Patent ID: 6194336
Filing Date: 2001-02-27
Classification: B82Y,C04B

Abstract:
A toughened alumina sintered body, consisting essentially of alumina and trace impurities, and having a flexural strength of 300 MPa or higher and a fracture toughness of 5 MPa.multidot.m.sup.1/2 or higher, which is fabricated by:a) adding an abrasion powder, comprising .alpha.-aluminum oxide powder having a size of 0.1 .mu.m or less, to a material comprising aluminum hydroxide containing trace impurities, in an amount of 0.01 to 20 mass % as seed crystals for .alpha.-aluminum oxide powder;b) calcining the mixture obtained in step a) at a temperature of 900.degree. to 1,200.degree. C. to obtain an .alpha.-aluminum oxide powder; andc) sintering the .alpha.-aluminum oxide powder obtained in step (b) to produce a sinter;and wherein the surface of the toughened alumina sintered body contains at least 20 surface % of anisotropic crystal grains having a major axis of 10 .mu.m or less, and an aspect ratio of 2 or higher.