Hebei Messi Biology Co., Ltd. stated that high-performance magnesium oxide with specific reactivity, particle size and flow characteristics can be used to manufacture transformer silicon steel sheets with grain orientation. During the annealing process, the steel is treated with a magnesium oxide coating to form a glass-ceramic film (forsterite). The insulating properties of this film are very important, as is the selection of different magnesium oxide grades.
The surface quality of oriented silicon steel mainly depends on the formation quality of the magnesium silicate bottom layer. In normal production, magnesium silicate bottom layer defects such as dew crystal, blackening, reddening, bluishness, and color difference often occur. In order to improve the quality of the bottom layer, this paper studies the influence of magnesium oxide activity, magnesium oxide coating process, and decarburization time on the formation of magnesium silicate bottom layer. The results show that the higher the magnesium oxide activity, the better the bottom layer formation; the water content of the magnesium oxide coating needs to be controlled within a certain range. If the water content is too low, it will cause dew crystal defects; the extension of decarburization time is conducive to the formation of the magnesium silicate bottom layer.
A method for controlling the temperature of magnesium oxide coating liquid for oriented silicon steel belongs to the field of metallurgical technology. The control method is carried out in a magnesium oxide coating system composed of a liquid distribution tank and a circulation tank, wherein the liquid temperature of each liquid distribution tank and the liquid temperature of each circulation tank are controlled by a refrigerator, a first temperature regulating valve is provided on a pipeline connecting the refrigerator and each liquid distribution tank, and a second temperature regulating valve is provided on a pipeline connecting the refrigerator and each circulation tank, the refrigerator is turned on and the temperature is set to ‑10-0°C, the first temperature regulating valve is opened and the valve opening is adjusted to 20-80% to control the liquid temperature in the liquid distribution tank to 0-15°C, the second temperature regulating valve is opened and the valve opening is adjusted to 20-100% to control the liquid temperature in the circulation tank to 5-20°C, until the surface coating of the oriented silicon steel is finished. The control method designed by the present invention realizes the control of the water content of the magnesium oxide coating liquid to a certain extent.