Optimisation of stainless steel cold spray coatings using mixed particle size distributions

• Published in: Surface & coatings technology Vol. 205; no. 21; pp. 5135 - 5140
• Main Authors: Spencer, K., Zhang, M.-X.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-08-2011; Elsevier
• Subjects: Applied sciences; Approximation; Austenitic stainless steels; Coating; Coatings; Cold spray; Cross-disciplinary physics: materials science; rheology; Densification; Density; Exact sciences and technology; Heat resistant steels; Kinetic metallization; Materials science; Metals. Metallurgy; Particle size; Particle size distribution; Physics; Porosity; Production techniques; Spray coating; Stainless steel; Stainless steels; Surface treatment; Surface treatments; Particle size; Kinetic metallization; Coating; Cold spray; Stainless steel; Particle distribution; Spray coatings; Hot spraying; Surface treatments; Kinetics; Coatings; Stainless steels
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2011.05.020

Porosity in type 316
L stainless steel cold spray coatings is studied from two different aspects. The first is to examine, for a given level of porosity, the effect of coating thickness on corrosion behaviour. Beyond a critical coating thickness the substrate is no longer attacked in polarisation tests, which has implications for coatings that contain some porosity (including some thermal spray coatings). The second aspect examined is to approximate the stainless steel particles as non-deforming, and apply the powder metallurgy practice of mixing particle size distributions to improve coating density. The results show that coatings sprayed using mixed particle size distributions can have similar properties to those sprayed using fine particles alone, but without the processing difficulties of fine particles such as inconsistent powder feeding or nozzle fouling.
► We address the issue of porosity in austenitic stainless steel coatings. ► These particles undergo little deformation on impact. ► With a small level of porosity, coatings beyond a critical thickness are protective. ► Mixing particle size distributions reduces coating porosity. ► This is a more practical approach than spraying with fine particles.