Silicon carbide porous ceramic and preparation method thereof

Abstract

The invention discloses silicon carbide porous ceramic and a preparation method thereof. The preparation method comprises the following steps: mixing and ball-milling fine stone ore and carbon powder; pressing and molding a mixture, and heating the mixture in a constant-temperature carbon tube furnace for continuous operation at 1850-2000 DEG C to generate silicon carbide whiskers; carrying out wet mixing and ball milling on the silicon carbide whiskers, short carbon fibers, monatomic silicon and a binder by taking absolute ethyl alcohol as a ball milling medium; drying to obtain powder; and sieving the powder, heating and extruding to form a profile, putting the profile into a high-temperature vacuum hot isostatic press, gradually heating to 1900 DEG C, filling gaseous silicon while performing nitrogen protection, and preserving heat for 3 hours to obtain the silicon carbide fiber porous ceramic body. According to the invention, the chopped carbon fiber and the monatomic silicon are subjected to in-situ reaction sintering, and whisker growth and mutual bridging growth of the silicon carbide whisker in the heating process are realized, so that the green body is sintered into the densified silicon carbide porous ceramic with constant volume.

Description

technical field [0001] The invention relates to the technical field of ceramic materials, in particular to a silicon carbide porous ceramic and a preparation method thereof. Background technique [0002] Regarding porous silicon carbide ceramics [Note: The pores here are naturally formed during the sintering process, which is different from honeycomb silicon carbide ceramics. Honeycomb silicon carbide ceramics belong to the honeycomb body]. At present, the more common solution is to use different particle sizes of silicon carbide powder , and then form the skeleton and pores with silicon carbide powder with larger particle size, and fill with silicon carbide powder with small particle size. Sufficient, can not achieve a good connection effect, the strength is poor; high, the crystal grains become larger, making the pore size smaller or blocked), to ensure that the generated silicon carbide plate maintains the pore size, the production process requirements are strict, and the...

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Problems solved by technology

[0002] Regarding porous silicon carbide ceramics [Note: The pores here are naturally formed during the sintering process, which is different from honeycomb silicon carbide ceramics. Honeycomb silicon carbide ceramics belong to the honeycomb body]. At present, the more common solution is to use different particle sizes of silicon carbide powder , and then form the skeleton and pores with silicon carbide powder with larger particle size, and fill with silicon carbide powder with small particle size. Adequate, can not achieve a good connection effect, the strength is poor; high, the crystal grains will become larger, making the pore size smaller or blocked), to ensure that the generated silicon carbide plate maintains the pore size, the production process is strict, and the yield is low

[0003] For dense silicon carbide ceramics, in order to achieve high density (the higher the density, the higher the strength), the current common solution is to use smaller particle size silicon carbide powder, because the smaller the particle size, the smaller the gap, which is convenient. Produce denser silicon carbide, and the smaller the particle size of the micro-powder processing, the higher the cost, and there will be escapes that are difficult to collect during processing, and agglomeration will occur in the mixture, so more binders and dispersants need to be added , sintering aids, etc., the more these components, the performance of the silicon carbide ceramic body formed later will be affected

Moreover, when using silicon carbide micropowder to process a dense silicon carbide ceramic body, the volume will shrink and deform. When producing complex structural parts and large structural parts, due to the difficulty in controlling deformation and shrinkage, it will lead to high process requirements and low product yield.

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