The role of PVD TiN coating in wear behaviour of aluminium extrusion die


Karamis M. B. , SERT H.

WEAR, cilt.217, ss.46-55, 1998 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

In this study, the wear behaviour and surface properties of a PVD TiN coated extrusion die were investigated. Both an extrusion die for aluminium profiles and the samples manufacturing from AISI H13 steel were hardened, tempered, nitrided and TiN coated by PVD method. The microhardnesses on the coated surface and cross-section of both nitrided and coated samples were determined. The maximum microhardness on the coated surface was obtained as 2090 HV0.02. Microstructures of treated surfaces were observed by optical microscopy. XRD and EDS analyses of coated samples were also performed. It was determined that the coating had some pores at the interface and that caused the poor bonding with nitrided surface. The coating also included different TiN compounds such as predominantly Ti2N, Ti3N2...x, Ti3TIN and Ti4N3...x. The wear performance of the coated die was examined under real extrusion conditions. The wear of the dies was determined by measurements of wall thickness and surface roughness variations on aluminium profiles produced by the coated and uncoated dies. Although the wear rate of the die could be considerably reduced by TiN coating, after the processing of about 50 billets, the coating was spalled. As a result of this spalling, the wall thickness and surface roughness of the products were increased. The surface roughnesses of products were also increased with their wall thickness. (C) 1998 Elsevier Science S.A. All rights reserved.