Hebei Messi Biology Co., Ltd. stated that it used salt lake brine to prepare silicon steel grade magnesium oxide. It used X-ray diffractometer, laser particle size analyzer, high and low vacuum scanning electron microscope and other analytical instruments to investigate the calcination of brine magnesium precipitation and calcination process to prepare silicon steel grade magnesium oxide. During the process, the calcination temperature and calcination time affect the activity, morphology and particle size of magnesium oxide. The results show that as the calcination temperature increases and the calcination time prolongs, the activity of magnesium oxide gradually decreases; as the calcination temperature increases, the morphology of magnesium oxide gradually transforms into regular flaky particles.
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 defects such as exposed crystals, blackening, redness, blueness, and color difference often occur. In order to improve the quality of the bottom layer, Hebei Messi Biology Co., Ltd. studied the influence of magnesium oxide activity, magnesium oxide coating process, and decarburization time on the formation of magnesium silicate bottom layer. The results showed that the higher the magnesium oxide activity, the better the bottom layer formation; oxidation The moisture content of the magnesium coating needs to be controlled within a certain range. If the moisture content is too low, it will cause dew crystal defects; prolonging the decarburization time is conducive to the formation of the magnesium silicate bottom layer.
The high-temperature annealing process of oriented silicon steel was simulated
in the laboratory. The evolution of the micromorphology of the reaction between silicon dioxide and magnesium oxide in the oxide layer was observed using a focused ion beam microscope (FIB), and the sample cross-section was analyzed using an energy spectrometer (EDS). The distribution patterns of elements such as Mg, Al, and Si in the near-surface layer were analyzed. Finally, transmission electron microscopy (TEM) was used to analyze the structural characteristics of the bottom layer of magnesium silicate of the finished sample.
The results show that: (1) the diffusion rate of magnesium ions is the main factor affecting the reaction of the bottom layer of magnesium silicate; (2) magnesium ions initially diffuse along the interface between the silica particles and the iron matrix, and gradually encapsulate the silica particles. coating; as the temperature further increases, magnesium ions begin to diffuse into the interior of the silica particles and react with them; (3) As the temperature increases, especially after the aluminum nitride decomposes, the aluminum in the steel base The magnesium silicate (Mg2SiO4) at the pinning site will gradually be completely converted into magnesium aluminum spinel (MgO·Al2O3).
