Effect of grit blasting and spraying angle on the adhesion strength of a plasma-sprayed coating
A study of the effects of grit-blasting and plasma-spraying angles on the adhesion strength of an alloy (Tribaloy 800) that was plasma sprayed on a titanium-base alloy is reported. Five different spray and grit-blast angles were investigated: 45°, 55°, 65°, 75°, and 90°. The surface texture in different directions was characterized by the classic average roughness and by a fractal analysis number using a two-dimensional fractal analysis method. The grit residue was measured by an x-ray spectrometer. The study showed that the maximum adhesion strength was close to a 90° blasting and spraying angle. However, the grit residue reaches its maximum at a 75° blasting angle. From the image analysis of the interface in different directions, it was found that the nonperpendicular grit blasting produces an anisotropic surface. The fractal analysis method showed a rather good correlation with the blasting angle. However, no good correlation between the fractal number and the adhesion strength was found.
Keywordsadhesion by mechanical interlocking fractal analysis plasma spraying surface roughness/morphology titanium and alloys
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