An abrasive blade tip treatment coating was developed which exhibited promising rub resistance against ceramic (graded ZrO2-Ni Cr) outer air seals. This blade/seal system was designed for advanced high pressure turbine sealing applications. The best tip treatment was produced by vacuum hot pressing a compact comprised of 50volume percent of coated 8-mil diameter silicon carbide (SiC) grits in a MERL 711 (CoNiCrAlY) alloy matrix. The SiC grits were radio frequency (RF) sputter coated with a 0.1-mil thick aluminum oxide diffusion barrier coating prior to insertion in the matrix. This compact was transient liquid phase bonded to prepared rig and engine blade tips. The abrasive blade tip withstood fabrication,bonding,and heat treatment cycles with little or no grit dissolution and degradation. Blade/seal dynamic rub tests produced little blade tip wear (compared with seal wear) with no dynamic rub impact problems or any loss of abrasive blade tip treatment structural integrity. (Author)
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