Effects of solid lubricants on friction and wear behaviors of the phenolic coating under different friction conditions

The phenolic coating filled with micro-MoS₂ or micro-graphite was prepared by spraying the coating precursors. The friction and wear behaviors of the unfilled and filled phenolic composite coating sliding against the steel ring were evaluated on an MHK-500 friction and wear tester under dry friction and under water lubrication conditions. The worn surfaces of the unfilled and filled phenolic coating and the transfer films formed on the surface of the steel ring were investigated using a scanning electron microscope (SEM) and an optical microscope (OM), respectively. FTIR analysis was performed to detect the chemical changes of the composite coating under different lubrication conditions. It was found that addition of graphite was effective in enhancing the wear life of the phenolic coating. Especially, the anti-wear ability of the phenolic coating was best when the content of graphite is 10 wt.%. However, the MoS₂ as filler was harmful to the friction and wear behaviors of the phenolic coating. The character of the fillers varied with the types of the solid lubricants and the transfer films of varied features formed on the counterpart steel ring, largely accounted for the different friction and wear behaviors of the unfilled and filled phenolic composite coating. Compared with under dry sliding, the phenolic composite coating filled with 10 wt.% MoS₂ or 10 wt.% graphite had lower friction coefficients and lower wear life under water lubrication. Since water hindered the formation of transferred films, and might penetrate and corrode the filler-matrix interface, the anti-wear ability of the phenolic composite coating reinforced with MoS₂ or graphite deteriorated under water lubrication.     

Abrasion Mechanism of Stainless Steel/Carbon Fiber-Reinforced Polyether-Ether-Ketone (PEEK) Composites

A new type of composite material, stainless steel fiber and carbon fiber-reinforced polyether-ether-ketone (PEEK), was investigated to study its friction and wear properties and mechanisms. The friction materials containing 11 ingredients were hot-pressed and tested using a pad-on-disc type wear tester under unlubricated sliding friction and wear conditions at a constant sliding speed. The worn surface morphology was observed by Field-emission Scanning Electron Microscope (FE-SEM) and Atomic Force Microscope (AFM). The role of transfer film was studied using X-ray photoelectron spectroscopy (XPS) to investigate the thermal decomposition of the friction material. The fade ratio of the composites was only 4.8%, the recovery ratio 107%, and the total wear ratio was as low as 0.99 × 10⁻⁷ cm³(N m)⁻¹, showing the perfect properties of heat stability and recovery, as well as high antiwear ability of the composites. Adherence abrasion and particle abrasion take place at higher temperature. A transfer film is formed, which may improve abrasive resistant performance to get stable friction coefficient and low abrasion value for composite friction materials.     

SU-8 nanocomposite coatings with improved tribological performance for MEMS

The increasing interests in micro-electro-mechanical systems (MEMS) has raised the requirement for photoresist materials with improved friction and wear properties for mechanically loaded 3D shaped microstructures. In this work, SU8 photoresist layers reinforced with different amounts of silica nanoparticles were produced and thermally treated. Dry sliding tests indicate that SU8 composite epoxies produced in the form of thin films exhibit similar or even better tribological properties than bulk epoxies. The SU8 nanocomposites exhibit reduced wear rates and frictional coefficient compared to the un-reinforced material. Further, nanoparticle content, heat treatment and nature of the sliding counter piece were found to affect wear and friction. The tribological behaviour was discussed in terms of mechanical properties and contact pressures.     

La_2O_3填充PA1010复合材料的摩擦磨损性能

采用热挤压方法制备了不同La2 O3含量的尼龙 10 10 (PA10 10 )复合材料。测定了复合材料的密度和硬度 ,在MM 2 0 0型环块试验机上考察了其摩擦磨损性能。用光学显微镜观察了材料表面磨痕和转移膜形貌。结果发现 :La2 O3能显著改善PA10 10的摩擦学性能 ,尤其是填充量为 15 %的PA10 10复合材料减摩耐磨性能最佳 ,其摩擦系数从未填充的 0 .87降到 0 .3 3 ,磨损率降低近 1个数量级。PA10 10的磨损主要表现为严重犁削、粘着、疲劳和塑性变形 ,其转移膜不均匀 ,且有脱落现象。PA10 10 15 %La2 O3复合材料的磨损主要表现为轻微犁削 ,其转移膜薄而致密 ,且均匀光滑。这与二者的耐磨性能相一致     

Sliding wear characteristics of solid lubricant coating on titanium alloy surface modified by laser texturing and ternary hard coatings

Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because of its severe adhesive wear tendency. The surface modifications through texturing and surface coating were used to enhance the surface properties of the titanium alloy substrate. Hard and wear resistant coatings such as TiAlN and AlCrN were applied over textured titanium alloy surfaces with chromium as interlayer. To improve the friction and wear resisting performance of hard coatings further, solid lubricant, molybdenum disulphide (MoS2), was deposited on dimples made over hard coatings. Unidirectional sliding wear tests were performed with pin on disc contact geometry, to evaluate the tribological performance of coated substrates. The tests were performed under three different normal loads for a period of 40 min at sliding velocity of 2 m/s. The tribological behaviours of multi-layer coatings such as coating structure, friction coefficient and specific wear rate were investigated and analyzed. The lower friction coefficient of approximately 0.1 was found at the early sliding stage, which reduces the material transfer and increases the wear life. Although, the friction coefficient increased to high values after MoS₂ coating was partially removed, substrate was still protected against wear by underlying hard composite layer.     

Wear and transfer characteristics of carbon fiber reinforced polymer composites under water lubrication

The tribological characteristics of carbon fiber reinforced polymer composites under distilled-water-lubricated-sliding and dry-sliding against stainless steel were comparatively investigated. Scanning electron microscopy (SEM) was utilized to examine composite microstructures and modes of failure. The typical chemical states of elements of the transfer film on the stainless steel were examined with X-ray photoelectron spectroscopy (XPS). Wear testing and SEM analysis show that all the composites hold the lowered friction coefficient and show much better wear resistance under water lubricated sliding against stainless steel than those under dry sliding. The wear of composites is characterized by plastic deformation, scuffing, micro cracking, and spalling under both dry-sliding and water lubricated conditions. Plastic deformation, scuffing, micro cracking, and spalling, however, are significantly abated under water-lubricated condition. XPS analysis conforms that none of the materials produces transfer films on the stainless steel counterface with the type familiar from dry sliding, and the transfer of composites onto the counterpart ring surface is significantly hindered while the oxidation of the stainless steel is speeded under water lubrication. The composites hinder transfer onto the steel surface and the boundary lubricating action of water accounts for the much smaller wear rate under water lubrication compared with that under dry sliding. The easier transfer of the composite onto the counterpart steel surface accounts for the larger wear rate of the polymer composite under dry sliding.     

A Fractional Factorial Design Study of Reciprocating Wear Behavior of Al-Si-SiC<Subscript>p</Subscript> Composites at Lubricated Contacts

The lubricated reciprocating wear behavior of two composites A319/15%SiC_p and A390/15%SiC_p produced by the liquid metallurgy route was investigated by means of an indigenously developed reciprocating friction wear test rig using a fractional factorial-design approach. The main purpose was to study the influence of wear and friction test parameters such as applied load, sliding distance, reciprocating velocity, counter surface temperature and silicon content in composites, as well as their interactions on the wear and friction characteristics of these composites. Two output responses (wear loss and coefficient of friction) were measured. The input parameter levels were fixed through pilot experiment conducted in the newly developed reciprocating friction and wear test rig. The counter surface material used for the wear study was cast iron having Vickers hardness of 244 HVN. It had been demonstrated through established equations that A390/15%SiC_p composite is subjected to low wear compared to the A319/15%SiC_p composite. The experimental results indicate that the proposed mathematical models suggested could adequately describe the performance indicators within the limits of the factors that are being investigated. The applied load, sliding distance, reciprocating velocity, counter surface temperature, and silicon content in composite are the five important factors controlling the friction and wear characteristics of the composite in lubricated condition. Moreover, the two factor interactions have a strong effect on the wear of composites. The results give a comprehensive insight into the wear of the composites.     

Improving tribological properties of Ti6Al4V alloy with duplex surface treatment

Ti-doped diamond like carbon films were deposited on both untreated and plasma nitrided Ti6Al4V alloy using Closed Field Unbalanced Magnetron Sputtering (CFUMBS) method and their tribological properties were evaluated by conducting sliding wear conditions. The influence of the nitrided layer on tribological behavior of Ti-DLC films was studied by means of XRD, SEM, scratch tester, microhardness tester and pin-on-disc tribotester. The microhardness results pointed out that the duplex treatment dramatically increased the surface hardness and reduced the plastic deformation of the alloy. Wear tests showed that Ti-DLC coatings on both untreated and nitrided surfaces caused a reduction in the coefficient of friction. The reason of the reduction in the coefficient of friction was found to be the formation of transfer film between the sliding surfaces. Wear rates demonstrated that wear resistance of duplex treated (Ti-DLC coating after nitriding) Ti6Al4V alloy was significantly improved.     

Evaluation of sliding wear behavior of graphite particle-containing magnesium alloy composites

1 Introduction More and more magnesium alloy products have been used in automobile and aerospace industries due to their low density, high specific strength and specific stiffness, good damping characteristic, excellent machineability and castability, etc…     

Microstructure and wear resistance of <Emphasis Type="Italic">in situ</Emphasis> porous TiO/Cu composites

An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti₂CO and Cu powder. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. Dry sliding un-lubricated wear tests show that the wear resistance of the composite is higher than that of the Cu-Al alloy ingot. The coefficient of friction test shows that, as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear rate variation trend of the oil-lubricated wear test results is similar to that of the un-lubricated wear test results. The coefficient of friction for oil lubrication is similar for different volume fractions of the reinforced phase. The wear resistance of the composite at a sliding velocity of 200 rpm is slightly larger than that at 50 rpm. The porosity of the composites enhances the high-velocity oil-lubricated sliding wear resistance.     

Study on Properties of Ti(C,N)/TiN Multi-Element-layer Films Plus Nanometer Lubrication Dry Films

STARTING from the binary TiN wear-resistancecoating system,multi-element PVD superhard films,e.g.(Ti,Al)N films,(Ti,Cr)N films and Ti(C,N)films,may possess better tribological properties'1"41.Forexample,Ti(C,N)films showed higher hardness andbetter thermal-wear resistance properties than TiNfilms[4-5].However,due to mismatch of physical andmicro-structural properties of the multi-element filmsand the substrate,premature failure may occur duringfilm deposition process or in applicatio…     

SiCp/A356复合材料高温干滑动摩擦磨损特性研究

借助UMT-2型摩擦磨损试验机详细研究了转速对 SiCp/A356复合材料干滑动摩擦磨损特性的影响,并用SEM、EDS和奥林巴斯激光共焦扫描显微镜观察并分析了其高温摩擦磨损行为。结果表明：铸态材料的磨损率增加幅度和摩擦系数曲线波动较大;T6态材料的磨损率增加幅度和摩擦系数曲线波动较小,表现出优异的摩擦性能。铸态材料的磨损机理主要由低转速时的氧化磨损和剥离磨损转变为高转速时的粘着磨损,而T6态材料主要由低转速时的氧化磨损转变为高转速时的剥离磨损和磨粒磨损。高转速区时,铸态材料的磨损断面中出现裂纹,而T6态材料只是存在简单的磨削痕迹和颗粒脱落现象,热处理后复合材料的高温耐磨性能明显提高。     

Study on mechanical properties of anodised film containing nano-diamond particles

Anodic-composite films containing nano-diamond particles (ND) were prepared on 7000 aluminium alloy using an anodising method. The micro-structures of the film were studied by scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and minitab software (version 16). The results indicate that the micro-hardness and wear resistance of the films were improved using the nano-additive. Thus, the wear loss of the composite (the film anodised in the bath containing of sulphric acid, oxalic acid and 85?g?L^?1 ND) evaluated by dry sliding friction test for 50?000 cycles at room temperature, was 0.4?mg compared to 3?mg in the absence of ND, a 750% improvement. The friction of ND composite anodic films is significantly less than the samples without the added particles. Moreover, the micro-hardness of the composite film reached a maximum value of 770?VHN. The results also show that the mechanical properties of the composite films are mainly dependent on the structure of the oxide films.     

二硼化钛对Al2024−TiB2非原位复合材料摩擦磨损性能的影响

用搅拌铸造法制备不同质量分数二硼化钛(TiB2)颗粒增强的铝基复合材料,并研究其摩擦磨损性能.采用销?盘式摩擦试验机对Al2024?TiB2复合材料进行干滑动磨损试验.为了研究摩擦学参数对复合材料的影响,对载荷、滑动距离和滑动速度等参数进行调整.显微组织表征结果表明,TiB2颗粒分散均匀并与基体有良好的结合.实验结果表...     

氮化钛 / 氧化钛复相陶瓷涂层的干滑动摩擦磨损性能

目的研究等离子喷涂Ti N/Ti O复相陶瓷涂层的微观组织结构、显微硬度及干滑动摩擦磨损行为和机理。方法采用等离子喷涂技术,在45#钢表面制备Ti N/Ti O复相陶瓷涂层。分析涂层的相组成,测试涂层的硬度。通过磨损试验研究Ti N/Ti O复相陶瓷涂层的磨损行为,并观察涂层的磨损形貌,测试磨损表面的成分组成,探讨Ti N/Ti O复相陶瓷涂层的磨损机理。结果 Ti N/Ti O复相陶瓷涂层均匀致密,平均厚度为350μm,具有明显的层状结构,孔隙率为4.3%,显微硬度为1444HV0.1。在载荷30~50 N、转速370~1102 r/min的范围内,Ti N/Ti O复相涂层与GCr15对磨的摩擦系数为0.0963~0.2778,磨损量为1.32~6.8 mg。随着载荷的增加,摩擦系数下降;随着载荷和转速的增加,磨损量增加。结论等离子喷涂制备的Ti N/Ti O复相涂层组织致密,显微硬度高,在低速低载荷时表现出较好的耐磨性,但随着载荷和转速的增加,耐磨性降低。涂层的磨损机制主要为磨粒磨损和粘着磨损。     

Research of the Tribological Properties of the Surface on 16Mn Steel by Plasma Nitriding and S-N-C Plasmas Composite Treatment

Sulfide layer with certain thickness was made on the nitrided surface of 16Mn steel by means of plasma S-C-N composite treatment. Under half lubricated condition, friction coefficient and wear loss of LY12 aluminum alloy were measured in sliding against samples of 16Mn treated by cubrizing and sulphiding respectively; In order to avoid the transfer of aluminum to the steel that lead to the inaccurate measurement of wear loss of carburized samples, Grl5 steel was adopted as counterpart face to measure the wear loss of them. SEM and EDAX were used for the morphological and chemical characterization of the wear surface and longitudinal cross-sections beneath sliding surface of LY12 aluminum alloy cirque and the wear tacks of the carburized samples and sulphided samples. Results show: The surface roughness,wear rate, average friction coefficient and magnitude of friction fluctuations of LY12 aluminum alloy cirque sliding against sulphided sample were all lower than sliding against carburized sample; Compared with carburized layer, sulfide layer of 16Mn steel can not only efficiently prevent the occurrence of adhesion when sliding against LY12 aluminum alloy, but also greatly lower the wear loss when sliding against Gr15 steel.     

Microstructure and Tribological Properties of PlasmaSprayed Ni/MoS2 Solid Lubrication Coating

A composite Ni based MoS2 solid lubrication coating was prepared using the plasma spraying technology with optimized process parameters.The tribological properties of the composite Ni/MoS2 coatings in air and vacuum were studied with a ball-on-disk friction and wear tester under dry sliding condition,respectively.XRD,SEM and EDS were adopted to analyze the microstructures of the coating before and after wear tests.Results showed that the deposition quality of the coating was good.The content of lubricant MoS2 was high.But the compactability of the coating with many superficial micrometersized defects such as pores and cracks was relatively low.The composite Ni/MoS2 coating exhibited excellent friction-reduction properties both in air and in vacuum conditions.In vacuum,the wear loss was greater because the severe spalling of top layer resulted from breakthrough of the adjacent defects.In air condition,the wear loss of the coating was relatively low but its friction-reduction ability may be weakened for the oxidation of MoS2.     

A356/SiC_P与列车实用中的有机闸片的滑动摩擦磨损特性

以铝基复合材料作为列车制动盘材料的实用化为目的,选用A356/SiC 20%(体积分数,下同)复合材料和AISI D2工具钢为摩擦材料,以中速列车实用中的有机闸片为对偶材料,进行对比干摩擦磨损试验,并分析比较了磨损特性.结果表明:铝基复合材料在小于200 N(3.98 MPa)的低载荷下,只存在轻微的氧化磨损,耐磨性比实用中的铁合金材料更好;而超过该载荷时,开始发生磨削磨损,磨损量逐步超过铁合金材料,当载荷达到400 N(7.96 MPa)时,由于严重的磨削磨损,磨损量剧增.而铁合金材料则随载荷和滑动速度增加,磨损率缓慢增加;磨损过程中的复合材料的摩擦系数平均值与载荷、滑动速度无关,始终保持0.3～0.4,同时随磨损距离的波动也非常小,而工具钢的摩擦系数平均值则对试验参数的敏感度相对大些,且摩擦系数平均值也比复合材料略小,即摩擦系数方面复合材料具有更好的特性.     

Morphological response of diamond films in dry sliding contact

Reciprocating dry sliding friction tests performed on diamond-coated tungsten substrates produced changes in the surface morphology. A right-cylinder-on-flat geometry was used for the tribotesting. The morphological changes were investigated with scanning electron and atomic force microscopy. The composition of the diamond film was determined with Raman spectroscopy. The frictional response of the coating is examined in relation to the surface changes. A wear model for diamond films in dry sliding contact based on the morphological response is presented.     

Ni-P/Ti/DLC多层膜的摩擦磨损性能

目的研究摩擦速度、载荷及加热温度对Ni-P/Ti/DLC多层膜摩擦磨损性能的影响。方法用化学镀镍磷工艺在模具钢基体表面镀上Ni-P层作切削层,采用过滤阴极真空电弧(FCVA)技术分别沉积Ti过渡层和DLC保护层。通过摩擦磨损实验,评价该多层膜的摩擦磨损性能。利用纳米压痕测试和拉曼光谱检测,研究该多层膜在不同加热温度下的硬度、弹性模量和结构成分。利用扫描电镜及表面轮廓仪分别对该多层膜的磨痕形貌和横截面轮廓进行分析。结果随着摩擦速度的增大,Ni-P/Ti/DLC多层膜的摩擦系数呈下降趋势,磨损率和磨损体积呈先减后增的趋势。不同载荷下的摩擦系数变化幅度较小,磨损率和磨损体积随着载荷的增大呈增加的趋势。随着加热温度的升高,摩擦系数呈下降趋势,磨损率和磨损体积呈先增后减的趋势。此外,随着加热温度的升高,多层膜表层DLC膜中石墨相逐渐增多,硬度和弹性模量随之呈先增后减的趋势。结论较高摩擦速度下,多层膜表层DLC膜石墨化趋势增强,摩擦系数变化幅度较大,且表面磨痕宽度和深度显著增加,磨损加剧。多层膜中软质的Ti金属层和硬质的DLC层,能有效提高多层膜在高载荷下的摩擦磨损性能。随着加热温度的升高,多层膜表层DLC膜中石墨相逐渐增多,摩擦过程更易生成转移膜。