Fiat Societa Per Azioni

Paul Popper

Angelo Giachello

Giuseppe Tommasini

Pier C Martinengo

PierCarlo Martinengo

Sintered silicon nitride articles are prepared by sintering a silicon nitride compact of a density of at least 1.3 g/cm.sup.3 in nitrogen gas atmosphere at substantially atmospheric pressure, while the compact is embedded in a protective powder comprising silicon nitride, boron nitride, or a mixture of silicon nitride and boron nitride, and one or more sinterization additives for silicon nitride, said additives being present in the protective powder in an amount of from 3 to 20% by weight.

Process for sintering silicon nitride compacts

Sintered silicon nitride articles are prepared from a silicon nitride compact by forming a silicon powder containing one or more sintering additives for silicon nitride into a compact having at density of at least 1.3 g/cm.sup.3, said additives being present in the powder in an amount such as to ensure an additive content of from 0.5 to 20 wt. % in the silicon nitride compact, nitriding the silicon compact by heating under nitrogen gas blanket at a temperature not exceeding 1500.degree. C., to convert said silicon into reaction bonded silicon nitride, and sintering the reaction bonded silicon nitride compact by heating in a nitrogen gas atmosphere at a temperature of at least 1500.degree. C.

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Newcastle, United Kingdom

Paul Popper