Evaluation Of Films Creep Deformation Property By Laser Thermal Stress Method And Simulation Of Finite Element

This article put forwards evaluation of films creep deformation property by laser thermal stress method based on the definition of films adhesive strength and current evaluation method. Its principle is: loaded laser onto film surface of samples, film and substrate will produce thermal stress with the action of thermal load, evaluated films creep deformation property and interface spalling or fracture in order to test film intensity and interface adhesive strength. On the basis of the principle of material creep deformation, this article focused on the study on the theory of high-temperature creep deformation induced by laser and some simulations have been done with the software of FEM, which included the following parts in detail:This article analyzed the current methods, principles, evaluating processed and their disadvantages in the methods of evaluating films creep deformation property, followed the domestic and foreign research trend of the evaluation of film adhesive strength, and put forwards a new method by laser thermal stress method to evaluate film creep deformation property.Beginning with the principle of material creep deformation, this article have had theoretic research on the films creep deformation process with the action of thermal load, establishes parametric equation of thermo mechanical response between film and substrate and interface; putting forwards a new method to judge film spalling and fracture and a mathematical model to reflect quantificationally the changing process of adhesive strength between film and substrate with the action of thermal load. Considering heat conduction, heat radiation and thermal convection and high non-linearity of material based on ANSYS. Here we chose film material of (Ti,Al) N and matrix material of WC-6%Co and finite element model, simulated finite element respectively on temperature field induced by laser with different energy density and pulse time after moving laser source and loading film surface, has mastered the changing relation between temperature and time and heat quantization law at the joint of film interface. According to constitutive equation of thermo elasticity of thermal expansion property of film and substrate, stress displacement relation, and stress balancing relation, simulated stress field for film and its substrate, has mastered the changing relation between film stress field and time, temperature at key points and stress curve. The simulative results and the existing experimental results are tally. Therefore, this method can discover quantificationally film creep deformation process and judge position and moment of spalling and fracture by mutation information of curve.