The must-have properties of magnesium oxide for silicon steel coating

Silicon steel sheet is called electric porcelain steel sheet abroad, and its main purpose is to make motor iron core and transformer iron core. In order to meet the requirements of the electrical and physical properties of the iron core, there is a high-temperature annealing process of 1200-1250 degrees Celsius for the silicon steel sheet during the manufacturing process of the grain-oriented silicon steel sheet. In order to complete the regular orientation arrangement of the iron metal atoms during the annealing process and form an excellent insulating film on the surface of the silicon steel sheet, this process must take 7 days to complete. In such a long high-temperature process, the general silicon steel The piece will turn into a lump of iron. Therefore, it is necessary to apply a high-temperature annealing release agent between the silicon steel sheets to prevent the sintering of the silicon steel sheets, and at the same time, the release agent must be able to form an excellent insulating film with the silicon on the surface of the silicon steel sheet.

The role of magnesium oxide is firstly as a high-temperature annealing separator in the manufacture of silicon steel sheets. At the same time, it has the function of forming a magnesium silicate glass insulating coating with silicon, and it can remove impurities such as sulfur and phosphorus in silicon steel during high-temperature reactions. effect. Hebei Messi Biology Co., Ltd. stated that silicon steel grade magnesium oxide must have the following properties:

1. It must have high chemical purity to avoid adverse effects on the formation of magnesium silicate coating under high temperature conditions.

2. It must have good suspension performance in water. When magnesia is coated on the surface of silicon steel sheets during the manufacturing process of silicon steel sheets, it is generally used to mix magnesia and water into a slurry for coating operation. In order to prevent the deposition of magnesia during the coating process, it is necessary to ensure that the magnesia Suspension properties in water.

3. Must have a low hydration rate. The hydration rate of magnesium oxide refers to the percentage of magnesium hydroxide generated from magnesium oxide in water under certain temperature conditions and within a certain period of time. The surface of the silicon steel sheet is coated with magnesium oxide slurry, rolled into a steel coil, and placed in a bell furnace for annealing. When annealing, the water must first be drained. The more magnesium hydroxide is formed, the longer the drainage time will be. On the other hand, too much water will easily form iron oxide with iron, which will affect the formation of magnesium silicate film. The hydration rate of magnesium oxide is a measure of silicon steel grade oxidation. Important indicator of magnesium.

4. Must have certain activity. Magnesium oxide with high activity is easy to react with silicon oxide to form magnesium silicate glass body, but too high activity will increase the hydration rate of magnesium oxide, which is unfavorable for the formation of magnesium silicate film and affects the activity of magnesium oxide. should be considered comprehensively.

5. Magnesium oxide slurry has stronger adhesion to the surface of silicon steel sheet. In this way, after magnesium oxide is coated on the silicon steel sheet and dried, it will not fall off from the steel sheet after strong vibration and friction.

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