribology family. Large-size and high-quality NPS crystals with up to 14 mm × 6 mm × 0.3 mm dimensions were grown using the chemical vapor transport method. The NPS nanosheets were obtained using mechanical exfoliation. The dependence of the NPS nanotribology on layer, velocity, and angle was systematically investigated using lateral force microscopy. Interestingly, the coefficient of friction (COF) of NPS with multilayers was decreased to about 0.0045 under 0.005 Pa vacuum condition (with load up to 767.8 nN), achieving the ultra-low friction state. The analysis of the frictional dissipation energy and adhesive forces showed that NPS with multilayers had minimum frictional dissipation energy and adhesive forces since the interlayer interactions were weak and the meniscus force was excluded under vacuum conditions. This study on the nanoscale friction of a ternary two-dimensional material lays a foundation for exploring the nanoscale friction and friction origin of other two-dimensional materials in the future.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"60 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737067","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

Enamel matrix proteins in promoting saliva lubrication 促进唾液润滑的釉质基质蛋白

IF 6.8 1区工程技术

Friction Pub Date : 2024-07-22 DOI: 10.1007/s40544-024-0873-8

Hujun Wang, Yue Tang, Haonan Qiu, Jingyang Hu, Yuan Su, Jing Zheng, Zhongrong Zhou

{"title":"Enamel matrix proteins in promoting saliva lubrication","authors":"Hujun Wang, Yue Tang, Haonan Qiu, Jingyang Hu, Yuan Su, Jing Zheng, Zhongrong Zhou","doi":"10.1007/s40544-024-0873-8","DOIUrl":"https://doi.org/10.1007/s40544-024-0873-8","url":null,"abstract":"Anti-wear performance of human enamel in the mouth is closely related to the lubrication of salivary pellicle. It is well known that the inorganic hydroxyapatite (HA) of the enamel plays an important role in the adsorption and pellicle-forming of salivary proteins on the enamel, but the role of enamel matrix proteins remains unclear. In this study, the adsorption and lubrication behavior of salivary proteins on original, heated, and deproteinated enamel surfaces was comparatively investigated using an atomic force microscopy and nano-indentation/scratch techniques. Compared with that on the original enamel surface, the adsorption and lubrication behavior of salivary proteins remains almost unchanged on the heated enamel surface (where the enamel matrix proteins are denatured but the size of HA crystalline nanoparticles keeps constant) but exhibits an obvious compromise on the deproteinated enamel surface (where the enamel matrix proteins are removed and agglomeration of HA crystallites occurs). The HA agglomeration weakens the electrostatic interaction of enamel surfaces with salivary proteins to cause a distinct negative influence on the adsorption and pellicle-forming of salivary proteins. Further, the negative effect is confirmed with a quartz crystal microbalance with dissipation. In summary, by regulating enamel nanostructure for appropriate electrostatic interactions between salivary proteins and enamel surfaces, the enamel matrix proteins play an essential role in the adsorption and pellicle-forming of salivary proteins on human enamel, and then contribute to saliva lubrication, which provides the enamel with an anti-wear mechanism. The findings will promote and assist the design of enamel-inspired anti-wear materials.\u0000","PeriodicalId":12442,"journal":{"name":"Friction","volume":"335 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737068","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