Tribological Properties of a Dendrite-reinforced Ti-based Metallic Glass Matrix Composite under Different Conditions

The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite (Ti42 Zr22 V1 4-Cu5 Be1 7 )prepared by copper mould casting were analyzed at different normal loads under the dry condition and rain-water.The results showed that the average value of the frictional coefficients and micro-hardness ascended with in-creasing the normal load,while the wear rate showed a trend of decline under the dry condition.The electrochemical test results showed that the surface of samples was pitting corroded in the rainwater.The matrices were corroded first.Then the dendrites were exposed,leading to the damage of the surface.Both the frictional coefficients and wear rate of the composite in the rainwater were larger than those under the dry condition,primarily owing to the corro-sion of chloride ions on the worn surface.The wear mechanisms of composites were mainly adhesive wear,accompa-nied by the abrasive wear under the dry condition and corrosive wear in the rainwater.The composites have higher wear resistance both under the dry condition and rainwater due to the lower wear rate.     

Tribological properties of Cu-La_2O_3 composite under different electrical currents

A new type of Cu-La2O3 composite was fabricated by internal oxidation method using powder metallurgy.Sliding wear behavior of the Cu-La2O3 composite was studied on a pin-on-disc wear tester under various electrical currents and applied loads.The worn surfaces were characterized using scanning electron microscopy and energy dispersive spectroscopy to probe the wear mechanisms.The results indicated that applied load had a significant effect on the wear rate of the Cu-La2O3 composite pins.The wear rate displayed the minimum value at the load of 50 N during electrical sliding processes.The corresponding wear mechanism was identified to be adhesive wear,abrasive wear,oxidation wear and arc erosion.     

C/C-Cu复合材料的摩擦磨损行为

采用无压熔渗方法制备1种新型的C/C-Cu复合材料,研究该材料与紫铜对偶在干摩擦往复运动条件下的磨损行为,系统考察载荷30～70 N和速度0.25～1.0 m/s范围内摩擦副材料的磨损性能;通过对磨损表面及磨屑的显微分析,建立C/C-Cu复合材料的磨损机制转变图。结果表明:在选定的试验条件下,根据C/C-Cu复合材料的磨损程度,可将磨损图划分为轻微磨损区和严重磨损区。在轻微磨损区,低载荷下的主要磨损机制为磨粒磨损和氧化磨损;在较高载荷下,磨损主要由磨屑膜的脱落引起;在严重磨损区,复合材料的磨损机制为剥落磨损。     

超音速火焰喷涂WC-12Co涂层的滑动磨损特性

利用超音速火焰喷涂工艺在铜基复合材料表面制备WC-12Co涂层.分析了涂层的微观结构、相组成和含量以及表面和截面硬度,并对涂层的摩擦磨损性能进行测试.结果表明：涂层组织和截面硬度分布均匀,耐磨性好,摩擦过程中会形成两种摩擦膜.磨损率随载荷增加而呈增大趋势,随转速的增加呈先减小后增大的趋势.涂层最适用的环境为300~500 r·min^-1和2~3 N,磨损率与滑动速度间的回归方程满足一元二次函数;磨损率与载荷间的回归方程满足指数方程.     

CrCN涂层在不同沉积温度下的摩擦学性能研究

利用多弧离子镀技术,在乙炔和氮气环境下,设定不同沉积温度(150℃、250℃、350℃、450℃),在316L不锈钢及单晶硅片上沉积CrCN涂层,通过XRD、XPS、SEM、纳米压痕仪和UMT-3多功能摩擦磨损试验机等涂层的微观结构、力学性能和摩擦学性能进行表征.结果表明:随着沉积温度的升高,CrCN涂层的硬度和模量呈现出递增的趋势,在沉积温度为450℃时达到最高,分别为24 GPa和354 GPa;摩擦系数和磨损率则呈现出先递减后递增的趋势,在沉积温度为350℃时达到最低,摩擦系数在大气和水环境下分别为0.38和0.23,磨损率在大气和水环境下则分别为1.717 1×10-6mm3/N·m和9.529 7×10-7mm3/N·m.同时,涂层在水环境中的摩擦系数和磨损率均低于大气环境中,说明水分子在摩擦过程中起到了较好的润滑作用.     

激光熔覆WC/Ni60B复合涂层在水润滑滑动摩擦环境下的磨损特性

采用激光熔覆技术制备了Ni60B镍基合金涂层以及微米WC、纳米WC和微-纳米WC颗粒增强的Ni60B基复合涂层（分别称为WCm、WCn和WCmn复合涂层）.对制备涂层在Amsler200磨损试验机上进行了不同载荷和滑动距离的水润滑滑动磨损试验.结果表明：WC颗粒的加入显著提高了Ni60B涂层的耐磨性.WCm复合涂层和纳米WCn复合涂层的耐磨性差别不大,但磨损形貌不同.涂层在水润滑环境下的磨损量均远远低于干滑动摩擦,其原因是水膜的支撑或隔离作用降低了涂层与磨轮之间的接触应力,水的冷却作用减少了摩擦热引起的温度升高,降低了涂层摩擦表面的温升和热软化.水润滑摩损条件下,WCm和WCn复合涂层中过饱和W元素发生扩散和聚集.     

热镀锌DC54钢板耦合变形的摩擦行为

采用自行研制的耦合变形的摩擦试验机,研究了热镀锌DC54钢带与淬回火处理的DC53冷作模具钢对偶滑块在耦合变形条件下的摩擦磨损行为,并用有限元分析了耦合变形的摩擦条件下钢带沿厚向和摩擦面的应力分布.结果表明,在耦合变形的摩擦条件下,塑性变形是影响钢带摩擦行为的主要因素,随载荷的增加,镀锌钢带与滑块间的摩擦因数增大,磨损越剧烈.     

炭/炭复合材料的摩擦学性能与摩擦磨损机理的研究现状

综合评述了C/C复合材料摩擦磨损性能的各项影响因素及摩擦机理的研究现状,指出C/C复合材料摩擦磨损研究存在的问题,并提出了在进一步研究中值得重点关注的课题。     

油润滑下Al/MoSi2材料的摩擦学特性

运用M-200型磨损试验机测定了油润滑下Al/MoSi2材料的摩擦磨损性能，采用SEM和X射线观察与分析了摩擦副表面的形貌和相组成，探讨了磨损机制。结果表明：采用20#机油润滑可有效地提高Al/MoSi2材料的摩察磨损综合性能；与干摩擦状态相比，其摩擦系统和磨损率分别下降了40%和60%；油润滑时，Al/MoSi2材料的磨损机制主要表现为疲劳点蚀和磨粒磨损。     

铸钢轧辊电火花沉积YG8涂层的组织结构和性能

采用新型电火花沉积设备,把YG8电极材料沉积在铸钢轧辊材料上,制备了WC沉积涂层,研究了其微观组织及耐磨性能.结果表明:沉积层主要由Fe₃W₃C、Co₃W₃C、W₂C和Fe₇W₆C等相组成;沉积层与基体冶金结合,具有纳米颗粒尺寸的Fe₇W₆、W₂C等硬质相弥散分布于沉积层中;沉积层的平均硬度为1 331 HV;沉积层较铸钢轧辊的磨损性能提高了2.3倍;沉积层的磨损机理以疲劳磨损为主,细小的弥散分布的硬质相是沉积层硬度及耐磨性提高的主要因素.