JP2003238250A - Yttria refractory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refractory for lining of various industrial furnaces necessitating high corrosion resistance, which has excellent corrosion resistance to molten slag and spalling resistance. <P>SOLUTION: The yttria refractory is obtained by blending so that Y<SB>2</SB>O<SB>3</SB>is contained in an amount of ≥60 and ≤99.9 wt.% and the balance is composed of one or more kinds of oxide among Al<SB>2</SB>O<SB>3</SB>, CeO<SB>2</SB>, ZrO<SB>2</SB>and MgO, then kneading the resulting mixture, forming, drying and firing at a high temperature. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory used for lining various industrial furnaces requiring high corrosion resistance. Heretofore, as a refractory used for lining various industrial furnaces requiring high corrosion resistance, a chromium oxide-containing refractory having excellent corrosion resistance to molten slag has been used. [0003] However, chromium is a component whose valence is liable to fluctuate, and is known to easily become harmful hexavalent chromium in an atmosphere containing an alkali salt. From the viewpoint of environmental issues, development of a refractory which does not contain chromium oxide and has excellent corrosion resistance to molten slag is required. [0004] Silicon carbide refractories are used as refractories containing no chromium oxide, but silicon carbide is a component that is easily affected by the atmosphere and has a stable durability. Has not been obtained. Then, in this invention, it aims at providing the yttria refractory for various industrial furnace lining which is excellent in the corrosion resistance with respect to a molten slag. [0005] To solve the above-mentioned problems, the yttria refractory of the present invention contains 60 wt% or more.
Contains 99.9 wt% or less of Y ₂ O ₃ , and the balance is Al ₂
O ₃ , CeO ₂ , MgO, and ZrO ₂ are blended so as to be composed of one or more oxides, and kneaded.
It is a refractory obtained by molding, drying and firing at high temperature. According to the present invention, the yttria refractory is Y ₂ O
_{3 It} is most preferable to use a high-purity material having a content of 99.9% by weight in terms of heat resistance, corrosion resistance and volume stability. However, since Y ₂ O ₃ is expensive, it is necessary to consider economics. 60 wt% or more and 99.9 wt% or less of Y ₂ O
₃ with the balance being Al ₂ O ₃ , CeO ₂ , MgO, Z
The most preferred refractory composition is one or more oxides of rO ₂ . A used for the rest
When the content of l ₂ O ₃ is increased beyond this range, heat resistance and corrosion resistance are reduced, while CeO ₂ , MgO, and ZrO are reduced.
_If the content of ₂ exceeds this range, the volume stability decreases, which is not desirable. [0007] Y ₂ compounded in the refractory brick according to the present invention.
As the O ₃ raw material, the Al ₂ O ₃ raw material, the CeO ₂ raw material, the MgO raw material, and the ZrO ₂ raw material, any of a sintered product and an electrofused product may be used.
In particular, it is preferable to use one not containing SiO ₂ or the like. Further, not only a single raw material made of a kind of oxide but also Y ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , Mg
A composite material composed of two or more oxides in any combination of O and ZrO ₂ can be used. Either a sintered product or an electrofused product may be used for the composite raw material, but it is preferable to use a material that does not contain impurities such as SiO ₂ that generates a low melting point material as described above. As the binder to be added to obtain a molded article, any of various known binders such as polyhydric alcohols, water, and phenolic resins may be used. The firing temperature in the present invention is preferably high-temperature firing at a temperature of 1750 ° C. or higher from the viewpoint of corrosion resistance and heat resistance. The present invention will be described in more detail below with reference to Examples and Comparative Examples. Each raw material component was added in the mixing ratio shown in Table 1,
A binder (phenolic resin) was added to the mixture, and the mixture was kneaded, followed by pressure molding into a refractory brick having a regular shape using a friction press. After the molded body thus obtained was appropriately dried, firing was performed in a tunnel kiln at 1750 ° C. for 7 hours to obtain a test brick. In addition, as each raw material in the examples and comparative examples shown in Table 1, raw materials having the composition ratios shown in Table 2 were used. Using these test bricks, the physical properties and properties shown in Table 1 were evaluated by the following measurement methods, and the results are also shown in Table 1. Bulk specific gravity and apparent porosity: JIS R2
It measured according to 205. Compressive strength: JIS R220
6 was measured. Hot linear expansion coefficient: JIS R220
7 was measured. [0015] The heat-resistant spalling property is measured by holding a sample of a regular brick at a surface of 114 x 65 mm from the tip to one third from the tip at 1500 ° C for 15 minutes and then at room temperature for 15 minutes. Forced air cooling. This operation was repeated 10 times as one cycle, and evaluated by the ratio (%) of the separated weight to the initial weight. For corrosion resistance, a test brick is lined inside a drum, and the brick is heated to 1850 ° C. for 3 hours with an oxygen-propane burner while rotating the drum. There C / S = 0.5 and C / S = 2.5 shown in Table 3
Was adjusted, and eroded at 1850 ° C. for 6 hours. Corrosion resistance of lining brick is erosion thickness (mm)
Was evaluated. [Table 1] [Table 2] [Table 3] It can be seen that Examples 1 to 6 have excellent corrosion resistance as compared with the conventional refractories containing chromium oxide and silicon carbide refractories as shown in Comparative Examples 1 and 2.
Further, it can be seen that the coefficient of linear thermal expansion is small and the volume stability is excellent. Comparative Examples 3 and 4 have a Y ₂ O ₃ content of 6
This is an example in which the content is less than 0 wt%, the volume stability is reduced, and the corrosion resistance is also reduced. The refractory used in the lining of various industrial furnaces that require high corrosion resistance to molten slag, the yttria refractory of the present invention containing a specific proportion of yttria component has a high corrosion resistance. It is more than twice as high as conventional chromium oxide-containing refractories.

Claims (1)

Claims: 1. An amount of 60 to 99.9% by weight of Y ₂ O ₃ and Al
A highly corrosion-resistant yttria refractory comprising one or more oxides of 0.1% to 40% selected from ₂ O ₃ , CeO ₂ , MgO and ZrO ₂ .