Reinforcement of FeCrAlY with Silicon Carbide (Carbon Core) Filament

摘要

In view of its high temperature stability (100 hr stress-to-rupture of 280 ksi at 2000 F), low density (0.115 lb. in. to the 3rd power) and high elastic modulus (60x10 to the 4th power psi) silicon carbide filament (carbon core) is an attractive candidate as a reinforcement for high temperature matrix alloys. However, it reacts with most metals at elevated temperatures and must be protected with a suitable barrier coating. For FeCrAlY, tungsten was found to be a good barrier material. Therefore 0.0005 in. thick coating of tungsten was applied to the filament by a continuous chemical vapor deposition process. The coated filament had 100 hr 2000 F rupture strength of 100-130 ksi. Composites of FeCrAlY containing about 30 v/o of the coated filament were fabricated using the diffusion bonding process and their tensile and stress-to-rupture properties were determined in the 1800 F - 2000 F range. While at room temperature the tensile strength of the composite was low, at elevated temperatures it approached values predicted by the rule of mixtures. At 1800 F, the 100 hr stress-to-rupture was 35 ksi. At higher temperatures, excessive coating-matrix interaction resulted in the degradation of the composite properties.