Stripping of Thermal Sprayed Oxide Coatings by Means of Laser Techniques, Water Jet and a Newly Developed Hybrid Method

Abstract

Abstract Many industrial applications require efficient stripping methods for thermal spray coatings, especially when cost-intensive substrate materials are utilized. A typical example is turbine components such as rotor blades with thermal barrier coatings (plasma-sprayed YSZ) in combination with nickel-based bond coatings. Unfortunately, the conventional stripping methods are dirty (contamination with grid blasting material), environmentally harmful (aggressive fluids, strong acid), or relatively ineffective (high tool load in mechanical milling). In order to avoid these disadvantages, alternative techniques such as removal by laser or by water jet stripping and hybrid methods, such as ultrasonic-based mechanical methods and a combination of water, laser, and cryo-techniques have been investigated. In this paper, newly developed stripping methods are compared to classic techniques. The evaluation considers user-friendliness, technological performance such as substrate-interaction, material emission, and economic considerations.