Abstract: A method for repairing a gas turbine stationary flowpath shroud. The method comprises providing a superalloy gas turbine stationary flowpath shroud that has previously been in service. The method further comprises preparing a restoration coating for application to the flowpath surface of the shroud by the steps of providing a precursor mixture comprising a higher-melting-point alloy component, a lower-melting-point alloy component, and a fugitive binder. A perform is prepared from the components and pre-sintered into a mildly curved form. The partially densified perform is applied to the flowpath surface and thermally bonded to the flowpath surface, forming a restoration coating.

Abstract: A method and apparatus for repairing a turbine engine vane segment of at least one airfoil disposed between band or platform members originally assembled in a designed relationship uses locating features integral with at least the band members and used in original assembly. For repair, the members are separated and at least one member is selected for reassembly, while preserving substantially in original form locating features of the selected member. A replacement member is provided for reassembly with the selected member, and the members are reassembled using the preserved locating features for positioning the members in the designed relationship. The apparatus provides elements for moving the segment members into and holding in the designed relationship.

Abstract: A method for repairing an environmental protective coated article portion of a gas turbine engine article made of a Ni base superalloy including Cr and at least about 6 wt. % total of Al and Ti comprises removing the coating, exposing the article portion to a reducing mixture of gases including, by weight, greater than 6% up to about 20% hydrohalogen gas with the balance principally hydrogen gas, and preferably about 10-15 wt. % hydrogen fluoride gas. Exposure is at a temperature in the range of about 1600.degree.-2000.degree. F. for a time, greater than about 2 hours, and preferably about 2-10 hours, sufficient to remove from within the article portion metal sulfides, Al, Ti, oxides of Al or Ti, or their combinations. Then the article portion is recoated. One form relates to weld repairing the article portion by removing Al or Ti or both to a depth up to about 0.003".

Abstract: A turbine engine vane segment, including spaced apart band or platform members and at least one airfoil member carried at metallic bonds between the platform members, is improved by providing at least one, but not necessarily all, of the segment members as an improved member having a directionally oriented Ni base superalloy microstructure with a stress rupture strength greater than the stress rupture strength of the balance of the segment members, which have a conventional generally equiaxed microstructure. For example, the balance of the members are conventionally cast from a Co base alloy. The coefficient of thermal expansion of the improved member is different from that of the balance of the members. A metallic bond including a brazed structure is provided between the improved member and the balance of the members, possessing strength sufficient to carry the stresses caused by differences in coefficients of thermal expansion of the dissimilar materials.

Abstract: A method for repairing a turbine engine vane segment of at least one airfoil disposed between band or platform members originally assembled in a designed relationship uses locating features integral with at least the band members and used in original assembly. For repair, the members are separated and at least one member is selected for reassembly, while preserving substantially in original form locating features of the selected member. A replacement member is provided for reassembly with the selected member, and the members are reassembled using the preserved locating features for positioning the members in the designed relationship. The apparatus provides elements for moving the segment members into and holding in the designed relationship.

Abstract: A method for removing a diffusion coating which includes Al from a Ni base alloy surface portion comprises mechanically removing substantially a coating outer portion disposed on a coating diffused inner portion, and then depleting Al from the exposed diffused inner portion. Such depletion is by exposing the inner portion to a reducing gas comprising greater than about 6 wt. % halogen gas, for example a mixture of up to about 20 wt. % of a hydrohalogen gas, such as hydrogen fluoride gas, with the balance principally hydrogen gas. The temperature of exposure is at least about 1600.degree. F., preferably about 1600.degree.-2000.degree. F. for about 2-10 hours.