A Study of Cr/CrN and Cr/CrN/CrAlN Multilayer Coatings for Permanent Mold Castings of Aluminum Alloys: Wear and Soldering Tendency

Abstract

Physical vapor deposition (PVD) coatings namely Cr/CrN, Cr/ CrN / CrAlN multilayers (period of μ = 4 with a Cr bonding layer 138 nm thick), have been synthesized on a quenched and tempered X38CrMoV8 steel to test their ability to avoid soldering during casting of aluminum alloys. Wear tests, optical profilemetry observations and demolding stress tests were carried out. Intermetallic compounds were formed and aluminum cast alloy soldering layer was found on surfaces of all tested pins, which were observed and quantified by SEM/EDS. Cr/CrN multilayers have been found to exhibit the best performance among all materials and coatings considered here. The results showed low friction coefficient of Cr/ CrN multilayers and the amounts of intermetallic compounds were lower than those formed on Cr/CrN/CrAlN ones.