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。     

Abrasive Wear Analysis of Plasma-Sprayed LaCeYSZ Nanocomposite Coatings Using Experimental Design and ANN

The abrasive wear characteristics of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings on Inconel 718 substrates was evaluated using AFS 50/70-grade silica sand as abrasives. This article depicts the dependence of abrasive wear characteristics of plasma-sprayed nanocomposite LaCeYSZ coatings on abrading distance, keeping the applied load constant. The influence of four operating parameters—that is, load, wheel speed, time, and temperature with four different levels each—on the performance output (i.e., abrasion wear rate) is studied using Taguchi's L₁₆ orthogonal array design and analysis of variance (ANOVA). Out of the four parameters, load has been found to be most significant factor followed, by speed of the abrasive wheel and temperature influencing abrasion. The morphology of the worn-out surface also showed microcutting and small crater formation in the binder matrix caused by the repetitive impacts of abrasive particles. It was observed that coating with nano-LaCeYSZ grains exhibited higher wear resistance compared to conventional YSZ coating and the reason may be attributed to embedded crack-arresting nanozones, which toughen the coating. An artificial neural network (ANN) approach is then implemented taking into account training and test procedures to predict the triboperformance under different operating conditions. This technique helps in saving time and resources for a large number of experimental trials and successfully predicts the wear rate of the coatings both within and beyond the experimental domain.     

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。     

Friction and wear behaviour of Thordon XL and LgSn80 in sliding against plasma-sprayed Cr2O3 coatings

This paper studies the friction and wear behaviour of two important bearing materials, Thordon XL and LgSn80, in dry and lubricated sliding vs. plasma-sprayed Cr₂O₃ coatings. As a reference, AISI 1043 steel is also studied under the same conditions. SEM, EDS and surface topography were employed to study the wear mechanisms. The results indicate that the Thordon XL/Cr₂O₃ coating pair gives the lowest dry friction coefficient (0.16) under a normal load of 45.3 N (pressure 0.453 MPa) at a velocity of 1 m/s. The dry friction coefficient of Thordon XL/Cr₂O₃ coating increases to 0.38 under a normal load of 88.5 N (pressure 0.885 MPa). The dry friction coefficients of the LgSn80/Cr₂O₃ coating are in the range of 0.31–0.46. Secondly, both dry wear rate under low normal load (45.3 N) and lubricated wear rate under a load of 680 N for Thordon XL are lower than those of LgSn80 in sliding against plasma-sprayed Cr₂O₃ coatings at a speed of 1 m/s. However, under a normal load of 88.5 N the dry wear rate of Thordon XL is much higher than that of LgSn80. Thirdly, a high viscosity lubricant (SAE 140) leads to lower wear for Thordon XL and LgSn80 than a low viscosity lubricant (SAE 30). Finally, the dominating wear mechanism for Thordon XL is shear fracture when against the plasma-sprayed Cr₂O₃ ceramic coating. For LgSn80 against plasma-sprayed Cr₂O₃ ceramic coating, abrasive wear is the governing failure mechanism.     

Dry sliding friction and wear properties of metallic glass coating and martensite stainless coating

The wire arc spraying process was used to prepare FeB-based metallic glass coating and 3Cr13 coating. The effects of wear parameters, such as sliding distance, linear speed and normal loads, on the wear performances of the coatings were analyzed in detail. The results showed that, with increase in sliding distance, linear speed and normal loads, the volume losses of the metallic glass coatings increased. The relationships between wear behavior and microstructure of the coatings were discussed. The metallic glass coating had excellent wear resistance. The relatively wear resistance of the metallic glass coating was about 2.6 times that of the 3Cr13 coating under the same testing conditions. The main failure mechanism of the metallic glass coating was brittle failure and fracture.     

接触应力和相对滑动速度对金属表面自修复膜生成的影响及机制

采用羟基硅酸镁粉体作为润滑油添加剂,在MMU-5G材料端面摩擦磨损试验机上,研究了不同接触应力和相对滑动速度对45^#钢/45^#钢摩擦副磨损表面自修复膜生成的影响及其机制,借助SEM及EDS测试分析摩擦副的表面形貌及表面成分组成。结果表明,接触应力和相对滑动速度对羟基硅酸镁粉体添加剂在磨损表面形成自修复膜影响显著。在接触应力为1.53,3.06,4.59,7.64MPa和在相对滑动速度0.416m/s的工况条件下,试样磨损表面有自修复膜生成。接触应力为3.06MPa和相对滑动速度为0.416m/s时,易于在短时间内达到磨损-自修复动态平衡,自修复效果最为理想。自修复膜的生成过程包含磨粒磨损和摩擦化学反应2个阶段。自修复膜的生成使得试样摩擦磨损表面平整光滑,可以有效降低金属磨损。     

Friction and Wear Behavior of WS2/Zr Self-lubricating Soft Coatings in Dry Sliding Against 40Cr-Hardened Steel Balls

WS₂ and WS₂/Zr self-lubricating soft coatings were produced by medium-frequency magnetron sputtering, multi-arc ion plating and ion-beam-assisted deposition technique on the cemented carbide YT15 (WC + 15 % TiC + 6 % Co) substrates. Microstructural and fundamental properties of these coatings were examined. Sliding wear tests against 40Cr-hardened steel using a ball-on-disk tribometer method were carried out with these coated materials. The friction coefficient and wear rates were measured with various applied loads and sliding speeds. The wear surface features of the coatings were examined using SEM. The results showed that the WS-1 specimen (with WS₂/Zr composite coating) has higher hardness and coating/substrate critical load compared with that of the WS-2 specimen (only with WS₂ coating). The friction coefficient of WS-1 specimen increases with the increase in applied load and is quite insensitive to the sliding speed. The wear rate of the WS-1 specimen is almost constant under different applied loads and sliding speeds. The WS-1 specimen shows the smallest friction coefficient and wear rate among all the specimens tested under the same conditions. The WS-1 specimen exhibits improved friction behavior to that of the WS-2 specimen, and the antiwear lifetime of the WS₂ coatings can be prolonged through adding Zr additives. The self-lubricating and wear mechanism of the WS₂/Zr coating was also found from the sliding wear tests.     

Wear behaviour of laser-treated plasma-sprayed ZrO2 coatings

The effect of laser remelting on the wear behaviour of plasma-sprayed ZrO₂ ceramic coatings was studied. The results showed that the porosity and roughness of the coatings were reduced significantly after laser treatment, and the bonding strength was apparently increased by the remelting process. However, there were extensive network cracks, as well as a few large bubbles, in the laser-treated coatings. Unlubricated pin-on-disc wear tests revealed that, when compared with as-sprayed ceramic coatings, the wear resistance was improved significantly after laser treatment. The wear resistance of laser-treated specimens increased with increasing laser power, and the minimum weight loss of the coating specimen occurred at a specific travel speed in laser processing. The main wear mechanism of the as-sprayed coatings was spallation of the coating, whereas the wear of laser-remelted specimens was dominated by ploughing and gouging (scratching).     

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.     

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.     

WC颗粒增强镍基合金喷熔层腐蚀磨损行为及其人工神经网络预测分析

采用氧一乙炔焰喷熔工艺制备了碳化钨（WC）颗粒增强镍基合金喷熔层,研究了它的腐蚀磨损行为。结果表明：喷熔层耐腐蚀磨损性能随WC含量增加而提高,WC含量在20％～30％范围内,喷熔层耐腐蚀磨损性能最佳,超过30％时,其耐腐蚀磨损性能下降。载荷增加,腐蚀磨损率增大;速度增加,腐蚀磨损率下降。低速重载荷时,WC颗粒增强效果明显,且含30％WC喷熔层耐腐蚀磨损性能最好;高速轻载荷时,因WC原电池效应显著,WC颗粒增强效果减弱。基于人工神经网络的喷熔层腐蚀磨损行为预测与实验结果吻合较好,对喷熔层的应用具有重要指导作用。     

Microstructure and Tribological Behavior of Laser in Situ Synthesized TiC-Reinforced Fe-Based Composite Coatings

Fe-based composite coatings reinforced with TiC particles were prepared by laser surface engineering from precursor of ferrotitanium and graphite. Microstructure of the composite coatings was comprised of dendritic TiC dispersed in a ferrite matrix. In situ dendritic TiC was formed by mechanism of precipitating from the liquid Fe–Ti–C alloy system. Composite coatings showed a substantial increase in microhardness in comparison to that of the substrate. Dry sliding wear tests performed at room temperature revealed that the in situ composite coating possessed a considerably reduced wear volume loss owing to the presence of in situ synthesized TiC. A relatively smooth surface was observed for in situ TiC/Fe composite coating due to its high resistance to ploughing and adhesion, which is caused by the uniformly dispersed TiC reinforcement with high volume fraction.     

铝合金表面Ni-SiC复合镀层的摩擦磨损性能

通过复合电沉积技术,在铝合金表面得到了不同SiC粒子含量的Ni-SiC复合镀层,研究了在干摩擦和液态石蜡润滑摩擦条件下载荷与SiC粒子体积分数对Ni-SiC复合镀层摩擦磨损性能的影响。结果表明:无论在干摩擦或润滑摩擦条件下,加入SiC粒子后的复合镀层其耐磨性均优于纯镍镀层,并随载荷的提高耐磨性下降。在干摩擦条件下,镀层中的SiC粒子体积分数在5.8％时复合镀层耐磨性最好;在润滑摩擦条件下,随镀层中SiC粒子体积分数提高,复合镀层耐磨性均提高。     

Monitoring of Wear Characteristics of TiN and TiAlN Coatings at Long Sliding Distances

TiN and TiAlN thin hard coatings have been widely applied on machine components and cutting tools to increase their wear resistance. These coatings have different wear behaviors, and determination of their wear characteristics in high-temperature and high-speed applications has great importance in the selection of suitable coating material to application. In this article, the wear behavior of single-layer TiN and TiAlN coatings was investigated at higher sliding speed and higher sliding distances than those in the literature. The coatings were deposited on AISI D2 cold-worked tool steel substrates using a magnetron sputtering system. The wear tests were performed at a sliding speed of 45 cm/s using a ball-on-disc method, and the wear area was investigated at seven different sliding distances (36–1,416 m). An Al₂O₃ ball was used as the counterpart material. The wear evolution was monitored using a confocal optical microscope and surface profilometer after each sliding test. The coefficient of friction and coefficient of wear were recorded with increasing sliding distance. It was found that the wear rate of the TiAlN coating decreases with sliding distance and it is much lower than that of TiN coating at longer sliding distance. This is due to the Al₂O₃ film formation at high temperature in the contact zone. Both coatings give similar coefficient of friction data during sliding with a slight increase in that of the TiAlN coating at high sliding distances due to the increasing alumina formation. When considering all results, the TiAlN coating is more suitable for hard machining applications.     

Comparative Study of Thermally Sprayed Coatings Under Different Types of Wear Conditions for Hard Chromium Replacement

The tribological properties of part surfaces, namely their wear resistance and friction properties, are decisive in many cases for their proper function. To improve surface properties, it is possible to create hard, wear-resistant coatings by thermal spray technologies. With these versatile coating preparation technologies, part lifetime, reliability, and safety can be improved. In this study, the tribological properties of the HVOF-sprayed coatings WC–17%Co, WC–10%Co4%Cr, WC–15% NiMoCrFeCo, Cr₃C₂–25%NiCr, (Ti,Mo)(C,N)–37%NiCo, NiCrSiB, and AISI 316L and the plasma-sprayed Cr₂O₃ coating were compared with the properties of electrolytic hard chrome and surface-hardened steel. Four different wear behavior tests were performed; the abrasive wear performance of the coatings was assessed using a dry sand/rubber wheel test according to ASTM G-65 and a wet slurry abrasion test according to ASTM G-75, the sliding wear behavior was evaluated by pin-on-disk testing according to ASTM G-99, and the erosion wear resistance was measured for three impact angles. In all tests, the HVOF-sprayed hardmetal coatings exhibited superior properties and can be recommended as a replacement for traditional surface treatments. Due to its tendency to exhibit brittle cracking, the plasma-sprayed ceramic coating Cr₂O₃ can only be recommended for purely abrasive wear conditions. The tested HVOF-sprayed metallic coatings, NiCrSiB and AISI 316L, did not have sufficient wear resistance compared with that of traditional surface treatment and should not be used under more demanding conditions. Based on the obtained data, the application possibilities and limitations of the reported coatings were determined.     

Wear transitions and mechanisms in lubricated sliding of a molybdenum coating

Wear tests were performed for a Mo coating sliding against bearing steel specimen under boundary lubrication conditions. Results were compared with (i) hardened carbon steel sliding against bearing steel and (ii) Mo coating sliding against boron cast iron. Tests indicated that the wear resistance of the Mo coating was superior to that of the uncoated hardened steel. The initial surface topographies of the coatings were suitable to facilitate the transfer of the applied load directly onto the phases and prevented the softer phase directly involved in the wear process. The morphology of the transfer layer formed on the Mo coating was identified by X-ray diffractometry. And the layers were expected to supply an in situ lubrication effect. The wear rates of the coating against a steel slider were lower compared with those worn against a cast iron slider. With increasing applied load, the probability of the harder phases crack and fracture increased until the fraction of the unfragmented phases on the contact surfaces was no longer adequate to support the load. The dominant wear mechanisms in each wear regime were discussed.     

Performance evaluation of multilayer thin film coatings under mixed rolling–sliding dry contact conditions

This paper focuses on the application of advanced finite element analysis to simulate the response of complex multilayer coatings when subjected to mixed rolling–sliding dry contact conditions, typical of those experienced by heavily loaded gear tooth flanks. In this study, a versatile model is developed to investigate the response of a variety of complex coatings. Through the investigation of three advanced surface coatings the developed model is shown to offer detailed subsurface stress and strain information, quantifying the benefits provided by the application of each coating.A number of rolling contact fatigue tests were also conducted to complement the computational simulations. An adapted twin disc testing machine was used to investigate the progressive wear rates of the three advanced surface coatings when subjected to mixed rolling–sliding contact at high load and in dry conditions. The result is a clear indication that advanced surface coating techniques can provide significant improvements in wear resistance and surface durability. From the rolling contact fatigue experiments conducted in this study, a multilayer tungsten carbide/carbon coating was shown to provide the most significant increase in surface durability with a 16-fold reduction in measured weight loss compared to the uncoated substrate over the 145,000 cycle test duration investigated.     

镍基纳米复合电刷镀层的滑动磨损性能研究

用电刷镀技术制得了镍基 n-SiO_2复合镀层、镍基 n-SiC 复合镀层以及镍基镀层,并对镀层的滑动磨损性能进行了试验研究.纳米复合镀层的表面形貌比较细腻,镀层中纳米粒子分布均匀,与基质金属结合紧密.显微硬度高,可达到 HV692,比镍基镀层提高约50%.滑动磨损试验结果表明,纳米粒子的加入可以提高镀层的耐磨性.纳米复合镀层的磨损机制以疲劳磨损为主,而纯镍镀层以粘着磨损为主.     

复合尼龙涂层的腐蚀—冲蚀磨损特性

本文对尼龙涂层及尼龙+5％Al_2O_3陶瓷颗粒和尼龙+5％SiC晶须复合涂层进行了腐蚀—浆体冲蚀磨损试验研究。研究了砂浆的pH值,冲击速度等参数对涂层的腐蚀冲蚀磨损的影响,对涂层表面的组织结构和形貌进行了观察分析,探讨了复合尼龙涂层的腐蚀冲蚀磨损机理,建立了V_e-pH-U腐蚀—冲蚀磨损三维图。     

Abrasive wear behavior of high speed steel and hard metal coated with TiAlN and TiCN

The wear behavior of M2 high speed HSS steel and WC hard metal coated with TiAlN and TiCN were investigated and compared, using the pin on disk standard test with different loads. The coating PVD process has been done by two different suppliers, using an industrial equipment unit with optimized conditions. The coated layers were measured and characterized. The load, sliding distance and velocity of 0.5 m/s were kept constant during the abrasion test in order to control these variables. The counterface disks used were electric steel sheets from three different suppliers. The lost volume and temperature at the pin end have been measured during the wear test. Comparisons of tribological performance for the coated HSS and hard metal were done, using a plot of lost volume versus sliding distance for substrates and coatings. The pin worn surfaces were observed using a scanning electron microscope. A significant increase in the wear resistance of M2 steel and WC hard metal when coated with TiAlN and TiCN was observed. Quality of these coatings depended upon the supplier. Excessive porosity has diminished the TiAlN counting wear resistance from one supplier. However, in general the performance of TiAlN is superior to TiCN. The pin wear rate depended on the disk microstructure.