Surface coating effects on contact stress and wear: An approach of surface engineering design and modelling

Abstract

The present paper is a dedication to Professor Tom Bell, a distinguished scientist and engineer, for his great contributions and achievements in surface engineering design and modelling. An initial attempt has been made in surface system design through combining the authors' previous achievements in understanding contact mechanics of surface engineering system. The approach is taken mainly from modelling the contact behaviour of multilayer surface system with real rough surface profiles in terms of contact stress and deformation, and both boundary and finite element methods have been employed to understand the system contact behaviour. Experimental investigations have also been carried out on the performance of surface engineered gears (steel and titanium). Tests were carried out on untreated, TiN coated, plasma nitrided and duplex treated steel gears under dry running conditions, and it has been shown that the duplex system gives the best wear resistance. For titanium gears, experimental tests were carried out on untreated and thermal oxidised titanium against steel gears and the thermal oxidised treated has showed a significant wear improvement compared to that for the untreated specimens. Finally, possible further investigations have been proposed.

Surface finish effect on dry sliding wear behavior of thermally oxidized commercially pure zirconium

“…The hard ZrO2 asperities not only had a ploughing action on the alumina ball to result in a large wear scar on the ball (Fig. 12), but also suffered from extremely high contact pressures, as predicted by the contact models developed for rough surfaces [23,30,31]. Thus the contact stresses were concentrated at the highest asperities and the stresses in the non-contacting areas and in the bulk of the OL must be much reduced.…”

Surface modification by multilayered W/W2N coating

“…Tensile stresses at the contact zone tend to separate the coating from the substrate, which can be eliminated by the film thickness adjustment and coating conditions in order to ensure that the coating/substrate adhesion strength can withstand the high contact stresses. 48,49 If the hardnesses of the two rubbing materials are of the same order, the wear rate of ball specimen will dominate that of the disc specimen due to higher bulk temperature of the balls near the contact zone. High temperature decreases the hardness of steels.…”

Degradation of metal–polymer composite submitted to uniaxial deformations in 3.5% NaCl solution

“…This can be interpreted as changes of the surface (lines, strain marks and grain boundaries) originating in the deformations of the Cr 2 O 3 grains [16]. The upper section of the figure shows a pit of about 1 μm in diameter, and further down it …”