Gas seal for turbine blade tip

A turbomachinery blade including a blade body and a blade projection about the radial outer periphery of the blade body, the projection including a metallic body and an abrasive outer tip, the improvement comprising:

• said outer 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 radially outwardly from said outer tip portion, 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.