Analysis of 8 common processes of black core defects in ceramic bodies | Goway Sharing
The influence of each process on the black heart
In the actual production process, especially once-fired white billet products, special control of organic matter and iron content is required. For example, the organic matter in mud raw materials, the coal content in talc, and even the quality of sodium rot will have an adverse effect on the product.
At present, corresponding equipment has appeared in the industry, which can remove branches and leaves in the material before the raw materials are added to the ball mill, but for humus, there is still no way. The impact can only be reduced by controlling its dosage. Such as the black talc in Jiangxi, the black inside is associated with coal-like substances. Once the amount is high, black hearts are prone to appear. However, low-sodium humate is produced from low-quality lignite and low-sodium, so the organic carbon chain length is relatively high, and when the amount is large, problems are relatively easy to occur.
The effect of body moisture on the black core is mainly used when the moisture in the body is high, which will result in fewer pore channels in the body. During firing, the exhaust channel is lacking when the organic matter is burned, and it is easy to cause organic matter. Combustion gas is not easy to escape. This impact is an indirect impact. During the rainy season in the south, the body color should be relatively dark.
The subdivision content in the green body is too high
In the green body, if the content of fine powder is too high, it will easily block the exhaust of the combustion gas, resulting in a black core phenomenon.
Add other pollutants to the powder
During the production process, special attention should be paid to accidental entry of pollutants. Such as the impact of carbon particles caused by incomplete combustion during spray drying, equipment leakage and oil dripping, and the belt wear and tear into the green body. These situations, if they occur, generally appear in individual products rather than on a large scale.
If the molding pressure is too high, the surface of the green body will be densified, so that the combustion gas in the green body cannot escape, and the black core phenomenon will also appear. Similarly, if the shape of the mold is more complex, the molding pressure of each area of the product is inconsistent, resulting in inconsistent densities in each area, and black core phenomenon may also occur.
Brick type thick
If the brick is too thick, it will also cause difficulty in gas removal, resulting in reduction reactions and black hearts.
Low glaze melting temperature
The glaze has a low initial melting temperature or contains low-temperature frit. At a lower firing temperature, the glaze will cover the surface of the body, making it difficult to exhaust the body. It may cause black hearts and even bubbling.
A good firing system can well restrain the appearance of black hearts. However, if the oxidation is insufficient, the firing time is too short, etc., which may cause black hearts. After all, due to the lack of mud, manufacturers may deliberately introduce organic matter in order to increase the strength of the green blanks. If the firing system is not arranged, the probability of black hearts will be greatly increased.
Generally speaking, control the organic content and iron content of the raw materials, the introduced body enhancer pay attention to control the carbon chain length, ensure the air permeability in the body, arrange a good firing system, and pay attention to the production environment. Good to prevent black hearts.