CN102115330A - Preparation method of solid phase sintering silicon carbide ceramics taking phenolic resin as carbon source - Google Patents

Abstract

The invention relates to a method for preparing solid-phase sintered silicon carbide ceramics using phenolic resin as a carbon source, belonging to the field of silicon carbide ceramics. The invention uses SiC powder, B ₄ C powder and phenolic resin as raw materials; B ₄ C powder accounts for the total 0.1-1wt% of the total amount, phenolic resin accounts for 5-30wt% of the total; then use water as a solvent, make the raw material into a 40-45wt% slurry, use SiC balls as grinding balls, mix, dry, pulverize, Screening, dry pressing and/or isostatic pressing, after debonding, sintering under Ar gas atmosphere. The density of the solid-phase sintered silicon carbide ceramic prepared by the invention is 3.10-3.16gcm ^-3 , and the bending strength is 300-500MPa.

Description

Preparation method of solid phase sintered silicon carbide ceramics with phenolic resin as carbon source

technical field

The invention relates to a preparation method of solid-phase sintered silicon carbide ceramics with phenolic resin as a carbon source, belonging to the field of SiC ceramics.

Background technique

SiC ceramics are widely used in industrial production due to their excellent high temperature stability, wear resistance and high thermal conductivity. Among them, solid-phase sintered SiC ceramics have a very low content of sintering aids, and no substances with lower melting points remain at the grain boundaries, and their physical and chemical properties have high temperature stability. Therefore, solid-phase sintered SiC ceramics have special application value. Solid-phase sintered SiC ceramics mainly use C and B as sintering aids. In previous studies, sintering aid C was introduced with C black and phenolic resin at the same time, which is not conducive to industrial production. Therefore, this patent introduces phenolic resin completely C source, while adding B ₄ C as a sintering aid, this method can reduce the amount of C black added, while increasing the amount of phenolic resin, which is beneficial to the molding of SiC ceramics. In addition, by adjusting the C content and temperature, SiC ceramics with different grain sizes and shapes can be obtained, which provides an experimental and theoretical basis for the optical processing of SiC ceramics.

Contents of the invention

The purpose of the present invention is to reduce the amount of additives, while making the sintering aid C uniformly mixed, and its preparation method is as follows:

(1) SiC powder, B ₄ C powder and phenolic resin are raw materials; B ₄ C powder accounts for 0.1-1wt% of the total amount, and phenolic resin accounts for 5-30wt% of the total amount;

The SiC powder and B ₄ C powder preferably have an average particle size of 0.1-1 μm;

The preferred cracking residual C rate of the phenolic resin is 40-60wt%,

(2) Using water as a solvent, make raw materials into 40-45wt% slurry, use SiC balls as grinding balls, mix, dry, pulverize, sieve, dry press and/or isostatic press molding, after debonding , sintered under Ar gas atmosphere;

The raw material: SiC ball mass ratio is 1:1-5;

The dry pressure is 20MPa-100MPa, and the isostatic pressure is 100MP-500MPa;

The sintering temperature is 1900-2300° C., and the holding time is 30-90 minutes.

In the present invention, under the ^same sintering system at 2200°C-1h, by adding different contents of phenolic resin, SiC ceramics with different densities and mechanical properties are obtained.

Table 1 shows the mechanical properties of SiC ceramics with different phenolic resin contents. Figure 1 shows the XRD curves of SiC sintered bodies with different phenolic resin contents. It can be seen from the figure that the SiC powder is mainly the 6H crystal form of α-SiC. After sintering at high temperature, some 6H is transformed into 4H crystal form, and the 4H phase is a high-temperature stable phase. Figure 2 is an optical photo of the microstructure of SiC ceramics with different phenolic resin content. It can be seen from the figure that with the increase of phenolic resin content, the grain size of SiC ceramics tends to decrease. For SiC ceramics with 10wt% phenolic resin added, SiC ceramics with different grain sizes and mechanical properties can be obtained through different sintering temperatures (Figure 3).

Table 2 shows the mechanical properties of SiC ceramics with 10wt% phenolic resin content at room temperature under different sintering systems.

Table 1

Table 2

To sum up, the present invention uses phenolic resin as the C source to prepare SiC ceramics, which can produce solid-phase sintered SiC ceramics with better mechanical properties and different grain shapes and sizes.

Description of drawings

Fig. 1 XRD curves of SiC ceramics with different phenolic resin contents a-10wt%, b-13.3wt%, c-16.7wt%, d-20wt%, e-23.3wt%.

Fig. 2 Optical photographs of corroded SiC ceramic surfaces with different phenolic resin contents, a-10wt%, b-13.3wt%, c-16.7wt%, d-20wt%, e-23.3wt%.

Fig. 3 Optical photographs of corroded SiC ceramics with 10wt% phenolic resin content at different sintering temperatures: a-2200°C/1h, b-2100°C/1h, c-2050/3h.

Detailed ways

Further illustrate the characteristics of the present invention below by specific embodiment, but the present invention is by no means limited to embodiment.

Example 1

SiC, sintering aid B ₄ C (0.5wt%) and phenolic resin (10wt%) total 100g, use water as solvent, make three kinds of powder into a slurry with a solid content of 45wt%, and use 200g of SiC balls as ball mill medium, mixed for 24 hours, and then dried in a thermostat at 80°C. Then grind and pulverize, and then sieve through a 100-mesh sieve, the obtained powder is molded under 16MPa pressure on a flat vulcanizer, and then isostatically pressed under 200MPa pressure. After debonding, it was sintered under normal pressure Ar gas atmosphere, the sintering temperature was 2200°C, and the holding time was 1h. The obtained SiC ceramics had a density of 3.14gcm ^-3 and a flexural strength of 304.9MPa.

Example 2

SiC, sintering aid B ₄ C (0.6wt%) and phenolic resin (20wt%) total 100g, use water as solvent, make three kinds of powder into a slurry with a solid content of 40wt%, and use 200g of SiC balls as ball mill medium, mixed for 24 hours, and then dried in a thermostat at 80°C. Then grind and pulverize, and then sieve through a 100-mesh sieve, the obtained powder is molded under a pressure of 16 MPa on a flat vulcanizer, and then isostatically pressed under a pressure of 200 MPa. After debonding, it was sintered under normal pressure Ar gas atmosphere, the sintering temperature was 2200°C, and the holding time was 1h. The obtained SiC ceramic had a density of 3.13gcm ^-3 and a flexural strength of 431.4MPa.

Claims (7)

1. resol is the preparation method of the solid-phase sintered silicon carbide ceramics of carbon source, it is characterized in that comprising the steps:

(1) SiC powder, B ₄C powder and resol are raw material; B ₄The C powder accounts for 0.1～1wt% of total amount, and resol accounts for the 5-30wt% of total amount;

(2) with water be solvent, raw material is made into the slurry of 40-45wt%,, mix as mill ball with the SiC ball, oven dry is pulverized, sieve, and dry-pressing and/or isostatic pressing, after the unsticking, sintering under Ar gas atmosphere.

2. by the described preparation method of claim 1, it is characterized in that described SiC powder and B ₄C powder median size is 0.1～1 μ m.

3. by claim 1 or 2 described preparation methods, it is characterized in that it is 40-60wt% that the residual C of described resol cracking leads,

4. by claim 1 or 2 described preparation methods, it is characterized in that described raw material: SiC ball mass ratio is 1: 1～5;

5. by claim 1 or 2 described preparation methods, it is characterized in that described dry-pressing pressure is 20MPa～100MPa.

6. by claim 1 or 2 described preparation methods, it is characterized in that described hydrostatic pressure is 100MP～500MPa;

7. by claim 1 or 2 described preparation methods, it is characterized in that described sintering temperature is 1900-2300 ℃, soaking time is 30-90min.

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