For the whole decision click here: o25811
Summary
The invention relates to a gas turbine component comprising a silicon-containing substrate and a bond coat layer directly overlying the substrate. The bond coat layer consists of a metal silicide selected from a group of various transition and lanthanide metals. The bond coat has the purpose of effectively adhering an environmental barrier coating (EBC) to the silicon containing substrate, even when the EBC is exposed to high operating temperatures in the excess of 1204ºC. The EBC protects the silicon containing substrate against oxidation and degradation. Although lacking specific reference to the group of various transition and lanthanide metals set out in claim 1, two prior art documents disclosing the use of metal silicide protective coatings on a silicon based substrate to allow operation at high operating temperatures were considered to render the invention obvious. The application was refused.