锌—镁—铝类水滑石及其煅烧产物摩擦性能与减摩抗磨机理研究

发布时间：2018-10-08 15:20

【摘要】：类水滑石化合物具有典型层状结构,层板组成元素种类多样,层间阴离子具有可置换性,广泛应用于催化、离子交换、吸附等领域。剪切力作用下,类水滑石层间相对滑动,作为极压抗磨修复材料具有独特优势。本文系统评价了镁铝类水滑石、锌铝类水滑石和锌镁铝类水滑石在四球摩擦试验、销-块摩擦试验(往复运动式)和销-盘摩擦试验(单向旋转式)等中的摩擦性能,创新性开展了三种类水滑石煅烧产物的摩擦行为研究,对比了类水滑石与传统极压抗磨剂石墨和二硫化钼的减摩抗磨性能。采用X射线粉晶衍射、扫描电子显微镜、能谱分析、X射线光电子能谱和俄歇电子能谱等表征手段,对类水滑石及其煅烧产物的成分、结构和微观形貌等进行了系统分析,深入研究了摩擦副表面成分及其变化规律,对减摩和抗磨机理进行了讨论,取得如下主要成果:镁铝类水滑石1000 oC煅烧产物、锌铝类水滑石及其850 oC煅烧产物抗磨损性能优异,减小磨斑直径均达到18%以上。锌镁铝类水滑石最佳添加量为0.5wt%,在高载荷(200 N~400 N)和适宜转速下减摩和抗磨效果显著。与传统固体极压抗磨添加剂石墨和二硫化钼相比,在特定试验条件下,类水滑石的抗磨损性能更为优异,与其较石墨和二硫化钼具有更高硬度和强度有关。销-块摩擦试验中,类水滑石的摩擦性能受载荷影响。类水滑石磨损表面含有ZnO(或MgO),ZnS,多种铁氧化物和含铁有机化合物,含碳氧键的有机物和石墨等,未见Al元素,表面氧化程度高,碳含量低。锌铝类水滑石和锌镁铝类水滑石与ZDDP协同作用,提高表面Zn含量。类水滑石煅烧产物促进Zn元素沉积于磨损表面,抗磨损性能显著,表面平整光滑区域Zn(或Mg)和O分布密集,Fe和C含量则降低,磨痕凹槽处C元素沉积。类水滑石及其煅烧产物减摩抗磨机理相近互通,即自修复保护膜理论,保护膜由上至下大致分为“富碳层”、“富氧层”和“过渡层”,厚度约100~200 nm。Zn和Mg在“富氧层”内均匀分布。类水滑石吸附于磨损表面,在剪切力下层板相对滑动,释放活性氧。纳米颗粒填补表面微裂纹。物理和摩擦化学等作用下,类水滑石在金属表面形成保护膜,起到减摩抗磨效果。类水滑石煅烧产物抗磨损性能优异,与其原位相变产物尖晶石的颗粒支撑和机械抛光作用有关。
[Abstract]:The hydrotalcite-like compounds have typical layered structure, various kinds of laminar elements and interlayer anions, which are widely used in the fields of catalysis, ion exchange, adsorption and so on. Under shear stress, the hydrotalcite-like stone is relatively sliding between layers, which has a unique advantage as extreme pressure antiwear material. The friction properties of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite and zinc magnesium aluminum hydrotalcite in four-ball friction test, pin-block friction test (reciprocating motion test) and pin-disk friction test (unidirectional rotation type) are systematically evaluated in this paper. The friction behavior of calcined products of three kinds of hydrotalcite was studied innovatively. The friction and antiwear properties of hydrotalcite were compared with those of traditional extreme pressure antiwear agents graphite and molybdenum disulfide. By means of X-ray powder diffraction, scanning electron microscope, X-ray photoelectron spectroscopy and Auger electron spectroscopy, the composition, structure and microstructure of hydrotalcite and its calcined products were systematically analyzed. The surface composition and its variation of friction pairs were studied in depth, and the antifriction and antiwear mechanisms were discussed. The main results were as follows: 1000 oC calcined products of magnesium and aluminum hydrotalcite, excellent wear resistance of zinc aluminum hydrotalcite and its 850 oC calcined products. The diameter of wear spot is reduced to more than 18%. The optimum addition amount of zinc-magnesium-aluminum hydrotalcite is 0.5 wt.The antifriction and anti-wear effects are remarkable under high load (200 Nb400N) and suitable rotational speed. Compared with graphite and molybdenum disulfide, the wear resistance of hydrotalcite is better than that of graphite and molybdenum disulfide, which is related to its higher hardness and strength than graphite and molybdenum disulfide. In the pin-block friction test, the friction performance of hydrotalcite is affected by load. The worn surface of hydrotalcite contains ZnO (or MgO) ZnS, a variety of iron oxides and ferric organic compounds, carbon-oxygen bond organic compounds and graphite, etc. No Al elements are found, and the surface oxidation degree is high, and the carbon content is low. Zinc aluminum hydrotalcite and zinc magnesium aluminum hydrotalcite have synergistic effect with ZDDP to increase surface Zn content. The calcined products of hydrotalcite promote the deposition of Zn on the wear surface, and the wear resistance is remarkable. The content of Zn (or Mg) and the dense distribution of Zn and C in the smooth and smooth area of the surface are decreased, and the C element is deposited in the grooves of wear marks. The anti-friction and anti-wear mechanism of hydrotalcite and its calcined products are similar to each other, that is, the theory of self-repairing protective film, the protective film can be roughly divided into "carbon-rich layer", "oxygen-rich layer" and "transitional layer" from top to bottom. The thickness of about 100 nm.Zn and Mg are evenly distributed in the "oxygen-enriched layer". The hydrotalcite adsorbed on the worn surface and slid relatively under shear stress to release reactive oxygen species. Nanocrystalline particles fill the surface microcracks. Under the action of physics and tribochemistry, hydrotalcite forms protective film on metal surface, which can reduce friction and wear. The excellent wear resistance of the calcined products of hydrotalcite-like products is related to the particle support and mechanical polishing of spinel, which is the in-situ phase change product.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB302.3

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