JPH0780714B2 - Ceramic sound absorbing plate and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ceramic sound absorbing plate, and more particularly to a sound absorbing body used in a sound absorbing exhaust tower that discharges high-temperature exhaust gas such as high-temperature steam.

[Conventional technology]

BACKGROUND ART Fibrous sound absorbers such as glass wool have been widely used in exhaust towers that exhaust high-temperature exhaust gas such as steam exhausted from various factories in order to muffle or absorb noise from exhaust pipes. However, once the fibrous sound absorber absorbs water due to water vapor or rainfall, it becomes difficult to completely remove the water, and the water absorption has a defect that the sound absorption rate is significantly lowered.

[Problems to be solved by the invention]

In order to make up for this defect, so-called ceramic sound absorbers have recently been used instead of fibrous sound absorbers, in which particles of crushed silica sand, true rock or ceramic style, etc., are bound with a heat resistant binder such as glaze. Natsuta. These sound absorbers can remove water very easily and quickly even if they absorb water.
Although no significant decrease in sound absorption coefficient is observed, it has a large specific gravity compared to conventional fibrous sound absorbers, and it is a large-sized device. However, it is difficult to control the molding conditions such as pressing because the quality control is difficult and the fluidity at the time of molding is poor, and it is impossible to supply a sound absorber with stable performance.

[Object of the Invention]

The present invention is intended to provide a ceramics sound absorbing body which solves the drawbacks of the conventional ceramics sound absorbing body.

[Means for solving problems]

The present invention is composed of ceramic particles containing mullite as a main component and having a particle size of 0.5 to 1 mm, and has a flow resistance of more than 14300 MKSr / m.
Ceramics sound absorbing plate characterized by less than 3400 MKSr / m and particle size of 0.5 to 1 mm, Al ₂ O ₃ of 60 wt% or more, SiO ₂
Of ceramic particles whose content is less than 40% by weight is molded using a heat-resistant binder and then fired to form mullite, which has a flow resistance of
A method for producing a ceramics sound absorbing plate, characterized in that the fired body exceeds 14300 MKSr / m and less than 33400 MKSr / m.

The present invention reduces the weight of a conventional ceramics sound absorber, facilitates production control, and supplies a product with stable performance. The inventors have found that the characteristics of the ceramics sound absorber are mainly aggregates. Focusing on the fact that it depends on the ceramic particles, various studies have been conducted by changing the composition and shape of the ceramic particles.

The present invention has been made as a result thereof. In the present invention, first, the aggregate component is limited to 60% by weight or more of Al ₂ O _{3 and} 40% by weight or less of SiO ₂ . This is kaolin-based clay, alumina, calcene stone, etc., at 1400 ° C or higher, preferably 1600 ° C.
It is made into mullite by firing above ℃. Mullite is an aluminosilicate mineral represented by the chemical formula 3Al ₂ O ₃ .2SiO ₂ . The properties are dense and excellent in thermal shock resistance, mechanical strength, acid resistance, etc. In particular, those containing 60% by weight or more of Al ₂ O ₃ are thermally stable and their properties are maintained up to a high temperature. Further, the higher the purity of Al ₂ O ₃ and SiO ₃ , the more desirable, but impurities such as Fe ₂ O ₃ , TiO ₂ , MgO, K ₂ O and Na ₂ O are
It is unavoidable that there is a few percent, but it does not cause any serious harm.

Secondly, the present invention is limited to particles sieved in the 0.5-1 mm range. In order to obtain a sound absorbing plate having a flow resistance in a preferable range within this particle size range, the particle shape is preferably spherical. The method of spheroidization is to add water to kaolin-based kiseki or kaseisen kiseki to make a kneaded clay, and to make pellets by extrusion molding, and to roll this into a spherical granulator, or water on the kiseki. In addition, it will be slurried and equipment such as a spray dryer will be used. Then, the spherical particles are fired at 1680 ° C. for about 1 hour to obtain mullite spherical particles.

According to the present invention, since the aggregate particles are sieved, it is possible to reduce the amount of the heat-resistant adhesive such as glaze used because it contains almost no fine powder, and the interparticle joining portion caused by melting It is possible to minimize the glass phase of

Specifically, by using spherical particles that are a mullite component and that contain almost no fine powder, compared to a panel that uses conventional shremot components and crushed particles that contain fine powder, about 1.5 times or more. It is possible to reduce the thickness of the sound-absorbing panel to be manufactured by about half.

In addition, the particle size of the aggregate particles was limited to the range of 0.5 to 1 mm because it was determined from the sound absorption characteristics and the flow resistance test result.
When it exceeds m, the flow resistance is small and there is almost no sound absorbing effect. On the contrary, when it is less than 0.5 mm, the flow resistance is too large and the air permeability is poor and the performance as a sound absorbing plate is not achieved.

The sound absorbing plate of the present invention has a flow resistance of more than 14300 MKSr / m, 334
It has a property of less than 00 MKSr / m.

In the case of spheroidizing, when a raw material is one having a binding property such as kaolin or caustic stone, and when pelletizing or slurrying, a binder for molding is not necessary, and only water may be blended to prepare the raw material. In addition, Al ₂ O ₃ or Al
When using non-caking raw materials such as alumina materials such as (OH) ₃ and silica powder, talc powder, methyl-cellulose, polyvinyl alcohol, organic binders such as wheat flour, in addition to water, are used. It is good to add and use. The added amount is about several% with respect to the powder raw material.

〔Example〕

Examples of the present invention will be described below. Table 1 shows the characteristics of the example product of the present invention and the sound absorbing panel prepared by the test method carried out for comparison. The aggregate used is caustic stone (Si
O ₂ : 42%, Al ₂ O ₃ : 56%, impurities 4%), kaolin (SiO ₂ :
45%, Al ₂ O ₃ : 38%, Impurity: 17%) and Al ₂ O ₃ (impurity 0.
The glaze used as a heat-resistant binder, which was prepared by appropriately mixing and firing 5%), was SiO ₂ 77.8%, Al ₂ O ₃ 13.
2%, MgO 3.3%, K ₂ O 5.1%, melting point 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, and the mixture was kneaded, press-molded into a plate shape using a 300 × 300 mm mold, 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 board using mullite spherical particles as an aggregate exhibited a bending strength that was twice as high as that of the conventional material. Further, the flow resistance and sound absorption coefficient, compared with the optimum particle size 1-2 mm in the case of crushed particles of conventional materials, since the shape and size of the pores change due to the spherical shape, in the case of spherical particles, The optimum particle size was 0.5 to 1 mm.

Even when the manufacturing conditions such as the amount of binder and molding pressure, which are important for product management, were changed, the quality variation was small.

[Advantages of the Invention] As described above, the ceramic sound absorber of the present invention is made of Al ₂ O 3.
₃ 60 wt% or more, 0.5 mainly composed of SiO ₂ 40 wt% or less
By using spherical particles in the range of 1 mm, high strength can be achieved, and even if the wall thickness is made thin, excellent sound absorbing performance is exhibited, so that it is possible to make a light-weight sound absorbing and exhausting tower that has never existed. Moreover, since the ceramic particles are regular spherical particles, it is possible to easily perform quality control and supply a sound absorbing body with stable performance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yajima et al. 1-1 No. 1 Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Masanori Nishida 1-1 1-1 Atsunoura-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industry Co., Ltd. Nagasaki Shipyard Co., Ltd. (56) Reference JP 61-64908 (JP, A) JP 62-6007 (JP, A) JP 62-223072 (JP, A)

Claims (2)

[Claims] 1. A ceramic sound absorbing plate comprising ceramic particles containing mullite as a main component and having a particle size of 0.5 to 1 mm and having a flow resistance of more than 14300 MKSr / m and less than 33400 MKSr / m. 2. A grain size of 0.5 to 1 mm, Al ₂ O ₃ content of 60% by weight or more, S
Characterized by forming ceramic particles containing 40% by weight or less of iO ₂ using a heat-resistant binder and then firing to mullite, and a flow resistance exceeding 14300 MKSr / m and less than 33400 MKSr / m. And a method for manufacturing a ceramic sound absorbing plate.