To reduce the amount of expensive inorganic fibers used and to facilitate the penetration of metal matrix into spaces by binding ceramic hollow balls of specific average grain size, inorganic fibers of respectively specified average fiber diameter and average fiber length, and ceramic grains of specific average grain size with a binding material.
Ceramic hollow balls of 20 to 150 μm average grain size, inorganic fibers of 1 to 10 μm average fiber diameter and 10 to 200 μm average fiber length, and ceramic grains of 1 to 10 μm average grain size are bound with a binding material to prepare a preform for metal matrix composite. It is preferable to regulate the proportions of the ceramic hollow balls, the inorganic fibers, and the ceramic grains to ≥20 wt.%, 10 to 60 wt.%, and ≤40 wt.%, respectively, and also to regulate the volume fraction of the preform, excluding the spaces in the hollow balls, to 10 to 50%. Glass balloons, etc., are used as the ceramic hollow balls, alumina silica short fibers, etc., are used as the inorganic fibers, and alumina powder, etc., are used as the ceramic grains, and further, colloidal silica, methyl cellulose, etc., are used as the binding material.
WADASAKO MITSUYUKI
IWATA KOJI
KANEDA KAZUMI
