Solidification and adhesion of molten paraffin impacted on metal substrate and subsequent cracking and delamination of the solidified coating

Abstract

Model experiments were conducted using paraffin wax in order to clarify a developing process of quenching stress in thermal barrier coating. A droplet of melted paraffin wax was dropped onto a circular metallic substrate, and a quenching strain generated at the substrate back surface was measured during solidification and adhesion process of droplet. Effects of several experimental variables, including substrate temperature, droplet materials and impinging velocity, were examined focusing on the developing process of quenching strain and fracture behaviors of solidified coating. A series of the model experiments revealed that the quenching strain was affected by substrate temperature, thickness of film and material properties of droplet, such as Young's modulus and coefficient of thermal expansion. During the solidification and adhesion process, cracking and delamination of the solidified coating were taken place depending on the substrate temperature and paraffin materials.