Laser cladding of Cu-Cr and Cu-W mechanically alloyed powders on Cu substrate

Details

Supervisors

Jacques, Pascal

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

Laser cladding is a really versatile process of manufacturing that combines powder metallurgy and laser welding. In this work, two powders, produced trough mechanical alloying, have been investigated to be used with this process in the objective to make a functional and protective coating on a pure copper substrate : Cu-80W and Cu-60Cr. Single-track trials and multi-tracks trials have been performed with various thickness substrate and process parameters. Cu-80W showed good results in terms of morphology of coating and microstructure with single-track trials. The microstructure produced has "plum-pudding"morphology : we observe a matrix of pure Cu with inclusions of Cu-80W grains powder. Parameters of the laser cladding equipment allow a wide variety of coating morphology. Multi-tracks trials showed unsolved problems at this time. The high absorbance combined to the low heat capacity of the tungsten lead to heat accumulation within the previous deposited clad and to insufficient heat input into the substrate. Cu-60Cr showed a wide variety in terms of microstructure. A wide solidification microstructure spectrum has been observed from a columnar to equiaxed microstructure in the clad deposition with a strong dependency with process parameters. This powder showed good results in multi-tracks trials despite incertitude that stays to be understood. In particular, important residual stresses remained following the process.