PROCESS FOR PRODUCING HOMOGENEOUS AND FINELY CRYSTALLINE SILICON NITRIDE CERAMICS, SHAPED PARTS PRODUCED IN SUCH A MANNER AND THEIR USE

• Main Authors: ROSENFELDER OTTMAR DR, RIEDEL GUNTER DR, HESSEL FRIEDRICH DR, DOTSCH PETRA, BOCKER WOLFGANG DR, STEINER MATTHIAS, BOBERSKI CORNELIA DR, KRUNER HARTMUT DR, HEINRICH JURGEN DR
• Format: Patent
• Language: Czech; English
• Published: 17.03.1999
• Edition: 6
• Subjects: ARTIFICIAL STONE; BLASTING; CEMENTS; CERAMICS; CHEMISTRY; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDINGMATERIALS; CONCRETE; CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES; ENGINE PLANTS IN GENERAL; HEATING; LIGHTING; LIME, MAGNESIA; MACHINES OR ENGINES IN GENERAL; MECHANICAL ENGINEERING; METALLURGY; REFRACTORIES; SLAG; STEAM ENGINES; TREATMENT OF NATURAL STONE; WEAPONS

Při výrobě homogenní a jemně krystalické siliciumnitridové keramiky se keramický prášek rozemele, smísí se s pomocnými tvarovacími prostředky, směs se zformuje na tvarové díly a slinuje se pod dusíkovou atmosféru. Slinování se provádí ve vícestupňovém procesu při teplotách T.sub.max .n.v rozmezí 1700 .sup.o.n.C až 1900 .sup.o.n.C za použití tlaku plynu v rozmezí 0,2 až 50 MPa, přičemž v prvním teplotním stupni se udružuje teplota 0,9 až 0,96.T.sub.max .n., po dobu 10 až 50 minut, za tlaku dusíku 0,2 až 1,2 MPa , ve druhém teplotním stupni se udržuje teplota 0,97 až 0,985.T.sub.max .n., po dobu 20 až 80 minut, za tlaku dusíku 3 až 6 NPa , a potom se provede zvýšení teploty na T.sub.max .sub..n.a zvýšení tlaku na 7 až 50 MPa.ŕ In a method of making a homogeneous and finely crystalline silicon nitride ceramic, ceramic powder is milled, mixed with shaping aids (processing aids, auxiliaries), the mixture is shaped to give shaped parts and the shaped parts are subsequently sintered under a nitrogen atmosphere. According to the invention, the sintering is carried out in a multistage process at temperatures Tmax in the range from 1700 to 1900@C using gas pressures in the range from 0.3 to 50 MPa. In a first temperature stage, a temperature of from 0.9 to 0.96 &cirf& Tmax is maintained over a period of from 10 to 50 minutes at a N2 pressure of from 0.2 to 1.2 MPa, while in a second temperature stage, a temperature of from 0.97 to 0.985 &cirf& Tmax is maintained over a period of from 20 to 80 minutes at a N2 pressure of from 3 to 6 MPa. The temperature is then raised to Tmax and the pressure is raised to from 7 to 50 MPa.