STUDY OF THE RESIDUAL MACROSCOPIC STRESS IN TIN COATINGS DEPOSITED ON VARIOUS STEEL TYPES (TUSA1)

Abstract

With a theta-2 theta decoupled X-ray diffractometer, using glancing angle X-ray diffraction optics, it is possible to study the residual macroscopic stress in thin films. In this paper, the residual macroscopic stresses are determined using a new method called the fixed crystal orientation (FCO) sin(2) psi method. In this method, a knowledge of the preferential orientation and the symmetry of the system studied is used to determine the psi values at which well-defined lattice plane reflections are measured. The FCO sin(2) psi method, especially developed to study the stresses present in highly preferentially oriented bodies, is used to determine the stress in highly textured TiN coatings with a thickness of 1.5 mu m. The measurements show that a biaxial stress state can be assumed and stresses ranging from -8.2 GPa to -12.1 GPa are measured. The stress values obtained with the FCO sin(2) psi method are compared with the stress values obtained using the conventional sin(2) psi method. The FCO method proves to be superior for this type of measurement.