Cu 표면에 Ni기 합금의 레이저 클래딩에 미치는 공정인자의 영향

Effects of processing parameters on the laser clad for Ni-based alloy on Cu substrate

  The electroplating of Ni or NiB on the Cu substrate has been conducted to improve the wear resistance and thus to increase the service life of continuous casting mold (Cu-1 wt%Cr-0.2wt%Zr). In this study, the characteristics of laser cladding with nickel-based alloy on Cu substrate were investigated to enhance the performance of casting mold at high temperature. In order to accommodate the difference of thermal expansion coefficient between Cu substrate and Ni-based alloy, Ni electroplated intermediate bonding layer was introduced between Cu substrate and Ni-based coating layer. The study investigated that the laser cladding parameters, such as powder carrying gas flow, powder feed rate and gun travel speed, had an effect on the clad thickness. Cracks and porosities were found at the interface between the cladding layer and the electroplated Ni layer. Or, they were detected in the layer for high cladding thickness. The substrate preheating restraint the crack initiation during cooling by reducing thermal stresses. Preheating temperature had relationship with porosity or crack occurred in the laser cladding layer. Hardness of laser cladding layer is 458.5Hv, Ni coating layer is 106Hv and Cu substrate is 128Hv.