Method for preparing high-temperature resistant silicon carbide
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A silicon carbide, high temperature resistant technology, applied in the field of ceramic materials, can solve problems such as limiting the scope of use, and achieve the effects of uniformity, easy control and simple equipment
Inactive Publication Date: 2011-11-23
NORTHWESTERN POLYTECHNICAL UNIV
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Due to SiO 2 Actively volatilizes at high temperature and low oxygen partial pressure. Therefore, the current use temperature of most silicon carbide is about 1700°C, which limits its application range. It is necessary to develop new methods to prepare silicon carbide and increase its active-passive oxidation conversion temperature. Increase the use temperature of silicon carbide to obtain high temperature resistant silicon carbide
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Embodiment 1
[0027] Embodiment 1, a kind of preparation method of high temperature resistant silicon carbide, carries out following steps successively:
[0028] 1) Add aluminum acetylacetonate to the liquid polycarbosilane, place it on a magnetic stirrer for stirring, the stirring time is 4 hours, the temperature is 80°C, and the mass fraction ratio of liquid polycarbosilane to aluminum acetylacetonate is: 9:1 ;
[0029] 2) Put the uniformly mixed raw materials into the cross-linking cracking furnace, first evacuate to -0.09MPa, then fill with argon to 0MPa, and keep the argon in circulation, the flow rate is 50-80ml / min, at 0.5-1.5℃ / The heating rate of min is increased to 200°C and 400°C in turn, and the temperature is kept for 4 hours respectively, and the cross-linking and curing are completed;
[0030] 3) ball milling the solid obtained above for 4 hours at a speed of 1200 cycles / min;
[0031] 4) The powder obtained by ball milling is formed by cold isostatic pressing to obtain a di...
Embodiment 2
[0035] Embodiment 2, a kind of preparation method of high temperature resistant silicon carbide, carry out following steps successively:
[0036] 1) Add aluminum acetylacetonate to the liquid polycarbosilane, place it on a magnetic stirrer for stirring, the stirring time is 4 hours, the temperature is 80°C, and the mass fraction ratio of liquid polycarbosilane to aluminum acetylacetonate is: 9:1 ;
[0037] 2) Put the uniformly mixed raw materials into the cross-linking cracking furnace, first evacuate to -0.09MPa, then fill with argon to 0MPa, and keep the argon in circulation, the flow rate is 50-80ml / min, at 0.5-1.5℃ / The heating rate of min is increased to 200°C, 400°C and 900-1100°C in turn, and the temperature is kept for 4 hours respectively, and the cross-linking cracking is completed;
[0038] 3) ball milling the solid obtained by cross-linking cracking, the ball milling time is 2 to 4 hours, and the rotation speed is 1200 cycles / min;
[0039] 4) Combine the above si...
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Abstract
The invention relates to a method for preparing high-temperature resistant silicon carbide. The method is technically characterized by comprising the following steps of: uniformly mixing liquid polycarbosilane and organic metal salt, crosslinking and curing, performing ball-milling, cracking at the temperature of between 900 and 1,100 DEG C, and performing high-heat treatment at the temperature of between 1,600 and 1,850 DEG C to obtain the crystalline silicon carbide containing a trace amount of metal elements. A SiO2 protection membrane which is obtained by performing high-temperature oxidation on the synthesized silicon carbide is SiO2 solid solution containing a trace amount of metal elements. The trace amount of metal elements reduces the activity of SiO2, and increases the conversion temperature of active and passive oxidation of the silicon carbide, so that the use temperature of the silicon carbide is increased. Compared with the prior art, the method has the advantages that: by introducing a trace amount of metal elements into the silicon carbide, the use temperature of the silicon carbide is increased from 1,700 to 1,800-1,850 DEG C, and equipment used by the preparationprocess is simple, safe and reliable, is easy to control and contributes to large-scale production.
Description
technical field [0001] The invention relates to the field of ceramic materials, in particular to a method for preparing high-temperature-resistant silicon carbide. Background technique [0002] Silicon carbide (SiC) ceramics have excellent properties such as small thermal expansion coefficient, high decomposition temperature, low density, high high-temperature strength, corrosion resistance, wear resistance, and ablation resistance, and are the most promising high-temperature structural materials used above 1300 °C One of them, widely used in heat-resistant, wear-resistant and harsh environments. [0003] Oxidation occurs when SiC ceramics are used at high temperatures, and the oxidation mechanism is divided into active oxidation and passive oxidation. Active oxidation occurs at high temperature and low oxygen partial pressure, and SiC material is oxidized to generate volatilized SiO, resulting in a reduction in material quality and subsequent material failure. Passive oxi...
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