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Your location: Home > Related Articles > Interpretation of the cause of damage to the enamel kettle and preventive measures-

Interpretation of the cause of damage to the enamel kettle and preventive measures-

Author:QINSUN Released in:2023-05 Click:130

The enamel kettle is formed by spraying high-silicon enamel on the surface of low-carbon steel tires and baking at a high temperature of about 900°C to adhere the enamel. enamel on the surface of metal steel tires. Due to the mechanical properties and physical properties of these two materials, the performance is different, so the reasons for the damage of the enamel kettle are also various. Generally, there are several reasons:

1. Mechanical damage The impact resistance of enamel is very low, and any metal or hard object will hit it. May damage enamel. Therefore, when using the enamel kettle, strictly avoid metal and hard objects falling into the kettle. If there is a blockage, it should be dredged with a plastic rod. 

 2. Damage caused by heat stress
The enamel kettle is fired at 900°C, and the enamel and the steel plate are bonded together after cooling. Since the linear expansion coefficient and elongation of enamel are small than that of steel plate, the deformation of enamel glass after cooling is less than that of steel plate, and the enamel is bonded by the steel plate to generate compressive stress. After the enamel kettle is made, the enamel glass experiences pre-compression stress, while the steel plate experiences pre-tensile stress. Since the prestress is related to the coefficient of linear expansion and elongation, and the coefficient of linear expansion and elongation is closely related to temperature, the working temperature of the enamel kettle has a great influence on the use of the enamel kettle. If the stress generated by the enamel exceeds its service stress due to large changes in temperasure, the enamel will be destroyed.

Therefore, the enamel layer of the enamel kettle changes quickly when it is cold or hot, and it is very easy to explode the porcelain. Therefore, the enamel kettle has a temperature resistance limit: the temperature is 200°C, and the temperature changes rapidly: cold shock <1IO~C, thermal shock <120°C. Too much difference between material temperature and kettle body temperature when feeding, too much steam when heating, and cooling too quickly can also lead to porcelain explosion. Therefore, the heating and cooling of the enamel kettle should be slow and even during use, and the cooling should be carried out in stages. 

 3. Processing stress damage
When processing the kettle body, a large amount of internal stress is generated due to rolling, de stamping and welding. These stresses must be completely eliminated before enamelling. If removal is not complete, the enamel will chip the porcelain. This damage tends to occur within the first three months after commissioning. Therefore, heat treatment or aging treatment of the embryo body can prevent the porcelain from bursting.

 4. Electrostatic puncture
Stir the liquid with suspended matter in the enamel kettle, the suspended matter will strongly rub against the enamel, and at the same time, the suspended matter itself will generate also friction, which will generate a large amount of static charge, high static electricity The charge has a strong puncture effect on the enamel, which will cause enamel pitting, so stirring the speed should not be too fast.

5. Corrosion by hydrogen evolution
The boiler envelopeenamel loire will chip and rust after being used for a period of time. Corrosion occurs by release of hydrogen (Fe+2HCl=FeC12+H2o some of the H atoms diffuse into the holes of the metal and combine into }b, these H: due to the compactness of the enamel, they can no longer diffuse outward, so when Hz accumulates to a certain extent, when a certain power is formed, the enamel breaks, so when cleaning the scale with pickling, a pad must be added and the coolant in the sheath should be neutral.

6.Unqualified substrate material
In order to save cost, some manufacturers use Q235 steel instead of virgin bod, which causes directly the gasification of carbon and sulfur in the steel during the enamel firing process, creating a space between the enamel layer and the substrate, the enamel A large number of air bubbles form on the interior of the couche, resulting in a decrease in the bond strength of the enamel. The enamel layer changes quickly when it\'s cold or hot, and porcelain is very easy to explode. Therefore, the enamel kettle is made of low carbon and low sulfur steel, which can prevent the porcelain from bursting.

7. The baking quality of enamel is not good
Some enamel kettle manufacturers have a simple production environment, rust removal and dust prevention do not are not up to standard, resulting in poor adhesion of the underglaze and the substrate. Some reduce the number of enamel firings, increase the thickness of each layer, make the internal strength too large, and affect the service life of the enamel kettle. Therefore, only in strict accordanceIt is with the manufacturing processes that the quality of the enamel pot can be guaranteed.