Influence of process variables on the quality of detonation gun sprayed alumina coatings

Detonation gun (D-gun) spraying is one of the most promising thermal spray variants for depositing high quality wear resistant coatings. Of all the ce ramic materials that can be D-gun sprayed, alumina (Al2O3) is the most wide ly established and these coatings have already gained industrial acceptance for diverse applications. The present study deals with a statistical desig n of experimental study of the D-gun spraying of Al2O3 powder. Coating expe riments were conducted, using a Taguchi-full factorial (L-16) design parame tric study, to optimize the D-gun spray process parameters. Four selected i mportant spraying parameters were considered in their upper and lower level s of the predefined range according to the test matrix, in order to display the range of processing conditions and their effect on the coating quality . Optical microscopy, scanning electron microscopy, X-ray diffraction, imag e analysis and hardness testing was used for characterization. Coating qual ities are discussed with respect to surface roughness, hardness. porosity a nd microstructure. The attributes of the coatings are correlated with the c hanges in operating parameters and their relative importance and contributi on ratios to overall variance are calculated. (C) 2000 Elsevier Science S.A . FLU rights reserved.