青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能

在MM-200摩擦磨损试验机上研究了青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能,采用扫描电镜(SEM)对磨损表面形貌进行了观测和采用X射线能谱分析(XPS)分析了涂层成分。结果表明,在水润滑条件下涂层摩擦因数和磨损率均低于干摩擦条件下;在水润滑条件下磨损机制为轻微磨粒磨损和犁削磨损,在干摩擦下主要是较为严重的粘着磨损和犁削。这是由于水润滑降低了摩擦副界面温度,提高了石墨润滑膜的韧性,改善了润滑效果,从而阻止了粘着磨损的发生,水还促进了钢偶件表面致密氧化膜的形成,从而减轻磨损。因此水润滑对涂层磨损性能有较大影响。     

铜碲硒铁合金的干摩擦磨损性能

利用环-盘式摩擦磨损试验机研究了铜碲硒铁合金的干摩擦磨损行为,分析了载荷和摩擦速度等参数对该合金摩擦磨损性能的影响,并用扫描电子显微镜对磨损形貌进行了观察.结果表明:铜碲硒铁合金的摩擦因数随载荷的增加变化不大,但随摩擦速度的增加而明显增大;合金的磨损率随载荷和摩擦速度的增加均增大;在轻载低速条件下,合金的磨损机制以犁削磨损和粘着磨损为主;在重载高速条件下,磨粒磨损和粘着磨损加剧.     

ZrO2晶型对铜基粉末冶金摩擦材料摩擦学性能的影响

采用粉末冶金加压烧结技术制备含单斜和立方2种晶型ZrO_2的铜基摩擦材料,研究在干摩擦及不同制动速度条件下,ZrO_2晶型对铜基粉末冶金摩擦材料摩擦学性能的影响;用光学表面分析仪和扫描电子显微镜分别对试样磨损表面形貌及磨屑形貌进行观察,探究ZrO_2晶型对粉末冶金摩擦材料摩擦学性能的作用机制。结果表明:在相同条件下,含单斜相ZrO_2摩擦材料的摩擦因数及磨损量均高于含立方相ZrO_2的摩擦材料;随着制动速度的升高,2种材料的摩擦因数均降低,而含立方相ZrO_2材料摩擦因数降幅较小,同时两者的磨损量均呈现先上升后降低的趋势。随制动速度提升,含单斜相ZrO_2的摩擦材料主要磨损机制由黏着磨损与犁削磨损转变为剥层磨损;而含立方相ZrO_2的摩擦材料主要磨损机制由犁削磨损转变为犁削磨损与氧化磨损,最后转变为剥层磨损。     

锌铝合金和铝青铜摩擦磨损特性的研究

研究了锌铝合金ＺＡ－Ｓｉ和铝青铜ＺＣｕＡｌ１０Ｆｅ３在２０号机油润滑条件下的摩擦磨损特性。结果表明：在一定的条件下，ＺＡ－Ｓｉ合金的耐磨性能和磨合性能均明显优于ＺＣｕＡｌ１０Ｆｅ３合金；二种合金的磨损机制主要是犁削，辗压和粘着，ＺＡ－Ｓｉ合金的粘着磨损具有延缓性和失效性的双重特性。     

腐蚀介质条件下NiCrBSi/WC喷熔层的摩擦学性能研究

采用氧-乙炔火焰喷熔工艺,制备了碳化钨颗粒增强镍基合金喷熔层(NiCrBSi/WC),研究了它在腐蚀介质条件下的摩擦磨损行为与机理,并考察了载荷、滑动速度对其摩擦磨损性能的影响规律。研究结果表明:NiCrBSi/WC具有良好的耐腐蚀磨损性能,且当WC含量为20%时,腐蚀磨损率最低;WC含量超过20%后,由于喷熔层存在“腐蚀原电池”效应,其腐蚀磨损率增大。NiCrBSi/WC的腐蚀磨损率随载荷增加而变大,随速度增大而减小。载荷的增加使喷熔层的犁削磨损加剧,导致摩擦系数和磨损率增大;速度的增大造成摩擦界面温度上升,可生成摩擦转移膜,从而降低了喷熔层的磨损率。     

高载荷条件下石墨-石墨摩擦副的摩擦学特性研究

利用研制的高载荷条件下摩擦因数测试装置,研究了石墨/石墨摩擦副在空气、水和油介质中的摩擦学特性。结果表明在4~15MPa范围内,随着载荷的增加,摩擦副在空气、水和油介质中的摩擦因数都逐渐降低;在油介质中摩擦副的摩擦因数最小,在水介质中摩擦因数变化最平稳,在空气中摩擦因数最大,且随载荷的增加变化幅度最大。磨损表面原始形貌对比分析表明,在空气中,摩擦副表面处于边界润滑状态,主要磨损机制是粘着磨损和犁削;水润滑条件下为轻微犁削;油润滑条件下,摩擦副表面处于为边界润滑和流体润滑状态,油中的减摩剂对试样表面有抛光作用。     

3Y-TZP陶瓷在水润滑条件下磨损特性的研究

采用销-盘式摩擦磨损试验机在水润滑条件下对3Y—TZP／（Mg，Y）-PSZ陶瓷摩擦副的磨损性能进行了试验研究。结果表明，3Y—TZP陶瓷的磨损率随着载荷和滑行速度的增加而增大。在低载低速下3Y—TZP陶瓷发生的是微量磨损，其磨损过程相当于抛光；随着载荷与滑动速度的增加，发生的是轻微磨损，相应的磨损机制为塑性变形和微犁削。在高载荷条件下发生了严重磨损，磨损的主要机制是表面断裂。     

WC/TiC层状陶瓷刀具与316L不锈钢间的干摩擦磨损性能研究

研究了在1 750℃下真空热压烧结而成的WC/TiC层状陶瓷刀具材料在干摩擦条件下与316L奥氏体不锈钢之间的摩擦磨损性能,并对磨损面进行了分析。结果表明:载荷和滑动速度对摩擦因数和磨损量的影响较大,随着载荷的不断增大,WC/TiC层状陶瓷刀具材料的摩擦因数和磨损量呈增大趋势;而随着滑动速度的增大,WC/TiC层状陶瓷刀具材料的摩擦因数先降后增,磨损量先增后降;在WC/TiC层状陶瓷刀具材料与316L奥氏体不锈钢的对磨过程中,材料的表面发生了犁削、颗粒及片层剥落现象,在磨损表面留有犁沟、凹坑、微裂纹和片层结构,其磨损机理为磨粒磨损和粘着磨损。     

基体材料对铜合金镶嵌轴承摩擦磨损性能的影响

在端面摩擦磨损试验机上对锡青铜、铝青铜、铝黄铜镶嵌轴承试样进行了常温下干摩擦对比实验,探讨了不同铜合金基体对镶嵌轴承摩擦磨损性能的影响。结果表明,锡青铜镶嵌轴承在各种实验条件下均表现出了优良的摩擦磨损性能,适合于用作轴承材料。铝黄铜和铝青铜镶嵌轴承的摩擦磨损性能较差,尤其是在载荷较大时性能更差。     

SiCp增强铝基复合材料与Kevlar增强摩擦材料摩擦副摩擦磨损机理研究

采用盘销式摩擦磨损试验机，对SiCp含量为20vol％的铝基复合材料和Kevlar增强摩擦材料组成的摩擦副在于摩擦条件下的摩擦磨损机理进行了实验研究。结果表明：摩擦副在跑合过程中，铝基复合材料中的SiCp颗粒对较软的有机复合材料产生犁削和微观切削效应，磨损机理为铝基复合材料的硬质颗粒对较软的有机复合材料的磨粒磨损；在跑合后的磨损试验中，摩擦材料磨损表面呈现出粘着磨损和塑性变形特征，随着转动速度的增加，塑性流动加剧；摩擦副接触表面发生材料的相互转移，并在铝基复合材料表面形成转移膜，且在较高速度下转移膜更易形成；在高速条件下，摩擦材料表面可见从铝基复合材料的铝合金基体中脱离的SiCp颗粒和熔融迹象；摩擦材料的磨损机理主要为磨粒磨损、粘着磨损和塑性变形。     

Tribological properties of Ni3Al-Cr7C3 composite coating under water lubrication

The tribological properties of Ni₃Al-Cr₇C₃ composite coating under water lubrication were examined by using a ball-on-disc reciprocating tribotester. The effects of load and sliding speed on wear rate of the coating were investigated. The worn surface of the coating was analyzed using electron probe microscopy analysis (EPMA) and X-ray photoelectron spectroscopy (XPS). The results show the friction coefficient of the coating is decreased under water lubrication. The wear rate of the coating linearly increases with the load. At high sliding speed, the wear rate of the coating is dramatically increased and a large amount of the counterpart material is transferred to the coating worn surface. The low friction of the coating under water lubrication is due to the oxidizing of the worn surface in the wear. The wear mechanism of the coating is plastic deformation at low normal load and sliding speed. However, the wear mechanism transforms to microfracture and microploughing at high load with low sliding speed, and oxidation wear at high sliding speed. It is concluded that the contribution of the sliding speed to an increase in the coating wear is larger than that of the normal load.     

电火花放电熔涂层在边界润滑条件下的磨损特性

用环块磨损试验机对铬电极电火花熔涂层及淬火低温回火态45^#钢的边界润滑滑动磨损特性进行了研究。结果表明,轻载低速条件下,熔涂层与45^#钢的边界润滑滑动磨损机制以犁沟划伤为主,熔涂层的磨损量与45^#钢的相当;重载高速条件下,熔涂层的磨损机理以粘着磨损和磨料磨损为主,而45^#钢的磨损机理以点蚀剥落为主：熔涂层的磨损量远比45^#钢的人。     

Tribological Behaviors of Self-lubricating Coating Prepared by Electrospark Deposition

Cu/h-BN self-lubricating coating was prepared on AISI1045 steel by electrospark deposition. The friction coefficient and wear rates were measured using the ball-on-disk method, and the tribological behaviors were discussed. Results showed that the friction coefficient decreased with an increase in sliding speed and load. The wear rate decreased with an increase in sliding speed and increased with an increase in load. The self-lubricating coating exhibited much lower friction coefficient and wear rate than the uncoated mild steel under the test condition. SEM micrographs show that the main wear mechanisms of the self-lubricating coating are abrasive wear and fatigue wear.     

Sliding tribological behavior of AlCrN coating

The sliding tribological behavior of the PVD AlCrN coating against Si₃N₄ ball have been investigated by using the CETR multi-functional UMT-2 test system under two sliding conditions (bidirectional and unidirectional). Reciprocating sliding tests (bidirectional) were performed under varied normal loads (5, 10 and 20 N) at sliding velocity of 0.48 m/min. Ball-on-disc tests (unidirectional) were performed at varied sliding velocities (0.48 and 5 m/min) under normal load of 5 N. The wear scars of the coating were evaluated by surface profilometer, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the sliding wear mechanism of the coating was consequently discussed. The results showed that AlCrN coating had excellent anti-abrasion properties. Both the normal load in reciprocating sliding test and the sliding velocity in ball-on-disc test had significant influence on the sliding tribological behavior of the AlCrN coating. The combination of abrasion and oxidation was the main sliding wear mechanism for the AlCrN coating. The wear resistant and thermally stable oxides formed by the tribo-chemical reactions of chromium and aluminum protected the AlCrN coating against wear admirably.     

Wear and friction behavior of sand cast brake rotor made of A359-20 vol% SiC particle composites sliding against automobile friction material

The effect of load range of 30-100 N and speed range of 3-12 m/s on the wear and friction behavior of sand cast brake rotor made of A359-20 vol% SiC particle composites sliding against automobile friction material was investigated. Dry sliding frictional and wear behavior were investigated in a pin-on-disc type apparatus. Automobile friction material was used as pin, while the A359-20 vol% SiC particle composites formed the rotating disc. For comparison, the wear and friction behavior of commercially used cast iron brake rotor were studied. The results showed that the wear rate of the composite disc decreased with increasing the applied load from 30 to 50 N and increased with increasing the load from 50 to100 N. However, the wear rate of the composite disc decreased with increasing the sliding speed at all levels of load applied in the present work. For all sliding speeds, the friction coefficient of the composite disc decreased with applied load. The worn surfaces as well as wear debris were studied using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyzer and X-ray diffraction (XRD) technique. At load of 50 N and speed range of 3-12 m/s, the worn surface of the composite disc showed a dark adherent layer, which mostly consisted of constituents of the friction material. This layer acted as a protective coating and lubricant, resulting in an improvement in the wear resistance of the composite.     

Predictive modelling of dry sliding wear in sealed plasma-sprayed Mo coating using response surface methodology

Plasma spraying is used to produce wear resistant coatings. However, the primary problem is the poor bonding strength between the coating and the substrate. The secondary problem is the high porosity in the as-sprayed coatings, which reduces the wear resistance of coating. In order to overcome these problems, the sealing of plasma-sprayed coating by electrodeposition has been used. The sealing of plasma-sprayed coatings alters the wear mechanism and wear resistance. The wear mechanism and wear resistance largely depends on the applied load, sliding speed and sliding distance. Hence, an effort has been made in the present work to study the effects of these parameters on wear volume loss using response surface methodology (RSM)-based mathematical models. The experiments were conducted as per Central Composite Design (CCD). It reveals that the applied load was the most predominant factor affecting the wear volume loss of the coating material. The sliding speed is the next most important parameter influencing the wear volume loss. The wear volume loss of the sealed plasma-sprayed molybdenum coating occurs mainly due to the formation of grooves, surface tribo films, fracture of splats and delamination of the coating.     

On dry sliding friction and wear behaviour of PEEK and PEEK/SiC-composite coatings

In this work, polyetheretherketone (PEEK) and PEEK/SiC-composite coatings were deposited on Al substrates using a printing technique to improve their surfaces performance. The objective of this work was to investigate coatings friction and wear behaviour. Especially, the effect of sliding velocity and applied load on coatings friction coefficient and wear rate was evaluated in range of 0.2-1.4 m/s and 1-9 N, respectively. Compared to Al substrate, the coated samples exhibit excellent friction coefficient and wear rate. For PEEK coating, under an applied load of 1 N, the increase in sliding velocity can result in decreasing of friction coefficient at a cost of wear resistance. Under a load of 9 N, however, PEEK coating exhibits the highest friction coefficient and wear rate at an intermediate velocity. These influences appear to be mainly ascribed to the influence of contact temperature of the two relative sliding parts. In most test conditions, the composite coating exhibits better wear resistance and a little higher friction coefficient. SiC reinforcement in composite coating plays a combined role. First of all, it might lead to energy dissipation for activation of fracture occurred on the interface of PEEK and the powders. Moreover, it can reduce coating ploughs and the adhesion between the two relative sliding parts.     

镍基合金喷熔层摩擦学行为与机制的研究

采用热喷熔工艺制备了两种镍基合金喷熔层,并选用高锰钢、不锈钢作为对比材料,研究了镍基合金喷熔层的摩擦磨损性能。研究结果表明：镍基合金喷熔层具有良好的耐磨损性能和较低的摩擦系数。镍含量对喷熔层的摩擦学性能有显著影响,高镍含量的镍基合金,其耐磨性能明显优于低镍含量的镍基合金。在低速轻载条件下,镍基合金喷熔层的磨损机理为微观犁削;高速重载时,表现为粘着磨损和磨料磨损,其中高镍含量的喷熔层表面形成了致密的转移膜,有效地降低了磨损率。     

采煤机滑靴激光熔覆铁镍基涂层的抗磨性能*

为提高采煤机滑靴在无油工况下的耐磨性,采用激光熔覆技术在45钢为基体上分别制备FeNiMo和FeNiMoSi涂层,并对其物相组成及硬度等进行分析。结果发现：制备的涂层结构致密,与基底保持了良好的冶金结合;FeNiMoSi涂层的平均硬度为438HV,分别约为基体（153HV）的2.8倍以及FeNiMo涂层（385HV）的1.1倍。通过往复式摩擦磨损试验机研究涂层的干摩擦磨损性能,并探讨其磨损机制。结果表明：随着载荷和滑动速度的增大,涂层的摩擦因数均呈现出减小的趋势;随着载荷的增大,涂层的磨损率逐渐升高;随着滑动速度的增大,FeNiMo涂层的磨损率出现先下降后上升的趋势,而FeNiMoSi涂层的磨损率则逐渐下降;涂层的磨损机制主要为磨粒磨损、塑性变形以及轻微的氧化磨损。总体来说,FeNiMoSi涂层相比FeNiMo涂层表现出更好的耐磨性能,这是因为涂层中Si元素的添加,不仅起到细晶强化作用,而且促进了FeSi金属间化合物相的生成。