Ion assisted physical vapour deposited (IAPVD) films typically have a high
state of residual stress. This residual stress comprises two components: a
thermal stress, which forms as the system cools to room temperature; and an
intrinsic stress which is caused by the processes of deposition. Much work
has been published on the tribology of surface coatings without considerat
ion of the residual stress. It was therefore considered desirable to develo
p a finite element (FE) simulation to be used either as a precursor to any
realistic mechanical study of the behaviour of such surface coatings, or to
be used as a tool to study the effects of varying the deposition parameter
s. The FE package chosen was ABAQUS. IAPVD is a process of simultaneous ion
bombardment and material condensation. Previous experimental work has show
n that the residual stress is related to deposition parameters, such as inc
ident ion and atom fluxes and energies, and recent molecular dynamics studi
es have indicated that trapped inert gas species play a major role in the m
echanism for creation of the intrinsic stress. The FE simulation assumes th
at the processes of ion bombardment and material deposition are consecutive
, but as the analysis time step tends to zero this assumption approximates
the simultaneity of the processes. Suitable mathematical descriptions are e
mployed in the bombarded region of the growing coating to simulate the macr
oscopic effects of the microscopic atomic collision phenomena and diffusion
processes. The predicted trends of mean stress and its distribution are si
milar to those observed in published experimental work. (C) 1999 Elsevier S
cience S.A. All rights reserved.