Metallographic Preparation of Thermal Spray Coatings: Coating Sensitivity and the Effect of Polishing Intangibles

The heterogeneous or composite nature of the thermal spray deposit can make choosing a metallographic preparation process very difficult. Hard vs. soft phases, brittle ceramics, and mixtures of many phases can create a variety of issues. When a procedure is developed, it becomes a necessity to document all the parameters or intangibles that define the process. Examples of procedure definition will be discussed and a suggested list of critical intangibles such as polishing abrasives (concentration vs. frequency of application), lubricant (pH, type), and many other factors will be highlighted.