ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 2 February 2012
Page Count: 11

Cracking Resistance and Impact Wear of Thin and Thick Hard Coatings Under Cyclic Loading

Kulu, Priit
Tallinn Univ. of Technology,

Saarna, Mart
Tallinn Univ. of Technology,

Sergejev, Fjodor
Tallinn Univ. of Technology,

Surženkov, Andrei
Tallinn Univ. of Technology,

Sivitski, Alina
Tallinn Univ. of Technology,

(Received 6 June 2011; accepted 14 December 2011)

Abstract

Among wear resistant coatings and deposition techniques physical vapour deposition of hard thin coatings and high-velocity oxy-fuel spraying of thick WC-Co-based powder coating have provided good wear protection against various types of wear including impact wear. Three different substrate and coating systems—hard metal-coating, cold work tool steel-coating and nitrided steel-coating—were studied. Mono- and multilayer coatings as well as duplex coatings were selected for testing. For characterization of coating systems nanohardness and microhardness as well as Rockwell adhesion test and single point indentation methods were used. Wear resistance of coatings was determined considering impact wear. The best adhesion determined by indentation was demonstrated by monolayer coating (TiN) on a hard metal substrate; the same coating system has a higher impact wear resistance. The coatings with multilayer structure (TiAlN) demonstrate better cracking resistance. Resistance to cracking as well as to impact wear depends on coating E/H ratio (at lower loads) as well as on substrate material E/H ratio (at higher loads). For characterization of resistance to plastic deformation for substrate H_s³E_s² ratio was used. The obtained data enable a comparison of cracking and impact wear resistance of a coated system and selection of an optimal coating for metal forming tools applications.

Keywords:
physical vapor deposition, hard coatings, indentation, cracking, impact wear

Paper ID: JAI104108
DOI: 10.1520/JAI104108
ASTM International is a member of CrossRef.