Gas seal with tip of abrasive particles

Claim 1

In a gas seal comprising a stationary member and a movable member, the members being in juxtaposition to provide therebetween a gas seal, one of said members including a projection, directed toward a surface of the other member, the projection having a metallic body and an abrasive outer tip which cooperates with said surface to inhibit gas flow therebetween, the improvement wherein: the tip of said projection is a composite of an inner tip portion and an outer tip portion, the inner tip portion comprising a shaped member discrete from the projection body, of an alloy resistant to oxidation, sulfidation and thermal fatigue at operating temperatures, and bonded with the metallic body of the projection, and the outer tip portion comprising a matrix based on an element selected from the group consisting of Cr, Co, Ni and alloys including Cr, Co and Ni and in which there is entrapped a plurality of abrasive particles protruding from said outer tip portion toward the surface of the other member, the particles having a hardness greater than the hardness of said surface of the other member, the outer tip portion bonded with said inner tip portion, the thickness of the matrix being less than the longest dimension of the abrasive particles in the direction of their protrusion from the outer tip portion.