Thermogravimetric Analysis for Aluminum Phosphate Sealed Alumina and Chromia Coatings

This paper examines plasma-sprayed alumina and chromia coatings, with and without aluminum phosphate sealing, in order to assess the stability of the as-sprayed layers and phosphate reaction as a function of temperature during the sealing process. Thermogravimetric analysis showed no changes in mass in the alumina layers, an increase of 1.7% in the mass of the chromia layers due to oxidation, and a 14% loss of mass in the sealed layers, which agrees well with the evaporation behavior of a pure seal. Paper includes a German-language abstract.