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利用自行设计的高能机械化学球磨机,在球料比为4:1,室温下经过30h球磨后,使钼粉在高纯氨气气氛中通过机械化学反应得到了fcc结构的超微Mo2N粉体,粉体平均粒度在100nm左右。球磨过程中NH3分子在钼粉新鲜颗粒表面上发生可离解式的化学吸附是机械化学过程中固态-气态反应的基本过程。此外,钼粉晶粒细化改变了Mo原子表面电子的不饱和性,从而促进了Mo与N的键合作用。以Ni60为粘结金属并分别加入5%、10%和15%(质量分数)的超微氮化钼粉体,利用等离子喷涂在40Cr钢基体表面形成热喷涂层。通过对涂层在300N压力条件下干磨2h的磨损试验表明,超微Mo2N粉体的加入使得涂层的耐磨性显著提高,并且涂层的耐磨性随Mo2N粉体加入量的增加而提高,其原因归结于超微氮化钼颗粒在涂层中的弥散强化和自润滑作用。
Using self-designed high-energy mechanical and chemical ball mill, the molybdenum powder was made into the ultrafine Mo2N powder with fcc structure through mechanochemical reaction in a high purity ammonia gas atmosphere after ball milling at a ball / material ratio of 4: 1 and room temperature for 30 hours. The average particle size of the powder is about 100nm. During the milling process, dissociative chemisorption of NH3 molecules on the surface of fresh molybdenum powder particles is the basic process of the solid-state reaction in mechanochemical process. In addition, the grain refinement of molybdenum powder changes the unsaturation of the electrons on the surface of Mo atoms, thus promoting the bonding between Mo and N. Ni60 as the bonding metal and were added 5%, 10% and 15% (mass fraction) of ultra-micro-molybdenum nitride powder, the use of plasma spraying 40Cr steel substrate surface thermal spray coating. The wear test of the coating under dry condition of 300N pressure for 2h shows that the wear resistance of the coating increases obviously with the addition of the ultra-fine Mo2N powder, and the wear resistance of the coating increases with the addition of Mo2N powder Increase, the reason attributed to the ultra-micro-particles of molybdenum nitride dispersion in the coating strengthening and self-lubricating effect.