Surface roughness in elastohydrodynamically lubricated (EHL) contacts may have a significant effect on component life and there is a need to be able to assess its effects quickly. This article describes a rapid calculation method, which provides accurate results where the amplitude of the roughness is relatively low and which gives good indications of the likely behaviour for higher amplitudes. In the first part, the effect of low-amplitude, sinusoidal roughness is examined, and it is shown that the behaviour can, for any wavelength and roughness orientation, be characterized by three complex quantities. Calculation of two of these is straightforward; the third requires curve fitting to the results obtained using a perturbation analysis. Details of the process are given. The second part of the article discusses how these results can be used to predict the behaviour of any rough surface under rolling-sliding EHL conditions.

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CrN is one of the most important transition metal nitrides, used as protective and anti-wear coating in modern engineering applications. However, CrN coatings are typically brittle and susceptible to catastrophic failure. In this paper, CrNiN coatings with differing Ni contents were deposited on tool steel substrates using a closed field unbalanced magnetron sputtering system. The effects of Ni addition on the microstructure and mechanical characteristics of CrN thin films were studied by combining nanoindentation tests with cross-sectional transmission electron microscopy. A columnar structure was observed in the CrN coating. With an increase in Ni content, the resultant columnar grains exhibited a high aspect ratio. Ni additions to CrN were

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Part 1 of this paper [1] described how the behaviour of low amplitude, sinusoidal roughness in elastohydrodynamically lubricated (EHL) contacts could be characterized by three complex quantities: attenuation of original profile, amplitude of complementary wave and its wave number and decay rate. This second part outlines how these results can be used to estimate, rapidly, the clearances and pressures in any rough EHL contact. The method is applied to a number of contacts for which accurate experimental results are available and it is shown that the process gives close estimates of the clearance and pressure distributions where the amplitude of the attenuated roughness is less than 50 per cent of the clearance and good indication of the behaviour of rougher surfaces.