JPS63185877A - Protective coating material for refractories available for smoke burning - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applied to oxidized tiles, which are applied to refractories such as shelves and centers used in a series of smoldering processes from firing to smoking of oxidized tiles. The present invention relates to a protective coating material for refractories used in

(Conventional technology) Conventionally, in order to smoke and fire oxidized tiles, the tile base is placed on a shelf made of refractory material such as mullite award refractory, placed in a kiln, and heated to the maximum firing temperature in an oxidizing atmosphere. The product is made by exposing the fired product to a reducing and fuming atmosphere during the cooling process to carburize and adhere a carbonaceous compound whose main component is carbon to the base material, which has the effect of increasing the tn aqueous property of the surface. be. However, although the roof tiles and roof tiles that are manufactured go through the oxidation and reduction/smoking process once, the refractories such as the kiln tools used to fire the roof tiles and roof tiles are used over and over again.
If such refractories are repeatedly exposed to a reducing atmosphere, the carburization phenomenon in which carbon accumulates in the refractories will increase. "Page 1321 "CO gas test method"
As described in the above section, carburized carbon can cause bricks to collapse, and there is still no technology that can prevent this carburization phenomenon in common with all refractories.

(Problem to be solved by the invention) For this reason, in the kiln tools made of refractories used for smoking firing, due to the remarkable carburizing effect during smoking firing, carbon penetrates between the particles of the refractory, and the firing process is difficult. Repeated use weakens the bonding force between refractory particles, resulting in a decrease in strength, which can lead to breakage in the kiln, and when such breakage occurs, the fired product collapses in the kiln during firing. In order to prevent carburization, which can lead to serious accidents, it is possible to coat the surface of the refractory with a glass layer, but since the glass layer has a low melting point and poor heat resistance, it may cause foaming during firing. This may cause the product to melt or adhere firmly to the product to be fired, causing product defects.

(Means for Solving the Problems) The present invention relates to a protective coating material for refractories used in smoking and firing in order to solve the above problems all at once. ``It is characterized by the addition of a flux substance that reacts with the alkaline component of the main components at a high temperature close to the maximum firing temperature to form a slightly amorphous substance.

The feldspar raw material that is the main component in the present invention is not only the feldspar raw material itself quarried from feldspar deposits, but also produced as a by-product during flotation of feldspar, anti-flinder, silica stone, frog's eye clay, kaolin, alumina, wollastonite, and feldspar. If the main component contains 40% by weight or more of feldspathic bone, the feldspathic raw material that is the main component is used in about 60 to 98% of the total weight. Ru. On the other hand, the flux material to be added to the main component may be one that reacts with the alkaline component in the main component at a high temperature close to the maximum firing temperature of the product to be fired to form a slightly amorphous material. Calcium carbonate, strontium carbonate, barium carbonate, lithium carbonate, blast furnace slag, dolomite, sodium carbonate, frit, crushed glass waste, etc. may be used as appropriate, and the amount of addition is 2 to 4.
The content is preferably about 0% by weight. Also, in order to improve coating properties on refractories, water and CM are added to the above components.
It is used by adding a glue such as C, and a coating layer thickness of about 0.2 to 1 mm is sufficient. Furthermore, if the above-mentioned flux substance is too small compared to the main component, the melting point of the coating material will be too high, and even if the maximum firing temperature is reached, the coating material will be mostly crystalline, and it will not reach the smoldering temperature range. On the other hand, if there is too much flux material, the melting point of the coating material will be low, and it will foam at the maximum firing temperature or fuse to the fired product, resulting in product defects. The amount of feldspar contained in the coating material may be adjusted according to the maximum firing temperature of the product to be fired so that it reacts at a high temperature close to the maximum firing temperature and forms a slightly amorphous substance. When there is less bone, there is less formation of amorphous material (therefore, carburization occurs).

(Function) The protective coating material for refractories used in such smoking firing is made into a slurry by adding water and glue, and then applied to the surface of shelf boards made of mullite refractories, mullite/cordierite refractories, etc. When the tile base is coated on the tile base and fired and smoked, first, when the maximum firing temperature is reached, the flux substance reacts with the alkali content in the feldspar raw material, which is the main component. Forms a slightly amorphous substance,
A mixture of crystalline and amorphous substances becomes a layer that prevents reducing atmospheric gases from penetrating into the surface layer of the refractory during the smoking process that follows this firing, and this layer also forms a layer that prevents the refractory from foaming. Since it does not melt and firmly adhere to the tile base, there is no possibility of product defects due to the tile and shelf sticking together, and when using such refractories for the second time or later, Since a layer is formed on the surface layer that is difficult for the reduction and fuming atmosphere gas to penetrate, there is no carburization phenomenon described above, and the bonding force between refractory particles is weakened, which reduces the possibility of strength deterioration and breakage. Durability is significantly increased. On the other hand, feldspar, silica, frog's eye clay, kaolin,
There is no carburization prevention effect unless the coating is coated with alumina or wollastonite alone and flux substances such as calcilum carbonate, barium carbonate, lithium carbonate, strontium carbonate, dolomite, or blast furnace slag are added.

(Example) Next, to describe an example, various coating material formulations were prepared in which calcium carbonate, barium carbonate, lithium carbonate, strontium carbonate, dolomite, and blast furnace slag were added in predetermined proportions to feldspathic raw materials. Prepared, add 0.3% by weight of CMC and 45 to 55% by weight of water, mix and grind in a ball mill to form a slurry, and further,
Add an appropriate amount of water and place it on a shelf made of mullite refractory.
Coated with Tsuru Atsushi. The dried tile base is placed on this shelf board and sent by a trolley to a tunnel furnace for firing oxidized tiles, with a maximum firing temperature of 1100°C and a smoking temperature of 950°C.
The table below shows the results of observing the carburizing situation when treated at temperatures between 850°C and 850°C, together with comparative examples.

(Effects of the Invention) As is clear from the above description, when the present invention is applied and used on the surface of a refractory, the surface layer of the refractory has a layer containing a mixture of crystalline and amorphous substances that makes carburization difficult. is formed, and even if the temperature is repeatedly raised to the maximum firing temperature and exposed to a lower reducing and smoking atmosphere, the carburization phenomenon in which carbon penetrates into the refractory base disappears, and the process of smoldering and firing the tiles is repeated. Even with the use of refractories, carbon accumulates between the refractory particles and the bonding strength between the refractory particles is less likely to weaken, resulting in less strength deterioration.
It has the advantage of not breaking in the kiln, and is effective as a protective coating for refractories used in smoking and firing, making it effective both for closing kiln tools and coating the refractory lining inside the kiln. This is an extremely large contribution.

[Brief explanation of the drawing]

The drawing is a graph showing the comparison results of a bending strength test in an exposure test in a tunnel kiln using a shelf board using the present invention and a shelf board not using the present invention.

Claims (1)

[Claims] Smoking firing characterized by having a feldspathic raw material as the main component and adding a flux substance that reacts with the alkaline component in the main component at a high temperature close to the maximum firing temperature to form a slightly amorphous material. A protective coating material used for refractories.