Thermal spray of doped thermal barrier coating material
A yttria stabilized zirconia ceramic thermal barrier coating ( 24 ) is applied to a substrate ( 22 ) using an oxy-acetylene spraying process by including in the coating a eutectic phase having a melting temperature sufficiently low to cause melting of the eutectic phase during the oxy-acetylene spraying process. The eutectic phase may be present in the powder ( 12 ) used for the spraying process, or it may be formed during the spraying process by the oxidation of a layer of metal applied to yttria stabilized zirconia particles. The use of an oxy-acetylene spraying process facilitates the application of the coating during in-frame repair of a gas turbine component.
1 . A method of depositing a ceramic thermal barrier coating material, the method comprising:
heating a powdered ceramic material in an oxy-fuel spraying process to produce a spray comprising eutectic phase material exhibiting a melting temperature sufficiently low such that the eutectic phase material is melted during the spraying process; and
directing the spray onto a surface where the eutectic phase solidifies to form a layer of thermal barrier coating material.
2 . The method of claim 1 , further comprising forming the eutectic phase during the spraying process by oxidizing a metallic coating applied to the powdered ceramic material.
3 . The method of claim 1 , further comprising forming the powdered ceramic material to comprise yttria stabilized zirconia particles coated with a layer of one of yttrium, hafnium, calcium, aluminum and cerium.
4 . The method of claim 1 , further comprising forming the powdered ceramic material to contain the eutectic phase material prior to the step of heating.
5 . The method of claim 4 , further comprising forming the powdered ceramic material to comprise a two-phase alloy of calcium zirconate and zirconium oxide.
6 . The method of claim 5 , further comprising forming the two-phase alloy to comprise the range of 50-35 mol % of calcium oxide and 50-65 mol% of zirconium oxide.
7 . The method of claim 4 , further comprising forming the powdered ceramic material to comprise a two-phase alloy of cerium oxide and zirconium oxide.
8 . The method of claim 7 , further comprising forming the two-phase alloy to comprise the range of 50-10 mol % of cerium oxide and 50-90 mol % of zirconium oxide.
9 . The method of claim 4 , further comprising forming the powdered ceramic material to comprise a ternary alloy comprising calcium oxide, alumina and zirconium oxide.
10 . The method of claim 4 , further comprising forming the powdered ceramic material to comprise a ternary alloy comprising cerium oxide, alumina and zirconium oxide.
11 . The method of claim 1 , further comprising using an oxy-acetylene spraying process to produce a spray comprising yttria stabilized zirconia and a melted eutectic phase.
12 . The method of claim 11 , further comprising using the oxy-acetylene spraying process to heat particles of yttria stabilized zirconia coated with a metal.
13 . The method of claim 12 , further comprising using the oxy-acetylene spraying process to heat particles of yttria stabilized zirconia coated with one of yttrium, hafnium, calcium, aluminum and cerium.
14 . The method of claim 1 applied to an in-frame component of a gas turbine engine.
15 . A product formed by the process of claim 1 .
16 . A product formed by the process of claim 11.