Wear protection in cutting tool applications by PACVD (Ti,Al)N and Al2O3 coatings

Various (Ti,Al)N-, Al2O3-, and (Ti,Al)N/Al2O3 multilayer coatings were deposited onto cemented carbide cutting tool inserts by a plasma assisted chemical vapor deposition (PACVD) technique. Al2O3 coatings were deposited using the gaseous mixture AlCl3, Ar, H2, and O2. (Ti,Al)N intermediate layers were deposited in the same device using the process mentioned and the gases AICl3, Ar, H2, TiCl4 and N2. The unique properties of (Ti,Al)N/Al2O3 multilayer coatings result in superior wear protection for cutting inserts applied in severe multifunction cutting processes. The influence of different deposition temperatures an structure and properties of the coatings like crystallographic phases, chemical composition, mechanical and technological properties is shown. PACVD (Ti,Al)N/Al2O3 coated cutting inserts with fine grained crystalline α/κ-Al2O3 offer performance advantages which are superior with respect to coatings deposited by chemical vapor deposition (CVD) due to the low deposition temperature applied. (author)