多孔UHMWPE的制备与摩擦学性能研究

用热压成型法制备多孔超高分子量聚乙烯(UHMWPE)和普通UHMWPE试样,在改制的摩擦磨损试验机上考察2种试样在水润滑和牛血清润滑下的摩擦磨损性能。结果表明:普通UHMWPE均处于边界润滑区域;多孔UH-MWPE在较低载荷下因可以获得额外的润滑而形成混合润滑,摩擦因数和磨损量较低,其磨损机制为轻微的擦伤磨损;随着载荷的增加,多孔UHMWPE试样的磨损量明显上升并高于同等条件下普通UHMWPE,呈现较严重的切削磨损;多孔UHMWPE只适合应用于低载工况下。     

石墨润滑下人字闸门底枢摩擦副摩擦学性能*

为研究石墨润滑条件下各参数对人字闸门底枢摩擦副摩擦磨损性能的影响，采用UMT-2多功能摩擦磨损试验机进行销-盘摩擦副试验，模拟闸门底枢低速重载工况条件，研究不同摩擦速度、石墨粒径下不同表面粗糙度人字闸门底枢摩擦副的摩擦磨损性能。试验结果表明：在不同转速工况下，表面粗糙度为0.8 μm的摩擦副采用粒径10 μm石墨颗粒润滑时润滑性能最优，表面粗糙度为2.0 μm的摩擦副采用粒径21 μm石墨颗粒润滑时润滑性能最优；随着转速增加，摩擦副摩擦因数与磨损量均增加。研究表明，石墨粒径大小和摩擦副表面粗糙度共同影响摩擦副摩擦学性能，这为闸门底枢的固体润滑剂选择和摩擦参数设计提供理论依据。     

不同环境介质下氧化铝陶瓷与耐蚀金属摩擦磨损行为

为优选海水淡化高压泵关键零部件耐磨性能材料,以Al_2O_3陶瓷与TC4钛合金、316不锈钢、2205双相不锈钢组成的配对摩擦副作为研究对象,利用立式万能摩擦磨损试验机开展干摩擦、纯水及海水3种环境介质下配对材料的摩擦磨损试验,定量得到各摩擦副摩擦因数、磨损量,并对摩擦试样的表面形貌进行分析;采用正交试验法分析载荷、转速、环境介质对摩擦因数和磨损量的影响规律。结果表明:在相同的条件下,TC4钛合金与陶瓷配副摩擦因数较小,2205双相不锈钢与陶瓷配副磨损量较小;环境介质对摩擦因数影响较大,载荷对磨损量的影响较大;海水环境下2205双相不锈钢和316不锈钢磨痕较浅,磨损机制为疲劳磨损、磨粒磨损和腐蚀磨损的交互作用。     

多因素影响的格莱圈材料摩擦磨损试验研究*

格莱圈由聚四氟乙烯(PTFE)矩形滑环和丁腈橡胶(NBR)O形圈组成。为了研究不同因素对于格莱圈密封材料摩擦磨损性能的影响,利用UMT-3多功能摩擦磨损试验机,通过改变往复频率、粗糙度、润滑状态研究格莱圈材料与45钢配副时的摩擦磨损性能,利用SEM对试块试验前后表面形貌进行观测,并对摩擦磨损机制进行分析。试验结果表明:在干摩擦和滴油润滑条件下PTFE材料相比NBR材料具有更为优异的摩擦磨损性能;NBR材料表面粗糙度过高或过低都会导致摩擦因数升高,表面粗糙度对具有自润滑性能的PTFE材料的摩擦因数影响不大;高往复频率会使NBR材料摩擦因数降低,过高或过低的往复频率都会使PTFE材料摩擦因数降低;NBR材料的磨损形式以磨粒磨损和黏着磨损为主,PTFE材料以黏着磨损和疲劳磨损为主。     

载流条件下的1Cr18Ni9Ti/浸金属碳摩擦磨损性能研究

在销-盘摩擦磨损试验机上试验了载荷、速度、电流对1Cr18Ni9Ti/浸金属碳对磨时的摩擦因数、磨损量及磨损形貌的影响。试验结果表明,载荷对1Cr18Ni9Ti/浸金属碳摩擦副的摩擦因数和销试样的磨损率有显著影响:载荷越大,摩擦因数越大,磨损率越低;摩擦因数、磨损率与速度的关系受载荷的制约。当低载时,以电流影响为主。销试样的磨损表面出现了粘着磨损,氧化磨损和电弧烧蚀。     

不同环境介质下TC4钛合金与工程塑料摩擦磨损行为研究

为优选透平式能量回收一体机关键零部件耐磨材料,以TC4钛合金与共聚甲醛、均聚甲醛、PEEK及改性PEEK组成的配对摩擦副作为研究对象,利用立式万能摩擦磨损试验机开展干摩擦、纯水及海水环境介质下配对材料的摩擦磨损试验,定量获得各摩擦副的摩擦因数和磨损量,并对摩擦试样的表面形貌进行分析。结果表明:在干摩擦环境下共聚甲醛摩擦因数和磨损量最小,在纯水和海水环境下改性PEEK摩擦因数和磨损量最小;TC4钛合金与均聚甲醛、共聚甲醛、PEEK配副时磨损机制为黏着磨损,主要表现形式为涂抹和擦伤,TC4与改性PEEK配副时磨损较轻微,主要表现形式为轻微磨粒磨损。     

SLM成形表面织构对TC4钛合金干摩擦磨损性能的影响

基于一步法思路,采用金属3D打印机基于激光选区熔化（SLM）技术制备表面带有凹坑织构的TC4钛合金试样,采用光学相机、超景深显微镜和扫描电镜观察织构成形情况,利用激光共聚焦位移测试仪和显微维氏硬度计分别测试表面粗糙度和表面硬度,在干摩擦条件下采用摩擦磨损试验仪考察不同载荷下织构密度对TC4钛合金试样摩擦学性能的影响,并使用扫描电镜对摩擦实验前后的表面形貌进行分析。研究结果表明：一步法SLM成形能够在TC4钛合金表面获得成形良好的直径500 μm的织构;随着织构密度的提高,钛合金试样表面粗糙度增大,表面硬度有所降低;干摩擦条件下,提高TC4钛合金试样织构密度有利于磨屑的收集从而减少试样的三体磨损,提高载荷有利于改善摩擦副接触状态;5 N载荷下40%织构密度试样的平均摩擦因数和磨痕宽度均最小,与无织构试样相比,平均摩擦因数和磨痕宽度分别降低12%和16%;40%织构密度下,载荷提高会引起摩擦因数的降低和磨损量增大,磨损表面犁沟和片状剥落增多。在干摩擦条件下,3D打印一步法制备的表面织构可以显著改善TC4钛合金的磨粒磨损和黏着磨损。     

不同润滑液下的Al2O3增强Y-TZP陶瓷/316L不锈钢生物摩擦学特性

采用销-盘式摩擦磨损试验机研究了氧化铝增强氧化锆(ADZ)陶瓷材料/316L不锈钢摩擦副在去离子水和小牛血清2种不同介质润滑下的生物摩擦磨损行为,并利用SEM观察了磨损表面形貌。结果表明:与去离子水相比,在小牛血清润滑条件下ADZ陶瓷的摩擦因数和磨损率降低。在去离子水润滑条件下ADZ陶瓷材料的磨损为轻微磨损,相应的磨损机制为塑性变形和微犁削;而在小牛血清润滑条件下,ADZ陶瓷材料的磨损为微量磨损,磨损过程类似抛光作用。     

旋耕机湿地弯刀的摩擦磨损性能试验研究

利用HSR-2M高速式往复摩擦磨损试验机,研究湿态条件下,湿地弯刀表面粗糙度、往复速度和法向载荷等对旋耕机湿地弯刀摩擦因数和磨损量的影响,并通过磨痕形貌分析其磨损机制。试验结果表明:摩擦因数和磨损量随着旋耕机湿地弯刀表面粗糙度的增大而增大;磨损量随法向载荷的增大而增大,而随往复速度的增大先减小后增大;摩擦表面温度随着法向载荷和相对运动速度的增大而增大;湿态条件下湿地弯刀的磨损机制以磨粒磨损为主,局部有点蚀现象出现。     

缸套表面微凹坑对Ｃｕ－Ｓｎ/Ｃｒ多镀层活塞环摩擦性能的影响

选用表面没有微凹坑的铸铁缸套和表面加工有微凹坑的铸铁缸套,分别与Cu-Sn/Cr多镀层活塞环配对,采用往复式摩擦磨损试验机进行摩擦磨损试验,通过测量配对副的摩擦因数和磨损量和分析试样磨损前后表面形貌和成分,探讨高强化工况下铸铁缸套表面微凹坑对Cu-Sn/Cr多镀层活塞环摩擦性能影响。结果表明:表面有微凹坑的缸套与Cu-Sn/Cr多镀层活塞环配对时的摩擦因数、缸套磨损量、活塞环磨损量比表面没有微凹坑缸套的配对副分别低4.05%、52.25%、8.50%;缸套表面的微凹坑能够为从活塞环表面脱落的Cu-Sn镀层提供镶嵌点,使Cu-Sn镀层起到二次润滑的作用,延长了其作用寿命,减小了配对副的摩擦因数和磨损量。     

Tribological and nanoscale research on model friction couples intended for hip joint prostheses

Abstract

The paper presents the results of tribological and nanoscale research on model friction couples intended for hip joint prostheses. The tribological tests were performed by means of reciprocating pin on plate testing machine. The investigated friction pairs contained plates rubbing against polymer pins. The test plates were made from seven kinds of ceramics containing different concentrations of ZrO₂ and Al₂O₃, and two kinds of Co–Cr alloy. The test pins were made from UHMWPE. Tribological tests were performed in conditions of Ringer solution circulation. On the basis of friction force measurements, for each investigated friction couple, the average coefficient of friction was calculated. On the basis of total wear measurements, for each investigated couple, the wear intensity was calculated. Before and after every test, the plates and pins were analysed by means of atomic force microscopy. The difference in plate surface roughness was determined by the results of the atomic force microscopy analyses.

It was stated, that in the case of investigated friction joints, working under reciprocating motion, the wear and friction coefficient correlates with the surface roughness of plate specimens. For the plates with higher surface roughness, the lower friction coefficient and also lower UHMWPE pin wear intensity were observed. The friction coefficient and wear intensity were increasing with decreasing surface roughness. The correlation is confirmed by the differences in material transfer process. Considering investigated friction couples, the pin polymer material is smeared on the ceramic plates with the highest surface roughness creating a thin polymer film. In the case of ceramic surfaces with the lowest surface roughness, the strong adhesive bounds are created and some large particles of polymer are transferred to ceramic surface.     

Fretting wear behavior of nitrogen ion implanted titanium alloys in bovine serum lubrication

Nitrogen ion implantation was performed on biomedical titanium alloys by using of the PBII technology to improve the surface mechanical properties for the application of artificial joints. The titanium nitride phase was characterized with X-ray photoelectron spectroscopy (XPS). The nanohardness of the titanium alloys and implanted samples were measured by using of in-situ nano-mechanical testing system (TriboIndenter). Then, the fretting wear of nitrogen ion implanted titanium alloys was done on the universal multifunctional tester (UMT) with ball-on-flat fretting style in bovine serum lubrication. The fretting wear mechanism was investigated with scanning electron microscopy (SEM) and 3D surface profiler. The XPS analysis results indicate that nitrogen diffuses into the titanium alloy and forms a hard TiN layer on the Ti6Al4V alloys. The nanohardness increases from 6.40 to 7.7 GPa at the normal load of 2 mN, which reveals that nitrogen ion implantation is an effective way to enhance the surface hardness of Ti6Al4V. The coefficients of friction for Ti6Al4V alloy in bovine serum are obviously lower than that in dry friction, but the coefficients of friction for nitrogen ion implanted Ti6Al4V alloy in bovine serum are higher than that in dry friction. Fatigue wear controls the fretting failure mechanism of nitrogen ion implanted Ti6Al4V alloy fretting in bovine serum. The testing results in this paper prove that nitrogen ion implantation can effectively increase the fretting wear resistance for Ti6Al4V alloy in dry friction, and has a considerable improvement for Ti6Al4V alloy in bovine serum lubrication.     

Biotribological properties of Ti/TiB2 multilayers in simulated body solution

Ti/TiB₂ multilayers with various modulation ratios were prepared by magnetron sputtering on biomedical titanium alloy Ti6Al4V. The tribological properties of the multilayers sliding against ultra-high molecular weight polyethylene under lubrication with Hank׳s solution were also investigated. The results demonstrated that the tribological properties strongly depended on the modulation ratios of multilayers. The coefficient of friction of multilayers with a modulation ratio of 1:5 was 0.1, a reduction by 28.6%; the wear volume loss of UHMWPE decreased by almost one order of magnitude compared to that of Ti6Al4V alloy, exhibiting excellent anti-friction and anti-wear properties. The oxidation wear of Ti6Al4V alloy could be restrained effectively and converted to abrasion wear and/or adhesive wear by the laminate structures in the multilayers, suggesting that this material may serve as a potential candidate for the surface modification of artificial joints.     

电场对WC-Co/Ti6Al4V摩擦磨损性能的影响

为了研究电场对摩擦副摩擦磨损性能的影响,在自行设计的高速摩擦磨损试验装置上,进行了WC-Co/Ti6Al4V摩擦副的摩擦磨损试验。结果表明：断开摩擦副热电回路可以有效地减小热电流对WC-Co/Ti6Al4V摩擦副摩擦磨损的影响,静电冷却环境下形成的强电场的效果更加明显,在抑制摩擦副磨损的同时还可以改善
Ti6Al4V磨损表面质量。通过扫描电镜及EDS能谱分析可知,静电冷却条件下的列宾捷尔效应削弱了钛合金的黏着能力,从而有效地减小了WC-Co的黏着磨损;WC-Co在高速摩擦时主要以黏着磨损、氧化磨损为主,同时伴有微裂纹的产生。
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Schiff碱铜(Ⅱ)配合物微纳米粉体改性UHMWPE初探

制备出稳定分散的乙二胺缩水杨醛Schiff碱铜(Ⅱ)配合物微纳米粉体,并用扫描电镜和红外光谱鉴定其结构和粒径.在25％(体积分数)小牛血清去离子水溶液边界润滑条件下,以5％(质量分数)微纳米乙二胺缩水杨醛Schiff碱铜(Ⅱ)配合物作为添加剂改性UHMWPE,与Ti6A14V配对进行往复摩擦磨损试验,并与其微米级粉体改性UHMWPE的摩擦学性能进行对比.结果表明,在改性添加剂质量分数为5％时,对于减少改性UHMWPE自身和对偶件Ti6Al4V的磨损和降低摩擦副的摩擦,乙二胺缩水杨醛Schiff碱铜(Ⅱ)配合物微纳米粉体比其微米级粉体更加有效.     

Surface morphology in engineering applications: Influence of roughness on sliding and wear in dry fretting

Influence of initial surface roughness on friction and wear processes under fretting conditions was investigated experimentally. Rough surfaces (Ra=0.15-2.52 μm) were prepared on two materials: carbon alloy (AISI 1034) and titanium alloy (Ti-6Al-4V). Strong influence of initial surface roughness on friction and wear processes is reported for both tested materials. Lower coefficient of friction and increase in wear rate was observed for rough surfaces. Wear activation energy is increasing for smoother surfaces. Lower initial roughness of surface subjected to gross slip fretting can delay activation of wear process and reduce wear rate; however, it can slightly increase the coefficient of friction.     

Experimental analysis of tribological behavior of UHMWPE against AISI420C and against TiAl6V4 alloy under dry and lubricated conditions

Friction and wear behavior of ultra-high molecular weight polyethylene (UHMWPE) sliding against AISI420C austenitic stainless steel and against TiAl6V4 alloy under dry and lubricated conditions were investigated with a reciprocating pin-on-flat tribometer for comparative purposes. The tests were conducted by varying frequency of the pin alternative motion and the applied normal load. For the tests in lubricated conditions a fluid containing a large amount of sodium hyaluronate has been chosen. By using an electronic precision balance the wear mass loss of the UHMWPE samples was evaluated accordingly. Friction is greatly reduced by the presence of UHMWPE and this is believed to be due to the formation of a lubricating film of UHMWPE in the contact zone. Furthermore, the experimental investigation shows that the AISI420C/UHMWPE gives, in dry conditions, better values in the wear rate and in the friction coefficient than the TiAl6V4/UHMWPE.     

钛合金微弧氧化层的摩擦学性能研究

利用微弧氧化技术在Ti6Al4V合金表面制备了富含钙、磷的多孔氧化陶瓷层,研究了微弧氧化层表面形貌、组成及摩擦学性能。研究结果表明,随着电压的升高,氧化层表面微孔孔径、粗糙度和Ca、P元素含量增大,显微硬度增大。25%小牛血清润滑条件下的微弧氧化层与ZrO2陶瓷球的摩擦学实验表明,微弧氧化层的摩擦因数高于Ti6Al4V钛合金,但磨损率明显降低,表明微弧氧化Ti6Al4V合金具有良好的耐磨性能。     

Reciprocating sliding of uniaxially-stretched ultra-high molecular weight polyethylene for medical device applications

Solid-state deformation of UHMWPE used in total joint prosthesis could be a relevant treatment prior to cross-linking to obtain high strength. However, little is known about the influence of chain alignment (texture) on sliding wear behavior. In this work, we analyzed i) the deformation mechanisms of UHMWPE resulting from a uniaxial tension (elongation of about 300%) and ii) the influence of the texture on the friction behavior resulting from ball-on-flat sliding tests (reciprocating sliding mode). Microstructural investigations show that tension induces a transformation of the initial lamellar morphology into specific microfibrillar morphology. White light interferometer (WLI) studies show that texturing causes an increase of the roughness by a factor of about two. After 50,000 sliding cycles, the cumulative dissipated energy decreases from 109,300-103,600 μJ for untreated UHMWPE to 64,600 and 43,150 μJ for textured UHMWPE, parallel and perpendicular to the texture direction, respectively. Considering that wear resistance increases with decreasing dissipated energy, textured UHMWPE may have anti-wear properties. However, cracks are noted at microscopic scale for textured UHMWPE. Regarding wear resistance, such defects are not suitable and can be avoided by reducing the roughness of textured UHMWPE prior to wear tests.     

New insights into wear of Ti6Al4V by ultra-high molecular weight polyethylene under water lubricated conditions

Laboratory studies indicate that sliding Ti6Al4V against soft ultra-high molecular weight polyethylene (UHMWPE) pins produces severe damage to the titanium and the lubricant (water) changes colour suggesting chemical change. Blackening of periprosthetic tissues associated with titanium wear debris was also observed in clinical investigations. To increase scientific understanding of the mechanism involved, systematic characterisation work has been conducted employing grow discharge spectrometry (composition), scanning electron microscopy (wear morphology) and cross-sectional transmission electron microscopy (phase identification). Experimental results show that hydrogen may play an important role in promoting the formation of abrasive particles in the Ti6Al4V/UHMWPE tribosystem under water lubricated conditions. The observed abnormal wear of Ti6Al4V by soft UHMWPE can be to a large extent attributed to hydrogen evolution and formation of titanium hydride. Based on experimental results and discussion, a hydrogen-assisted wear mechanism is proposed.