Ceramic thermal barrier coating for rapid thermal cycling applications
AssigneesUnited Technologies Corporation, Cummins Engine Company, Inc.
InventorsAlan J. Scharman, Thomas M. Yonushonis
Life of this patent
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Abstract
A thermal barrier coating for metal articles subjected to rapid thermal cycling includes a metallic bond coat deposited on the metal article, at least one MCrAlY/ceramic layer deposited on the bond coat, and a ceramic top layer deposited on the MCrAlY/ceramic layer. The M in the MCrAlY material is Fe, Ni, Co, or a mixture of Ni and Co. The ceramic in the MCrAlY/ceramic layer is mullite or Al.sub.2 O.sub.3. The ceramic top layer includes a ceramic with a coefficient of thermal expansion less than about 5.4.times.10.sup.-6 .degree.C.sup.-1 and a thermal conductivity between about 1 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1 and about 1.7 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1.
Claims6
A metal article having a thermal barrier coating that is subjected to rapid thermal cycling, wherein the thermal barrier coating is characterized by:
- (a) a metallic bond coat deposited on the metal article,
- (b) at least one MCrAlY/ceramic layer deposited on the bond coat, wherein M is Fe, Ni, Co, or a mixture of Ni and Co, and the ceramic in the MCrAlY/ceramic layer comprises mullite, Al.sub.2 O.sub.3, zircon, sillimanite, sodium zirconium phosphate, fused silica, cordierite, or aluminum titanate, and
- (c) a ceramic top layer deposited on the MCrAlY/ceramic layer, wherein the ceramic top layer has a porosity of between about 10% and about 30% and comprises a ceramic with a coefficient of thermal expansion less than about 5.4.times.10.sup.-6 .degree.C.sup.-1 and a thermal conductivity between about 1 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1 and about 1.7 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1, whereby the ceramic in the ceramic top layer allows the coating to withstand temperature variations of at least about 110.degree. C. between a temperature at a portion of the coating's surface and the coating's mean surface temperature.
Dependencies are inferred from the claim text.