JPS6012303B2 - Heat shock resistant ceramic sound absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal shock-resistant ceramic sound absorber that is particularly excellent as a sound absorber for sound absorbing exhaust towers and the like that discharge high temperature exhaust gas such as high temperature steam.

Conventionally, fibrous sound absorbers such as glass wool have been widely used in exhaust towers that discharge high-temperature exhaust gases such as steam discharged from various factories to muffle or absorb noise from exhaust pipes, etc. ing. However, once fibrous sound absorbing materials absorb water due to water vapor or rain, it becomes extremely difficult to remove the water completely, and the fibrous sound absorbing material has the fatal drawback that its sound absorption coefficient drops significantly due to water absorption.

In order to compensate for this drawback, recently, instead of fibrous sound absorbers, so-called ceramic sound absorbers have been used, which are made by combining silica sand, tributary rock, or crushed particles of ceramic tiles with a binder such as synthetic resin or water glass. It started to be done.

Even if these ceramic sound absorbers absorb water, they can be removed extremely easily and quickly, so there is no significant decrease in sound absorption coefficient. It has the disadvantage of being destroyed by impact.

The thermal shock-resistant ceramic sound absorber of the present invention solves these conventional drawbacks, and has a thermal expansion coefficient of 6 to 3.5 x 1.
Ceramic particles with a thermal expansion coefficient of 5-2.
This is a thermal shock-resistant ceramic sound absorber bonded with continuous pores using a heat-resistant binder mainly composed of glass with a temperature of 5 x 10-6/°C.

More specifically, the thermal shock-resistant ceramic sound absorber of the present invention has a coefficient of thermal expansion of 6 to 3.5 x 10-6/°C (
Ceramic particles, preferably having a particle size of 0.4 to 3 degrees, obtained by crushing and sizing ceramic materials such as porcelain, ceramics, or refractories within the range of 20 to 600 degrees Celsius, are Preferably 2.5 to 1×1 than ceramic particles
5 to 2.5 x 10-6/℃ (20
It is coated with a heat-resistant binder mainly composed of glass or vitreous material such as pongee (within the range of 600 °C to 600 °C), and after forming into a plate with continuous pores, the softening temperature and melting temperature of the heat-resistant binder are determined. This is a thermal shock-resistant ceramic sound absorber that is sintered at a temperature between

An example of the composition of the ceramic used in the present invention is as follows.

Ceramics kneading A 203 20~60% SiQ 30~80% K20~Na20 1~5% Mg○~Ca0 1~20% Others (impurities) 1~5% Thermal expansion coefficient 6~3.5~lo- 6/°C Next, an example of the composition of the glass binder used in the present invention is as follows.

The composition of the glass bonding agent must be a combination of 10 to 30% neutral oxide, 50 to 80% acidic oxide, and 5 to 20% basic oxide, and the respective oxides may be selected from the above examples. It is not limited to.

In the present invention, a ceramic having strong mechanical strength with a thermal expansion coefficient smaller than that of glass than that of ceramics is coated with glass having a thermal expansion coefficient slightly smaller than the thermal expansion coefficient of glass, and is fired at a temperature higher than the glass melting temperature.
When cooled, "ceramics have a larger coefficient of thermal expansion than glass, so they contract more in volume than glass. As a result, the glass covering the surface of the ceramic particles is pulled inward, and as a result, it is compressed in the direction of the glass surface." Force will be applied.

When a ceramic sound absorber is rapidly heated or cooled, the difference in temperature distribution causes a difference in temperature and tensile force is generated internally, but the ceramic sound absorber of this application has a compressive force built into the glass that binds the ceramic particles. This is because the material cancels out the tensile force generated by rapid heating or cooling, resulting in a sound absorbing material with high thermal shock resistance. In addition, in the present invention, the thermoplasticity coefficient of the ceramic particles is 6 to 3.
The reason why it is limited to 5×10-6/℃ is because if the thermal expansion coefficient of the ceramic particles exceeds 6×lo-6/℃, the thermal shock resistance of the ceramic sound absorber will decrease and it will be easily destroyed when used in high-pressure steam, etc. 3.5.
If it is less than ×10-6/°C, only specific expensive ceramic particles are present and it is not practical, and the difference in coefficient of thermal expansion with the heat-resistant binder becomes small, which is preferable from the viewpoint of improving thermal shock resistance. It's something that doesn't exist.

In addition, the thermal expansion coefficient of the heat-resistant binder is 5 to 2.5 × 10-
The reason for limiting the value to 6/°C is that if the temperature exceeds 5 x 10-6/°C, the sound absorber will be easily destroyed by thermal shock, and the lower limit was set at 2.5 x 10-6/°C. This is because there is no practical heat-resistant binder that is lower than this.

Next, examples of the present invention will be described.

Various ceramic materials having various compositions and coefficients of thermal expansion listed in the table are crushed into strips using a roll-type crusher.
Ceramic particles sized to a particle size of 0.5 to 2 were prepared.

Separately, heat-resistant binders having various compositions and heat transmission coefficients listed in the table were prepared.

Then, by combining the ceramic particles and heat-resistant binder listed in the table, the mixture of ceramic particles and heat-resistant binder was kneaded and molded into a plate shape using a 300 x 300 x 3 mould. Press molded into. As a result, a thermal shock-resistant ceramic sound absorbing body of the present invention (shame: 1 to lung: 10) was obtained. For comparison, reference products (No. 11 to No. 18) using ceramic particles and a heat-resistant binder outside the hot air expansion coefficient range defined in the present invention were used, and commercially available products were compared to conventional products. (M.19 to No.20) were prepared respectively.

Each of these ceramic sound absorbers was held in a temperature bath at 400° C. for 15 minutes, and then put into 20 qo water and held in each powder for one cycle of a rapid heating and cooling test and a bending test.

The results are shown in the table.

As is clear from the results of the examples on the ship table, the coefficient of thermal expansion of the ceramic particles is 6 x 3.5 x 10-6/℃, and the coefficient of thermal expansion of the heat-resistant binder is 5 to 2.5 x 10-6/℃. Ships of the invention within range. 1~Side. No. 10 was confirmed to have extremely excellent thermal shock resistance, and the reference product Lung. 11~M. 18 and Yuzu. 1
9~No. It was confirmed that the conventional product No. 20 had poor thermal shock resistance.

As described above, the thermal shock resistant ceramic sound absorber of the present invention has unprecedented thermal shock resistance due to the combination of ceramic particles with a limited thermal bulk coefficient and a heat resistant binder with the same limited thermal expansion coefficient. An excellent ceramic sound absorber has been obtained, and since it is made of ceramic, it has the advantage that the sound absorption coefficient is less likely to decrease even when exposed to water vapor or rain.

Claims (1)

[Claims] 1 Al_2O_320~60%, SiO_230~8
0%, K_2O+Na_2O1~5%, MgO+CaO
Thermal expansion coefficient is 6 to 3.5 x 10^-^6/ at 1 to 20%
Ceramic particles at ℃, 10-30% neutral oxides, 50-80% acidic oxides, 5-20% basic oxides, and a glassy material with a thermal expansion coefficient of 5-2.5 x ^-^6/℃ Ceramic particles are coated with a heat-resistant binder containing as the main component and the coefficient of thermal expansion of the glassy particles is 2.5 to 1 x 10^-^6/°C smaller than that of the ceramic particles, and continuous pores are provided. A thermal shock-resistant ceramic sound absorber characterized by being sintered and bonded.