Abradable seal having particulate erosion resistance
AssigneeUnited Technologies Corporation
InventorWilliam F. Otfinoski
Life of this patent
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Abstract
Porous plasma arc sprayed powder metal abradable materials used in knife edge labyrinth seals of gas turbine engines have their resistance to erosion improved when a thin ceramic surface layer containing fine aluminum particulate is applied. The fine equiaxed particulate and ceramic are applied as an aqueous liquid so that both the particulate and cermic matrix material fill the surface pores, without penetrating further into the powder metal material and thereby adversely affecting desirable abradability characteristics.
Claims14
An abradable seal structure of the multiple knife edge type comprises of a porous powder metal plasma arc sprayed deposit having 26-40 percent density on a metal substrate, wherein the deposit is characterized by having interlocked to its surface a layer material comprised of equiaxed particulates in a ceramic matrix, wherein the hardness of the particulates is no greater than the hardness of the metal of said sprayed deposit;
- the particulates are substantially smaller than the surface pores of said sprayed deposit, and some of said particulates are contained within said surface pores;
- sand said layer material improves the resistance of said sprayed deposit to erosion when the seal is rubbed by said knife edges.
The method of improving the erosion resistance of a porous powder metal abradable seal having greater than 26 percent density percent on a metal substrate, comprising the step of applying to the seal surface a layer material comprised of liquid and fine equiaxed metal particulates;
- flowing the layer material into the surface pores of the seal without flowing said material into the pores beneath the surface;
- and curing said material to form on the surface of the seal a layer comprising metal particulates in a ceramic matrix wherein the hardness of the metal particulates is no greater than the hardness of the metal of the abradable seal.
Dependencies are inferred from the claim text.