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(11) | EP 0 166 676 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Abrasive surfaced article for high temperature service |
| (57) A very thin abrasive material (26) on a substrate (24, 28) is comprised of ceramic
particulates (30) contained within a metal matrix (36). The particulates extend fully
through the matrix from the substrate surface (32) to the machined free surface (44)
of the abrasive. In a representative 0.38 mm abrasive the particulates are sized nominally
at 0.42-0.50 mm and have an aspect ratio of less than 1.9 to 1. This enables a high
density of particulates, in the range 33-62 per cm2, while at the same time ensuring good bonding in that most of the particulates are
fully surrounded by matrix. When the abrasive is applied to the tip of a superalloy
gas turbine engine blade (20), about 10-50% of the matrix metal is removed after machining.
This allows the machined ceramic particulates (30) to project into space and to thus
better interact with ceramic abradable seals. In the preferred practice of the invention
the particulates are alumina coated silicon carbide contained in a nickel superalloy
matrix. |