La2O3改性Ti/MoS2镍基复合涂层微观组织和 摩擦学性能研究

目的 为提升Ni60A+Ti/MoS2复合涂层的力学性能和摩擦学性能。方法 利用激光熔覆技术在HT270灰铸铁表面制备了La2O3改性镍基自润滑复合涂层,通过硬度测试、摩擦磨损实验、XRD测试分析和扫描电镜分析,对比分析了La2O3添加量对复合涂层的微观组织、相组成、显微硬度和室温及200 ℃条件下摩擦学性能的影响。结果 La2O3改性后的涂层主要由CrNiFeC、NiTi、(Fe,Cr)7C3、Cr7C3、TiC、Ti2CS、MoS2相和La2O3组成。添加La2O3后可以明显细化晶粒,使组织更加均匀致密,提高了熔覆层显微硬度及耐磨性。当La2O3的添加量为1.0%时,涂层的硬度值最高达776HV0.2。La2O3改性后,涂层的摩擦学性能也得到了优化。室温时,1.0%La2O3涂层的磨损失重仅为1.8 mg,摩擦系数为0.48,与未添加La2O3的涂层相比,磨损失重降低了47.1%,摩擦系数也明显降低;200 ℃高温磨损时,1.0%La2O3涂层的磨损失重降低了41.3%,摩擦系数降低到0.50。结论 La2O3的加入可以有效提高涂层的减摩性和耐磨性等摩擦学性能,同时还能优化涂层的组织结构和硬度等力学性能。采用激光熔覆技术制备的La2O3改性镍基涂层,力学性能和摩擦学性能得到有效提高。     

The effect of substrate surface integrity on the surface properties of TiCrN coating applied via the CAE-PVD method

This study aims to investigate how the predeposition machining processes such as magnetic grinding, turning machining, and wire electrical discharge machining can influence the surface properties including electrochemical and tribological behavior of TiCrN nanostructured coating applied on Mo40 steel substrate. A physical vapor deposition technique using cathodic arc evaporation was used to apply the coating. The crystallographic phases and the microstructure of the coating were studied by X-ray diffraction and scanning electron microscope, respectively. Rockwell-C, electrochemical impedance spectroscopy and potentiodynamic polarization, and pin-on-disk wear tests were employed to evaluate the adhesion strength, corrosion behavior, and tribological property of specimens, respectively. The electrochemical results after 24 h of exposure to 3.5 wt% NaCl solution showed that TiCrN coating pretreated with a turning process with polarization resistance of about 3525.32 Ω.cm² had the best corrosion resistance among all specimens. This was because of the improvement of the smoothness, surface quality, and adhesion after the turning process. On the other, the friction coefficient of the grounded sample is less than that of other ones. This is probably due to its higher adhesion strength and higher surface smoothness.     

Nickel-based metal−organic framework-derived whisker-shaped nickel phyllosilicate toward efficiently enhanced mechanical,flammable and tribological properties of epoxy nanocomposites

Metal−organic framework-derived materials have attracted significant attention in the applications of functional materials. In this work, the rod-like nickel-based metal−organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology. Then, the nickel phyllosilicate whiskers were evaluated to enhance the mechanical, thermal, flammable, and tribological properties of epoxy resin. The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix, improving the tensile strength and elastic modulus by 13.6% and 56.4%, respectively. Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings, it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities. Additionally, it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature. Moreover, the wear rate of epoxy resin nanocomposites was reduced significantly by 80% for pure epoxy resin by adding 1 phr whiskers. The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites.     

钛合金表面织构化与构建生物活性涂层的研究进展

医用钛合金作为临时基质的植入材料对周围新组织的生长具有特殊的诱导作用。针对椎弓根螺钉固定系统对钛合金基材表面机械性能和生物活性的共同需求,表面织构与生物活性涂层对钛合金表面的改性展示出独特的优越性。文中详细介绍了钛合金表面织构化对其摩擦学性能和生物相容性的影响,以及构建生物活性涂层的种类;总结了钛合金表面织构的作用机理,生物活性涂层的改善机制,阐述了表面织构化与构建生物活性涂层各自的局限性,并指出钛合金作为生物医用材料仍需要解决的问题及未来的研究趋势。     

石墨烯在PAO基础油中的摩擦学性能

为了改善石墨烯在润滑油中的分散稳定性,利用一种高分子量丁二酰亚胺（分散剂A）辅助石墨烯分散于聚α-烯烃（PAO4）基础油中,采用紫外-可见分光光度法对其分散稳定性进行了监测,并使用UMT-3多功能摩擦试验仪和ContourGT-K型三维轮廓仪考察了石墨烯/PAO4分散液的摩擦磨损性能,利用扫描电子显微镜（SEM）、能谱仪（EDS）和X射线光电子能谱（XPS）对磨痕表面的形貌和元素组成进行定性和定量分析。结果表明：分散剂A可有效提高石墨烯在PAO4中的分散稳定性,加入分散剂A后,石墨烯/PAO4分散液静置一周后的相对浓度为0.667,是未加分散剂的分散液的7.8倍;石墨烯作为润滑油添加剂能显著提升摩擦磨损性能,添加0.8 mg/mL的石墨烯和质量分数为0.2%的分散剂A,跑合期从670 s缩短至250 s,磨损体积减少了55%。     

偏压对自源笼形空心阴极放电制备Si-DLC薄膜结构和性能的影响

针对利用笼形空心阴极放电在大工件表面制备DLC薄膜时,笼网内大工件操作困难、大工件影响放电的问题,开发了自源笼形空心阴极放电方法,在不同偏压（-300~0 V）条件下于Si （100）表面制备了Si-DLC薄膜,考察了偏压对Si-DLC薄膜结构和性能的影响。结果表明：获得Si-DLC的沉积速率达到7.90 μm/h。由偏压引起的高能离子轰击使薄膜的组织结构更为致密,降低了表面粗糙度和H含量。Si-DLC薄膜中的sp³/sp²值随偏压增加先上升后下降,薄膜纳米压入硬度和弹性模量也呈现相同规律。偏压为-200 V沉积的Si-DLC薄膜具有最高的sp³/sp²（0.69）、H/E和H³/E²值,表现出致密的结构和优异的摩擦性能,摩擦因数低至0.024,磨损率为1×10^-6 mm³/Nm。说明自源笼形空心阴极放电是一种有效制备大面积DLC膜的工艺,-200 V偏压是最优化的参数。     

Cr/WC/DLC薄膜的多环境摩擦学性能

采用磁控溅射法,在304不锈钢上制备Cr/WC/DLC多层梯度过渡类金刚石薄膜,利用场发射扫描电子显微镜(SEM)、拉曼光谱仪(Raman)、纳米压痕仪、划痕测试仪等分析薄膜的微观结构和力学性能,利用UMT-3多功能摩擦磨损试验机考察其在大气、去离子水、发动机油3种环境下的摩擦学性能。结果表明:该薄膜的多层梯度设计使其膜基间结合力得到了有效改善,且硬度高达32.6GPa,在3种环境下均具有优异的摩擦学性能。在大气环境下,薄膜具有较低的平均摩擦因数,为0.094;但具有3种环境下最大的磨损率,为7.86×10-8 mm3(N·m)-1;在去离子水环境下,薄膜的平均摩擦因数较高,为0.124;而其磨损率较低,为5.26×10-8 mm3(N·m)-1;在发动机油环境下,固-油复合润滑效应使薄膜具有更加优异的摩擦学性能,其平均摩擦因数和磨损率均为3种环境下的最小值,分别为0.065和4.44×10-8 mm3(N·m)-1。     

45钢表面化学镀Ni-B涂层的耐蚀性及摩擦学性能

针对45钢在海水环境中耐蚀性及耐磨性能差的问题,采用化学镀技术在45钢表面上构筑Ni-B涂层,利用扫描电子显微镜、原子力显微镜、X射线衍射仪和硬度计对涂层表面形貌、晶体结构和硬度进行表征,通过电化学动电位极化评估涂层的耐蚀性能,并考察涂层在3.5%NaCl溶液下的减摩和耐磨性能。结果表明:钢表面上化学镀Ni-B涂层呈"花瓣"状的非晶态结构,在3.5%NaCl溶液中的自腐蚀电位为-0.47V,相对于基体提高了0.06V,自腐蚀电流密度为8.991×10-6 A/cm2,相对于基体下降近两个数量级。同时,在3.5%NaCl溶液下,Ni-B涂层的摩擦因数相对于基体下降0.1,磨损宽度更窄。     

超音速火焰喷涂WC-27CrNi涂层转动微动摩擦学行为

利用超音速火焰喷涂技术在LZ50钢基材表面制备WC-27Cr Ni涂层。对WC-27Cr Ni涂层及其基体材料在干态不同角位移幅值下进行转动微动磨损试验,并利用扫描电子显微镜、能谱仪和3D轮廓仪对磨痕进行微观分析。试验结果表明:与基材相比,WC-27Cr Ni涂层在部分滑移区的运行范围向左移动,滑移区的运行范围增大。在部分滑移区,涂层的摩擦系数呈"跑和-爬升-稳定"3个阶段,明显低于基材,且损伤十分轻微;滑移区,涂层剥落的硬质颗粒使得稳定阶段摩擦系数高于基材,磨损机制为磨粒磨损、氧化磨损和剥层。     

碳织物增强聚合物基自润滑材料摩擦学性能研究进展

从聚合物基体、组分改性、碳织物增强工艺、材料摩擦磨损机制等方面综述碳织物增强树脂基自润滑复合材料摩擦学研究现状。比较热塑性与热固性树脂基体在该类材料中的应用特点,介绍聚合物本体改性和减摩增强填料改性提高摩擦学性能的各种方法,总结当前摩擦学研究中碳织物增强制备工艺及典型材料的摩擦学性能,指出减摩机制、磨损形式、摩擦温升为该类材料摩擦学性能研究中关注的焦点。温度范围广、力学性能优良、易加工成型、无污染的新型材料与成型工艺为今后碳织物增强聚合物基自润滑复合材料摩擦学研究中的首选。