纳米复合镀Al_2O_3层激光强化

Laser Strengthening Nano-Composite Plating Al_2O_3 Coating

在H13钢表面通过纳米复合镀（NCP）的办法预置纳米Al2O3镀层，然后通过高功率连续CO2激光处理预置表面，采用扫描电子显微镜（SEM）观察了镀层处理前后表面及截面形貌，利用X射线能谱（EDS）仪、X射线衍射（XRD）仪对处理前后的镀层进行了元素分析和物相分析，测试了处理前后镀层显微硬度及磨擦系数的变化。结果表明，激光处理后，强化层表面平整光滑，与基体形成冶金结合，成分均匀，组织细密。纳米Al2O3颗粒均匀分布在强化层表面，强化层显微硬度为原镀层的1．5～1．8倍，强化层摩擦系数约为镀层的1／2，基体的1／3。强化层和基体的表面主要以磨粒磨损为主，而纳米复合镀层则是磨粒磨损和黏着磨损综合作用的结果。

Nano-Al2O3 coating was prepared on the surface of H13 steel by nano-composite plating （NCP） and then treated by high power continuous wave CO2 laser. Scanning electron microscope （SEM） was used to observe the surface and cross section morphologies of coating before and after laser treatment. Energy dispersive X-ray spectroscope （EDS） was utilized to analyze elements distribution on the surface of coating before and after laser treatment. X-ray diffractometer （XRD） was employed to analyze the microstructure of coating before and after laser treatment. The changes of micro-hardness and coefficients of friction before and after laser treatment were observed. The results revealed that strengthened coating had good performance such as flat surface, uniform component, fine microstructure and metallurgical bonding with parent metal. Nano-Al2O3 particles were distributed on the surface of strengthened coating uniformly. The micro-hardness of the strengthened coating was 1.5- 1.8 times of untreated coating, while its coefficient of friction was about half of untreated coating and one third of parent mental. For the surface of strengthened coating and parent metal, grain-abrasion was dominate, however the NCP Al2O3 coating included grain-abraslon and sticking abrasion.