Correlations between in-flight particles, splats and coating microstructures of Ni20Cr thermally sprayed by flame and arc spray processes

Abstract

Correlations between in-flight particle, splat and coating microstructure of thermally sprayed Ni20Cr were investigated. Flame spray and arc spray systems were employed for spraying Ni20Cr powder and Ni20Cr wire, respectively. The results showed that the arc spray process produced a broader size distribution for both in-flight particles and splats compared to flame process. Flower-like splat morphology was obtained from the arc spray whereas a pancake-like splat was obtained by flame spray. Ni20Cr coating sprayed by arc process had a denser microstructure, lower porosity and better adhesion at the interface. This could be due to the higher temperature and velocity from the arc spray process enhancing the melting and adhering for coating formation.