硅酸盐粉体作为润滑油添加剂在金属磨损表面成膜机制

Formation Mechanism of Self-repair Coatings on the Worn Metal Surface Using Silicate Particles as Lubricant Oil Additive

在润滑油中添加蛇纹石硅酸盐粉体,采用MM-200摩擦磨损试验机研究了45#钢-45#钢摩擦副磨损表面的自修复陶瓷膜层形成机制,借助SEM及EDAX测试分析自修复陶瓷膜层的表面形貌及表面成分组成。结果表明摩擦能量对硅酸盐添加剂在磨损表面形成自修复膜层有很大的影响:自修复膜层为氧化物陶瓷材料,主要成分来自于硅酸盐添加剂。在低载荷300 N时,摩擦因数减小,硅酸盐添加剂不能转移到磨损表面,不能形成自修复膜层,仅仅起到减磨作用。下试样的失重随磨损时间增加而增加;在试验时间为20 h时,试样失重达到最大值,随后试样的失重反而减小。在载荷为600 N、900 N,试验时间30 h摩擦磨损后,在金属表面形成自修复保护膜,磨损表面比较平整光滑,无明显的片层剥落和犁沟,摩擦发生在自修复陶瓷材料之间,摩擦因数增加。硅酸盐添加剂在机械剪切作用下变形,在金属的磨损表面上铺展,并且在摩擦磨损过程中不断向摩擦表面转移,形成了均匀光滑的自修复膜层。自修复膜层隔离了金属摩擦表面的直接接触,摩擦磨损发生在自修复膜层之间,有效地降低了金属的磨损。

Formation mechanism of self-repair coating on the worn surfaces of 45 steel pairs were investigated by using MM-200 friction and wear tester under lubricated condition with silicate additives. The surface images of self-repair coatings and their chemical composition were detected by using SEM and EDAX. The experimental results show friction energy has a great effect on the formation of self-repair coating on the worn surface. Self-repair coatings are oxide ceramics which mainly comes from silicate additive. The silicate additive can reduce the friction coefficient of the friction pairs, but can＇ t be transferred onto the worn surface of the friction pairs surface of 45 steel at the load of 600 N,900 N and test smooth without obvious wear scars and plough compared under lower loads of 300 N. Self-repair coatings form on the worn time of 30 hours. The surface of the self-repair coatings are very with that without silicate additive. Silicate additive deforms between the friction pairs under shearing stress and prolongs along the worn surface of the friction pairs. Silicate additive continuously shifts from the lubricating oil into the worn surface in the course of friction and wear, and self-repair coatings are formed. Even though the friction coefficient is higher than that without silicate additive, the self-repair coatings on the surface of 45 steel avoid the direct contact of friction pairs. Friction and wear can only take place between the self-repair coatings instead of metal friction pairs ,thus improve the wear resistance of the metals. The components of the self-repair coatings mainly come from the silicate additive.