JPS6221762A - Silicon carbide refractories - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silicon carbide refractory whose composition has been improved to improve its high-temperature properties.

[Prior art and its problems] Silicon carbide refractories occupy an important position in industry due to their excellent fire resistance and heat resistance, and are widely used, for example, in shelf boards for firing pottery, other firing jigs, and sheaths. has been done. Conventional silicon carbide refractories are generally made by mixing nearly 10% clay with silicon carbide particles, cross-wired and fired, and bonding the silicon carbide particles to each other by silicate in the clay.

However, conventional silicon carbide refractories have a problem in that they are susceptible to softening and deformation and oxidation at high temperatures due to the low fire resistance and mechanical strength of silicate constituting the connective tissue.

[Means for solving the problems and their effects] The present invention has the following features:
This was done to solve the above problems, 82-9
It consists of silicon carbide particles of 4% by weight (hereinafter all % refers to weight%) and 18 to 6% connective tissue, and the silicon carbide particles are 30 to 55% of 500μ or more and 5 to 500μ of 500μ to 100μ. 30%, 100μ~10μ 15~45%, 10μ
The following has a particle size distribution of 2-15%, and the connective tissue is
For 100 parts by weight of 5i02, 4.0 to 12.0 parts by weight of M2O3 (M is a metal element, the same applies hereinafter) and 0.2 parts by weight of MO.
~2.0 parts by weight, MzOIfio.

1 to 1.0 parts by weight and 0.5 to 10 parts of vanadium oxide
．． It is characterized by the composition of the zero double part.

Such a configuration consists of silicon carbide particles whose particle size distribution is adjusted to be somewhat larger than the above particle size in consideration of grain refinement due to oxidation of silicon carbide particles during firing, together with appropriate connective tissue forming components if necessary. Add organic binder and water and knead.
It is obtained by molding and drying this, and then firing it in an appropriate atmosphere.

As the connective tissue forming component added to silicon carbide particles, 0
．． 3 to 0.5 parts by weight of mineral raw materials, 0.2 to 0.5 parts by weight of alkaline earth oxides, namely MO and vanadium oxide (
V2OS> is most preferred.

Of the above-mentioned necessary compositions of connective tissue, some silicon dioxide, M2O3, M2O, and MO can be obtained from mineral raw materials, but vanadium oxide is hardly obtained from mineral raw materials, so it must be prepared separately from mineral raw materials. It is necessary to add Further, if the amount obtained from the mineral raw material alone is insufficient, it is necessary to separately add MO. Although some of the silicon dioxide in the connective tissue is obtained from mineral raw materials, most of it can be obtained by partial oxidation of silicon carbide particles by selecting appropriate silicon carbide particle size and firing conditions. The firing conditions can be arbitrarily selected by, for example, combining an oxidizing atmosphere and a neutral to weakly oxidizing atmosphere.

If the connective tissue has the above composition, it will exhibit excellent high-temperature properties and will significantly improve softening deformation resistance, oxidation resistance, mechanical strength, and heat-width impact strength at high temperatures, as is clear from the examples described below. . In particular, it has been confirmed that the presence of vanadium oxide in an appropriate amount greatly improves oxidation resistance.

In addition, among the necessary components of connective tissue, M2O3 is mainly F
Consists of e2Q3 and Al2O3, the ratio of which is 1:0.5
Most preferably, the ratio is ˜1:1.5, and the MO is, for example, CaO.

The reason why the particle size distribution of silicon carbide particles was determined as above is as follows.
Mainly, the filling properties of silicon carbide particles in the refractory structure,
This is to increase mechanical strength by promoting F and sinterability, and to generate an appropriate amount of silicon dioxide. Further, the reason why the weight ratio of silicon carbide particles and connective tissue is determined as described above is to improve oxidation resistance and softening deformation resistance particularly at high temperatures.

[Example] The invention will now be illustrated by some examples.

In Examples 1 to 9, the particle size distribution of silicon carbide (SiC) and the composition of the connective tissue are within the range of numerical values described in the claims, as shown in Tables 1 and 2. On the other hand, Comparative Examples 1 to 3 differ from these values in the weight ratio of silicon carbide particles to connective tissue and the particle size distribution of silicon carbide particles.
The MO content is outside the range of 0.2 to 2.0 parts by weight relative to 0 parts by weight, and it does not contain vanadium oxide.

As is clear from each person, in each Example, the bulk specific gravity is larger and the apparent porosity is significantly reduced compared to each Comparative Example. This means that dense connective tissue has been formed.

Along with this, the bending strength at room temperature has improved by about 50%, and the bending strength at high temperatures (1400°C) has also increased by 80%.
It has improved by more than %. Moreover, the high-temperature oil deformation, which indicates high-temperature properties, is reduced by an order of magnitude, and the oxidation increase rate also shows a remarkable decreasing trend. This means that it has excellent softening deformation resistance and oxidation resistance at high temperatures.

In addition, for high-temperature surface deformation, the test piece size is 400 x 50.
X10mmF, span 300mm, load 15K (7, I
/ff1400°C, holding 1110D [measured under the conditions (7). In addition, the oxidation increase rate is
℃, 100cc/m i of oxygen in 90℃ saturated steam
It was measured under conditions of 200 hours of exposure.

[Effects of the Invention] As described above, the present invention is characterized in that silicon carbide particles of a predetermined particle size are bonded by a connective tissue of a predetermined composition consisting of silicon dioxide, M2O3, M2O, MO, and vanadium oxide. As a result, a dense and high-strength connective tissue is formed, resulting in carbonization that significantly improves not only mechanical strength at room temperature but also high-temperature properties such as softening and deformation resistance and oxidation resistance at high temperatures. This has the excellent effect of providing a silicon refractory.

Claims (1)

[Claims] 1. Consisting of 82 to 94% by weight of silicon carbide particles and 18 to 6% by weight of connective tissue, the silicon carbide particles include 30 to 55% by weight of 500μ or more, and 5 to 30% of silicon carbide particles of 500μ to 100μ. It has a particle size distribution of 100μ to 10μ by 15 to 45% by weight, and 10μ or less to 2 to 15% by weight, and the connective tissue is 4.0% by weight of M_2O_3 (M is a metal element) with respect to 100 parts by weight of SiO_2. ~12.0 parts by weight, MO is ~0.2
A silicon carbide refractory having a composition of 2.0 parts by weight, 0.1 to 1.0 parts by weight of M_2O, and 0.5 to 10.0 parts by weight of vanadium oxide. 2. The silicon carbide refractory according to claim 1, wherein M_2O_3 is composed of Fe_2O_3 and Al_2O_3, and the weight ratio thereof is 1:0.5 to 1:1.5. 3. Claim 1 in which MO mainly consists of CaO
The silicon carbide refractory according to item 1 or 2.