PRODUCTION OF PREFORM

PURPOSE:To obtain a preform without any internal defect due to the entrainment of bubbles and in which a fibrous material, etc., are uniformly dispersed by defoaming a slurry contg. the fibrous material by evacuation, then dehydrating and forming the slurry. CONSTITUTION:A whisker (e.g. aluminum borate whisker and potassium titanate whisker), a fibrous material selected from the inorg. fibers (e.g. silicon carbide fiber and alumina fiber) and further a powder are used to prepare a slurry. The slurry is treated in vacuum to remove the bubbles in the slurry and then formed to obtain a preform. A metalic composite material obtained from the preform is hardly fluctuated in the characteristic such as mechanical strength, wear resistance and sliding property and is useful as the various structural materials.