Silicothermic reduction method for improving thermal conductivity and mechanical properties of silicon nitride ceramic substrate material
A technology of silicon nitride ceramics and thermal conductivity, applied in the field of inorganic non-metallic materials, can solve the problems of reducing the strength of silicon nitride, grain growth, etc., and achieve the reduction of liquid phase content, intergranular phase content reduction, and mechanical properties Reduced effect
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Embodiment 1
[0051] With 4mol% Y 2 o 3 and 8mol% MgO as a sintering aid, and 88mol% α-Si 3 N 4 Powder, add 0.1wt% Si, mix by ball milling, and sieve after drying to obtain a uniformly mixed powder; then dry press molding under 30MPa pressure, and then perform cold isostatic pressing under 300MPa pressure; the obtained The green body was put into a BN crucible, held at 1200 °C for 8 h under vacuum for deoxidation pretreatment; then sintered at 1900 °C under pressure, with a heating rate of 5 °C / min, N 2 The pressure is 1MPa, and the holding time is 4h; after sintering, cool to 1000°C at a cooling rate of 15°C / min, and then cool to room temperature with the furnace.
[0052] The thermal conductivity of the silicon nitride ceramic material prepared in Example 1 is 95.50W·m -1 ·K -1 , the three-point flexural strength is 834±24MPa, and the fracture toughness is 8.77±0.21MPa m 1 / 2 .
Embodiment 2
[0054] With 1mol% Y 2 o 3 and 4mol% MgSiN 2 As a sintering aid, with 95mol% α-Si 3 N 4 Powder, add 1wt% Si, mix by ball mill, sieve after drying to obtain uniformly mixed powder; then dry press molding under 30MPa pressure, and then carry out cold isostatic pressing treatment under 250MPa pressure; the obtained billet The body was put into a BN crucible, held at 1200 °C for 8 h under flowing Ar for deoxidation pretreatment; then sintered under pressure at 1900 °C, where the heating rate was 10 °C / min, N 2 The pressure is 2MPa, and the holding time is 12h; after sintering, cool to 1000°C at a cooling rate of 15°C / min, and then cool to room temperature with the furnace.
[0055] The thermal conductivity of the silicon nitride ceramic material prepared in Example 2 is 118.75W·m -1 ·K -1 , the three-point bending strength is 785±11MPa, and the fracture toughness is 9.98±0.27MPa m 1 / 2 .
Embodiment 3
[0057] With 2mol% Yb 2 o 3 and 8mol% MgO as a sintering aid, and 90mol% α-Si 3 N 4 Powder, add 4wt% Si, mix by ball mill, sieve after drying to obtain uniformly mixed powder; then dry press molding under 40MPa pressure, and then carry out cold isostatic pressing under 200MPa pressure; the obtained billet The body was placed in a BN crucible, and deoxidized pretreatment was carried out at 1400 °C for 6 h under flowing Ar; then it was sintered at 1900 °C under pressure, with a heating rate of 10 °C / min, N 2 The pressure is 2MPa, and the holding time is 2h; after sintering, cool to 1100°C at a cooling rate of 5°C / min, and then cool to room temperature with the furnace.
[0058] The thermal conductivity of the silicon nitride ceramic material prepared in Example 3 is 89.60W m -1 ·K -1 , the three-point flexural strength is 856±17MPa, and the fracture toughness is 7.91±0.17MPa m 1 / 2 .
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