Advanced functional coatings deposited using supersonic atmospheric plasma spraying

Abstract

This paper presents the latest results of the ITAM team’s work in the development of the supersonic version of a spraying DC plasma torch «PNK-50» and demonstrates possibilities of Supersonic-APS method. Increasing the speed of the plasma flow to the level of 2000–2500 m·s⁻¹ has allowed deposition of functional coatings with outstanding properties. Thus, using the low-enthalpy (low-temperature) S-APS regime, low porosity (P = 0.3–1.6%) wear-resistant coatings from powder materials of NiCr alloy and WC/CoCr carbide composite were obtained, demonstrating characteristics previously available only to high-speed HVOF and DS methods. The use of the high-enthalpy (high-temperature) regime of S-APS provided spraying of refractory yttria stabilized zirconia (YSZ) oxide coatings with porosity of only 2.5% using conventional powder feedstock. The methods of SPS and LPPS made it possible to obtain advanced coatings of YSZ ceramics: thermal barrier coatings (TBC) with a columnar structure and high-density gas-tight coatings. Also ceramic coatings with a pronounced bimodal surface profile were obtained demonstrating super-hydrophobic effect.