Investigation of AlSi coatings prepared by laser-assisted atmospheric plasma sprayingof internal surfaces of tubes

摘要

Laser-assisted atmospheric plasma spraying (LAAPS) is a new one-step coating process performed in air wherebythe laser beam interacts with the plasma torch at the substrate or coating surface during deposition to generate acoating that is metallurgically bonded to the substrate. This hybrid process was developed in order to combine thespecific advantages of APS and laser cladding. In this paper, the development of a hybrid gun for coating internalsurfaces of tubes and cylinder bores by LAAPS is presented. The process was optimized for spraying AlSi30coatings on internal surfaces of aluminum alloy cylinder bores. Single-pass coatings with thicknesses of 300-400μm and metallurgical bonding to the substrates can be realized by applying an optimized parameter set. Thedependence of coating microstructure on spray parameters was investigated by metallographic preparation andoptical microscopy. Surface pretreatment must be performed to eliminate the strongly adhering oxide layer on thealuminum alloy substrate and to attain metallurgical bonding of coating to substrate.