Medium temperature chemical vapor deposition (MTCVD) coatings, on cemented
carbide cutting tools, have gained prominence in the machining of gray and
nodular cast iron, stainless steels and other abrasive workpiece materials,
that require increased edge toughness of the cutting tools. Although MTCVD
TiCN is the most common coating layer used in the current popular cutting
tools, other coatings like MTCVD ZrCN used in conjunction can offer potenti
al performance improvements in machining.
Properties of mono- and nanolayer hard coatings of TiCN and ZrCN, deposited
on carbide substrates by MTCVD, are discussed in this paper. Evaluations o
f the texture of coatings, along with interfacial features of these hard co
atings, are characterized by X-ray diffraction (XRD), scanning electron mic
roscopy (SEM), and optical microscopy. Surface smoothness/surface roughness
was determined on as-coated inserts and compared with physical vapor depos
ition (PVD) and conventional chemical vapor deposition (CVD) coated tools.
Failure mechanism modes of these various coating designs, in machining of n
odular iron and 4340 steels, are discussed for delineating the wear propert
ies of the coatings. (C) 1999 Elsevier Science S.A. All rights reserved.