Variations of Thermally Sprayed Materials by Means of Coupled Property Response

Abstract

Emerging applications in electrical systems and components require the development of new and novel characterization methods for thermal spray coatings. Thermal spray is a complex process in which there are several multivariable dependencies. The relationship between processing and coating properties are often not fully understood. Traditional mechanical properties are not sufficiently sensitive to characterize and classify the electrical response of a material and therefore new methods must be developed to fill the gaps in characterization methods related to electrical properties. It is necessary to develop new test methods which dynamically allow the determination of coating properties. In the past, single property measurements have been achieved but it is the goal of this work to combine two properties in an attempt to gain insight into the microstructural changes of these complex coatings through coupled property response. Particularly of interest is the variation in resistance as a function of mechanical strain via bending, as a function of thermal loading, and as a function of uniaxial mechanical tensile strain. It has been demonstrated that monitoring the electrical resistance while imposing a mechanical strain through bending provides knowledge into the thermal spray coating, thus providing a useful qualitative characterization method. The splat to splat interfaces were determined to exhibit a similar affect to that of ceramics, namely slip and stick mechanisms. The slip and stick mechanism was apparent by the hysteresis displayed through cyclic loading of the sample.