A kind of high thermal conductivity silicon nitride ceramic material and preparation method thereof
A technology of silicon nitride ceramics and raw materials, which is applied in the field of high thermal conductivity silicon nitride ceramic materials and its preparation, can solve the problems of high single substance cost of rare earth metals, high activity of rare earth metals, complex preparation process, etc., and reduce phonon scattering , The effect of reducing the content of intergranular phase and reducing the content of lattice oxygen
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Embodiment 1
[0050] With 1mol% Y 2 o 3 and 19mol% Mg as a sintering aid, and 80mol% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder; then dry-pressed under a pressure of 20MPa, and then subjected to cold isostatic pressing under a pressure of 300MPa; the green body obtained is put into a BN crucible , at N 2 At 600°C for 4 hours for magnesia thermal reduction pre-sintering treatment; the obtained green body was sintered at 1800°C under pressure, and the heating rate was 5°C / min, N 2 The pressure is 2MPa, and the holding time is 4h; after sintering, cool to 1200°C at a cooling rate of 10°C / min, and then cool to room temperature with the furnace.
[0051] The thermal conductivity of the silicon nitride ceramic material prepared in Example 1 is 77.56W·m -1 ·K -1 , The three-point bending strength is 1024±42MPa.
Embodiment 2
[0053] With 5mol% Y 2 o 3 and 10mol% Mg as a sintering aid, and 85mol% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder; then it is dry-pressed under a pressure of 20MPa, and then subjected to cold isostatic pressing under a pressure of 250MPa; the green body obtained is put into a BN crucible , held at 800°C for 6h under Ar for magnesia thermal reduction pre-sintering treatment; the obtained green body was sintered at 1850°C under pressure, and the heating rate was 10°C / min, N 2 The pressure is 3MPa, and the holding time is 6h; after sintering, cool to 1000°C at a cooling rate of 10°C / min, and then cool to room temperature with the furnace.
[0054] The thermal conductivity of the silicon nitride ceramic material prepared in Example 2 is 95.25W·m -1 ·K -1 , The three-point bending strength is 906±18MPa. The micro-morphology of the polished surface of the silicon nitride ceramics prepared in this embodiment is as follows...
Embodiment 3
[0056] With 2mol% Y 2 o 3 and 8mol% Mg as a sintering aid, and 90mol% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder; then it is dry-pressed under a pressure of 30MPa, and then subjected to cold isostatic pressing under a pressure of 300MPa; the green body obtained is put into a BN crucible , held at 750°C for 2h under Ar for pre-sintering treatment; the obtained green body was sintered at 1900°C under pressure, and the heating rate was 5°C / min, N 2 The pressure is 3MPa, and the holding time is 12h; after sintering, cool to 1200°C at a cooling rate of 10°C / min, and then cool to room temperature with the furnace.
[0057] The thermal conductivity of the silicon nitride ceramic material prepared in Example 3 is 123.08W·m -1 ·K -1 , The three-point bending strength is 747±21MPa.
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