Wear Behavior of Bronze Hybrid MMCs Coatings Produced by Current Sintering on Steel Substrates

In this work, a bronze matrix (90 wt% Cu + 10 wt% Sn) was reinforced with SiC and graphite particulates using mechanical alloying and a subsequent current sintering technique. The mechanically ball-milled bronze hybrid matrix composite powders reinforced with 5.0 wt% SiC and 5.0 wt% graphite were cold-compacted on a 1040 steel substrate under a pressure of 300 MPa. The compacted structure was sintered at atmospheric conditions to nearly a full density within 10 min using current sintering, in which the powders were heated by a low voltage and high current and compressed simultaneously. The samples were sintered at three different applied currents (1,500, 1,700, and 1,900 A) to provide dense and well-bonded coatings on steel substrates. Microhardness testing and optical and scanning electron microscopes (SEM) were used for microstructural characterization of the hybrid composites. The tribological characterization of the resulting composites was tested by a block-on-disk method for determination of the wear loss and friction coefficient behaviors against a steel disk. It was pointed out that increasing applied current during the sintering/coating process resulted in obtaining high-hardness and wear-resistant hybrid composite coatings.     

纳米硼酸盐的摩擦学特性初探

本文对利用二氧化碳超临界干燥法制备出的纳米硼酸镧、纳米硼酸铈、纳米硼酸镍及纳米硼酸铜四各粒子,进行了常规的摩擦学性能评定,并与市售的商品ＺＤＤＰ进行了对比,表明其性能差异不大。在自选设计的特殊摩擦试验中,ＺＤＤＰ却与四种纳米硼酸盐表现出了极大的差异,证明了纳米粒子独特的摩擦学特性。     

纳米ZnO填充的PTFE基复合材料摩擦学性能研究

得胜０００型摩擦磨损试验机研究了不同体积含量的纳米氧化锌（ＺｎＯ）填充的ＰＴＦＥ基复合材料在于摩擦条件下与不风对摩时的摩擦学性能,并利用扫描电子微镜（ＳＥＭ）对ＰＴＦＥ及纳米ＺｎＯ／ＰＴＦＥ复合材料的微观结构、磨损表面和转移膜进行了观察和分析。结果表明,纳米ＺｎＯ／ＰＴＦＥ复合材料的摩擦性能与纯ＰＴＦＥ基本相当,但耐磨性明显优于后者,纳米ＺｎＯ在复合材料中的最佳含量为１５ｖｏｌ．％左右。     

Ekonol对Ekonol—石墨—PTFE自润滑复合材料的摩擦学性能的影响

本文研究了聚对－羟基苯甲酸酯（Ekonol)的含量对Ekonol-石墨－PTFE自润滑复合材料的摩擦磨损性能的影响,试验结果表明：随着Ekonol含量的增大,复合材料的摩擦系数有所上升,但其均在0．19以下,当Ekonol含量低于20％时,其上升幅度较大,而当Ekonol含量高于20％时,其上升幅度较平缓;复合材料的磨损量最初随着Ekonol含量的增大呈现急剧减少,在Ekonol含量为25％时出现了一个极小值,此后又呈现缓慢的上升。扫描电子显微镜（SEM）对复合材料磨损后表面形貌的观测表明：当Ekonol含量较低时复合材料发生的是严重粘着磨损,而当Ekonol含亘较高时,复合材料发生的是疲劳磨损,说明了Ekonol的填加可明显地提高此复合材料的抗粘着能力。     

载荷对丁腈橡胶摩擦学特性的影响

采用栓－盘式摩擦磨损试验机考察了载荷对丁腈橡胶摩擦学特性的影响,分析了其作用机理,结果表明,丁腈橡胶的摩擦系数和磨损均随损均随载荷的增加而降低;在较低载荷时,丁腈橡胶表现为滞后摩擦,在较高载荷时,表现为粘着摩擦,在较低的滑动速度下,载荷的改变不会引起丁腈橡胶摩擦过程中摩擦化学反应的发生,只是产生简单的分子机械断裂。     

Tribological Properties of Paraffinic Oil with Nanodiamond Particles

Friction accounts for a large amount of energy lost in mechanical systems and applications. Nanofluids, with particles less than 100 nm, added to a base fluid have been proven to be effective in reducing friction and wear. Diamond has superior mechanical, thermal, optical, electrical, and chemical properties. Therefore, nanodiamond holds a lot of promise for use in nanofluids. The tribological properties of oil-based nanofluids with spherical nanodiamond particles with the size of 3–10 nm in diameter were investigated using a ball-on-disk friction test by varying nanodiamond concentration, sliding velocity, normal load, and disk roughness. The friction testing was performed using a UMT-2 Micro Tribometer. Wear analysis was performed and chemical composition of the disk surface was examined using a WYKO 3D surface profiler and X-ray photoelectron spectroscopy. In general, the addition of nanodiamonds to oil leads to a reduction in the coefficient of friction but an increase in wear of the disk.     

Wear Behavior of Multiwalled Carbon Nanotube/AZ31 Composite Obtained by Friction Stir Processing

Multiwalled carbon nanotubes were homogenously dispersed into a magnesium alloy (AZ31) using friction stir processing. The microstructural features, mechanical behaviors including microhardness, and wear properties were investigated. The results showed a significant improvement in wear resistance in the friction stir-processed AZ31 alloy containing multiwalled carbon nanotubes compared to that of the as-received alloy. This was attributed to its higher microhardness and lower coefficient of friction due to the presence of finer matrix grains and uniform dispersion of multiwalled carbon nanotubes.     

修饰的纳米铜粒子对合成机油抗磨性能研究

分别采用不同的摩擦磨损试验机考察了DDP修饰的纳米铜粒子对合成机油摩擦磨损性能的影响。结果表明，DDP修饰的纳米铜粒子作为添加剂，提高了摩擦副的耐磨减摩性能。     

Tribological Sensitivity of PTFE/Alumina Nanocomposites to a Range of Traditional Surface Finishes

Wear tests were performed with polytetrafluoroethylene (PTFE) + Al ₂ O ₃ nanocomposites on various manufactured surfaces to determine whether or not the wear resistance of these nanocomposites is a strong function of surface preparation. Four different surface finishes of grade 304 stainless steel counterfaces were used: electropolished (R _q = 88 nm), lapped (R _q = 161 nm), wet-sanded (R _q = 390 nm), and dry-sanded (R _q = 578 nm). PTFE + Al ₂ O ₃ nanocomposites made from powders of roughly 2-20 μm PTFE (matrix) and ～44 nm Al ₂ O ₃ (filler) were prepared at filler weight percentages of 0, 1, 5, and 10% and tested on each surface finish. Additionally, 5 wt% 44-nm nanocomposites were compared to identically prepared 5 wt% 80- and 500-nm Al ₂ O ₃ filled PTFE composites on each surface. Friction coefficients were between 0.12 and 0.19 and wear rates decreased from K = 810 × 10^{? 6} mm ³ /(Nm) for the 5 wt% 500-nm alumina-filled PTFE on the dry-sanded surface to K = 0.8 × 10^{? 6} mm ³ /(Nm) for the 5 wt% 80-nm filled composite on the lapped surface. It was found that the minimum wear rate occurred on the lapped counterface for every composite, and the wear rate is a strong function of the transfer film thickness and morphology.     

A Study on the Sliding Wear of Hybrid PTFE/Kevlar Fabric/Phenolic Composites Filled with Nanoparticles of TiO2 and SiO2

TiO₂ and SiO₂ nanoparticles were introduced into hybrid polytetrafluoroethylene (PTFE)/Kevlar fabric/phenolic composites. The results showed the incorporation of TiO₂ nanoparticles can reduce the wear rate of the fabric/phenolic composite at elevated temperatures, although the wear of hybrid PTFE/Kevlar fabric/phenolic composite did not change much when TiO₂ or SiO₂ nanoparticles were used as filler. The wear behavior was explained in terms of morphology of transfer films and worn surfaces. There was a good correlation between the morphology of transfer film and wear results.     

Effect of Cu Nanoparticles on the Tribological Performance of Attapulgite Base Grease

This study investigated the effect of Cu nanoparticles on the tribological properties of attapulgite base grease. It was found that the friction reduction ability and antiwear property of the base grease can be improved with the addition of Cu nanoparticles. Under the lubrication of grease containing Cu nanoparticles, a smoother and more compact tribofilm was formed on the rubbing surface. The tribofilm is mainly composed of Cu, FeO, Fe₂O₃, FeOOH, CuO, and SiO. In addition, the content of iron oxides and silicate oxide formed in the tribofilm was increased by the introduction of Cu nanoparticles.     

Impact of Plateaued Surfaces on Tribological Performance

Plateaued surfaces are surfaces that have been machined to simulate those that result from normal running in and are said to have advantages over conventional or non-plateaued surfaces. However, the evidence is lacking. This study evaluates the tribological performance of plateaued and non-plateaued surfaces on a pin-on-disk tribometer. The honing pattern of an engine cylinder bore was simulated on the disks. These disks have similar average surface heights with either plateaued or non-plateaued surface finish. Friction, wear and scuffing resistance of plateaued and non-plateaued disks were evaluated. Results from the pin-on-disk tribometer show that in the hydrodynamic lubrication regime plateaued and non-plateaued disks have the same friction, while in the mixed lubrication regime the plateaued surface has less friction. The author's findings also reveal that plateaued surfaces tend to have higher wear resistance but lower scuffing resistance. It also confirms the conventional wisdom that plateaued surfaces have shorter running-in wear period.     

Tribological performance of Al2O3/NiCr coating

The tribological performance of Al₂O₃/NiCr coating deposited on steel (SM45C) was investigated under lubrication. The parameters of sliding wear consist of normal load and coating thickness. Test result showed that there was no evidence of an improved bonding strength in the coating. However, the wear resistance of the Al₂O₃/NiCr coating was significantly greater than that of the Al₂O₃ coating. It was evident that the residual stress for the AI2O3 coating was higher than that of the Al₂O₃/NiCr coating from the scratch test failure of coating. The bond coating played an important role in decreasing the residual stress. Also, it was found that the residual stress had a notable influence on the wear mechanism.     

杂氮硅三环的防锈性能和摩擦性能研究

本文用铜片腐蚀测定仪研究了杂氮硅三环的抗腐蚀性能。四球摩擦实验机探讨了要氮硅三环的摩擦学性能，实验证明杂氮硅三种作为环保型水基金属加工液添加剂具有良好抗腐蚀性能和一定的减摩抗磨性能。     

妥尔油酸酯与ZDDP复配的摩擦学特性研究

合成了油溶性环氧类妥尔油酸酯，并以合适比例与ZDDP复合作添加剂，在四球摩擦试验机上研究了其摩擦磨损性能，发现其复合剂具有优异的抗磨性，摩擦系数明显降低及其承载能力明显提高，用ImageVIew数字化图像处理系统观察了摩擦表面，表明该复配体系在磨擦表面可形成较为致密的保护膜。     

Tribological Behavior of Si3N4-hBN Ceramic Materials without Lubrication under Different Test Modes

Unlubricated tribological behaviors of silicon nitride–boron nitride (Si ₃ N ₄ -hBN) composites were investigated with two test modes in air by using a pin-on-disc tribometer. Under upper-disc-on-bottom-pin test mode, the addition of hBN to Si ₃ N ₄ resulted in a significant decrease of the friction coefficient, from 0.54 for Si ₃ N ₄ against Si ₃ N ₄ to 0.19 for Si ₃ N ₄ -20% hBN against Si ₃ N ₄ . The surface analysis indicated that a tribochemical film consisting of SiO₂ and H ₃ BO ₃ was formed on the wear surfaces. The formation of tribochemical film might be attributed to the embedment of wear debris into the spalling pits on the wear surfaces of Si ₃ N ₄ -hBN specimen. The wear debris reacted with moisture in air, and the resultant tribochemical film lubricated the wear surfaces. Under upper-pin-on-bottom-disc test mode, the wear mechanism was dominated by abrasive wear, and no tribochemical products could be detected on the wear surfaces. A slight decrease of the friction coefficient, from 0.85 for Si ₃ N ₄ /Si ₃ N ₄ to 0.56 for Si ₃ N ₄ /Si ₃ N ₄ -30% hBN, was obtained, which might be attributed to the layered structure of hBN.     

润滑油中CuS纳米粒子的摩擦学性能研究

本文用合成工艺简单、成本低廉、易于工业化生产的液相法制备了CuS纳米粒子,并对该粒子在润滑油中的摩擦学性能进行了研究。结果表明,CuS纳米粒子加入润滑油中,能极大地提高基础油的抗磨减摩性能。     

有机复合锡盐的摩擦学性能研究

本文用四球摩擦试验机探讨了有机锡盐及其与T202复合后锡盐的摩擦学性能,试验证实：有机锡盐与T202具有良好的协同效应, 使润滑油承载能力增大和耐磨性增强。     

Tribological properties of high temperature resistant polymer composites with fine particles

The tribological properties of two kinds of high temperature resistant thermoplastic composites, polyetheretherketone (PEEK) and polyetherimide (PEI), reinforced with short carbon fibre (SCF), graphite flakes, and sub-micro particles of TiO₂ and ZnS, were investigated in dry sliding conditions. Friction and wear experiments were conducted on a pin-on-disc apparatus, using composite pins against polished steel counterparts, performed within moderate pv-ranges at room and elevated temperatures (up to 150 °C). It was found that conventional fillers, i.e. SCF and graphite flakes, could effectively enhance both the wear resistance and the load-carrying capacity of the base polymers. With the addition of sub-micro particles, the frictional coefficient and wear rate of the composites were further reduced especially at elevated temperatures. On the basis of microscopic observation of worn surfaces, dominant wear mechanisms are discussed.     

Correlation Between Tribological Parameters and Wear Mechanisms of Homogeneous and Heterogeneous Material

This study intended to investigate the effect of tribological parameters on wear mechanisms and friction coefficient for homogeneous and heterogeneous materials. Particularly, effects of particle geometry and normal load on the tribological behaviour of an aluminium alloy and nodular cast iron have been developed. These materials are used in two industrial applications. The first one is used to transport granular material. It has been shown that damage of used truck’s buckets is produced. However, the nodular cast iron is used in automobile industry thanks to its lower density, good wear resistance and its low friction coefficient. A scratch test was used and the wear mechanisms were observed for different attack angles. The normal load was also varied and correlation between wear mechanisms, tribological parameters and friction coefficient was highlighted.