Micromechanism characteristics of modified Al-Si coating by laser melt injection CeO2 nano-particles

In order to improve the oxidation and corrosion resistance of metallic bonding layer, the in situ function gradient coating possessing the oxidation and corrosion resistance structure was fabricated on the surface of Al-Si coating by laser melt injection nano-CeO2. The micrograph, characteristic parameters of morphology and microdefect, microstructure of melten pool of modified Al-Si coating were investigated. The results show that the modified Al-Si coating can be prepared successfully. Optimum laser power, scanning speed and laser beam diameter was 150 W,1500 mm.min(-1) and 2 mm, respectively. The microscopic morphology and the characteristic parameters of molten zone were directly related to the conducting direction of the input energy. The plastic change of melten pool was the main reason for the total crack length at different levels. Increasing laser power properly was benefit for reducing the emergement of the crack. The method of introducing fine particles by laser melt injection almost brought no pore defects. The effect of the inner diffusion barrier was enhanced, and the outer layer was rich in rare earth and fine grains. (C) 2017 Elsevier B.V. All rights reserved.