JPH0214880A - Production of vitreous carbon composite material - Google Patents

Abstract

PURPOSE:To obtain the title composite with uniform high mechanical strength performance by kneading a blend comprising a carbonizable liquid thermosetting resin and ceramic reinforcing material with its viscosity regulated within a specified range and by calcining a form produced by heating and curing the above kneaded product. CONSTITUTION:The viscosity of a blend of a carbonizable liquid thermosetting resin with ceramic short fiber is regulated within the range 100-1000poise, and the blend is kneaded under shear force and heated to effect curing. Thence, the resultant cured form is calcined in a non-oxidative atmosphere at >=900 deg.C. It is preferable that the ceramic short fiber be silicon carbide whisker 0.1-1.0mum in diameter and 30-100mum in length and 5-30wt.% of this fiber be incorporated into said liquid resin. Said thermosetting resin is one convertible into vitreous carbon by carbonization such as phenolic resin or furan resin, being in a liquid state at initial condensed stage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a glassy carbon composite material reinforced with ceramic short fibers and having high strength performance.

[Conventional technology]

Glassy carbon has a gas-impermeable, non-porous structure with extremely fine constituent particles compared to general carbon materials, so applications that take advantage of this structural characteristic are being developed in a variety of fields. However, since this material is originally composed of carbonaceous material, there is a limit to the increase in strength, and the lack of strength is an essential drawback, especially when used as a structural material.

As a measure to improve the lack of strength of glassy carbon, a method has been proposed in which the structure of glassy carbon is compositely reinforced with ceramic whiskers.

For example, Japanese Patent Application Laid-Open No. 61-155259 discloses that glassy carbon with excellent mechanical strength is obtained by molding and hardening a mixture of thermosetting resin powder and ceramic whiskers, which produces glassy carbon when carbonized, and then firing. A complex is disclosed.

[Problem to be solved by the invention]

However, in the above-mentioned prior art, homogeneous mutual dispersion is not achieved because a dry mixing method is used in which the thermosetting resin, which is the material for forming the glassy carbon skeleton, and the ceramic whisker, which is the reinforcing material, are mixed together. However, there is a problem that the reinforcing structure of the glassy carbon composite material that is finally produced becomes inhomogeneous.

Originally, the dispersibility of ceramic whiskers is very poor.
It is known that considerable technology is required when combining with a matrix. The main reason for this is that ceramic whiskers have a tendency to become entangled with each other in a fluffy state, and this is a major reason why homogeneous mixing by a dry method is not possible.

The inventors have found that by replacing the conventional dry mixing method with a wet mixing method and adjusting the viscosity of the mixture of the liquid thermosetting resin and ceramic reinforcing material to a range of 100 to 1000 poise, an extremely homogeneous mixing state can be obtained. This knowledge led to the development of the present invention.

Therefore, it is an object of the present invention to provide a method for producing a glassy carbon composite material with homogeneous high strength performance by a wet mixing method.

[Means to solve the problem]

The method for manufacturing a glassy carbon composite material according to the present invention that achieves the above object includes blending ceramic short fibers into a carbonizable thermosetting resin liquid and adjusting the viscosity of the blend to a range of 100 to 1000 poise. After kneading while applying shearing force, heat curing is performed, and the resulting cured molded product is heated for 90 minutes in a non-oxidizing atmosphere.
The gist of the structure is to carry out firing treatment at a temperature of 00°C or higher.

The carbonizable thermosetting resin used in the present invention is a resin that converts into glassy carbon by carbonization, such as a phenolic resin or a furan resin, and is usually used in a liquid state in the initial condensation stage. served.

Chopped fibers or single crystal whiskers of alumina, silica, silicon carbide, silicon nitride, etc. are used as the ceramic short fibers, but the most suitable reinforcing material is a reinforcing material with a diameter of 0.1 to 1.0 μm. Length 30-100μm
It is a silicon carbide whisker with the following properties.

If the amount of ceramic short fibers added to the carbonizable thermosetting resin liquid is less than 5% by weight, the reinforcing effect will not be sufficiently enhanced, and if it exceeds 30% by weight, it will impair the formation of a non-porous structure. Therefore, it is desirable to mix it in a range of 5 to 30% by weight.

In the wet mixing process, ceramic short fibers are mixed with a carbonizable thermosetting resin liquid and kneaded while applying shearing force. 100~
An important condition is to adjust it to 1000 poise.

Adjustment of the viscosity of this blend is a necessary element to homogenize the mixture through the combination of shear force, and under conditions where this is outside the viscosity range of 100 to 1000 poise, it becomes extremely difficult to obtain a normal homogeneous dispersion state. . The viscosity of the compound is adjusted by controlling the initial condensation degree of the carbonizable thermosetting resin liquid used, or by diluting the resin liquid with an organic solvent.

Shearing force can be applied by applying various kneading devices such as a Miki roll mill, a pressurized niegu, a roll mill, and an extruder, but among these devices, the Miki roll mill provides the strongest shearing effect and is therefore used for this purpose. suitable for

After the kneaded material is formed using methods such as die molding or roll forming, it is precured in a temperature range of 50 to 100°C, and then heat cured under conditions that raise the temperature to 180 to 300°C. do.

Next, the cured molded body is heated in a furnace maintained in a non-oxidizing atmosphere by a conventional method to 900°C or higher, preferably 1000°C to 100°C.
Firing treatment is performed in a temperature range of 500'C.

[For production]

According to the manufacturing process using the above-mentioned wet mixing method, a mixture of a carbonizable thermosetting resin liquid and ceramic short fibers is adjusted to a viscosity range of 100 to 1000 poise, and then kneaded while applying a shearing force. In the process, environmental conditions are created in which the mutual dispersion of both components proceeds extremely smoothly, and through this action, the short fiber component is uniformly dispersed in the matrix resin liquid, and the interfacial adhesion is also improved due to the shearing action.

Therefore, it is possible to obtain a glassy carbon composite material that is extremely homogeneous and has high strength performance without variations in structure.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Examples 1 to 3, Comparative Examples 1 to 2, liquid (viscosity: 4 poise) phenolic resin [Sumitomo Jurez ■, "Sumilight Resin PR-940"] with a diameter of 0.1 to 1 μm and a length of 50 to 100 μm Silicon carbide whiskers [manufactured by Tokai Carbon ■, “Toka Rice Power-Pa”]
After blending with a delta ratio of 20% by weight, the viscosity of the blend was adjusted to five levels ranging from 80 to 1200 poise by diluting with methanol. Each of the viscosity-adjusted formulations was transferred to a horizontal three-roll mill (roll gap spacing: 0.3 M) and kneaded for 10 minutes under operating conditions of a rotation ratio of 1:3, a rotation speed of 12 Orpm, and a rotation speed of -0.75. Next, the kneaded product was molded, precured at 80°C for about 10 hours, and further heated at 180°C for 1 hour to completely cure the resin component. The hardened molded body was placed in a firing furnace maintained in an N2 gas atmosphere, and heated for 1000
Calcined at °C.

Various physical properties were measured for each glassy carbon composite material thus obtained and are shown in Table 1. this house,
The percentages in parentheses for Shore hardness and bending strength are the same.
This figure shows the range of variation when measurements were taken at three different locations on the specimen.

From the results in Table 1, Comparative Example 1 where the viscosity of the formulation was 80 poise
It can be seen that Comparative Example 2 with 1200 poise has lower strength characteristics than the Example.

Comparative Example 3 A glassy carbon composite material was produced by a dry mixing method in which silicon carbide whiskers were blended with self-curing phenolic resin fine powder at a ratio of 20%, mixed in a mortar, and then compression molded. When the physical properties of this material were measured as shown in Table 1, the apparent specific gravity was 1.49 g/d, and the job hardness (H) was 1.
．． 10 (±10%), bending strength 980 kg/cJ (
±21%) and flexural modulus of 3100 kg10n', it was confirmed that the strength performance was inferior to the measured values of Examples 1 to 3, and the variation was large.

[Effects of the Invention] According to the present invention, it is possible to efficiently produce a glassy carbon composite material that always has homogeneous high-strength properties with no variation in structure, so it can be effectively applied to applications such as structural materials. can do.

Claims (2)

[Claims] 1. Ceramic staple fibers are blended into a carbonizable thermosetting resin liquid, the viscosity of the blend is adjusted to a range of 100 to 1000 poise, kneaded while applying shearing force, and then heated and cured.
A method for producing a glassy carbon composite material, which comprises firing the obtained cured molded body at a temperature of 900° C. or higher in a non-oxidizing atmosphere. 2. 2. The short ceramic fibers are silicon carbide whiskers having a diameter of 0.1 to 1.0 μm and a length of 30 to 100 μm, and are blended in an amount of 5 to 30% by weight with respect to the carbonizable thermosetting resin liquid. A method for producing a glassy carbon composite.