金属材料的激光表面改性及其在摩擦学中的应用
Laser Surface Modification of Metals and its Tribological Applications
-
摘要: 作者对激光表面处理的各种方法和现有技术水平进行了综述介绍,并就其在改善金属材料表面摩擦磨损性能方面的研究和应用,以及今后的发展都作了简要的分析和讨论。激光相变硬化能使处理的工件形成具有表面压应力的硬质马氏体表面,因而可以降低表面的磨损速率。在金属工件上通过激光包覆高抗磨、抗热、抗腐蚀和抗疲劳的高硬质合金甚至致密陶瓷,在严格控制工件材料对包覆合金稀释的情况下,可使底材获得高的摩擦学性能。激光合金化通过选择合金元素和基底材料能有选择地改进低成本工件的表面,使其具有优异的物理、化学和机械性能。激光上釉是通过细化铸造组织、减少偏析及形成高度过饱和固溶体等亚稳定相乃至非晶态而提高了材料的耐磨性、抗氧化性和抗腐蚀性能。激光冲击硬化是通过在材料表层内形成冲击波而引起“损伤”来改变表层的组织和性能。Abstract: Several methods and technologies for laser surface treatment of metals are reviewed in this paper. The tribological applications of this treatment and its future development are briefly discussed. Laser transformation hardening provides the treated workpieces with hard mar- tensitic surface that has compressive stresses. Hence, reduction in wear rate of treated surfaces is achieved. Laser cladding offers feasibility to apply high anti-wear, anti-corrosive and heat-resisting cladding alloys as well as ceramics on workpieces, the good tribological properties will be obtained by reducing the amount of dilution of cladding alloy with the workpieces. Laser alloying offers the possibility to produce high performance surfaces by selecting the alloying elements and substrate. Laser glazing gives potential to enhance wear-resistance by refining grain structure, reducing segregation, producing supersaturation solid solution body and metastable or amorphous phases. Laser shock hardening may change the structure and properties through forming shock wave and causing damage in the surface layer of metal.