An environmentally resistant patch includes one or more rare earth silicates, wherein an inorganic composition of the environmentally resistant patch includes, once cured, from about 80 mole percent to about 100 mole percent of a rare earth monosilicate and/or rare earth disilicate composition and from about 0 mole percent to about 20 mole percent of an inorganic additive, and, wherein the environmentally resistant patch has, once cured, an adhesive strength of at least about 3 MPa and a coefficient of thermal expansion of from about 3.5.times.10.sup.-6/.degree. C. to about 7.5.times.10.sup.-6/.degree. C.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT
 This invention was partially made with government support under government contract No. DE-FC26-05NT42643 awarded by the Department of Energy. The government has certain rights to this invention.