E. Kusano et al., Adhesion and hardness of compositionally gradient TiO2/Ti/TiN, ZrO2/Zr/ZrN, and TiO2/Ti/Zr/ZrN coatings, THIN SOL FI, 334(1-2), 1998, pp. 151-155
A technique using compositionally gradient interlayers has been applied to
TiO2/Ti/TiN, ZrO2/Zr/ZrN, and TiO2/Ti/Zr/ZrN multi-compositional coatings t
o enhance the adhesion of hard coatings to substrate. The coatings were pre
pared by de reactive magnetron sputtering using a combination of a Zr or a
Ti metal target and a pure Ar, an Ar-O-2 mixture, or an Ar-N-2 mixture disc
harge gas, onto a borosilicate glass substrate. Adhesion of coatings to the
substrate was estimated by a scratch method. The hardness of coatings was
measured by a nano-indentation method. Without an interface, ZrN coatings s
howed a very poor adhesion. By using glass/ZrO2/Zr or glass/TiO2/Ti composi
tionally gradient interface layers, the adhesion strength of ZrN coatings w
as enhanced to the adhesion strength almost equal to or higher than those o
f TiO2 or ZrO2 single layer coatings. From the results of internal stress e
valuation, it was found that a high internal stress causes a poor adhesion
of ZrN coatings. Hardness of coatings with a ZrN overlayer were 20 to 35 GP
a and larger than those of coatings with a TiN overlayer. The increase in t
he hardness by inserting a compositionally gradient interface was observed
in ZrO2/Zr/ZrN and TiO2/Ti/Zr/ZrN systems. (C) 1998 Elsevier Science S.A. A
ll rights reserved.