JPS63230566A - Cordierite base sintered body and manufacture - 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] [Purpose of the invention]

(Industrial Application Field) The present invention relates to a catalyst carrier for use in an automobile exhaust gas purification device,
This article relates to a cordierite sintered body with low thermal expansion properties and a method for producing the same, which is used as a material for chemical industrial equipment and other parts or products that require excellent heat resistance and thermal shock resistance. . (Prior Art) Conventionally, as a ceramic material having low thermal expansion characteristics, cordierite (corporeal stone, 2Mg0, 2AJLzO3, 5Si02 or Mg2) has been used.
(A text 4315018), lithium aluminum silicate (Li20-Adan203・SiO2), e.g. β-
Subodumen
4SiO□ or Li2 (AJI2 S in O
12)) and Titanium Ugly 7tk Mi (A 2O3” T
i 02 * Riha AJI. Ti05) and the like are known. Among these, cordierite has excellent heat resistance and corrosion resistance, and has a coefficient of thermal expansion (α) of 2.0X10-
Because it is low (1/”0) (room temperature to 1000°C) and relatively inexpensive, it is widely used, such as heat-resistant tableware, equipment parts for the chemical industry, porcelain for high-temperature and high-frequency electrical insulation, It is used as a material for catalyst carriers for automobile exhaust gas purification devices, etc. On the other hand, although lithium aluminum silicate also has excellent heat resistance and corrosion resistance, it is inferior to the above-mentioned cordierite, and aluminum titanate is Although the expansion coefficient (α) is very small at 0.2XlO-(1/℃) (room temperature to 1ooo℃), the strength of the sintered body is lower than that of the above-mentioned cordierite, and the decomposition point is 1250℃. It is lower than the decomposition point (1500°C) of the cordierite mentioned above and has inferior heat resistance, so it is not used much industrially. In this case, by utilizing the crystal anisotropy of cordierite and orienting the C-axis direction, which has low thermal expansion of cordierite crystal, in a certain direction, the coefficient of thermal expansion in that direction ( By lowering α) to 1.3 to 1.5×10−(1/”0), the thermal shock resistance is improved and the catalyst carrier is made to withstand thermal shocks frequently applied to the catalyst carrier. (Problem to be solved by the invention) However, in recent years, there has been a trend towards purification and regulation of exhaust gas even in automobiles equipped with diesel engines. , Catalysts for exhaust gas purification devices for vehicles equipped with diesel engines are required to have better thermal shock resistance (i.e., low thermal expansion characteristics) and heat resistance than catalysts for exhaust gas purification devices for vehicles equipped with gasoline engines. It is impossible to use conventional catalyst carriers for exhaust gas purification devices for vehicles equipped with gasoline engines as a carrier, and it is hoped that a material with excellent heat resistance and low thermal expansion properties that is even smaller than conventional cordierite will emerge. It was rare. (Objective of the Invention) The present invention has been made in view of the above-mentioned conventional demands, and provides a cordierite sintered body with excellent heat resistance and low thermal expansion characteristics that are smaller than that of conventional cordierite. For example, it can be fully applied as a catalyst carrier for exhaust gas purification devices for vehicles equipped with diesel engines.
The object of the present invention is to provide a cordierite sintered body that can be used for other chemical industrial equipment, insulating porcelain, and the like, and a method for producing the same.

[Structure of the invention]

(Means for Solving the Problems) The cordierite sintered body according to the present invention contains 10 to 40% by weight of aluminum titanate, 5 to 10% by weight of zircon, and the remainder substantially cordierite. It is characterized by consisting of. The present invention was developed as a result of various experiments and research in developing a cordierite sintered body with excellent heat resistance and low thermal expansion characteristics that are even smaller than conventional cordierite. In order to further suppress the thermal expansion of conventional cordierite and to further improve its heat resistance, we added aluminum titanate and zircon to cordierite. It was confirmed that by adding this material, it was possible to obtain a cordierite sintered body with even better heat resistance and thermal shock resistance than conventional cordierite. In the cordierite sintered body according to the present invention, aluminum titanate (for example, A2O3・TiO2 or A2T
i05) has an 8 expansion coefficient (α) of 0.2XIO-F(1
/”O) (room temperature to 1000℃), which contributes to lower thermal expansion of cordierite and greatly improves thermal shock resistance.In order to obtain this effect, aluminum titanate However, if it is too large, the disadvantageous characteristic of aluminum titanate, which is low strength, will appear, reducing the strength of the sintered body, so the content should be 40% by weight or less. On the other hand, zircon (e.g. ZrO2*5tO2 or Z
r5iO4) simultaneously suppresses the decomposition of aluminum titanate and cordierite at high temperatures, contributing to further improving the heat resistance of the sintered body. In order to obtain such an effect, it is necessary to use zircon in an amount of 5% by weight or more. However, if it is too large, the coefficient of thermal expansion of the sintered body (
α) and decreases thermal shock resistance, so 1
The content was set to 0% by weight or less. And cordierite (for example, 2Mg0.2A
03・5Si02 or M g 2 (A fL4S
i50□8) has traditionally been a material with excellent heat resistance and thermal shock resistance, so it will be left as the remainder, and in order to improve the heat resistance of cordierite, an appropriate amount of zircon will be added as mentioned above, and in order to reduce thermal expansion. An appropriate amount of aluminum titanate was added to. The method for producing a cordierite sintered body according to the present invention includes:
0 to 40 weight % of aluminum titanate or (and) a raw material consisting of a component capable of producing aluminum titanate corresponding to the above weight %, and 5 to 10 weight % of zircon or (and)
By mixing a raw material consisting of a component capable of producing zircon corresponding to the above weight % and a raw material consisting of a component capable of producing cordierite or cordierite for the remainder, molding the mixture, and firing the resulting molded body. The method is characterized in that a cordierite sintered body is produced, and the raw materials are specified as described above, and the average particle size of each raw material is adjusted to a more desirable range as shown below. According to Ma L 1l-7N-1Jl 1-,
C;ノL,)-Ll or Ll Eva-concave aluminum titanate is interposed, and zircon is present between the cordierite and aluminum titanate, which makes it more heat resistant than conventional cordierite. This method is characterized by producing a cordierite sintered body with excellent thermal shock resistance. In the present invention, aluminum titanate is added in an amount of 10 to 40% by weight for the above-mentioned reason in order to reduce the thermal expansion of cordierite and thereby improve its thermal shock resistance. The material is not limited to aluminum titanate, but may be partially or entirely composed of components capable of producing aluminum titanate at high temperatures. More desirably, the average particle size of aluminum titanate is 2 Jlm or less. The reason for this is that if the average particle size exceeds 2 Jlm, the inherent low strength of aluminum titanate tends to affect the strength of the sintered body, so it is more desirable to set it to 2 Jlm or less. In addition, zircon is added in an amount of 5 to 10% by weight for the above-mentioned reason in order to improve the heat resistance of cordierite, but in this case, it is not limited to all of the zircon; Alternatively, all the components may be made of components capable of producing zircon at high temperatures. More preferably, the average particle size of zircon is 5 to 20.
Let it be μm. The reason for this is that when the average particle size of zircon is smaller than 5 μm, the effect of simultaneously suppressing the decomposition of aluminum titanate and cordierite at high temperatures becomes small, and when it is larger than 20 μm, the coefficient of thermal expansion of the sintered body increases. This is because there is a tendency to Furthermore, the remaining cordierite is used to exhibit its excellent heat resistance and low thermal expansion properties, but in this case as well, it is not limited to all cordierite. Part or all of the material may be made of a component that can produce cordierite at high temperatures. The cordierite raw material may be made of kaolin, talc, alumina, or a component capable of producing oxides thereof, so that it can become cordierite after firing. In this case, kaolin (kaolin mineral; for example, A 20
3*2Si02 ・2H20 or AR2S i 20
s (OH) 4) has an average particle size of 0.3 μm or more so that the orientation by extrusion molding is good, and an average particle size of 50 gm or less so that the effect of suppressing decomposition is obtained. It is more desirable to use
Talc (talc; e.g. 3Mg0, 4Si02, H2
O or Mgs Si 40+ o (OH) 2
) has an average particle size of 0.3 gm or more to ensure good orientation during extrusion molding, and an average particle size of 50 μm or less to maintain the effect of suppressing decomposition. More preferably, the average particle size of alumina (for example, Al2O2) is in the range of 0.1 to 20 gm so that the fine structure of the sintered body can be well controlled. Composition, more preferably MgO: 11 to 16 parts by weight, Ami203: 33 to 41 parts by weight, SiO2: 43 to 41 parts by weight.
It is more desirable to mix the composition so that the composition is 56 parts by weight, and after firing, the average grain size of cordierite crystals is 5 to 50 gm.If the average grain size of cordierite is smaller than 5 gm, Orientation by extrusion molding cannot be achieved properly, and if the thickness exceeds 50 tm, microcracks are likely to occur due to thermal shock, and there is a risk that thermal shock properties will deteriorate. In this way, more preferably the average particle size is 2 pLm.
10 to 40% by weight of the following aluminum titanate, more preferably 5 to 10% by weight of zircon with an average particle size of 5 to 20 gm, and the balance preferably 5 to 40% by weight. 50 ILm of cordierite was weighed, and each raw material and average particle size were adjusted so that the fine structure of the sintered body obtained thereafter could be controlled, and these were mixed together with an appropriate binder to form a clay-like material. Molding 1 For example, by extrusion molding, the molded body is passed through a mesh to form a honeycomb-shaped molded body, and the molded body is fired with kaolin and talc oriented to form a cordierite sintered body having a honeycomb structure, such as diesel. A catalyst carrier for an exhaust gas purification device for a vehicle equipped with an engine is obtained. In this case, the average particle size of the kaolin and talc is 0.3 μm.
When the average particle size is smaller than 5, it becomes difficult to orient the kaolin and talc by extrusion molding.
When it is larger than 01Lm, the effect of suppressing decomposition may be lost and decomposition may occur partially. (Example) Kaolin (average particle size 2.5 ILm), talc (average particle size 2.0 μm), alumina (average particle size 1.07 zm or less), and cordierite composition (MgO: 14 parts by weight,
A-203: 36 parts by weight, SiO2: 50 parts by weight), aluminum titanate (average particle size 1.8 gm) was mixed with 0 to 50% of the mixed powder as shown in Table 1. Weight% and zircon (average particle size 5.Oem)
Similarly, as shown in Table 1, 0 to 15% by weight was added and wet-mixed to obtain a raw material powder. Next, 10 parts by weight of a binder for extrusion molding was added to 100 parts by weight of the raw material powder, and the mixture was thoroughly kneaded in a vacuum (or under reduced pressure) while removing air bubbles to form a clay-like mixture, and then extrusion molding was performed. The dimensions of the extrusion molded product are: Width = 30mm
, thickness: 0.3 mm.
50℃ (However, No. 1 in Table 1 is the conventional cordierite composition, which decomposes at 1450℃, so 1440℃)
℃) for 0.5 hours to obtain each sintered body. Next, the coefficient of thermal expansion of each sintered body is 9. Aluminum titanate (A
The decomposition rate of fL203/TiO2) and the softening point of the sintered body were measured. In this case, the thermal expansion coefficient is the linear expansion coefficient in the direction parallel to the extrusion direction, and the decomposition rate of aluminum titanate is 1
This figure shows the results of examining the decomposition rate of aluminum titanate by powder X-ray method after it was left at 250°C for 5 hours. As is clear from the results shown in Table 1, the sintered body of the present invention example (No. 3 It is clear that .4.5) has a smaller coefficient of thermal expansion and a higher softening point than the conventional sintered body made only of cordierite (NO, 1). On the other hand, the sintered body of the comparative example containing less aluminum titanate (No.
2) has a large coefficient of thermal expansion, whereas the comparative example sintered body (No. 6), which contains a large amount of aluminum titanate, has a lower strength and a lower softening point; It was observed that the thermal expansion coefficient of the sintered body (No. 7) had a large value.

【Effect of the invention】

As explained above, the cordierite sintered body according to the present invention contains 10 to 40% by weight of aluminum titanate and 5% by weight of aluminum titanate.
It has a composition consisting of ~10% by weight of zircon and the remainder is essentially cordierite, so it has better heat resistance than conventional cordierite materials, and has a smaller coefficient of thermal expansion. Catalysts for exhaust gas purification devices for diesel engine vehicles require superior heat resistance and thermal shock resistance than conventional catalyst carriers for exhaust gas purification devices for gasoline engine vehicles. It has very excellent effects in that it is fully applicable as a carrier and can also be applied to other chemical industrial equipment members, insulating porcelain, and the like. Further, the method for producing a cordierite sintered body according to the present invention includes a raw material consisting of 10 to 40% by weight of aluminum titanate or a component capable of producing aluminum titanate corresponding to the above weight%, and 5 to 10% by weight of aluminum titanate. % of zircon or a component that can produce zircon corresponding to the weight %, and a raw material that consists of the remaining cordierite or a component that can produce cordierite are mixed and then molded and the resulting compact is fired. By doing this, we were able to produce a cordierite sintered body, which can be used as a catalyst carrier for exhaust gas purification devices for vehicles equipped with diesel engines, which require better heat resistance and thermal shock resistance than conventional ones. The very advantageous effect is that it is possible to produce cordierite sintered bodies that are fully applicable.

Claims (7)

[Claims] (1) 10-40% by weight of aluminum titanate and 5-10% by weight of aluminum titanate
% by weight of zircon and the balance substantially of cordierite;
A cordierite sintered body characterized by consisting of. (2) A raw material consisting of 10 to 40% by weight of aluminum titanate or a component capable of producing aluminum titanate corresponding to the above weight%, and 5 to 10% by weight of zircon or the above weight%.
A raw material consisting of a component capable of producing zircon equivalent to
A method for producing a cordierite sintered body, which comprises mixing the remaining cordierite or a raw material consisting of a component capable of producing cordierite, and then firing the molded body obtained by molding. (3) Claim (2) characterized in that the average particle size of aluminum titanate is 2 μm or less, the average particle size of zircon is 5 to 20 μm, and the average particle size of cordierite is 5 to 50 μm. A method for producing a cordierite sintered body as described in . (4) Cordierite sintering according to claim (2) or (3), wherein the raw material consisting of components capable of producing cordierite consists of kaolin, talc, and alumina. How the body is manufactured. (5) The average particle size of kaolin is 0.3 to 50 μm, the average particle size of talc is 0.3 to 50 μm, and the average particle size of alumina is 0.1 to 20 μm, and the average cordierite produced is The method for producing a cordierite sintered body according to claim 4, wherein the particle size is 5 to 50 μm. (6) The blending ratio of kaolin, talc and alumina is
The composition of cordierite is MgO: 11 to 16 parts by weight,
Al_2O_3: 33-41 parts by weight, SiO_2: 43
The method for producing a cordierite sintered body according to claim 4 or claim 5, wherein the amount is 56 parts by weight. (7) The cordierite according to any one of claims (2) to (6), wherein the molded body is used as a catalyst carrier for an engine exhaust gas purification device having a honeycomb structure. A method for producing quality sintered bodies.