Characterization of cold-sprayed nickel-base coatings.

The Cold Gas Dynamic Spray Method (CGDS) requires high-kinetic energy particles to obtain dense coatings. The aim of this study is to characterize some properties of CGDS coatings and compare them to the bulk materials. Pure nickel and nickel-base alloys (NiCrAlY, CoNiCrAlY, and Hastelloy C) are sprayed on 316L steel substrates. Coating thickness is about 700 mu m. The particle velocity at impact is measured using an imaging technique based on a fast-shutter CCD camera and a high-power diode laser. The original powder characterization involves particle size, density, chemical composition and hardness, and coating analysis includes micro hardness, nano hardness (performed in the first 60 mu m of the coating), Young modulus determination and porosity level. The hardness test results make it possible to determine effects of this specific property on the sprayability with this process.