High heat conductivity silicon nitride ceramics material and preparation method thereof
A silicon nitride ceramic, high thermal conductivity technology, applied in the field of inorganic non-metallic materials, can solve problems such as difficulty in sintering, and achieve the effects of high thermal conductivity, improved thermal conductivity, and improved flexural strength
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[0020] The invention provides a silicon nitride ceramic material with high thermal conductivity and a preparation method thereof. Adding rare earth fluoride YF to silicon nitride powder 3 and alkaline earth metal oxide MgO, after ball milling, drying, crushing, and sieving processes to obtain a uniformly mixed composite powder, and then use the HIGH-MULTI5000 multifunctional sintering furnace produced by Fuji Denpa Corporation in Japan at 1800 ° C and 0.1 MPa Hot-press sintering under a nitrogen atmosphere and an axial pressure of 0.3t for 1 hour, then raise the temperature to 1900°C, and sinter under a nitrogen pressure of 1 MPa for 3 hours under normal pressure to prepare the high thermal conductivity, high-strength silicon nitride ceramics of the present invention .
[0021] Rare earth oxides can purify crystal grains and promote the growth of silicon nitride columnar crystals during the sintering process of silicon nitride ceramics, and the research of the present inventi...
Embodiment 1
[0037] Embodiment 1 adds 5wt% YF in silicon nitride powder 3 and 3wt% MgO as a sintering aid, adding alcohol and ball milling and mixing for 24 hours, drying and grinding, and passing through an 80-mesh sieve to obtain a uniformly mixed composite powder. Put the powder into a graphite mold, and prepare silicon nitride ceramics according to the above-mentioned sintering process.
[0038] The relative density of the obtained silicon nitride ceramics is 99.6%, and it can be detected from its structure that it contains silicon nitride grains and MgY 4 Si 3 o 13 The grain boundary phase has a thermal conductivity of 97W / mK, a bending strength of 848MPa, a Vickers hardness of 19GPa, a dielectric constant of 8.4, and a dielectric loss of 1×10 -3 , the volume resistivity is 1.2×10 13 Ω·m.
Embodiment 2
[0039] Example 2 is basically the same as Example 1 except that the added amount of MgO is 2wt%.
[0040] The relative density of the obtained silicon nitride ceramics is 99.5%, and it can be detected from its structure that it contains silicon nitride grains and MgY 4 Si 3 o 13 The grain boundary phase has a thermal conductivity of 89W / mK, a flexural strength of 722MPa, a Vickers hardness of 19GPa, a dielectric constant of 8.9, and a dielectric loss of 7×10 -4 , the volume resistivity is 1.2×10 13 Ω·m.
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