A liquid-phase sintered silicon carbide ceramic with high thermal conductivity and its preparation method
A silicon carbide ceramic and liquid phase sintering technology, applied in the field of high thermal conductivity ceramics, can solve the problems of low thermal conductivity and lattice defects of polycrystalline silicon carbide ceramics, and achieve the effect of high resistivity and high thermal conductivity
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[0034] As an example of the preparation method of high thermal conductivity liquid-phase sintered silicon carbide ceramics, it includes: first adding the dispersant to water or absolute ethanol to make a solution, and the addition amount is 0.5wt% to 1.0wt% of the mass of the powder; then adding The raw material powder is mixed with SiC balls as grinding balls to form a slurry; then the slurry is dried and sieved to obtain a uniformly mixed powder, and the obtained powder is dry-pressed and then loaded into a hot-pressing mold or directly Hot press mold pre-press forming. After the sample and the mold are vacuum debonded together, they are sintered under hot pressing and argon at a temperature of 1800-2000°C and a holding time of 30-120 minutes to prepare a sample (high thermal conductivity liquid phase sintered silicon carbide ceramic).
[0035] After processing the high thermal conductivity liquid phase sintered silicon carbide ceramics, its various properties were tested. ...
Embodiment 1
[0040] 95wt% SiC, 5wt% Y 2 o 3 -Er 2 o 3 Sintering aid (Y 2 o 3 and Er 2 o 3 The molar ratio is 1:1), TMAH1.0g, using water solvent, the powder is made into a slurry with a solid content of 45wt%, and 200g SiC balls are used as the ball milling medium, and the planetary ball mill is mixed for 4h. Then dry and sieve, the obtained powder is pre-pressed at 10 MPa, and packed into a hot-pressed graphite mould. Debond at 1000°C under normal pressure and vacuum conditions, and then hot-press sintered under Ar atmosphere, the sintering temperature is 2000°C, the holding time is 1h, and the hot-pressing pressure is 30MPa. The density of the obtained SiC liquid phase ceramics is 3.29g cm -3 , Hv 5.0 =21.64±0.11GPa,K IC =3.71±0.22MPa·m 1 / 2 . The obtained ceramics were made into small discs with a thickness of Φ10mm and a thickness of 2.5mm, and the measured thermal conductivity λ was 152.32±0.29w / (m·K). Its microstructure see figure 1 and figure 2 , it can be seen from t...
Embodiment 2
[0042] 95wt% SiC, 5wt% Y 2 o 3 -CeO 2 Sintering aid (Y 2 o 3 and CeO 2 The molar ratio is 1:1) 100g in total, the powder is prepared into a slurry with a solid content of 50wt% by water solvent, 200g of SiC balls are used as the ball milling medium, and the planetary ball mill is mixed for 4 hours. Then dry and sieve, the obtained powder is directly loaded into a hot-pressed graphite mold, and pre-pressed with a pressure of 5 MPa. Then hot press sintering under Ar atmosphere, the sintering temperature is 1900°C, the holding time is 1h, and the hot pressing pressure is 60MPa. The obtained SiC liquid phase ceramics have a density of 3.25 g cm -3 , Hv 5.0 =18.72±0.41GPa,K IC =3.95±0.21MPa·m 1 / 2 . The obtained ceramics were made into a small disc with a thickness of Φ10mm and a thickness of 2.5mm, and its thermal conductivity λ was measured to be 161.63±1.60w / (m·K). For its microstructure, see image 3 and Figure 4 , it can be seen from the figure that the microstruct...
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