Tribological Properties of PVA-H Composites Reinforced by Nano-HA Particles

The friction and wear behaviors of tribological mechanical components were studied on a four-ball tester under dry conditions, and the wear mechanism was analyzed by observed worn surface using a scanning electron microscope （SEM）. It was found that the friction and wear properties were improved by the addition ofnano HA particles. The composite containing 1 wt% nano HA had the optimum friction coefficient. It is also found that the addition of nano HA increases the wear resistance of oure PVA-H and PVA-H composites.     

Wear performance of Ni/ZrO<Subscript>2</Subscript> infiltrated composite layer

The Ni/ZrO2 was used as raw materials to fabricate the surface infiltrated composite layer with 1-4 mm thickness on cast steel substrate through vacuum infiltrated casting technology. The microstructure indicated that the infiltrated composite layer included surface composite layer and transition layer. Wear property was investigated under room temperature and 450 ℃. The results indicated that the abrasion volume of substrate was 8 times that of the infiltrated composite layer at room temperature. The friction coefficient of infiltrated composite layer decreased with the increasing load. The wear resistance of infiltrated composite layer with different ZrO2 contents had been improved obviously under high temperature. The friction coefficient of infiltrated composite layer was decreased comparing with that at room temperature. The oxidation, abrasive and fatigue abrasion was the main wear mechanism at room temperature. Oxidation abrasion, fatigue wear and adhesive wear dominated the wearing process under elevated temperature.     

The Wear Process of PTFE Coatings Under Vacuum Conditions

The wear process of PTFE coatings sliding against GCrlS-bearing steel ball under vacuum conditions was investigated, and the hardness of the PTFE coatings on both sides of wear track was measured. The experimental results showed that the friction coefficient of the PTFE coatings increases with the increase of sliding distance under different sliding velocities. And the friction coefficient of the PTFE coatings increases with the increase of sliding distance under different sliding loads. The wear rate of PTFE coatings decreases with the increase of sliding distance. And the majority of the wear produced during the whole wear process of PTFE coatings sliding against GCr-15 steel ball comes from the early period of friction. The hardness of PTFE coatings on both sides of wear track increases as the distance increases and distributes symmetrically around the wear track. Scanning electron microscope （SEM） was utilized to investigate the worn surface of PTFE coating, h was found that the worn surface of PTFE coating is characterized by sever plastic deformation and spalling of the PTFE coating. The edge of wear track is characterized by micro cracking.     

Tribological behavior of MC Nylon6 composites filled with glass fiber and fly ash

To improve tribological property of MC Nylon6,the glass fiber and fly ash reinforced monomer casting nylon composites(GFFAPA)were prepared by anionic polymerization of ε-caprolactam.The friction and wear behaviors of composites under dry condition,water lubrication and oil lubrication were investigated through a ring-black wear tester.Worn surfaces were analyzed using a scanning electron microscope.The experimental results show that the tensile strength and hardness of nylon composites are obviously improved with reinforcement increasing.Compared to MC nylon,the lowest friction coefficient and wear rate of glass fiber reinforced nylon composites(GFPA)with GF30% respectively decrease by 33.1% and 65.3%,of fly ash reinforced nylon composites(FAPA)with FA20% decrease by 5.2% and 68.9% and of GFFAPA composites with GF30% and FA10% decrease by 57.8% and 89.9%.The main wear mechanisms of FAPA composites are adhesive and abrasive wear and of GFPA composites with high proportion are abrasive and fatigue wear.The worn surfaces of GFFAPA composites are much multiplex and the optional distributing glass fiber and fly ash have a synergetic effect on the wear resistance for GFFAPA composites.Compared with dry friction,the friction coefficient and wear rate under oil lubricated conditions decrease sharply while the latter reversely increase under water lubricated conditions.The wear mechanisms under water lubricated condition are principally chemical corrosion wear and abrasive wear and they become boundary friction under oil lubricated condition.     

In situ prepared Al-Si alloy matrix composites reinforced by γ-Al2O3p

A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al（SO4）2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly distributed in the matrix. The results of dry sliding wear tests show that the wear resistance of the composites increases with increasing mass fraction, and the volume loss is considerably lesser than that of the matrix and is lesser than that of the composites by adding γ-Al2O3 particles directly.     

Hot Deformation Behavior of Mg2[KG-*2]B2[KG-*2]O5 Whiskers Reinforced Al Composite

The hot deformation behavior of Mg2B2O5w/Al composite was investigated by compression test at different temperatures and different strain rates. The constitutive equation was established by taking peak stresses as the function of temperatures and strain rates. It was found that the hyperbolic sine law creep equation is in good agreement with the experimental results and can be applied to all flow stresses under various deformation conditions. The apparent activation energy of the composite is 138. 64 kJ /mol, which is approximately equal to that of lattice self-diffusion of pure Al.     

Microstructure and tribological properties of laser clad Ni-Ag/Tic composite coating

Ni-Ag/TiC composite coating was prepared on the 45 steel substrates by means of laser cladding. Microstructure and wear properties of composite coatings were analyzed using optical microscopy, field emission scanning electron microscopy and wear machine. The experimental results show that defects, such as cracks and pores, do not occur in the laser-cladded Ni-Ag/TiC composite coating and 45 steel substrate, and they present good metallurgical bonding between them. Compared with Ni/TiC composite coating, micro- hardness values of the two coatings do not present evident differences. The wear experiment result shows that Ni-Ag/TiC composite coated with Ag possesses low friction coefficient and good wear resistance compared with Ni/TiC composite coating.     

Microstructural characterization and mechanical property of Fly Ash/Al-25Mg composites

Fly ash/Al-Mg composites are fabricated by powder metallurgical method. The morphology and structure of fly ash/A l-Mg composites are characterized by scanning electron microscope （SEM） and X-ray diffraction, respectively. The influences of different fly ash content on the friction and wear behavior of the composites are investigated at a constant sliding velocity of 400 r/min and the worn mechanism of composites is discussed. The results indicate that the friction coefficient is steadily lower than that of Al alloy matrix at the lower fly ash content and loads. For the fly ash/Al-Mg composites, the wear mechanism is characterized as abrasive wear and adhesive wear under small normal load and at low fly ash content, and it is characterized as delamination wear and abrasive wear transferred onto the counterpart under high normal load and at high fly ash content.     

Microstructure and wear resistance of in situ NbC particles reinforced Ni-based alloy composite coating by laser cladding

The in situ synthesized NbC particles reinforced Ni-based alloy composite coating was produced by laser cladding a precursor mixture of Ni-based alloy powder,graphite and niobium powders on a steel substrate.The microstructure,phase composition and wear property of the composite coating were investigated by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and dry sliding wear test.The experiment results show that the composite coating is homogeneous and free from cracks,and about 0.8 mm thick.The microstructure of the composite coating is mainly composed of NbC particles,CrB type chromium borides,γ-Ni primary dendrites,and interdendritic eutectics.CrB phases often nucleate and grow on the surface of NbC particles or in their close vicinity.NbC particles are formed via in situ reaction between niobium and graphite in the molten pool during the laser cladding process and they are commonly precipitated in three kinds of morphologies,such as quadrangle,cluster,and flower-like shape.Compared with the pure Ni-based alloy coating,the microhardness of the composite coating is increased about 38%,giving a high average hardness of HV0.21000,and the wear rate of the composite coating is decreased by about 32%,respectively.These are attributed to the presence of in situ synthesized NbC particles and their well distribution in the coating.     

Relationship among wear-resistance of three-body abrasion, substructure and property in martensite steels

The effects of subsurface hardness on wear-resistance of martensitic steel 20Cr, 40CrSi, 60Mn, T8 and T10 in three-body abrasion under static load was investigated. It shows that the characteristic of the subsurface hardness distribution and the abrasive wear resistance is related to the substructure near the worn surface. The substructure of the tested martensite steel has an apparent relationship with the carbon content and steels with moderate carbon content and hardness exhibit good resistance to abrasive wear. The competition of the work-hardening effect and the temper softening effect, which resulted from deformation and friction heat generating during abrasive wear is considered to be a main reason for the relation among wear-resistance, hardness and substructure. At the test conditions, the wear-resistance of 40CrSi is the best.     

挤压铸造ZA27合金的力学性能及摩擦磨损性能

研究了挤压铸造对ZA27合金力学性能的影响,挤压铸造可以显著地提高ZA27合金的常温力学性能和高温力学性能.随着比压的增加,其综合力学性能提高.比压为750 MPa时,与金属型重力铸造合金相比,抗拉强度提高了约19.2%,硬度提高了约25.5%,伸长率增加了12.3%.采用MM-W1立式万能摩擦磨损试验机研究了比压对ZA27合金的摩擦磨损性能的影响,结果表明,在转速为200 r/min,载荷为100 N,摩擦副为45钢,20号机油润滑条件下,挤压比压为750 MPa时,合金的摩擦磨损性能较好.     

Friction and wear performances of cathodic arc ion plated TiAlSiN coating under oil lubricated condition

TiAlSiN coating was deposited on H13 hot work mould steel using cathodic arc ion plating (CAIP). The surface-interface morphologies and phases of the obtained coating were analyzed using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively, and the morphologies, distributions of chemical elements and profiles of worn tracks were also researched using scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), and optical microscope (OM), respectively. The friction-wear performances of TiAlSiN coating under oil lubricated and dry fiction conditions were investigated, and the wear mechanisms of TiAlSiN coating were discussed. The experimental results show that the coating is primarily composed of (Ti, Al)N, AlTiN, and TiN hard phases, Si₃N₄ exists between the (Ti, Al)N crystal grains, increasing the coating microhardness to 3200HV. The TiAlSiN coating has excellent performances of reducing friction and wear resistance, the average coefficient of friction (COF) of TiAlSiN coating under oil lubricated condition is only 0.05, lowered than the average COF of 0.211 under dry friction condition, the wear rate decreases by about 81.2% compared with that under dry friction condition. The wear mechanism of TiAlSiN coating under oil lubricated and dry friction conditions is composed of abrasive wear, fatigue wear, and abrasive wear, respectively. The internal friction of oil lubrication is a main factor of decreasing fatigue wear.     

高强度锌铝合金摩擦性能的试验研究

为了探讨高强度锌铝合金摩擦性能，介绍了在不同载荷、充分润滑条件下，ＺＡ２７锌铝合金的滑动摩擦系数、磨损量的测试．测试结果显示ＺＡ２７锌铝合金的减磨性优于锡青铜，接近锡基巴氏合金     

Comparison of the Wear Behavior of UHMWPE Lubricated by Human Plasma and Brine

The effect of plasma and brine lubricants on the friction and wear behavior of UHMWPE were studied by using the geometry of a Si3N4 ball sliding on a UHMWPE disc under patterns of uni-directional reciprocation and bi-directional sliding motions. The worn surface and wear particles produced in these two lubricants were analyzed. Sliding motion pattern affected the friction coefficients lubricated with plasma, while seldom affected that lubricated with brine. UHMWPE lubricated with plasma showed about half of the wear rate of that lubricated with brine. The two rates were 0.75 pg/m and 2.19 pg/m for the two motion patterns, respectively. However, wear particles generated in plasma included a greater amount of small particles, compared to that in brine. In uni-directional reciprocation, the main wear mechanism is ploughing both in plasma and in brine. In bi-directional sliding modes, the significant characteristic is ripples on the worn surface in plasma, while there are oriented fibers on the worn surface in brine.     

反应热喷涂法制备陶瓷涂层的研究

首先通过差热-失重分析和XRD测试手段对反应热喷涂Al＋TiO2＋H3BO3混合粉体以制备Al2O3/TiB2复合陶瓷涂层的可行性进行了分析.然后对喷涂后试样涂层的耐磨性进行了研究.结果表明：Al＋TiO2＋H3BO3混合粉体差热-失重分析和在1200℃烧结后XRD测试分析均表明完全可以反应生成所需的Al2O3/TiB2复合陶瓷涂层.所制备陶瓷涂层的耐磨性要比基体提高1倍左右.     

Al_2O_3/Al合金复合材料的耐磨性的研究

以国产氧化铝短纤维作为增强体,制备了氧化铝短纤维增强铝合金复合材料。本文研究了这种材料的耐磨性能,研究结果表明,氧化铝短纤维具有增强作用,复合材料比基体有高得多的硬度;在润滑条件下,复合材料的磨损率比基体的低,在较大载荷作用下,复合材料表现了优良的抗粘着磨损的能力,在一般磨损情况下,纤维体积率小于15％,可保证复合材料有足够的耐磨性。     

激光熔覆钛基复合涂层的显微组织和硬度分析

采用激光熔覆快速非平衡合成方法制备了原位反应合成TiB增强钛基复合材料.用Y2O3、Ti和B的混合粉末在Ti-6Al-4V基体表面激光熔覆制得TiB/Ti复合涂层.采用X线衍射仪(XRD)、扫描电子显微镜(SEM)、能量散射光谱仪(EDS)和硬度测试等方法,研究了原位合成TiB/Ti复合涂层的显微结构和显微硬度.结果显示:激光熔覆层的相结构主要为α-Ti和TiB两相,TiB增强相均匀地分布于复合涂层中,熔覆层的硬度值高于基体Ti合金的硬度值1倍以上,Y2O3含量(质量分数w,全文同)为1％的激光熔覆涂层内部的增强相组织最为均匀、细小,且硬度值也最高,平均硬度(HV)值约为830.     

纳米Si3N4颗粒填充铸型尼龙的摩擦学性能研究

为了研究纳米Si3N4颗粒作为填料对铸型尼龙（MC尼龙）的摩擦磨损性能的影响，选用两种复合材料在MM－200摩擦磨损试验机上进行了试验研究，并借助于扫描电镜观察了磨损形貌，探讨了磨损机理，研究结果表明，在干摩擦条件下，Si3N4颗粒填MC尼龙与钢环对摩的摩擦数随载荷的升高而降低，在相同载荷时均高于纯尼龙，在一定的滑动速度下，Si3N4颗粒填充MC尼龙的耐磨性能与载荷大小有关，当载荷较低时，复合材料的耐磨性能比纯尼龙好，其磨损机理主要是磨粒磨损和粘着磨损，当载荷较高时，复合材料的耐磨性能不如纯尼龙，其磨损机理主要是疲劳剥落，并有磨粒磨损和粘着磨损。     

B4C／TiO2／Al复合材料制备及其性能

采用热压法制备了B4C／TiO2／Al复合陶瓷材料，试验结果表明，TiO2和Al的加入，使得B4C／TiO2／Al复合材料的硬度、抗弯强度和断裂韧性比纯B4C陶瓷材料有较大程度的提高；而且，添加相促进了复合材料的烧结．利用热力学和X射线衍射分析研究烧结过程中的化学反应，分析结果表明，复合材料中没有发现TiO2，Al，Al2O3;同时在复合材料中出现了TiB2，因为在热压过程中TiO2-B4C反应生成TiB2．分析了B4C／TiO2／Al复合陶瓷材料的微观结构和增韧机理．