The Effect of Hard Coating Properties on Substrate Stresses Under Tribological Loads

A study has been carried out using finite element methods to investigate the influence of hard coatings on substrate stresses under tribological and thermal loads. The study was performed under a uniform distribution of traction (normal and tangential pressure) and temperature. The stresses have been calculated in terms of the ratio of the modulus of elasticity between coating and substrate and the ratio of the coating thickness to the loading strip length at different coefficients of friction and temperatures. The heat transfer problem was solved with regard to a variety of coating properties and the output temperature applied as a thermal load in the structure problem. It is shown that altering the coating modulus of elasticity and coefficient of friction in the presence of a temperature change affects the maximum equivalent stress in the substrate and changes its location. The simulations carried out are discussed in terms of the potential benefits of plasma-based surface coatings and treatments in improving tool performance and the requirements for coating design specifications which will allow design engineers to build surface treatments into new tool designs.