Corrosion and erosion performance of HVOF/TiAlN PVD coatings and candidate materials for high pressure gate valve application

Abstract

The main objective of this paper is to study the slurry erosion and corrosion behavior of WC10Co4Cr, Armcore ‘M’ Stellite 6 and 12 HVOF coatings, TiAlN PVD coating, selected steels, such as X20Cr13, 17Cr–4Ni pH steel and Ti6Al4V titanium alloy alongwith conventional hard weld deposits of Stellite 6 and 21. The slurry erosion studies were carried out at 60° angle of impingement for the velocities in the range of 15–20 m/s using mineral sand of −40 to +80 mesh. The corrosion studies were carried out as per ASTM B 117-73 for 100 h. During slurry erosion testing, WC10Co4Cr HVOF along with TiAlN PVD coating are found out, to be the best coating materials followed by HVOF coating of Armcore ‘M’ material. However, for corrosion, Ti6Al4V, Stellite 6 and 21 hard weld deposits and 17Cr–4Ni pH steel turned out to be the best materials followed by HVOF coating of Stellite 6 and 12. HVOF coatings of WC10Co4Cr and Armcore ‘M’ materials corroded significantly, however, TiAlN PVD coating corroded very badly even after 24 h of testing.