Defects of Enamel Products Caused by Stress
During the production and processing of enamel products, cracks, de-porcelain, etc. are more common defects, with an important influencing factor is "stress." Stress refers to an interactive force generated by the object due to external or cause (force, humidity, temperature field changes, etc.), and is used to resist the effects of the external cause, and attempt to restore the object from the deformation position to The position before deformation. It is briefly analyzes how the stress is the defect of enamel products caused by the stress.
First, permanent stress and temporary stress
There are two stresses of enamel products. It is called permanent stress during processing, and the stress generated during use is temporary stress.
Second, the cause analysis of stress
There are many reasons why the permanent stress is caused. The most important thing is the thermal expansion difference of the enamel and the metal. The larger the difference between the expansion coefficient between the enamel layer and the metal, the larger the permanent stress generated after the product is fired, the enamel layer It is possible to produce cracks or decomposed.
The size of the temporary stress is a big relationship with the thermal conductivity of the enamel layer. In the process of use, if the thermal conductivity of the porcelain layer is poor during use, there is a phenomenon that expands or shrinks unevenness when heated or cool is uneven, and thus stress is produced.
Third, the defects caused by stress
The stress is the degree of damage to the enamel article, in addition to the elasticity of the enamel frit , the pressure-resistant tensile strength, thermal expansion and other properties, and the thickness of the porcelain layer is related to the thickness of the billet, the blank shape and the mechanical strength of the blank.
1. The better the elasticity of the porcelain enamel frit , the better the buffer performance, and the crack produced by stress will be reduced;
2. When the thickness of the metal blank is not changed, the thickness of the porcelain layer increases, the elastic decrease, the possibility of the cracked or de-phenyle of the enamel layer caused by the permanent stress; the thickness of the slab is increased when the thickness of the porcelain layer is not changed. The possibility of cracks or de-phenamines caused by temporary stress will be reduced. In order to prevent the production of defects, enamel manufacturers can reduce the thickness of the enamel layer and increase the thickness of the blank;
3. The shape of the blank and the mechanical strength of the body: the shape is flat, particularly the inner surface of the concave spherical shape, which is not easy to produce cracks or depleted porcelain, and the outer surface of the spherical surface is precipitated, and the smaller the radius of curvature of the spherical surface is smaller. Dechanical.