Comparative study on tribology and microhardness of laser synthesized Ti-Al2O3/Zn coatings on Ti-6Al-4V alloy

ABSTRACT

The study of laser cladding of 90Ti-10Al₂O₃, 90Ti-8Al₂O₃-2Zn and 90Ti-4Al₂O₃-6Zn coatings onto Ti-6Al-4V alloy, with intention to produce defect-less, high microhardness and wear resistant coating was carried out. The coatings were deposited onto Ti-6Al-4V alloy at 900 W laser power and 0.6 m/min laser scan speed. Microstructures and phase constituents of the developed coatings were investigated by using a scanning electron microscope (SEM) and X-ray diffractometer correspondingly. Vickers microhardness tester and pin-on-disk tribometer were employed to characterize microhardness and wear behaviour of the Ti-Al₂O₃/Zn coatings respectively. SEM was also used to examine the worn track. It was observed that 90Ti-10Al₂O₃ coating yielded optimal microhardness along with maximal wear resistance in comparison to the other coatings and Ti-6Al-4V alloy. It has been established that laser cladding of Ti-Al₂O₃ coating with Zn contents on Ti-6Al-4V alloy alleviates the formation of cracks, however, microhardness and wear properties are negatively affected.     

高频感应熔覆NiTiFe合金涂层摩擦学性能研究

为增强金属材料表面的耐磨性能,采用高频感应熔覆技术,在HT300基底表面制备出NiTiFe合金涂层;利用扫描电子显微镜(SEM)、能谱仪(EDS)、显微硬度计和X射线衍射仪(XRD)对NiTiFe合金涂层的微观组织、元素组成、硬度、相组成和与基底的结合情况进行表征与分析;通过摩擦磨损试验机对涂层的摩擦学性能进行测试,对其摩擦磨损机制进行分析。结果表明：涂层组织致密,无裂缝和空隙,成型质量良好,平均厚度达到0.7 mm,与HT300基底实现了冶金结合;涂层中主要包含Fe2Ti、Fe6.94Ti0.36和Ni3Fe三种相,Fe元素的加入使涂层的晶格发生畸变,硬度提高,平均硬度达到997.36HV,约为HT300基底平均硬度值的5倍。通过摩擦磨损试验发现,试验前期,NiTiFe合金涂层与对摩副之间的摩擦因数较低,维持在0.2左右,对摩副的失效导致摩擦副之间的接触形式发生改变,摩擦因数产生阶跃;随着载荷的增加,涂层上呈现的磨痕宽度在不断增加,对摩副由于磨损造成的材料去除后暴露出的面积也在不断增大。摩擦磨损试验后,NiTiFe合金涂层摩擦表面光滑平整,仅出现了轻微的磨粒磨损,磨损体积远小于对摩副...     

激光熔覆合金表面耐磨性试验研究

使用CO2激光器对45#钢表面进行Co基和Ni基合金熔覆处理。利用销盘式摩擦试验机对激光熔覆表面进行摩擦磨损试验,研究干摩擦和润滑条件下磨损机理。Ni合金熔覆层比Co基耐磨性要好。润滑条件下,两种合金的耐磨性比干摩擦都得到很大提高。     

65Mn钢表面激光熔覆温度场模拟及性能研究

为了探究不同激光熔覆工艺参数对温度场的影响,利用ANSYS软件对激光熔覆温度场进行模拟。在选定工艺参数下,通过激光熔覆技术在65Mn钢表面熔覆Ni60A合金粉,并与镍基焊条电弧焊试验进行对比。对两种熔覆层的显微组织、显微硬度及摩擦磨损性能进行观察和测试。结果表明：激光熔覆温度场的最高温度与激光功率、频率成正比,而与扫描速度成反比。在激光功率580 W,扫描速度100 mm/min,频率4 Hz,脉宽8 ms的工况下,温度场最高温度达到2 092.1℃。激光熔覆层主要由等轴晶、柱状晶组成,而电弧焊覆层组织的晶粒组织粗大,存有大量树枝晶。激光熔覆层晶粒更加致密,组织均匀,强度、塑韧性性能更好。在硬度与耐磨性方面,激光熔覆层硬度平均值为531.24 HV_0.2,电弧焊熔覆层硬度平均值为492.46HV_0.2,且激光熔覆对硬度的提高效果更加显著。激光熔覆层的磨损率为4.9×10^-4 mm³·N^-1·m^-1,是基体的3/5。磨损机理由严重的粘着磨损转变为轻微的磨粒磨...     

激光熔覆Ni/TiC复合涂层组织与性能

采用激光熔覆技术在45钢样品表面制备了Ni/TiC复合涂层,利用光学显微镜、SEM,EDS,XRD、显微镜硬度计及摩擦磨损试验机等检测设备研究了Ni/TiC复合涂层的组织和性能。试验结果表明：Ni/TiC复合涂层没有出现裂纹、孔洞等缺陷,涂层与基体之间具有良好的冶金结合,涂层显微硬度沿层深皆呈明显的阶梯状分布,最外表面的熔覆层硬度最高,约为800 HV;熔覆试样的比磨损率比基体试样的比磨损率下降了86.5％,表明Ni/TiC复合涂层具有较好的耐磨性能。     

Deposition of duplex Al2O3/TiN coatings on aluminum alloys for tribological applications using a combined microplasma oxidation (MPO) and arc ion plating (AIP)

Microplasma oxidation (MPO) has recently been studied as a cost-effective plasma electrolytic process to provide thick and hard ceramic coatings with excellent surface load-bearing capacity on aluminum alloys. However, for sliding wear applications, such ceramic coatings often exhibit relatively high friction coefficients against many counterface materials. Although coatings deposited by physical vapour deposition (PVD) techniques such as TiN coatings are well known for providing surfaces with a high hardness, in practice they often exhibit poor performance under mechanical loading, since the coatings are usually too thin to protect the substrate from the contact conditions. In this paper, these challenges were overcome by a duplex process of microplasma oxidation and arc ion plating (AIP), in which an alumina layer Al₂O₃ was deposited on an Al alloy substrate (using MPO as a pre-treatment process) for load support, and a TiN hard coatings were deposited (using AIP) on top of the Al₂O₃ layer for low friction coefficient. Microhardness measurements, pin-on-disc sliding wear tests, and antiwear tests using a Timken tester were performed to evaluate the mechanical and tribological properties. Scanning electron microscopy (SEM) was used to observe coating morphology, and to examine wear scars from pin-on-disc test. The research demonstrates that a hard and uniform TiN coating, with good adhesion and a low coefficient of friction, can successfully be deposited on top of an alumina intermediate layer to provide excellent load support. The investigations indicate that a duplex combination of MPO coating and TiN PVD coating represents a promising technique for surface modification of Al alloys for heavy surface load bearing application.     

Comparison of wear behaviour of plasma-sprayed Al2O3 coatings with and without laser treatment

This paper studies experimentally the effects of CO₂ laser-treatment on the wear behaviour of plasma-sprayed Al₂O₃ coatings, in linear contact sliding (dry, abrasive and lubricated) against SAE 4620 steel. Tests were carried out using a block-on-ring friction and wear tester, under different loads at different speeds. The wear mechanism and the changes in adherence, porosity and microstructure by laser treatment were also investigated. Results show a better wear behaviour for both laser-treated ceramic coating and its paired steel under dry and abrasive conditions, compared with the case without laser treatment. The lubricated wear behaviour of the laser-treated ceramic coating, however, is not improved. The changes in microhardness, porosity and adherence caused by the laser treatment are responsible for the change in wear behaviour of the ceramic coating.     

Tribological performance of an ionic liquid as a lubricant for steel/aluminium contacts

The wear and friction behaviour of an ionic liquid 1‐ethyl‐3‐hexylimidazolium tetrafluoroborate (L206) was investigated as a lubricant for steel/aluminium contacts using an Optimol SRV® oscillating friction and wear tester. The elemental composition and chemical nature of the antiwear films generated on the aluminium surface were analysed using a scanning electron microscope with a Kevex energy dispersive X‐ray analyser attachment (SEM/EDS) and X‐ray photoelectron spectroscopy (XPS). A low friction coefficient (˜0.05) was recorded when lubricating with L206; a small amount of water (5 wt. %) in L206 effectively reduced the wear volume and greatly increased the microhardness of the aluminium alloy, but had little effect on the friction coefficient. The SEM/EDS results showed that severe corrosive wear occurred on the aluminium alloy when lubricating with neat L206, which could be avoided by the addition of water in L206. The XPS results indicated that the species AlF₃, Al₂O₃, AlO(OH), and Al(OH)₃ formed during friction; there was no indication of boron on the worn surfaces.     

Synergy Between Corrosion and Wear of Electrodeposited Ni–W Coating

In this study, a block-on-ring wear tester was employed to investigate the tribocorrosion behavior of the electrodeposited Ni–W coating. Columnar grains embedded with lamellar and nanocrystalline microstructure were found in the fabricated Ni–W coating. The passivation of the Ni–W alloy was observed in the potentiodynamic polarization curve measured in 5 wt% NaCl solution. The result showed that with the raise of the applied overpotential, both the wear rate and the surface W-content of the coating increased. On the contrary, the accompanying coefficient of friction decreased with the potential. Small pitting and cracking occurred on the tested specimen. This microcracking structure was also observed in the corroded zone of the Ni–W coating by using TEM microscopy. A further XPS analysis determined the corrosion film was composed of Ni(OH)₂, NiO, and WO₃ on the corroded surface. The formation of this porous corrosion film at high overpotential was found to cause an accelerated weight loss and thereby, the interaction between wear and corrosion, of the Ni–W coating under tribocorrosion.     

NAK80模具钢表面激光熔覆钴基合金涂层的组织和摩擦磨损性能

采用激光熔覆方法在NAK80模具钢表面制备钴基合金熔覆层,用扫描电镜、X射线衍射仪分析了熔覆层的显微组织,通过干滑动摩擦试验研究了熔覆层的摩擦磨损性能,分析了其磨损机制,并用三维表面形貌仪观察磨损试样的表面形貌。结果表明:熔覆层的主要组成相为Cr23C6、Co3Mo2Si、MoC、FeCr和γ-Co;熔覆层由涂层与基体界面处的平面晶区、涂层中部的胞状树枝晶区和表层的网状等轴晶粒区组成;经激光熔覆处理后的NAK80模具钢表面硬度和耐磨性得到了显著改善,与NAK80模具钢相比,熔覆层表面的平均摩擦因数降低了约34%,比磨损率下降了约91.3%;熔覆层的磨损机制为粘着磨损和轻微的显微切削。     

Effects of anti-wear additives on friction and wear properties of Cr2O3 coating

The effects of some anti-wear additives on the friction and wear behaviour of plasma-sprayed Cr₂O₃ coating were investigated using a block-on-ring tester at ambient conditions. The results show that zinc dialkyldithiophosphate (ZDDP), tricesyl phosphate (TCP) and tributyl phosphate (TBP) significantly reduce the wear of Cr₂O₃ coating lubricated by paraffin oil. Additive concentrations as well as sliding time have great influence on the wear. The friction coefficient varies slightly with test conditions. The analysis by XPS of worn surfaces indicates that the wear resistance of these additives is due to the formation of tribochemical reaction films by reacting with Cr₂O₃ coatings.     

Investigations of Wear Response of Pure Mg and Mg-0.4 Ce-Y2O3/ZnO Nanocomposites Using a Single and Repeated Scratch Tests

ABSTRACT

This work examines the micrometer-scale wear behavior of pure Mg and its composites at various loads (100–500 mN) under single and multiple scratch conditions. The Mg-0.4Ce alloy reinforced with nanoparticles of zinc oxide (ZnO) and yttrium oxide (Y₂O₃) is investigated. The effect of reinforcement addition on wear characteristics and the coefficient of friction (COF) was evaluated. Moreover, the influence of number of scratches on wear quantification and wear mechanism was deduced at different loads. The results suggest that both the mechanical and tribological performance of ZnO-reinforced composite is significantly better than that of the Y₂O₃-reinforced composite, which can be attributed to a low COF and higher strengthening due to ZnO addition.     

Effects of Loadings on Friction and Wear Behaviors of Cathodic Arc Ion Plating AlTiN Coating at High Temperature

A layer of AlTiN coating was deposited on YT14 cutting tool by cathodic arc ion plating (CAIP) and the coefficients of friction (COFs) of the AlTiN coating under different loads at a temperature of 800°C were investigated with a high-temperature wear tester. The wear morphologies, chemical elements, and phases of the coating after wear were analyzed with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD), respectively, and the contours of wear tracks were investigated with a comprehensive measurement tester for material surface performance. The effects of loads on COFs and wear resistance of the AlTiN coating were analyzed, and the wear mechanism of the AlTiN coating at high temperature is discussed. The results show that the mixed oxides of Al₂O₃ and TiO₂ are produced under high temperature to improve the lubrication performance and wear resistance of the AlTiN coating. The average COFs of the coating under loads of 5, 7, and 9 N are 0.6495, 0.5897, and 0.3898, respectively. The COFs of the coating decrease with increasing load; as a result, the AlTiN coating is suitable for heavy loads at high temperature. The friction and wear mechanisms of the AlTiN coating are primarily composed of oxidation wear and abrasive wear, accompanied by fatigue wear and adhesive wear.     

9SiCr表面激光熔覆合金/20MnSiV磨损性能研究

采用Ni合金和Co合金对9SiCr工具钢表面进行激光熔覆，并将熔覆层与20MnSiV配副在干摩擦和油润滑条件下进行磨损试验。采用扫描电子显微镜对磨损表面形貌进行分析，发现油润滑条件下二者的耐磨性有很大提高，其磨损形式主要是磨粒磨损。Ni合金熔覆层与20MnSiV配副时磨损相对较小。     

四种核电用包壳材料的微动磨损性能研究

在切向微动磨损试验机上对4种核电用包壳材料(Zr合金、Zr/Cr涂层、FeCrAl和ODS-FeCrAl)进行切向微动磨损试验,考察不同包壳材料的微动磨损特性.研究结果表明:不同包壳材料的摩擦因数、耗散能曲线和形变有显著差异;4种包壳材料在切向微动过程中均处于部分滑移区.通过分析磨痕微观形貌和磨痕轮廓,发现ODS-Fe...     

Tribological characteristics of low-pressure plasma-sprayed A12O3 coating from room temperature to 800 °C

The tribological characteristics of low-pressure plasma-sprayed (LPPS) Al₂O₃ coating sliding against alumina ball have been investigated from room temperature to 800 °C. These friction and wear data have been compared quantitatively with those of bulk sintered alumina to obtain a better understanding of wear mechanisms at elevated temperatures. The friction and wear of Al₂O₃ coating show a strong dependence on temperature, changing from a mild to a severe wear regime with the increase of temperature. The coefficient of friction at room temperature is approximately 0.17 to 0.42, depending on applied load. The tribochemical reaction between the coating surface and water vapor in the environment and the presence of the hydroxide film on the Al₂O₃ coating reduce the friction and wear at room temperature as contrasted to those of bulk sintered alumina. At intermediate temperatures, from 400 to 600 °C, the friction and wear behavior of Al₂O₃ coating depends on the inter-granular fracture and pull-out of Al₂O₃ grains. At above 700 °C, formation and deformation of fine grain layer, and abrasive wear in the form of removal of fine alumina grains further facilitate the friction and wear process of Al₂O₃ coating.     

Studying tribological characteristics of alumina- and zirconia-based ceramics

Tribotests of ceramic specimens of various compositions (Al₂O₃-1% TiO₂, ZrO₂-5.3% Y₂O₃, Al₂O₃-15% (ZrO₂ + 5.3% Y₂O₃)) were carried out under dry friction conditions. It has been shown that all of the specimens have a high wear resistance, while the Al₂O₃-15% (ZrO₂ + 5.3% Y₂O₃) specimens have the lowest wear rate and the highest microhardness. This is due to the fine-grained structure of these specimens and their higher density compared to that of the other ceramic compositions.     

Experimental study of the speed-dependence tribotechnical characteristics of some plasma-sprayed oxide coatings at elevated temperatures

The effect of the sliding speed on friction and wear characteristics of plasma-sprayed ceramic coatings (Al₂O₃-13% TiO₂, ZrO₂-8% Y₂O₃, Al₂O₃-modified) was studied. Plasma-sprayed coatings are not hard and have high layered structure. Abrasion of coatings in the friction pair with steel and bronze counter-bodies occurs through brittle detachment conglomerated regions with low cohesive resistance. The modified coating (Al₂O₃) has the highest wear resistance and the lower coefficient of friction compared to the coatings (Al₂O₃-13% TiO₂, ZrO₂-8% Y₂O₃) in the studied velocity range (0.1–10 mm/s). Laser melting can be used as an efficient way of increasing the tribotechnical properties of plasma-sprayed oxide coatings.     

Friction and wear properties of lead-free aluminum alloy bearing material with molybdenum disulfide layer by a reciprocating test

Friction and wear behavior of Al–Sn–Si alloy with MoS₂ layer under lubricated condition was investigated by a reciprocating friction tester. It became clear that the Al–Sn–Si alloy with MoS₂ layer showed about 70% lower friction and about 1/10 lower wear depth compared to the Al–Sn–Si alloy. The worn surfaces of the Al–Sn–Si alloy with MoS₂ layer were observed and analyzed by a SEM, a TEM and an EDX. It indicated that the sliding surface of the counterface had larger area of Mo than the area of Al which was transferred from the Al–Sn–Si alloy with MoS₂ layer by sliding, resulting in low friction and high wear resistance.     

Influence of Polyfluo-Wax on the Friction and Wear Behavior of Polyimide/Epoxy Resin–Molybdenum Disulfide Bonded Solid Lubricant Coating

Polyimide/Epoxy resin–molybdenum disulfide bonded solid lubricant coatings (denoted as PI/EP-MoS₂) were prepared. The influence of polyfluo-wax (denoted as PFW) on the microhardness and friction and wear behavior of as-prepared PI/EP-MoS₂ lubricant coating was measured using a microhardness tester and a reciprocating ball-on-disc tribometer, respectively. The worn surfaces of the lubricant coatings were observed with a scanning electron microscope, and their wear rate was determined with a Micro XAM surface mapping microscope. Moreover, the transfer films formed on the counterpart steel ball surfaces were analyzed by X-ray photoelectron spectroscopy. Results indicate that the incorporation of a proper content of PFW filler is effective at improving the antifriction performance of the PI/EP-MoS₂ lubricant coating while maintaining better wear resistance. Moreover, the friction coefficient of the lubricant coating decreases with increasing content of PFW from 2 to 10%, and the one with a filler content over 6% PFW has a steady friction coefficient of 0.07. The improvement in the antifriction performance of the lubricant coating with the incorporation of the PFW filler is attributed to the excellent lubricity of homogeneously distributed PFW.