JP2007003140A - Window material for combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a window material for a combustion device, particularly for an oil stove having a superior antifouling function preventing easy adhesion of combustion residues or the like, and preventing easy loss of transparency. <P>SOLUTION: The window material for the combustion device is comprised by coating an oxide based ceramic film having an antifouling property on a surface of SiO<SB>2</SB>-Al<SB>2</SB>O<SB>3</SB>-Li<SB>2</SB>O-based transparent crystallized glass. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a window material for a combustion apparatus, and more particularly to a window material for an oil stove.

  The function of the window in a combustion device or the like is to increase the visual warmth by transmitting heat rays emitted from the internal flame to the outside to increase the heating effect and making the flame visible. Also, the function of the window is to make it possible to observe the combustion state of the flame from the outside, and these windows have to withstand the high temperature generated by the flame and the thermal shock at the time of ignition. Therefore, the material used for the window of the combustion apparatus is required to be transparent and have low thermal expansion, high strength, heat resistance, and thermal shock resistance.

Currently, borosilicate glass, quartz glass, and Li ₂ O—Al ₂ O ₃ —SiO ₂ transparent crystallized glass are used as the window material for combustion devices such as heating appliances. Cannot be said to have sufficient heat resistance and thermal shock resistance, and quartz glass is excellent in thermal properties but expensive. On the other hand, Li ₂ O—Al ₂ O ₃ —SiO ₂ transparent crystallized glass has a low coefficient of thermal expansion and high strength, and thus has excellent heat resistance and thermal shock resistance, and is manufactured at a relatively low cost. Therefore, it is widely used (see Patent Document 1).

In Patent Document 2, β-quartz solid solution is precipitated as the main crystal, the average linear thermal expansion coefficient in the range of 30 to 380 ° C. is −10 to 10 × 10 ⁻⁷ / ° C., and β-OH is 0 _{Li 2 O-Al 2 O 3} -SiO 2 based transparent crystallized glass which comprises .35 / mm or more is disclosed.

This crystallized glass has a β-OH of 0.35 / mm or more by controlling the oxygen concentration contained in the fuel as a heat source for melting and increasing / decreasing the amount of water in the combustion gas. Even if it is exposed to ₂ SO ₄ gas for a long time, it has an advantage that the surface of crystallized glass is not clouded. For this reason, this crystallized glass is widely used as a window material for a combustion apparatus.
JP-A-1-308845 JP 2000-44282 A

As described above, Li ₂ O—Al ₂ O ₃ —SiO ₂ -based transparent crystallized glass has excellent characteristics, and thus is widely used as a window material for a combustion apparatus, but Li ₂ O—Al ₂ The O ₃ —SiO ₂ based transparent crystallized glass itself does not have sufficient antifouling properties. Therefore, combustion residue such as soot discharged from the fuel such as soot adheres to the surface of the crystallized glass, the transparency of the crystallized glass is lost, and the aesthetics as a window material of the combustion device There was a problem that was damaged. In addition, when a carbide component or the like adheres to the surface of the crystallized glass, the infrared transmission characteristics of the crystallized glass are lowered, and the heating effect of the combustion apparatus is impaired.

  In particular, since the window material of a combustion device such as an oil stove is incorporated in the combustion device, it is necessary to disassemble the combustion device in order to clean the window material, and to separate the window material and the combustion device. there were. Furthermore, in general, the window material of a combustion device such as an oil stove has a cylindrical shape, and combustion residue is mainly attached to the inner surface of the cylinder, so that it is more difficult to clean the window material. There were also circumstances.

  In addition, oil stoves used in cold districts are usually operated with a high heat quantity during the winter, so the window material of the combustion equipment is given antifouling properties and the window material is maintained. Making it free was an important issue.

  In view of such circumstances, conventionally, in order to prevent adhesion of dirt on the glass surface, it has been considered to make the glass surface water- and oil-repellent. For example, in JP-A-9-2840, a water-repellent thin film is formed by forming a fluorine-based chemical adsorption film on a glass surface. Japanese Patent Application Laid-Open No. 2002-326841 also considers processing the surface roughness of glass to 0.05 to 0.4 μm and coating the surface with a water- and oil-repellent coating of a silane compound. Yes.

  However, since the coating film shown in the above document is an organic compound-based film including a silane compound, it has poor heat resistance, and has a heat resistance sufficient to withstand actual use as a window material for a combustion apparatus. Did not have temperature.

As a result of various studies, the present inventor has made SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass having an oxide-based ceramic coating film having antifouling properties on the surface as a window material for a combustion apparatus. The above-mentioned problems have been solved by using and the present invention has been proposed.

Specifically, in order to achieve the above object, first, the present invention provides an oxide ceramic having antifouling property on the surface of a SiO ₂ —Al ₂ O ₃ —Li ₂ O based transparent crystallized glass. It is a window material for a combustion apparatus in which a film is coated.

Second, the present invention is characterized in that the oxide ceramic film is SiO ₂ .

  Thirdly, the present invention is characterized in that the combustion device is an oil stove. In the present invention, the “petroleum stove” refers to a stove that uses petroleum-derived liquid fuel such as a light oil stove, a kerosene stove, and a heavy oil stove.

  Fourthly, the present invention is characterized in that the window material for the combustion apparatus has a cylindrical shape.

Fifth, SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass is expressed in terms of% by weight, with SiO ₂ being 63 to 75%, Al ₂ O ₃ being 15 to 25%, and Li ₂ O being 1 to 5%, MgO is 0 to 4%, ZnO is 0 to 5%, TiO ₂ is 0~6%, ZrO ₂ is 0~3%, P ₂ O ₅ is 0~2%, Na ₂ O is 0 2% and K ₂ O has a composition of 0 to 2%.

  The present invention will be described in detail below.

An oxide ceramic coating film is formed on the surface of the SiO ₂ —Al ₂ O ₃ —Li ₂ O transparent crystallized glass of the present invention. The oxide ceramic coating film has antifouling properties against combustion residue such as carbide. Combustion residues that contaminate the window of combustion equipment include fuel residues such as soot (carbide, sodium component, chlorine component, calcium component, etc.), foreign matter such as dust, packing material residue, etc. included.

As the oxide ceramic film, Al ₂ O ₃ , TiO ₂ , SiO ₂ , ZrO ₂ or the like can be used. These oxide-based ceramic films have lower surface free energy than the SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass and have a smooth surface, so that dirt is less likely to adhere to them. In particular, SiO ₂ is preferable as the oxide ceramic film for the following reasons.

Thermal expansion coefficient of the SiO ₂ is because it approximates the _{SiO 2 -Al 2 O 3 -Li 2} O -based transparent crystallized thermal expansion coefficient of the glass, the stress is hardly enters the coating film, good adhesion of the film It is. Further, the refractive index of SiO _{2 is} because it approximates the _{SiO 2 -Al 2 O 3 -Li 2} O system transparent crystallized refractive index of the glass, _{SiO 2 -Al 2 O 3 -Li 2} O -based transparent crystallized Even if the SiO ₂ coating film is formed on the glass, the transparency of the crystallized glass is not impaired, and the beauty of the crystallized glass is not lost.

The film thickness of SiO ₂ formed on the surface of the SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass is preferably 300 to 2000 mm, more preferably 500 to 1500 mm, and still more preferably 800 to 1200 mm. When the SiO ₂ film thickness is larger than 2000 mm, interference color is generated in the film and the aesthetic appearance is impaired.

The coating film of SiO ₂ can be formed by various methods. For example, there is a method in which a liquid Si alcoholate is applied to the surface of the crystallized glass by dipping, spraying or brushing. There is also a method of directly forming the SiO ₂ film on the surface of the crystallized glass by a method such as sputtering or low pressure CVD. In particular, in the present invention, it is preferable to form a coating film of SiO _{2 by} the following method.

First, a SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass on which a coating film is to be formed is prepared. Next, liquid Si alcoholate is applied to the surface of the crystallized glass by dipping. In particular, when the crystallized glass has a cylindrical shape, when Si alcoholate is applied to the surface of the crystallized glass by dipping, coating unevenness is unlikely to occur on the inner and outer surfaces of the cylinder, and a uniform film thickness can be easily formed. preferable.

Next, heat treatment is performed at 100 ° C. to 1000 ° C. to decompose the organic component, thereby forming a coating film of only the oxide component SiO _{2 on} the surface of the crystallized glass. If the heat treatment temperature is lower than 100 ° C., the organic components are not sufficiently decomposed, and if it is higher than 1000 ° C., there is a possibility that SiO ₂ is thermally decomposed. The heat treatment temperature is preferably 400 ° C to 800 ° C, more preferably 500 ° C to 700 ° C.

The method for forming a coating film of SiO ₂ by this method has a feature that it can be formed simply by applying a heat treatment after applying Si alcoholate, and is extremely easy to operate.

Note that oxide ceramic films other than SiO ₂ can also be formed by coating such as dipping, spraying, brushing, sputtering, and low pressure CVD.

The SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass is expressed in wt%, and SiO ₂ is 63 to 75%, Al ₂ O ₃ is 15 to 25%, Li ₂ O is 1 to 5%, MgO 0-4%, ZnO 0-5%, TiO ₂ 0-6%, ZrO ₂ 0-3%, P ₂ O ₅ 0-2%, Na ₂ O 0-2%, K ₂ O preferably has a composition of 0 to 2%.

  The reason why the composition range of the crystallized glass in the present invention is limited as described above is as follows.

SiO ₂ is a glass network former and an essential component for constituting a crystal. However, if the SiO ₂ content is less than 63%, the glass tends to devitrify and the chemical durability is deteriorated. On the other hand, when SiO ₂ is more than 75%, the meltability of the glass is deteriorated.

Al ₂ O ₃ is an essential component for constituting the crystal. However, when Al ₂ O ₃ is less than 15%, the glass tends to be devitrified and the chemical durability is deteriorated. Further, when Al ₂ O ₃ is more than 25% is poor meltability.

Li ₂ O is an essential component for constituting a crystal. However, when Li ₂ O is less than 1%, desired crystals are hardly precipitated. On the other hand, when Li ₂ O is more than 5%, the chemical durability of the glass is deteriorated, and cracks, peeling and the like are likely to occur.

  MgO is a component for constituting a crystal. However, when MgO is more than 4%, the thermal expansion coefficient becomes too large.

  ZnO is also a component for constituting a crystal, but if it is more than 5%, the glass tends to devitrify.

TiO ₂ acts as a nucleating agent, but when it exceeds 6%, the color tone becomes brown and the transparency is impaired.

ZrO ₂ acts as a nucleating agent, but if it exceeds 3%, the glass tends to devitrify and the chemical durability is deteriorated.

When the total amount of TiO ₂ and ZrO ₂ is less than 3%, the function of nucleation is not sufficient, resulting in coarse crystals and poor chemical durability. On the other hand, when the total amount of TiO ₂ and ZrO ₂ is more than 9%, the meltability of the glass is deteriorated and the color tone becomes brown and the transparency is impaired.

When P ₂ O ₅ is more than 2%, chemical durability is deteriorated.

Na ₂ O and K ₂ O act as fluxing agents, but if they are more than 2% each, the chemical durability is remarkably deteriorated.

Furthermore, clarifiers such as As ₂ O ₃ , Sb ₂ O ₃ , SnO ₂ , Cl and SO ₃ can be added up to 2% in total. Further, other components can be added within a range that does not impair the characteristics.

In particular, Neoceram N-0 manufactured by Nippon Electric Glass Co., Ltd. is preferably used as the SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass. Neoceram N-0 is transparent, excellent in infrared transmission characteristics and mechanical strength, has a thermal expansion coefficient of −3.0 × 10 ⁻⁷ / ° C. in a temperature range of 30 to 750 ° C., and has a thermal expansion coefficient close to 0. Therefore, it has the feature that it does not break even when a thermal shock of 800 ° C. is applied.

  In the crystallization of the crystallized glass of the present invention, the temperature is increased from 720 to 760 ° C. at a rate of 160 to 200 ° C./hour, and maintained at that temperature (nucleation temperature) for 0.5 to 20 hours for nucleation. Next, the temperature is raised to 800 to 880 ° C. at 20 to 60 ° C./hour, and the crystal growth is performed at that temperature (crystal growth temperature) for 0.5 to 20 hours. Is preferred.

  If the rate of temperature rise to the nucleation temperature is slower than 160 ° C./hour, crystal nuclei will be formed before reaching the nucleation temperature. When the rate of temperature rise to the nucleation temperature is faster than 200 ° C./hour, crystal nuclei are not sufficiently formed. Further, when the nucleation time is shorter than 0.5 hours, crystal nuclei are not sufficiently formed. If the nucleation time is longer than 20 hours, the crystal grows until the crystal growth temperature is reached.

  If the rate of temperature rise to the crystal growth temperature is slower than 20 ° C./hour, the crystal becomes coarse before reaching the crystal growth temperature. If the rate of temperature rise to the crystal growth temperature is faster than 60 ° C./hour, the crystal does not grow sufficiently. Further, if the crystal growth time is shorter than 0.5 hours, the crystal does not grow sufficiently. If the nucleation time is longer than 20 hours, the crystal becomes coarse.

(Example)
As the SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass, Neoceram N-0 (outer diameter 130 mm, length 150 mm, wall thickness 1.8 mm) manufactured by Nippon Electric Glass Co., Ltd. was used. This crystallized glass is dipped in a liquid Si alcoholate, and the Si alcoholate is applied to the surface of the crystallized glass. Next, a heat treatment was performed at 600 ° C. for 30 minutes to form a 1000 Å thick SiO ₂ film on the surface of the crystallized glass.

The above-mentioned cylindrical SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass was continuously used for 200 hours as a window material for a petroleum stove. The combustion temperature of the stove was adjusted to a temperature at which the outer surface temperature of the crystallized glass cylinder was 400 ° C., and kerosene was used as the fuel for the oil stove. This condition is an accelerated test for evaluating the antifouling property of the coating film, and it can be determined that the antifouling property of the coating film has a long-term antifouling property if there is no combustion residue residue attached under this condition. .

As a _{result, SiO 2 -Al 2 O 3 -Li} 2 O -based transparent crystallized glass coated with SiO ₂ film, no adhesion of the combustion product residues and the like, the visible light transmittance is equivalent to the initial value, transparency Was held. Moreover, the infrared transmission characteristic of the crystallized glass also maintained the initial value, and the heating effect of the petroleum stove was not deteriorated.

As a result, it is judged that the SiO ₂ —Al ₂ O ₃ —Li ₂ O transparent crystallized glass coated with the SiO ₂ film can be used continuously for a long period of time as a window material for an oil stove without maintenance. .

(Comparative example)
A sample having the same shape and the same material as the cylindrical SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass used in the examples was used as a comparative sample. However, unlike the example, the surface of the crystallized glass was not coated with the SiO ₂ film. As in the above example, the transparent crystallized glass was continuously used for 200 hours as a window material for a petroleum stove. As in the example, the combustion temperature of the stove was adjusted to a temperature at which the outer surface temperature of the crystallized glass cylinder was 400 ° C., and kerosene was used as the fuel for the petroleum stove.

As a result, the SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass not coated with the SiO ₂ film has a gray combustion residue residue attached to it, and the transparency is remarkably impaired. The light transmittance was significantly reduced. In addition, the infrared transmission characteristics of the crystallized glass were lowered due to the adhesion of gray combustion residue and the like, and the heating effect of the petroleum stove was lowered. Furthermore, the appearance of the crystallized glass has been impaired due to adhesion of gray combustion residue and the like.

As a result, the SiO ₂ —Al ₂ O ₃ —Li ₂ O transparent crystallized glass not coated with the SiO ₂ film cannot be used continuously for a long time as a window material for petroleum stoves without maintenance. It is judged.

(The invention's effect)
As described above, the window material for a combustion apparatus made of the SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass on which the antifouling oxide ceramic coating film according to the present invention is formed is a combustion product. It is clear that residues and the like are difficult to adhere, and the transparency is not easily lost, and has an excellent antifouling function.

  Therefore, since the window material for a combustion apparatus according to the present invention can be maintenance-free for a long time, it is particularly difficult to clean a combustion residue residue and the like adhering to the window material surface. Suitable as a material.

Claims (5)

A window material for a combustion apparatus, wherein an oxide ceramic film having antifouling properties is coated on the surface of a SiO ₂ —Al ₂ O ₃ —Li ₂ O transparent crystallized glass. The window material for a combustion apparatus according to claim 1, wherein the oxide ceramic film is SiO ₂ .   The window material for a combustion apparatus according to claim 1 or 2, wherein the combustion apparatus is an oil stove.   The window material for a combustion apparatus according to any one of claims 1 to 3, wherein the window material for the combustion apparatus has a cylindrical shape. SiO ₂ —Al ₂ O ₃ —Li ₂ O-based transparent crystallized glass is expressed in wt%, SiO ₂ is 63 to 75%, Al ₂ O ₃ is 15 to 25%, Li ₂ O is 1 to 5%, MgO 0-4%, ZnO 0-5%, TiO ₂ 0-6%, ZrO ₂ 0-3%, P ₂ O ₅ 0-2%, Na ₂ O 0-2%, K The window material for a combustion apparatus according to any one of claims 1 to 4, wherein ₂ O has a composition of 0 to 2%.