镍基高温自润滑复合材料的摩擦学行为研究

发布时间：2018-01-12 11:19

本文关键词：镍基高温自润滑复合材料的摩擦学行为研究　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于高温自润滑材料在高温下优异的摩擦学性能,使其在一些摩擦系统中已经被广泛应用,通过将固体润滑剂添加到一些高温合金材料中能明显改善其在高温下的摩擦学性能,但是一些固体润滑剂受温度和氧化作用所限制。SrSO_4和Ag是非常有效的高温固体润滑剂,本文以SrSO_4和Ag为添加剂添加到Ni-Cr高温合金中以获得广域温度范围内摩擦学性能优异的Ni基复合材料。本文采用化学沉淀法制备了SrSO_4纳米粉体,将制得的SrSO_4纳米粉体和Ag作为高温固体润滑剂添加到Ni基合金中,采用放电等离子烧结法分别制备了Ni-Cr高温合金、不同组分的NiCr-SrSO_4和NiCr-SrSO_4-Ag复合材料。通过XRD、SEM、XPS、TEM及摩擦磨损试验机分别测试了不同复合材料的组织结构、力学性能及广域温度范围内的摩擦学性能,分别探讨了SrSO_4及Ag的添加对复合材料摩擦学性能的影响,并揭示了复合材料在广域温度下的自润滑机理。采用放电等离子烧结法成功制备出了Ni-Cr高温合金。Ni-Cr基体在室温、200℃、400℃和600℃下的摩擦系数分别为0.5、0.49、0.41和0.41,对应的磨损量分别为2.77×10-4mm3/(Nm)、3.2×10-4mm3/(Nm)、1.3×10-4mm3/(Nm)和2.53×10-4mm3/(Nm)。通过选择合适的工艺参数,利用化学沉淀法可以获得长片状SrSO_4纳米粉体。利用放电等离子法制备出不同SrSO_4含量的NiCr-SrSO_4复合材料。结果证明,SrSO_4的加入能明显改善复合材料在高温下的摩擦学性能。当SrSO_4的添加量为10wt.%时,复合材料的力学性能有所上升并且能获得在高温情况下比较优异的摩擦学性能,含10wt.%SrSO_4的NiCr-SrSO_4复合材料在400℃和600℃下的摩擦系数大小分别为0.32和0.2左右,其在400℃和600℃下的磨损量也很低,分别为1.44×10-5mm3/(Nm)和2.4×10-5mm3/(Nm)。NiCr-10SrSO_4复合材料能获得比较优异的高温摩擦学性能主要是由于在磨损表面所形成的由不同的氧化物(NiO和Cr2O3)和有自润滑性能的盐类(SrSO_4和SrCrO4)所组成的润滑膜。采用SrSO_4的添加量为10%,同时加入润滑相Ag利用放电等离子烧结法制得不同Ag含量的NiCr-SrSO_4-Ag复合材料。Ag的加入能有效降低复合材料在中低温情况下的摩擦系数,但同时也会使其在400℃和600℃下的摩擦系数有所上升,分别为0.41和0.3。Ag的添加量的增加并不能使NiCr-SrSO_4-Ag复合材料的摩擦系数有所改善,但是能降低复合材料在广域温度范围的磨损量大小。NiCr-10SrSO_4-20Ag复合材料能获得在广域温度比较优异的摩擦学性能主要是由于在磨损表面所形成的由不同的氧化物(NiO、Cr2O3和Ag2O)和有自润滑性能的盐类(SrSO_4和SrCrO4)所组成的润滑膜以及熔融的Ag颗粒的协同作用。
[Abstract]:The tribological properties of high temperature self-lubricating materials at high temperature are excellent, which has been widely used in friction system, the solid lubricant is added to some high temperature alloy material can obviously improve the tribological properties at high temperature, but some solid lubricating agent by temperature and oxidation of.SrSO_4 and Ag is high temperature limit the solid lubricant is effective, this paper takes SrSO_4 and Ag as additive is added to Ni-Cr alloy to obtain Ni composite wide temperature range of excellent tribological properties. In this paper, using the chemical SrSO_4 nano powder was prepared by precipitation method, the prepared SrSO_4 nano powder and Ag as high temperature solid lubricant is added to the Ni group in alloy by spark plasma sintering method were used to prepare Ni-Cr alloy, NiCr-SrSO_4 and NiCr-SrSO_4-Ag composites with different components. Through XRD, SEM, XPS, T EM friction and wear testing machine were used to evaluate different structures of composite materials, mechanical properties and Tribological Properties of wide temperature range, respectively discusses the influence of the addition of SrSO_4 and Ag on the tribological properties of the composites, the self lubrication mechanism of composite materials in wide temperature and reveal. Successfully prepared by spark plasma sintering preparation of Ni-Cr high temperature alloy.Ni-Cr substrate at room temperature, 200 degrees, 400 degrees and 600 degrees of friction coefficient under 0.5,0.49,0.41 and 0.41 respectively, the wear amount corresponding to 2.77 * 10-4mm3/ respectively (Nm), 10-4mm3/ (Nm), 3.2 * 1.3 * 10-4mm3/ (Nm) and 2.53 * 10-4mm3/ (Nm) through. Select the appropriate parameters, using chemical precipitation method can obtain flake SrSO_4 nano powder by spark plasma. NiCr-SrSO_4 composite material were prepared with different SrSO_4 content. The results show that the addition of SrSO_4 can significantly improve the composite The tribological properties of materials under high temperature. When the SrSO_4 content is 10wt.%, the mechanical properties of the composites increased and can obtain excellent tribological properties under high temperature, friction coefficient of NiCr-SrSO_4 composites containing 10wt.%SrSO_4 at 400 DEG C and 600 C respectively about 0.32 and 0.2, in 400 C and 600 C of the wear rate is very low, which was 1.44 * 10-5mm3/ (Nm) and 2.4 * 10-5mm3/ (Nm).NiCr-10SrSO_4 composite can obtain excellent tribological properties at high temperature is mainly due to the wear surface of the formed by different oxides (NiO and Cr2O3) and self-lubricating properties (salt SrSO_4 and SrCrO4) lubricant film are formed. The amount of SrSO_4 was 10%, at the same time can effectively reduce added lubricating phase Ag with different Ag content by spark plasma sintering of NiCr-SrSO_4-Ag.Ag Composites Low friction coefficient of composite material in low temperature, but also the increased friction coefficient at 400 DEG C and 600 C, respectively 0.41 and 0.3.Ag addition amount and can not increase the friction coefficient of NiCr-SrSO_4-Ag composites was improved, but can reduce the wear of composite materials in size.NiCr-10SrSO_4-20Ag the composite material can be obtained in the wide temperature range of excellent tribological properties of wide temperature is mainly due to the wear surface of the formed by different oxides (NiO, Cr2O3 and Ag2O) and self-lubricating properties of salts (SrSO_4 and SrCrO4) synergistic lubrication film composed of Ag particles and molten.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333

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