PURPOSE: To suppress reactivity with alkalis and prevent the crazing and peeling of a coated layer by produced hydrogen by mixing the Fe-Si powder used for the coating material of a coated electrode with an aq. NaOH soln. of specific concn. and heating and drying the soln. followed by roasting.
CONSTITUTION: The Fe-Si power contg. 20W40% Si used as a component for the coating material of a coated electrode is treated with an aq. NaOH soln. The aq. NaOH soln. used is prepd. by adding and mixing the aq. soln. of ≥0.1% NaOH concn. at 5W100% the weight of Fe-Si to and with the Fe-Si powder in such a way that the NaOH weight in the aq. soln. is 0.1W2% the Fe-Si weight. Next, it is heated and dried at 80W200°C, after which it is roasted at 550W850°C, so that an oxidized film is formed by the NaOH stuck on the surfaces of the Fe-Si. It is does not produce hydrogen by reacting with the alkaline component in water glass as a binder used for the coating material, obviates the occurrence of crazing and peeling of the coating by gaseous hydrogen and improves the yield of coating of coating material.
HAYASHI KUNIAKI
MIKI HIDEJI
YAMANOUCHI NAOKI
INOHARA YOSHIO
