The opacification of enamel enamel is mainly due to the diffuse reflection of light caused by opacity particles. So, what are the main forms of opacification caused by opacity particles?

1. Crystallization and opacification

This form of opacification is mainly caused by introducing a certain amount of opacifying agent into the enamel formula, so that they can be fully dissolved in the enamel matrix at high temperature during melting, and then dissolve into the matrix when the product is fired. The opacity particles crystallize from the glass phase to produce opacity (such as the opacity of titanium enamel). The other is that it dissolves into the enamel matrix at high temperature, and crystallizes at the granulation (sheet) temperature to produce opacity, such as the opacity of fluorine-containing raw materials.

2. It is dispersed phase and partially dissolved at high temperature, and the dispersed phase is emulsified when it is rapidly cooled into granules (tablets).

When the enamel is melted, the opacifying agent dissolves or disperses in the enamel melt, and when it is quenched into granules (pieces) after melting, the opacity is precipitated from the matrix, or dispersed in the glass phase space in the form of particles, causing opacification ( Such as the opacification of antimony enamel).

3. Solid particle insoluble fine dispersion emulsion

When the frit is ground into a enamel slurry, a certain amount of opacifying agent, such as SnO2, NaSbOs, etc., is added. When the product is fired within a short period of time, it is impossible to completely dissolve into the enamel matrix, and most of it is dispersed and suspended in it as fine solid particles, resulting in opacification.

4. Gas opacification

Gas opacification is mainly due to the SiFCOz formed during the melting of enamel, and the small bubbles formed by the decomposed gas of organic matter and fluorine added during the grinding of enamel slurry, which are dispersed in the enamel matrix, causing light to scatter and produce opacity.

The opacifying agent introduced during frit grinding, such as SnO2 and ZrO2 dispersed in solid particles, increases the viscosity of the enamel and makes it difficult for the gas to escape when the product is fired. At the same time, the impurities contained in them will decompose at high temperature and produce bubbles. Therefore, it is beneficial to the opacification of enamel.

5. Liquid emulsion

This kind of opacification is caused by introducing ZrO2 into the enamel. When the glass body is at high temperature, the phenomenon of liquid separation between silica glass and zirconium glass will cause opacification.

6. Microcrystalline opacification

Microcrystalline opacification is to place the fired and still transparent product in a specific temperature range for a long time heat treatment, so that tiny crystals with a diameter of 0.5 to 20 microns and different sizes are precipitated inside the enamel, causing light. Scattering causes opacification.

This kind of enamel has higher physical and chemical properties than ordinary enamel, but the luster of the porcelain surface is poor. It can be coated with a layer of light enamel to improve its luster.

In fact, two or more opacity forms of enamel often exist at the same time. Hunan Nolifrit is a supplier of enamel frits and inorganic pigments, providing customers with one-stop service, if you have any needs, please contact us!