HVOF-sprayed insulation coatings for applications in power electronics

Electrically insulating coatings with high breakdown strengths, high electrical resistances and high thermal conductivities are necessary for applications in the field of high-power electronic components. In this paper, the potential of HVOFsprayed coatings for high-power electronic components was investigated using 20 different powders. These powders are aluminium oxide ceramics which contain admixtures of chromium, titanium and magnesium oxides. As the essential result of this paper, it may be stated that not only pure aluminium oxide but also spinel (Al2O3-28MgO) satisfy the requirements on the electric insulation. So that the volume resistivity becomes high enough, these insulation coatings should be sealed subsequently and the quantity of contaminations such as Na2O or Fe2O3 must be lower than 0.1%.