Surface Residual Stress Measurement Using Curvature Interferometry

Abstract

Surface roughness plays an important role in the delamination wear caused by rough surface contact. A recent dislocation model analysis predicts that nano-scale contacts of surface steps induce nucleation of dislocations leading to pro-load and anti-load dislocation segregation near the contact surface. Suh dislocation segregation generates a sub-layer of tensile residual stress in a much thicker layer of compressive residual stress near the surface. The tensile sub-layer thickness is expected to be about 50 to 100 times the step height. In order to verify the predictions of the model analysis, contact experiments are carried out on polycrystalline aluminum surface to determine the existence of the tensile sub-layer. The variation of the residual stress along the thickness direction is measured using a newly developed high sensitivity curvature-measurement interferometer. The residual stress distribution measured with sub-nanometer spatial resolution indicates that contact loading leads to formation of a highly stressed sub-layer of tensile residual stress within a much thicker layer of compressive residual stress. Implications of tensile residual stress for delamination wear are discussed.

Role of Oxide Stress in the Initial Growth of Self-Organized Porous Aluminum Oxide

“…Monitoring of stress changes in aluminum samples during anodizing and oxide dissolution was accomplished through measurements of sample curvature, by phaseshifting curvature interferometry [36]. A detailed description of the curvature interferometry method, along with validation and comparisons to traditional deflectometry measurements, may be found in an earlier paper [20].…”

Factors Controlling Stress Generation during the Initial Growth of Porous Anodic Aluminum Oxide

“…As in our prior work, in situ stress measurements were carried out using phase-shifting curvature interferometry [24]. A detailed description of this method, including comparisons with traditional deflectometry measurements, is found in an earlier paper [23].…”

In Situ Stress Measurement During Aluminum Anodizing Using Phase-Shifting Curvature Interferometry

“…[1][2][3][4][5][6][7][8][9]14,15 Since stress resolution scales with the square of the substrate thickness, sputtered metallic layers on thin inert wafers are frequently used as samples to maximize resolution. 16, 17 Floro and Chason developed an improved version of this technique that relies on monitoring the deflection of an array of equally spaced laser beams reflected from the substrate to measure all components of in-plane substrate curvature with high resolution and robustness. 18 The liquid medium in electrochemical cells imposes restrictions on stress measurements.…”