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Fabrication of Transparent Silicon Nitride from Nanosize Particles
Author(s) -
Pechenik Alexander,
Piermarini Gasper J.,
Danforth Stephen C.
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb04422.x
Subject(s) - sintering , materials science , silicon nitride , diamond , compaction , amorphous solid , composite material , fabrication , metallurgy , silicon , crystallography , chemistry , medicine , alternative medicine , pathology
Compaction of ultrafine silicon nitride (Si 3 N 4 ) powder at high pressures and various temperatures followed by pressureless sintering was investigated. The powder, consisting of nearly spherical particles (16 nm in diameter) of amorphous stoichiometric Si 3 N 4 , was pressed in a diamond anvil cell under pressures up to 5 GPa and temperatures ranging from liquid nitrogen to 500°C. Quality of compaction, evaluated by visual transparency and hardness of the produced compacts, depended on the amount of adsorbed gases on the surface of the particles and on the temperature of compaction. Visually transparent compacts were produced by pressing the starting powder without outgassing in liquid nitrogen under 5 GPa. The transparent compacts exhibited a hardness of 1200 kg/mm 2 after pressing in the diamond anvil cell at 500°C for 3 h at 5 GPa. After subsequent pressureless sintering conducted for 1 h at 5 GPa. After subsequent pressureless sintering conducted for 1 h at 1400°C in a tube furnace under nitrogen, the hardness of these samples increased to over 2000 kg/mm 2 and the visual transparency was maintained. The results demonstrated that transparency was maintained. The results demonstrated that transparent compacts of nanosize amorphous Si 3 N 4 particles could be sintered to high hardness at relatively low temperatures without using sintering aids or applying pressure during sintering.