Patent ID: 7993701

Claim:
A composite structure forming method comprising the steps of: a) creating internal strain ranging between 0.25 to 2.0% in brittle material fine particles having an average particle size of 0.1 to 5 μm; b) causing the brittle material fine particles in which the internal strain has been created to collide with a substrate surface at a speed of 50-450 m/s; c) deforming or fracturing the brittle material fine particles by impact of the collision: d) mutually joining of the collided fine particles occurring through contact of newly generated active surfaces formed by the deforming or fracturing; and at the same time e) forming an irregularity on the surface of the substrate caused by the collision of the brittle material fine particles with the substrate; thereby forming a polycrystalline structure made of the brittle material on the irregularity.