Refractory porcelain enamel passive control coating for high temperature alloys

摘要

Porcelain enamel for use as a thermal control coating on high-temperature, nonferrous superalloy substrates is made up of a high-refractory-content boroaluminum silicate glass frit containing zirconium oxide, lithium fluoride, alkali metal and alkaline earth oxide-flux, zinc oxide and a submicron disperse phase of cubic-stabilized zirconium oxide. Enamel coatings embodying the invention exhibit favorable optical properties and a high coefficient of thermal expansion, providing compatibility with substrates of nonferrous superalloys and enabling coated parts of such alloys to withstand severe thermal cycling conditions without cracking.