机械模具导向滑板Fe-Mo-石墨自润滑材料摩擦学性能研究

采用粉末冶金工艺,制备了3种不同石墨含量的Fe-Mo-石墨自润滑材料,测定了3种材料的密度、硬度和抗压强度,并对材料的组织和不同摩擦速率下的摩擦学性能进行分析和研究,最后采用扫描电镜(SEM)和X射线衍射仪(XRD)对磨痕表面形貌和成分进行表征。结果表明,复合材料中石墨添加质量分数为1.0%时,材料组织以铁素体为主相,此时的摩擦系数较为稳定,磨损率随摩擦速率的提高而增大,磨损机制主要为粘着磨损;石墨添加质量分数高于1.0%时,材料组织以珠光体为主相,摩擦系数随摩擦速率提高而增大,但磨损率随之减小,且摩擦速率高于0.5m/s时,磨损率量级为10~(-8)cm~3/N·m,属于轻微磨损。材料中珠光体、Fe_2MoC的生成,以及摩擦过程中生成的Fe_2O_3、Fe_3O_4是Fe-Mo-石墨材料在高的摩擦速率下具有优良耐磨性的主要原因。     

含石墨的青铜-钢背双金属材料的微摩擦学特征

通过粉末冶金工艺制备了含石墨的青铜-钢背复合材料,采用多功能微摩擦磨损测试仪和扫描电镜等检测分析手段,研究了石墨含量对材料的硬度、显微组织和摩擦磨损性能的影响,并考察了摩擦磨损机理。结果表明:随着石墨含量的增加,材料的硬度逐渐降低;材料的摩擦磨损性能是随着石墨含量的增加先逐渐提高,后逐步降低;在石墨含量为3%(质量分数)时,材料的平均摩擦系数、最大摩擦系数和摩擦系数变化幅度等摩擦磨损性能最佳;在既定试验条件下,合适的石墨含量和材料硬度是保证石墨能够在摩擦面上成膜良好和充分发挥固体润滑剂作用的关键。     

Ni—Cr／hBN自润滑复合材料的摩擦学性能研究

采用粉末冶金技术制备Ni—Cr／hBN自润滑复合材料,研究hBN含量及摩擦栽荷对Ni—Cr／hBN复合材料的性能及摩擦磨损行为的影响．结果表明：随hBN含量增大,Ni—Cr／hBN复合材料的密度、抗弯强度和摩擦系数均逐渐减小．当载荷为20N时,Ni—Cr／hBN复合材料的磨损速率随hBN含量的增大而减小：当栽荷为60N和100N时,磨损速率随hBN含量增大呈先减小后增大的趋势．当hBN含量不变时。磨损速率随载荷增大而逐渐增大．通过探讨Ni—C汕BN自润滑复合材料的润滑与磨损机理可知。材料的摩擦系数取决于hBN的含量,而磨损速率与材料的力学性能有关．当hBN含量为9％（质量分数）,摩擦载荷为60N时,Ni—Cr／hBN自润滑复合材料具有最佳的摩擦学综合性能．     

MoS2?Ag?V2O5对镍基材料摩擦磨损性能的影响

采用粉末冶金烧结工艺制备了含不同润滑剂（MoS₂、Ag和V₂O₅）的镍基自润滑复合材料,研究了镍基复合材料在室温至600 ℃之间的摩擦磨损性能,通过X射线衍射仪、扫描电子显微镜和Raman光谱等分析相组成和磨损形貌。结果表明:镍基自润滑复合材料的摩擦系数随温度的增加呈先增加后降低的趋势。在室温条件下,随着Ag含量的增加,复合材料的摩擦系数减小;在600 ℃,随着V₂O₅含量的增加,复合材料的摩擦系数和磨损率均降低。在中低温,镍基自润滑复合材料主要由MoS₂和Ag起润滑作用,降低材料摩擦磨损;在高温,复合材料发生了摩擦化学反应,生成新的钼酸银润滑相,润滑机理是由钼酸银和V₂O₅的协同润滑效应。     

石墨添加量对热压镍铬钼-石墨复合材料性能的影响

本论文研究了热压制备添加石墨的镍铬钼复合材料的力学性能及摩擦磨损特性。结果表明，随着石墨添加量的增加，复合材料的抗拉强度和伸长率逐渐下降，硬度逐渐上升，摩擦系数逐渐变大。其中添加石墨后的复合材料硬度明显高于不添加石墨的基体合金硬度，石墨添加量（质量分数）为1％时复合材料的磨损率最低。新材料中由于添加石墨而形成的硬质碳化物及游离石墨的存在，正是这种力学性能及摩擦磨损变化规律的根本原因。     

石墨含量对铜基摩擦材料摩擦磨损性能的影响

采用粉末冶金压烧技术制备了含不同质量分数石墨的铜基摩擦材料,研究了石墨含量对摩擦材料微观组织、磨损性能和磨损机理的影响。结果表明:铜基体的连续性随石墨含量增加而降低,动摩擦系数随石墨含量的增加先增加后降低,磨损量随着石墨含量的增加而减小;材料的磨损机理为犁沟式磨料磨损;石墨质量分数为16%时,试样动摩擦系数和静摩擦系数最高并且稳定,具有最好的摩擦磨损性能。     

新型铁基固体自润滑复合材料摩擦学特性的研究

为了开发新型的高温固体自润滑材料,采用粉末冶金法制备了添加羰基镍包覆石墨和CaF2的新型铁基自润滑材料,研究了该材料的力学及摩擦学性能。结果表明:在室温下,添加CaF2的复合材料的摩擦系数变化甚微,而磨损率出现增加的趋势;但是,在500℃高温下,复合材料的摩擦系数却随着CaF2含量的增加而不断降低,磨损率先降低后又逐渐增加;当CaF2添加量为5%(质量分数)时,复合材料在较宽温度范围内均具有优异的摩擦学性能。获得了具有良好综合性能的高温固体自润滑材料。     

自润滑材料滑动摩擦失效分析

通过滑动摩擦磨损实验,评价试样的磨损性能,结合自润滑材料的摩擦特性（μ-n）曲线和自润滑滑动摩擦磨损机理,利用SEM研究摩擦磨机理,得知自润滑材料失效的实质是：在滑动摩擦的后期,自润滑向干摩擦过渡,最终转变为干摩擦,而干摩擦的磨损量比自润滑的高3个数量级,使材料的磨损量急剧升高,材料因磨损量过大而失效,其磨损机理粘着磨损。     

石墨的铜包覆量对自润滑材料的性能影响

采用粉末冶金方法,选取铜质量分数分别为30%和60%的铜包石墨与铜粉制备铜基石墨自润滑材料,并对不同包覆量的石墨制备的固体自润滑材料的性能进行分析。结果表明,铜包覆量为30%的石墨制成的固体自润滑材料在20N载荷下的最小摩擦因数为0.13,对应的抗压强度为192 MPa,力学性能和摩擦磨损性能好;选用包覆含量为30%的铜包石墨可以与铜粉制成减摩润滑效果好且力学性能优的固体自润滑材料。     

关于发展自润滑材料的研究

本文研究在不给油状态下长期使用的自润滑轴承材料的有关烧结复合材料。从节省资源和再利用资源的观点出发,该材料用铸铁或铜合金铸件切屑所制成的粉末作为原料,添加作为固体润滑剂的石墨、或在铁基烧结材料中浸渍热可塑性树脂而制成。一、铸铁粉烧结材料的摩擦磨损特性 1.铸铁粉烧结材料     

WEAR AND FRICTION STUDIES OF NICKEL–TUNGSTEN CARBIDE–GRAPHITE COMPOSITES

Abstract

Wear and friction studies have been carried out on pressed and sintered composites of 75–95% theoretical density. Carbonyl nickel and tungsten carbide, both with a particle size of 5 μm, and natural crystalline flake graphite with an approximate size of 1·1 μm were used. The wear specimens were run against a rotating (100 rev/min) steel cylinder. The wear-resistance correlates well with the ratio of the volume fraction of tungsten carbide to that of graphite (WC/graphite); there is a minimum in weight loss at a ratio near unity. This effect is explained in terms of powder coating with graphite during blending, which affects grain-boundary formation and grain growth during sintering; supporting metallographic evidence is given. The wear-debris particle size produced is related to wear; the wear rate increases with increasing particle size. Residual porosity in the materials reduces wear-resistance. The wear rate does not correlate with hardness or coefficient of friction; the results of wear tests in oil or water are very similar to those for tests run in air.     

陶瓷材料AIN及TiCN中氧、氮的测定

本文介绍了采用LECO TC-136氧/氮测定仪测定陶瓷材料AIN,TiCN中氧及氮的惰气熔融脉冲加热法。该法用Ni-Sn作助熔剂,用“高温”型石墨坩埚提取气体。Al_2O_3及TiO_2中氧回收率分别是100.1％和98％,氮的分析值与化学法比较是满意的。     

EFFECTS OF PROCESSING AND POWDER CHARACTERISTICS ON THE WEAR AND FRICTION PROPERTIES OF SOME NICKEL-BASE MATERIALS

Abstract

Pure nickel and nickel-based binary and ternary materials containing tungsten carbide and graphite dispersions have been studied. Three types of carbide powder and six types of graphite, different in size, shape, and structure (one in each group being nickel-coated) were studied to varying degrees. The smallest carbide powder (0·35 μm) possessed the best wear-resistance and the lowest coefficient of friction. The larger and coated types of graphite are somewhat superior; however, considerable amounts (～ 40 vol.-%) are needed to improve wear-resistance substantially and reduce the coefficient. Use of the coated type of carbide leads to rather high coefficients (0·58-0·76) under dry testing conditions. Several effects of the presence of a small amount of oxygen in the sintering atmosphere are discussed; a most interesting result is the marked improvement in the wear-resistance of pure nickel treated to produce a dispersion of nickel oxide. With some powders blending can lead to reduced wear-resistance, while with others increasing the blending time has no effect. Several of the findings confirm the interpretation of the results of the previous study regarding the dependence of wear on the ratio of the volume fraction of tungsten carbide to that of graphite, based on microstructural considerations. Wear-resistance cannot be correlated with high hardness.     

反应合成的TiC对铜基摩擦材料摩擦磨损性能的影响

研究了反应合成的TiC对铜基摩擦材料摩擦磨损性能的影响,结果表明:随着Ti含量的增加,Ti与铜基摩擦材料中的润滑剂石墨反应生成了硬度较高的TiC;TiC对基体起弥散强化作用,使铜基摩擦材料的硬度相应升高;Ti含量较高的铜基材料在较高的载荷和滑动速度下具有较小的磨损率。     

Tribological characteristics of aluminum-50 Vol Pct graphite composite

Friction and wear in composites containing 50 vol pct granular or flake graphite in 2014 aluminum alloy have been measured for different normal loads and sliding velocities ranging from 25 to 100 N and 0.5 to 3 m/s, respectively. The coefficients of friction and wear are significantly lower in the composites, as compared to those in the matrix alloy containing no graphite. The transition to severe wear takes place at a higher load and sliding velocity as compared to the base alloys, particularly in composites containing granular graphite. In composites containing flake graphite, friction and wear depend on sliding direction relative to the orientation of the flake. This behavior has been explained on the basis of subsurface deformation, leading to transfer of graphite to the tribosurfaces, and the plastic flow of constituent alloy, resulting in covering of the embedded graphite by the matrix alloy.     

放电等离子烧结制备镍掺杂石墨-铜复合材料组织性能研究

通过超声波分散结合行星球磨对复合粉末进行混料，利用放电等离子烧结技术（SPS）制备镍掺杂石墨-铜复合材料。运用扫描电子显微镜（SEM）、X射线衍射（XRD）、硬度计和摩擦磨损试验机等方法，研究了不同镍掺杂含量对石墨-铜复合材料组织和力学性能的影响。结果表明:通过该工艺制备石墨-铜复合材料石墨均匀分散于铜基体，并与铜基体形成良好的界面结合。随着镍掺杂含量的增加，石墨-铜复合材料相对密度和硬度逐渐增加。当镍掺杂含量（指质量分数）为7.0%时，石墨-铜复合材料相对密度为95.2%，HV_0.5硬度为53.4，摩擦系数相对较低，磨损表面较光滑，此时综合性能较好。      

Wear and friction behavior of metal impregnated microporous carbon composites

Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the composites is very sensitive to the size and distribution of the microstructural constituents.     

Mechanical Properties and Friction／Wear Behavior of Copper Alloyed Powder Composites

Copper alloyed powder composites containing nanoparticles were developed by hot pressing. Effects of nanoscale activated sintering aid and fine ceramic particles Al2O3 on hardness, working quality, and behaviors of friction and wear of the composites have been studied, compared with the composites including mieroscale activated sintering aid and microscale ceramic particles. The microstructures of the samples were analyzed by SEM. The resuits show that the materials with nanoscale sintering aid and fine ceramic particles have better mechanical properties and abrasive resistance than the materials with microscale activated sintering aid and microceramic particles. Moreover, element mutual transfer occurs between samples (strip) and abrasive wheel (ring).