Advances in chemically vapour deposited wear resistant coatings

Abstract
The aim of this paper is to review recent advances in the area of chemical vapour deposition of wear resistant coatings. The development of the coating structures from the early single TiC coatings to modern multilayer coatings of TiC, Ti(C,N) and Al₂O₃ will be described briefly. Enhanced techniques to deposit Ti(C,N) coatings at lower deposition temperatures leading to increased adhesion and toughness of the tool are dealt with. The chemical reactions occurring in the interfacial part of the cemented carbide substrate are explained and the interfacial structures of the coating-substrate and coating-coating interfaces are discussed in light of adhesion and cutting performance. Development of the first generation alumina layers with poor coating uniformity and undefined crystal structures to tailor-made Al₂O₃ coatings composed α-Al₂O₃, κ-Al₂O₃ or γ-Al₂O₃ modifications or combinations of these will be described. In addition to production scale aspects on deposition of Al₂O₃, recent developments concerning wear properties, stabilities and nucleation control of the α-Al₂O₃, κ-Al₂O₃, and γ-Al₂O₃, polymorphs will be reported.