Role of zinc coating at liquid-vapor interface during laser material processing of zinc coated steel

摘要

In laser material processing, one of the major interests is characterizing interfacial phenomena induced by thermal phase changes of materials. The interfacial characteristics in the laser processing of multi-coated materials show different behaviors compared to those of single material processing. The difference in thermo-physical properties of the coated and primary materials induces the contrasting characteristics of multiple interfacial phenomena including temperature, recoil pressure, capillary force, and thermo capillary force. The influence of coating layer to the interfacial physics evolutions is difficult to be modeled mathematically when the laser beam penetrates the multi-coated material layer by layer. This paper addresses the role of the zinc coating at the liquid-vapor interface during the laser processing of zinc coated steel, as a representative case of multi-coated materials. Computational modules incorporating the zinc layers were established and selectively applied at the locations where the zinc coatings exist to investigate the interfacial phenomena. The level set method was integrated with the modules to track the evolution of the liquid-vapor interface in a self-consistent manner. The interfacial phenomena characteristics were estimated by a 3D mathematical simulation study. A reflective topography method was employed to validate the mathematical model and to supplement our understandings of the interfacial evolution.