Abstract
There is a clear need to understand how the microstructure of a surface coating dictates its properties and how these microstructure-property relationships change as afunction of temperature. Both high temperature hardness and X-ray diffraction studies have been performed which show the importance of understanding the way the coating microstructure changes with temperature if its mechanical properties at these temperatures are to be explained. Residual stress, hardness, and lattice strain are reduced as the temperature increases and the changes are not reversible. These changes are discussed in light of the variations in coating microstructure.