JPH03243795A - Production of silicon steel sheet having fine appearance of coating film - Google Patents

Abstract

PURPOSE:To stably produce a silicon steel sheet having fine appearance of its coating film by electrodepositing SiO2 in a sodium silicate soln. contg. specified metal ions before process annealing in a stage for producing a grain- oriented silicon steel sheet. CONSTITUTION:SiO2 is electrodeposited on the surface of a cold-rolled silicon steel sheet by 0.01-2 g/m<2> in a sodium silicate soln. contg. 0.1-10 g/l metal ions of one or more among Fe, Cu, Al, Sn, Se, Ni, Cr, Mn and Ti before process annealing in a stage for producing a grain-oriented silicon steel sheet. The silicon steel sheet with the electrodeposited SiO2 is then subjected to process annealing and finish annealing to produce a grain-oriented silicon steel sheet having fine appearance of its coating film.

Description

[Detailed Description of the Invention] C. Industrial Field of Application j The present invention relates to a method for manufacturing a silicon steel sheet with an excellent coating appearance, and more specifically, it relates to a method for manufacturing a silicon steel sheet with an excellent coating appearance, and more specifically, it relates to a process for manufacturing a grain-oriented silicon steel sheet in which a trace amount of M g 2 Si 0 formed in intermediate annealing by depositing SiO2
The present invention relates to a method for reinforcing SiO2, and in particular to a suitable concentration and ions to be included in a solution in a SiO2 electrodeposition method.

[Prior Art] A method is known in which the Mg2SiO4 formed in the intermediate annealing is strengthened by electrodepositing a small amount of SiO2 on the rolled sheet before the intermediate annealing during the manufacturing process of grain-oriented silicon steel sheets. It is known to carry out cleaning treatment in sodium silicate.

[Problem to be solved by the invention J When performing cleaning treatment in this sodium silicate,
Since the liquid does not contain metal ions, S i 02 has the disadvantage of not being electrodeposited. In addition, since the amount of SiO2 electrodeposited has a larger contribution from the SiO2 concentration than the current density,
The amount of SiO2 electrodeposited cannot be controlled unless the concentration of the solution is controlled.

An object of the present invention is to provide a method for forming an appropriate film thickness of SiO2 on a silicon steel plate by introducing metal ions into a sodium silicate solution and maintaining the sodium silicate concentration at an appropriate value.

[Means for Solving the Problems] The present invention takes the following technical means to achieve the above problems. That is, when electrodepositing SiO2 on a rolled plate before intermediate annealing during the manufacturing process of grain-oriented silicon steel,
Fe, Cu, Aff, Sn, Se, Ni, Cr,
At least one kind of metal ion selected from Mn and Ti is added to SiO2 at a rate of 0.1-10g/ff.
Supply f! 0.01 in this solution.
It is characterized in that ~2 g/rn' of SiO2 is electrodeposited on the rolled plate. By such technical means, when the metal ions are brought into close contact with the rolled plate, SiO2 is embedded in those ions and electrodeposited, resulting in a strong M during the intermediate annealing process.
g 2 Si O4 can be formed, and a silicon steel plate with excellent coating appearance can be manufactured.

C action] Since SiO2 itself has no electric charge, no electrodeposition reaction occurs even if it is electrolytically treated in an electrolytic bath. However, Si
O2 is deposited electrophoretically in the electrolytic cell due to electrostatic attraction. This adsorption force is very weak, so if left as it is, it will easily peel off. Therefore, if metal ions are introduced into the electrolytic tank, the metal ions will be absorbed into the SiO2
SiO2 is deposited firmly on the surface of the silicon steel sheet.

The degree of 5iO2fi is preferably 2 to 10%, and the higher the degree, the better the electrodeposition efficiency, but it becomes saturated when it exceeds 10%.

If the metal ion content is less than 1 g/I2, the metal ion injection effect will be insufficient, and if it is contained in more than 10 g/β, the effect will be saturated, so 0.1 g/ff
−10 g/β.

If the amount of SiO2 electrodeposited on the rolled sheet is less than 0.01 g/d, it will be difficult to form a coating after intermediate annealing and final annealing, and defects will be observed, and if it exceeds 2 g/d, point-like coating defects will occur. At 0.01 to 2 g/rn'', a defect-free SiO2 steel plate with excellent appearance can be obtained.

[Example] After electrolytically treating 3% Si steel in sodium orthosilicate to which Cu'0 was added, intermediate annealing, final annealing, and flattening annealing were performed.

The electrolytic treatment conditions are as follows.

Concentration of sodium orthosilicate = 2%, 4%, 6%, 8%, 1
5 levels of 0%.

Concentration of Cu'+, no input, 0.1g/ff, 5g/β
, log/β, and 12g/β.

Current density/2A/d resistance, 5A/drrf', IOA/d
Three levels of rrl' Regarding the electrolytically treated rolled sheet under each of these conditions, Si
The amount of O2 attached is fluorescent x1j! Measured at

The experimental results are shown in FIGS. 1 to 5.

Figure 1 shows Si when 5 g712 of Cu2+ is added.
From Figure 1, which shows the relationship between the concentration of Si02, current density, and amount of Si02 deposited, the amount of Si02 deposited increases as the current density increases, but the influence of SiO2i1 degree is greater than that. I understand.

FIG. 2 shows the case where Cu'+ was not added, and no electrodeposition of SiO2 was observed in all cases.

FIG. 3 shows the case where Cu2+ was added at a concentration of 10 g/β, and shows the same tendency as FIG. 1.

FIG. 4 shows the same tendency as FIG. 1 when Cu2+ was added at a concentration of 0.1 g/ff.

Figure 5 shows the case where Cu'+ was added at 12 g/β, and the results are almost the same as in Figure 3, and the amount of electrodeposition of SiO2 is effective even if the concentration of Cu2+ is increased by more than log/N. Or it doesn't improve.

In addition, Cu'10 is Fe, AI2. Sn, Se.

Similar results were obtained when Ni, Cr, Mn, and Ti ions were substituted.

Next, the S i 02 adhesion amount of the rolled plate subjected to the above electrodeposition treatment is Og/ba, 0.005g/n1", O, O1g/rn
", 0.05 g/rri", O, 1 g/rfl",
0.5 g/rn", 2 g/m', 5 g/r
r? , 10 g/m'' were subjected to intermediate annealing and final annealing, respectively, and the appearance of the coating was inspected.

Those with a SiO2 adhesion amount of Og/m'' and 0.005 g/m'' are peeled off, making it difficult to form a film, and S
For samples 6 with an iO2 adhesion amount of 5 g/rn'' or more, a film was formed, but point-like film defects occurred.Also, 0, 01
6 between g/rn'' and 2 g/rr1'' resulted in a coating without defects.

[Effect of the invention 1 According to the present invention, electrodeposition of SiO2 is made possible by introducing metal ions into the SiO2 source solution before intermediate annealing during the manufacturing process of grain-oriented silicon steel sheets, and this SiO2
By controlling the adhesion amount, it is possible to obtain a good coating on the silicon steel plate after intermediate annealing and final annealing.

[Brief explanation of drawings]

FIGS. 1 to 5 are graphs showing the relationship between the concentration of SiO2, the current density, and the amount of deposited SiO2 when the amounts of metal ions Cu'10 are different.

Claims (1)

[Claims] 1 In electrodepositing SiO_2 on the rolled plate before intermediate annealing during the manufacturing process of grain-oriented silicon steel sheet, Fe, Cu, Al, Sn, Se, Ni, Cr,
0.1 to 10 g/l of at least one ion selected from Mn and Ti is contained in the solution.
A method for producing a silicon steel sheet with an excellent coating appearance, characterized by electrodepositing 2 g/m^2 of SiO_2 on a rolled sheet.