Abrasive ceramic matrix turbine blade tip and method for forming

An abrasive coating on a nickel superalloy substrate, the abrasive coating comprising;

• an alloy layer on the substrate, the alloy layer consisting essentially of, in weight percent, about 14 to about 18 percent chromium, about 9.75 to about 11.45 percent cobalt, about 6.45 to about 6.95 percent aluminum, about 5.95 to about 6.55 percent tantalum, about 1.85 to about 2.35 percent rhenium, about 0.5 to about 1.75 percent hafnium, about 0.02 to about 0.11 percent carbon, about 0.006 to about 0.03 percent zirconium, up to about 1.1 percent silicon, up to about 0.01 percent boron, with the balance being nickel and incidental impurities;
• a ceramic layer overlying the alloy layer so as to form an outer surface of the abrasive coating, the ceramic layer being yttria-stabilized zirconia;
• and
• a single layer of microcrystalline oxide particles dispersed between the alloy layer and the ceramic layer so that about 30 to 60 volume percent of the particles is embedded in the alloy layer and so that about 60 to about 95 volume percent of the particles is embedded within the alloy and ceramic layers, such that at least some of the particles project above the outer surface of the abrasive coating formed by the ceramic layer.

A method for forming an abrasive coating on a substrate, the method comprising the steps of;

• depositing an MCrAl alloy on the substrate;
• incorporating a dispersion of abrasive particles into the MCrAl alloy after an initial layer of the MCrAl alloy is formed, such that continued deposition of the MCrAl alloy causes the abrasive particles to be partially embedded therein;
• and
• depositing a ceramic layer of yttria-stabilized zirconia on the MCrAl alloy so as to form an outer surface of the abrasive coating, the abrasive particles being partially embedded in the ceramic layer such that at least some of the abrasive particles project above the outer surface of the abrasive coating formed by the ceramic layer.