Agency for Defense Development

Seung Su Baek

Yong Kee Baek

Sung Min Lee

Ki Min Lee

Won Ho Lee

Hyoun-Ee Kim

Suk-Joong L Kang

Eul Son Kang

A silicon nitride sintered body is obtained by mixing 2.about.16 wt % of Yb.sub.2 O.sub.3 as a sintering additive with Si.sub.3 N.sub.4 powders including unavoidable impuirities, pressing the mixed powder into a desired form, and gas-pressure sintering the thusly pressed form, whereby an inner region of the sintered body has a fine microstructure, and an outer region thereof has a mixed microstructure in which elongated grains and fine grains co-exist and a method for manufacturing a silicon nitride sintered body, includes the steps of: adding and mixing 2.about.16 wt % of Yb.sub.2 O.sub.3 powder as a sintering additive into a silicon nitride (Si.sub.3 N.sub.4) powder; ball-milling the mixed powder to obtain a slurry; drying and classifying the slurry; press-forming the resultant powder in a die uniaxially and isostatically; and gas-pressure sintering the resultant compact body at a temperature in the range of 1800.about.2000.degree. C., whereby an inner region of the resultant sintered body has a fine microstructure, and an outer region of the resultant sintered body has a mixed microstructure in which elongated grains and fine grains co-exist.

Silicon nitride sintered body with region varying microstructure and

A sialon composite and fabrication method thereof in which the phase of a surface layer thereof is modified differently from that of the bulk. The surface layer is modified to .alpha.-sialon or .alpha.-.beta. sialon composite but the bulk is .beta.-sialon. Also, the surface layer is modified to .beta.-sialon or .alpha.-.beta. sialon composite but the bulk is .alpha.-sialon.

Method of producing a surface modified sialon composite

Growing community of inventors

Daejon, South Korea

Seung Su Baek