Self-reinforced silicon nitride ceramic of high fracture toughness

摘要: A process for preparing a self-reinforced silicon nitride ceramic body of high fracture toughness comprising hot-pressing powder mixture containing nitride, densification aid such as sodium oxide, conversion lanthanum oxide and compound, gallium which enhances growth β-silicon whiskers-under conditions that the in situ formation whiskers having aspect ratio occur. novel strength is disclosed crystalline phase wherein at least about 20 volume percent form an average 2.5; glassy second densificaton aid, compound whiskers, amount silica; not greater than 10 weight total other phases. The may also include minor amount, e.g., up to 5.0 percent, based upon ceramic, aluminum or boron nitride. optionally includes secondary reinforcing material carbide whiskers.