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Process in the production process of Nitride bonded Silicon Carbide
- Jan 17, 2019 -

When Nitride bonded Silicon Carbides are produced, firstly weigh 75%-87% of coal-refined silicon carbide materials, 12%-20% of metal silicon powder, 0.5%-4.0% of silica fine powder, and rare earth oxides. 0.2%-1.0%, then weigh 12%-16% of the binder and 0.1%-0.4% of the curing agent based on the weight of the above raw materials, and mix and mix the ingredients uniformly; the uniformly mixed ingredients are vibrated and poured.


After the pouring is completed, the cast product is placed at room temperature for 8h-24h, and the semi-finished product is placed at room temperature for 16h-26h after demolding; the cured semi-finished product is transferred to the oven, the oven temperature is adjusted to 55°C, the heat preservation is 8h, and the 80°C insulation is 8- 12h, 120 ° C heat preservation 12-60h; the dried semi-finished product was transferred to an electric furnace, sintering under nitrogen atmosphere; finally, under nitrogen atmosphere with the furnace naturally cooled to room temperature, that is, a Nitride bonded Silicon Carbide.


In the nitriding process of Nitride bonded Silicon Carbides, not only the nitriding temperature is high, the nitriding time is long, and the nitriding reaction in the firing process is an exothermic reaction. In order to avoid the occurrence of undesirable phenomena, the introduction of rare earth oxides such as cerium oxide, cerium oxide, cerium oxide, cerium oxide, etc., can effectively promote the nitriding reaction of silicon powder, increase the nitriding rate, and promote the crystal phase of silicon nitride formed in situ. Development, thereby increasing the bulk density of the fired product, reducing the apparent porosity and improving the high temperature bending strength of the material, the load softening temperature point, and the like.


The appropriate introduction of the silica micropowder in the Nitride bonded Silicon Carbide improves the flowability of the castable on the one hand and facilitates the casting. On the other hand, the appropriate introduction of the silica can also be converted into silicon nitride at a high temperature in a nitrogen atmosphere or Silicon oxynitride. Different nitride grains or whiskers are evenly distributed inside the material, interlacing and interlacing, which improves the toughness of the material and the normal temperature, high temperature flexural strength and thermal shock