Two-step penetration: a reliable method for the measurement of mechanical properties of hard coatings

A two-step penetration method using the microindentation technique is presented to investigate the mechanical properties of hard coatings in this article. This method employs a large-load indentation step, first to exhibit the influences of substrate deformation and coating thickness on the measured hardness values, and then selects a small load, based on the results of the first step to perform the measurement. Since with this small load, the measurement will not be affected by the substrate, the hardness and elastic modulus of the coatings can be obtained precisely. Experiments with TiN coatings deposited on high-speed steel substrate shows that by using this two-step penetration method, the mechanical properties of hard coatings can be measured accurately and reliably.