JPS63139042A - Manufacture of ceramic formed body - 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 ceramic molded body using lime aluminate as a binder, particularly a catalyst carrier and a ceramic burner.

The present invention relates to a method for manufacturing a ceramic molded body useful as a heat radiator.

BACKGROUND ART Conventional Art 1 A ceramic molded body using lime aluminate as a binder is a lime aluminate as described in JP-A-61-156277.

Molten silica, titanium dioxide, an organic molding aid, etc. are mixed, water is added, and the mixture is kneaded and extruded into a desired shape. After that, assimilation and curing.

It was obtained by drying, then heat treatment to decompose and remove the organic molding aid, impregnating with water and drying.

Problems to be Solved by the Invention The ceramic molded body obtained by the above conventional manufacturing method is
Although it maintains its strength during the final drying stage, there is a problem in that once it is exposed to high temperatures, its strength rapidly decreases. This is thought to be because the bond formed between lime aluminate and other materials by impregnation with water is easily broken at high temperatures.

The present invention solves these problems and aims to provide a method for producing a ceramic molded body that has sufficient strength even after heat treatment at high temperatures.

Means for Solving the Problem In order to solve this problem, the present invention adds a step of impregnating at least a cerium or lanthanum salt in solution after the decomposition and removal step of the organic forming aid, and then heat-treating. It is something.

The pore volume of the ceramic molded body whose organic molding aid has been decomposed and removed at a temperature of 300'C or more increases to more than twice its original pore volume, as shown in FIG. In particular, those with a pore diameter of 5Qo8 or less,
The volume occupied by the so-called menhole increases significantly. The molded body in this state is immersed in a solution of cerium or lanthanum salt to impregnate the pores with cerium or lanthanum salt. Next, by heat treatment, the cerium or lanthanum salts in the pores become oxides, respectively, and are firmly bonded to the molded body material surrounding the pores. As a result, the strength of the molded article increases significantly.

Examples [Example 1] 5 parts by weight of lime aluminate, 45 parts by weight of fused silica, and 5 parts by weight of titanium dioxide were mixed with 5 parts by weight of carboxymethyl cellulose as a molding aid. To this mixed powder, 125 parts of water was added and kneaded, and the material was extruded into a honeycomb shape using a die. Then 80'
After solidifying and curing in hot water at 12°C, it was dried at 12o'C. The molded body was treated at 300'C for 1 hour, and then immersed in aqueous nitrate solutions of cerium, lanthanum, zirconium, and neodymium, so that each metal oxide was supported at 10 g/l per apparent volume of the molded body. . Each was then heat treated at 100'C for 30 minutes.

From the obtained honeycomb-shaped ceramic molded body, Otsu 5×7.6
X 101nlI:I test piece (effective cross-sectional area o, 24d
) was cut out, and the compressive strength was measured by applying a load at a constant speed in the vertical direction of the grid using a compression testing machine. Table 1 shows the average value of the compressive strength of 10 samples of each molded body.

[Example 2] Molded bodies treated at 300°C for 1 hour in the same manner as in Example 1 to decompose and remove organic molding aids were immersed in methanol solutions of cerium, lanthanum, zirconium, and neodymium alkoxides, respectively. , each metal oxide was supported at 101/e per apparent volume of the molded body. Each was then heat treated at 1000°C for 30 minutes. Table 1 shows the compressive strength of the obtained honeycomb-shaped ceramic molded body.

[Example 3] Molded bodies treated at 300'C for 1 hour to decompose and remove organic molding aids in the same manner as in Example 1 were immersed in nitrate aqueous solutions with varying concentrations of cerium and neodymium. 1 to 20 g of metal oxide per apparent volume of molded body
It was supported in the range of /l. Then each is 1000°
It was heat-treated at C for 30 minutes. The compressive strength of the obtained honeycomb-shaped ceramic molded body is shown in FIG.

[Comparative example]

Similar to Example 1, the molded body was treated at 300°C for 1 hour to decompose and remove the organic molding aid, and then immediately heated at 1000°C for 3 hours.
Heat treatment was performed for 0 minutes.

Table 1 As shown in Table 1, the compressive strength of the ceramic molded body supported with cerium oxide increased by approximately 44% in the case of Example 1 and by approximately 50% in the case of Example 2, compared to the unsupported product of the comparative example. do. Approximately the same effect can be seen in supporting lanthanum oxide. On the other hand, the strength of molded bodies supported with zirconium or neodymium oxides is not much different from that of unsupported molded bodies.

FIG. 1 shows, as an example of the present invention, the compressive strength of a molded article when the amount of supported cerium and neodymium oxides was varied in the range of 1 to 209/l.

When cerium oxide is supported, the compressive strength begins to increase at 17 g/1 or more, and reaches a plateau at 1'4/1 or more. On the other hand, when neodymium oxide is supported, 1
No significant increase in compressive strength was observed even when the loading amount was increased. Similarly, supporting lanthanum oxide also improves the strength as in the case of cerium.

The reason why the compressive strength is greatly improved when supporting cerium or lanthanum oxides is that the cerium or lanthanum salts penetrate into the micropores (pores) that are formed after the organic forming aid is decomposed and removed. This is thought to be due to the fact that it forms a strong bond with the other materials that make up the ceramic molded body during the heat treatment process. On the other hand, when oxides of zirconium or neodymium are supported, it is thought that the strength does not increase significantly because these salts do not easily enter the micropores homogeneously. The reason why the strength reaches a plateau even if more than a certain amount of cerium oxide is supported is that after the micropores are filled with cerium salt, even if the amount of cerium is further increased, it simply adheres to the outer surface of the micropores. This is thought to be because it is not related to strength.

Therefore, since cerium and lanthanum are particularly effective in improving the strength of the carrier, it is natural that the same effect can be expected even if a mixture of these is used.

Effects of the Invention As described above, according to the present invention, the strength of a ceramic molded body can be increased by a simple process of impregnating at least cerium or lanthanum salt in solution after decomposing and removing an organic molding aid, and then heat-treating. This has the effect of being able to do this.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the supported amount of each oxide of cerium and neodymium and the compressive strength of the ceramic molded body, and Figure 2 is a diagram showing the relationship between the heat treatment temperature and pore volume of the ceramic molded body. . Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2: Thermal temperature of all Lwi compounds (g/)

Claims (1)

[Claims] A method for producing a ceramic molded body using lime aluminate as a binder, which comprises decomposing and removing an organic molding aid, impregnating at least a cerium or lanthanum salt in solution, and then heat-treating.