45钢表面激光熔覆Al_2O_3陶瓷涂层的研究

STUDY ON LASER CLADDING Al_2O_3 CERAMIC COATING ON 45 STEEL

采用SEM，TEM及EDAX等手段研究了45钢表面Al2O3－NiCrAl复合陶瓷涂层的组织结构，实验结果表明：Al2O3－NiCrAl复合陶瓷等离子喷涂层的组织呈层片状，面层由α－Al2O3和少量的γ－Al2O3组成，Al2O3与NiCrAl及NiCrAl与基体间均为机械结合界面：激光熔覆层组织为单一的α－Al2O3柱状晶、过渡合金与基体间形成了良好的冶金结合界面，Al2O3与NiCrAl间的界面结合状况得到了明显的改善，在激光熔覆过程中存在着分层凝固机制．熔敷层硬度达2423－2664HV0．

The structure of Al2O3 -NiCrAl composite ceramic coatings on 45 steel is studied by SEM,TEM and EDAX. The results show that the structure of Al2O3 -NiCrAl composite ceramic coating sprayedby plasma is lamellar in shape, the Al2O3 coating is consist of α-Al2O3 and a little amount of γ-Al2O3,and the interfaces of Al2O3/NiCrAl, and NiCrAl/substrate are mechanical combining. There exists aunitary α-Al2O3 columnar crystal in the coatings cladded by laser. There is a metallurgical combininginterface between transitional alloy and substrate. The interfacce between Al2O3 and transitional alloy hasbeen improved obviously by laser cladding. There is the straticulate solidification mechanism in the lasercladding. The microhardness of the coatings cladded by laser can reach 2423 - 2664 HV0.2