In situ observation of the cracking behavior of TiN coating on 304 stainless steel subjected to tensile strain

• Published in: Thin solid films Vol. 352; no. 1; pp. 173 - 178
• Main Authors: Chen, B.F., Hwang, J., Yu, G.P., Huang, J.H.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 08.09.1999; Elsevier Science
• Subjects: Adhesion strength; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Fractures; Interface; Mechanical and acoustical properties; adhesion; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Physics; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Tensile test; TiN coating; TiN coating; Tensile test; Interface; Adhesion strength; Inorganic compounds; Crack formation; Transition element compounds; Tensile tests; Cracking; Mechanical properties; Shear strength; Residual stresses; Ceramics; Solid-solid interfaces; Experimental study; Coatings; Adhesion; Titanium nitrides; Thin films; Stainless steel-304
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(99)00342-9

The validity of a periodic cracking model capable of evaluating the interfacial shear strength of a ceramic film on metal substrate system was tested in a highly residual-stressed TiN coating-304 stainless-steel substrate system. In situ observation of the cracking behavior of the coating was conducted while the TiN-coated tensile specimen was being pulled inside the chamber of a scanning electron microscope. Four sequentially developed morphologies of the crack and/or inter-crack-spacing of the coating, i.e. multiplication, stabilization, cross-linking and spallation, were observed. Inter-crack-spacings of the fragmented coating were analyzed and identified with their respective initiation mechanisms, thereby testing the claims made by the model. Stringent criteria for selecting the characteristic inter-crack-spacing were articulated to improve the accuracy of the calculated maximum interfacial shear stress. Lastly, a modified periodic cracking model, which incorporates the contribution from residual stress and the new rule for selecting the characteristic inter-crack-spacing, was presented. The interfacial shear strength of the subject system evaluated through the modified model is 0.65±0.06 GPa, which is of the order of magnitude of the substrate's yield shear strength.