JPH07149558A - Sound absorbing plate of ceramic and its production - Google Patents

Abstract

PURPOSE:To improve sound absorbing performances by mixing Al2O3-containing ceramic particles with a heat-resistant binder, forming and firing. CONSTITUTION:Ceramic particles containing >=99.8wt.% Al2O3, having 0.2-0.4mm average particle diameter is mixed with a heat-resistant binder, kneaded, formula and fired to give sound absorbing plates of ceramic having 30-40vol.% porosity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sound absorbing plate and a manufacturing method thereof, and more particularly to a sound absorbing plate used in a sound absorbing exhaust tower or the like for discharging high temperature exhaust gas such as high temperature hot air and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a fiber sound-absorbing plate such as glass wool and silica sand, true rock or ceramic style is used to mitigate or absorb noise in an exhaust tower that discharges high-temperature exhaust gas such as steam discharged from various factories. A so-called ceramic sound absorbing plate obtained by crushing etc. is used. However, the fibrous sound absorbing plate has a defect that once it absorbs water due to water vapor or rainfall, it becomes difficult to completely remove the water, and the sound absorbing coefficient is remarkably lowered by the water absorption. In addition, the sound absorbing plate crushed with silica sand, true rock or ceramic style can remove water very easily and quickly even if it absorbs water, so no significant decrease in sound absorption coefficient is seen, but the specific gravity is higher than that of the fibrous sound absorbing plate. The sound absorbing plate is large and thick in terms of strength, and there is a drawback that the device becomes large.

[0003]

SUMMARY OF THE INVENTION To compensate for this drawback,
Recently, development of a lightweight and high-strength sound absorbing plate by combining ceramics with glass wool or metal fiber has been underway. However, it is difficult to uniformly disperse these fibers such as glass wool in the ceramics, and it is difficult to introduce the metal fibers because the thermal expansion coefficient is different from that of the ceramics.
There was a situation where a high-strength sound absorbing plate could not be supplied.

In order to overcome the drawbacks of the conventional sound absorbing body, the present inventors have made heat-resistant ceramic spherical particles having a particle diameter of 0.5 to 1 mm, Al ₂ O ₃ 60% by weight or more and SiO ₂ 40% by weight or less. We proposed a ceramics sound absorber that is formed by molding with a strong binder and then firing it (Japanese Patent Application No. 62-2515).
75). Although the above-mentioned ceramic sound absorber has solved the drawbacks of the conventional sound absorbers, it is still unsatisfactory in terms of light weight and high strength, and there has been a demand for a lighter and stronger sound absorber.

In view of the above-mentioned state of the art, the present invention is to provide a ceramic sound absorbing plate which is lighter and has higher strength than the proposed ceramic sound absorbing body, and a method for producing the same.

[0006]

MEANS FOR SOLVING THE PROBLEMS The present invention comprises: (1) ceramic particles containing Al ₂ O _{3 in an amount} of 99.8% by weight or more and having an average particle size of 0.2 to 0.4 mm; And a porous binder layer having a porosity of 30 to 4
A ceramic sound-absorbing plate characterized by being 0% by volume. (2) Al ₂ O ₃ 99. with an average particle size of 0.2 to 0.4 mm.
A method for manufacturing a ceramics sound absorbing plate, comprising forming 8% by weight or more of ceramics particles by using a heat resistant binder, and then firing. Is.

[0007]

In the present invention, the aggregate component is Al ₂ O ₃ : 9.
It was specified as having a high purity of 9.8% by weight or more. This is because they are excellent in thermal stability, mechanical strength, acid resistance and the like. Further, by using the crushed particles sieved in the range of the average particle diameter of 0.2 to 0.4 mm, the area of the inter-particle joint portion generated by melting the heat resistant adhesive such as glaze is expanded, and high strength is obtained. It was made possible. Specifically, Al
₂ O ₃ By using the crushed particles having a high purity component and containing almost no fine powder, compared to the panel using the conventional mullite component and the crushed particles containing no fine powder,
The strength of the sound absorbing panel can be increased to about four times or more, and the thickness of the sound absorbing panel to be manufactured can be reduced to about 1/4.

Further, since the aggregate is Al ₂ O _3, it is superior in corrosion resistance as compared with the mullite component. Furthermore, by adjusting the porosity to 30 to 40%, the sound absorbing performance and the high strength are excellent. There is a feature that can be compatible.

[0009]

EXAMPLE An example of the present invention will be given below to clarify the effect of the present invention. The following Table 1 also shows the characteristics of the sound absorbing panel prepared by the examples of the present invention and the test method carried out for comparison and the characteristics of the conventional sound absorbing panel. The aggregate used was fused alumina (Al ₂ O ₃ : 99.83 wt%, Si
O _2: 0.03wt%, impurities 1.6 wt%), glazes used as heat-resistant binder is SiO _2: 77.8wt%, A
l ₂ O ₃ : 13.2 wt%, MgO: 3.3 wt%, K
₂ O: 5.1 wt% and the melting point is 1300 ° C.
Water glass No. 4 was used.

For the trial production of the panel, glaze and water glass were added to the aggregate particles, kneaded, press-formed into a plate shape using a mold of 300 × 300 mm, and the molded product was sintered to obtain a sound absorbing plate. . The characteristics of the obtained sound absorbing plate were evaluated by bending test, porosity, flow resistance and sound absorbing performance.

As is clear from the results of the examples in Table 1,
The ceramic sound absorbing plate using alumina particles as an aggregate exhibited a bending strength four times stronger than that of the conventional material. Also, the flow resistance and sound absorption coefficient are the optimum particle size of 1 to 2 mm for the crushed particles of conventional materials.
Compared with the above, since the pore diameter and the porosity are changed by setting the thickness to 0.2 to 0.4 mm, the wall thickness of 5 mm was most suitable.

FIG. 1 shows a backscattered electron image of a cross section of the ceramic sound absorbing plate of the present invention. In FIG. 1, 1 is Al ₂ O ₃ aggregate particles, 2 is a heat-resistant binder that continuously binds between Al ₂ O ₃ aggregate particles, and 3 is a void.

[0013]

[Table 1]

[0014]

As described above, since the ceramic sound absorbing plate of the present invention uses the crushed particles in the range of 0.2 to 0.4 mm, which contains 99.8% by weight or more of Al ₂ O ₃ as a main component, It is possible to increase the strength and shows excellent sound absorption performance even if it is made as thin as 1/2 the thickness of the previously proposed ceramic sound absorber (Japanese Patent Application No. 62-251575). Can be a sound absorbing and exhaust tower. Moreover, since the ceramic particles are of high purity, it is possible to supply a sound absorbing plate with stable performance. Furthermore, since Al ₂ O ₃ is the main component, the corrosion resistance is also excellent.

[Brief description of drawings]

FIG. 1 is a photograph showing a structure of particles of a ceramic sound absorbing plate according to an embodiment of the present invention.

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Claims (2)

[Claims] 1. Ceramic particles containing Al ₂ O _{3 in an amount} of 99.8% by weight or more and having an average particle size of 0.2 to 0.4 mm,
A ceramic sound-absorbing plate having a heat-resistant binder layer for bonding the particles and having a porosity of 30 to 40% by volume. 2. Al ₂ O having an average particle size of 0.2 to 0.4 mm.
₍₃₎ A method for producing a ceramic sound absorbing board, which comprises forming 99.8% by weight or more of ceramic particles using a heat-resistant binder and then firing the molded particles.