Metal fibre reinforced hydroxy-apatite ceramics

Abstract

The reinforcement of hydroxy-apatite ceramics with metal fibres is discussed. Hastelloy X and FeCralloy fibres were dispersed in hydroxy-apatite powder slurry. The fibre-powder slurries were dried and sieved over a wide aperture sieve. The resulting granules were used for die pressing. Volume fractions used were 10, 20 and 30%. The compacts obtained in this way were isostatically repressed at 4 k bar. These compacts showed considerable strength and toughness. Hot-pressing of the compacts was done at about 1000'C and a pressure between 0.2 and 1.0 k bar for 15 min. The resulting materials were characterized by fractography and strength, fracture toughness, Young's modulus and hardness measurements. Both strength and fracture toughness increased while Young's modulus and hardness decreased with increasing volume fraction of fibres. The strength and fracture toughness of composites containing 20 vol % metal fibres showed an increase of the strength and fracture toughness by a factor of about 2 and 6, respectively, as compared with the strength of about 100 M Pa and a toughness of 1 .0 MPa m^1/2 for the sintered, pure matrix materials. The results obtained are also promising for other metal fibre-ceramic matrix composites.