JPS6086807A - Formation of insulating film for electromagnetic iron plate - Google Patents

Abstract

PURPOSE:To improve annealing resistance by mixing metallic oxides consisting of Al2O3, SiO2, MgO, etc., mean grain size thereof is kept within specific range values, with a phosphate group film. CONSTITUTION:At least one kind of a chromate anhydride, a chromate and a bichromate is added to a phosphate aqueous solution by 10-70pts.wt. as CrO3 to 100pts.wt. phosphoric ions PO4. Corrosion resistance is insufficient when the quantity of addition is smaller than 10pts.wt., and Cr<6+> is reduced insufficiently when it is larger than 70pts.wt. One kind or more of metallic oxides selected from Al2O3, SiO2 and MgO, mean grain size thereof extends over 0.1-4mum, are compounded. Films are fusion-bonded mutually when grain size extends over 0.1mum or less, and bonding is deteriorated when grain size exceeds 4mum. A treating liquid having such a composition is applied on the surface of an electromagnetic ion plate while being agitated, and baked.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an insulating coating on the surface of an electromagnetic iron plate, particularly for the purpose of improving the annealing resistance required during strain relief annealing.

Generally, the characteristics required for the insulation coating of electromagnetic iron plates are as follows:
It has excellent electrical insulation, adhesion, punchability, weldability, corrosion resistance, heat resistance, chemical resistance, etc., and a high space factor.

Hitherto, various insulating coatings for strings have been developed and improved in order to satisfy these required characteristics. Among the many insulating coatings that have been proposed, phosphate coatings are the only completely inorganic coatings that have been used for the longest time. The components of the coating are usually phosphates and a small amount of chromic acid (salt) to improve corrosion resistance and heat resistance. The features of this phosphate coating include extremely good weldability, excellent chemical resistance such as 7 Leon resistance, and no deterioration of magnetic properties due to carburization during strain relief annealing. .

On the other hand, since this coating is an inorganic coating, it has poor punchability with steel molds, but recently, with the spread of carbide molds, its punchability has become comparable to other coatings. It is an indispensable coating for machine motors and high-grade electromagnetic iron plates.

However, this type of phosphate coating has the drawback of very poor annealing resistance. In other words, after punching an electromagnetic iron plate, it is annealed to remove processing strain in order to improve its magnetic properties. This is caused by wear and tear, which causes deterioration of the magnetic special order. For this reason, it is used to prevent deterioration of magnetic properties by separating the adhesion and fusion. It is inefficient because a work step is required to separate this adhesion or fusion.

On the other hand, as a method to improve annealing resistance, a method of applying a treatment solution containing a mixture of phosphoric acid, chromic acid, boric acid, a water-soluble organic compound having a thio bond, and alum (Japanese Patent Publication No. 5
5-1348) has been proposed. Although this method shows satisfactory performance in terms of electrical insulation properties after annealing, the fusion between films is strong and causes deterioration of magnetic properties, so an operation is required to separate the fusion. It is. Further, due to the anion 304II- remaining in the coating, there is a drawback of poor corrosion resistance.

As a result of various investigations and studies aimed at solving the above-mentioned drawbacks of phosphate-based coatings, the present invention has been developed by incorporating a small amount of finely powdered metal oxide f as will be described in detail later. Insulating coating with excellent annealing resistance without damage
The purpose of this study is to provide a treatment method for this purpose.

That is, the gist of the present invention is that at least one
At least one compound selected from the group consisting of chromic anhydride, chromate and dichromate, based on 100 parts by weight of phosphate ion PO4 contained in the aqueous solution, is added to an aqueous solution containing a phosphate of ai. 10 to 7 as 0r03
At203.0 parts by weight and an average particle size of 0.1 to 4 kon.
5i02 and Mh.

An aqueous solution containing 5 to 30 M parts of at least 18 selected metal oxides is applied to the surface of an electromagnetic iron plate to a dry weight of 0.5 to 3.52, It's about burning.

The reason why it is preferable to keep the ingredients and treatment conditions of the treatment liquid used in the present invention within the above ranges is as follows.

The treatment liquid used in the present invention is an aqueous solution containing one or more phosphates such as magnesium, calcium, zinc, and aluminum as a main ingredient. At least one selected from chromic anhydride, chromate, and dichromate is added to these phosphate aqueous solutions, and the chromate is a magnesium salt, and the dichromate is magnesium, calcium, and zinc. , potassium and the like are preferred. The addition amount of these is preferably 10 to 70 parts by weight based on 100 parts by weight of phosphate ion PO4 as 0r03. If the amount added is less than io parts by weight, corrosion resistance will be insufficient and adhesion after strain relief annealing will also be poor. On the other hand, if the amount exceeds 70 parts by weight, the reduction of Or'+ by baking will not be sufficient and soluble Or'+ will remain in the ruptured membrane, absorbing moisture from the atmosphere and causing stickiness.

The metal oxide used in the present invention has an average particle size of 0.
At20s, 8 i02 and λ of 1-4 μm
490, and may be a hydrated salt thereof. However, a material that becomes a sol in an aqueous solution is not preferable because it causes the films to fuse together during strain relief annealing after film formation. Also, the average particle size is OJ t! It is also unfavorable if there are no rn drops because the coatings will fuse together during strain relief annealing. On the other hand, if the Y average particle size exceeds 4 pm, this is not preferable because the space factor decreases and adhesion deteriorates. Therefore, the average particle size is limited to 0.001 to 4 μm. The amount of these additives to be added is 5 parts by weight per 100 parts by weight of the phosphate ion PO4, which is not preferable because the unboiled materials will fuse together during distorted annealing, resulting in deterioration of the magnetic properties. Furthermore, the electrical insulation properties are also poor. On the other hand, if it exceeds 30 parts by weight, it is not preferable because adhesiveness deteriorates. For this reason, the amount added is 5~30r! is limited to Keigyo.

The recombinant treatment solution may be uniformly applied to the surface of the electromagnetic iron plate using a grooved rubber roll or spray force while stirring, and then baked. In addition, the coating amount is 0.5 to 3.5 in terms of dry M amount.
If the f/rl range is good, and the Moriyama is less than 0.5 f/rl, sufficient electrical insulation will not be obtained and the corrosion resistance will be poor, and if it is more than 3,5 f/rl, the coating after strain relief annealing will be poor. This is because peeling is likely to occur.

As for the part temperature, if it is lower than 300C, it will take a long time to bake, and if it is higher than 7000C, the range of appropriate baking conditions is narrow, so it is inappropriate for one part, so 300 to 70C.
A temperature range of 0°C is preferred.

Another 5g! 8. For the purpose of reducing the alcohol content or shortening the baking time, suitable nitric acid groups or nitrites may be added.On the other hand, by adding colloidal silica, colloidal alumina, etc. to the above treatment liquid, it is possible to Effective in improving insulation. Further, an appropriate amount of a surfactant may be added as necessary.

Hereinafter, the method for forming an insulating film on an electromagnetic iron plate according to the present invention will be described in detail with reference to Examples.

[Example 1] As mentioned above, when deterioration of electrical insulation due to strain relief annealing, which is a drawback of phosphate coatings, and deterioration of magnetic properties due to close contact between iron plates or fusion between coatings, conventional methods were used. There is a desire to prevent the above-mentioned drawbacks without impairing the properties of phosphate-based coatings, and in the present invention, in response to this demand, a treatment solution containing finely powdered metal oxides is used. Changes in the magnetic properties of electromagnetic iron plates by strain relief annealing (750° C. x 2 hours, N2 gas atmosphere) were carried out under the force conditions shown below, and the results are shown in FIG. In the if diagram, ■ marks are coatings containing no metal oxides (conventional phosphate coatings), coatings containing metal oxides that do not become sol in an aqueous solution (coatings of the present invention), and Δ marks are coatings containing no metal oxides (conventional phosphate coatings); This shows a coating containing metal oxides that becomes a sol. The solid line indicates the magnetic properties (iron loss W□5150) when each sample is in a fused state (in close contact!)
The broken lines (x marks) are the measurements taken after the fusion of each sample was released.

(Material used: Electric iron plate equivalent to JIS S 60, plate thickness 0.5U (2) Treatment liquid composition (a) Treatment liquid of the present invention Magnesium monophosphate My (HI PO4) 13
To 100 parts by weight of PO4 in a 0% aqueous solution, 320 parts by weight of chromic anhydride, At(NO
x) 20 parts by weight of s, 3M hydrous magnesium aluminum silicate with an average particle size of 1.6 ttm, 0.15 hts 03.8 S sO2.9H 0 2-40 parts by weight.

(b) Comparison and control (a) No addition of hydrous magnesium silicate/aluminum silicate (conventional phosphate-based) in the treatment solution, and average particle size of 0.0000 0.0000 sol in an aqueous solution instead of hydrated magnesium/aluminum silicate. 8p hydrated silica 5i02 ・n
Hlo 2-40 M Okibe.

(3) Coating and Baking Conditions The coating solution with a specific gravity of 1.06 was applied to the electromagnetic iron plate using a 0.51 bitsam roll and baked at a temperature of 450C for 80 seconds. The amount of coating is 0.5 to 3.59 an on dry weight.
It was within the range of

(4) Measurement of iron loss (W) 5150 The material obtained by the above treatment was
After punching a ring sample with an inner diameter of 65;
After strain relief annealing was performed under a pressure of /aTf, the fused ring sample was wound to measure iron loss. Thereafter, the fusion bond was released, the wire was wound, and the measurement was performed again. Strain annealing condition company N2
The temperature was maintained at 7500° C. for 2 hours in an atmosphere.

(5) Results The measurement results of iron loss (W□5150) are plotted and fc As is clear from the graph in Figure 1, it is clear that the conventional film containing no metal oxide (see the [phase] mark in Figure 1) ) is extremely poor at 85 or higher in the fused state. 6.5 when measured after fusion and dissociation
w/Kt. On the other hand, in the film of the present invention, which contains hydrated magnesium aluminum silicate (see mark 0 in Figure 1), the amount added is phosphate ion PO41.
When the amount was 6 parts by weight or more relative to 00 parts by weight, the iron loss value in the fused state and after the fusion and dissociation (see the X mark and broken line in Figure 1) was 6.5' WAy, which was good with no difference. . On the other hand, when hydrated silica, which becomes a sol in an aqueous solution, is added, even if the additive is 30 parts by weight to 100 parts by weight of PO4, the amount is 7.4 parts by weight (after fusion and dissociation (see the X mark and broken line in Figure 1 number is 6
．． It is 9 in 5w/.

[Example 2] Next, tests were conducted on film properties under the following conditions for the case where the treatment solution according to the present invention was used and the case where a conventional phosphate treatment solution was used, and the results are shown in Table 1. Shown below.

(Material used: Electric iron plate equivalent to JI8860, plate thickness 0.5 (2) Treatment liquid composition (C) Treatment liquid of the present invention Magnesium monophosphate My (H2P 04) x
Potassium dichromate KzOrlol was added to 100 parts by weight of PO4 in an aqueous solution containing 30 parts by weight and silica 8i (hlo parts) with an average grain size of 83 μm.

(d) 10 parts by weight of silica 8iCh in the treatment liquid treatment ff(c) of the present invention was added to 30 parts by weight.
Added to the weight section.

(e) Comparison control (conventional phosphate treatment solution) Magnesium monophosphate M, (PO4 in Hri P04h301 aqueous solution)
For 100 parts by weight, 20 parts by weight of chromic anhydride and 20 parts by weight of aluminum nitrate At(NOs)s.

(3 coats, baking conditions The above treatment liquid with a coating specific gravity of 1.06 was spray coated on the electromagnetic iron plate while stirring, and the excess coating liquid was removed by 0.7M.
Piztego five flor, Shizurushi and Shi.

Baking was performed at a temperature of 500°C for 70 seconds. The coating weight ranged from 1.2 to 1.6 f~ on a dry weight basis.

(4) Annealing resistance The material obtained by the above treatment was
s 5 after punching a ring sample with an inner diameter of 65 mm
After strain relief annealing was performed under a pressure of Kf/d 2 , iron loss (W 2 ) was measured in the fused state and in the state after fusion dissociation.

5150 On the other hand, after shearing the material to 30 x 100 mm, the lap allowance was 15
c++! After laminating the film and subjecting it to strain relief annealing under a pressure of 5Kf15N, the fusion strength of the film was examined by the single lap method using a tensile tester.

The strain relief annealing conditions were held at 750° C. for 2 hours in an N3 atmosphere.

(5) Results In terms of annealing resistance, the core loss (W15150) in the fused state is 6.5 to 6.5 for the coating of the present invention.
7vtAy, which is approximately equal to 6.5w/lv after fusion and dissociation.

In comparison, the conventional phosphoric acid-based coating has a 78.4
Very bad w/Kf.

On the other hand, looking at the fusion strength, in the case of the film of the present invention, it is 0.1
Kf/cd or less, which separates with a weak force of +2) K, whereas in the conventional film, the bonding strength is 3.8 Ky/cd, which is a strong fusion.

Regarding other characteristics according to the present invention.

As shown in Table 1, there was no inferiority to those of conventional coatings.

As is clear from the above various examples, as in the processing method of the present invention, a specific F
Fine gold F4 that does not become sol in an aqueous solution of I acid-based processing solution.
By adding oxides.

An electromagnetic iron plate insulating coating that significantly improves the deterioration of magnetic properties caused by adhesion between steel plates and fusion between coatings after strain relief annealing, which was a conventional drawback without impairing the coating properties of conventional technology. The present invention provides a method for forming.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the influence of metal oxide addition t in the phosphate coating on iron loss after stress relief annealing. Procedurally correct (method) 1. Description of the case 1982 Patent Application No. 195901 2 Name of the invention Method for forming an insulating coating on electromagnetic steel plates 3 Name of person making the amendment (125) Kawasaki Steel Co., Ltd. 4 Agent 101 Telephone 864-4498 Address
3-2-2-5 Iwamoto-cho, Chiyoda-ku, Tokyo, date of amendment order January 31, 1980, 6, subject of amendment

Claims (1)

[Claims] In an aqueous solution containing at least one phosphate, at least one selected from the group consisting of chromic anhydride, chromate, and dichromate is added to 100 parts by weight of phosphate ion Po4 contained in the aqueous solution. 10 ~ 70 parts by volume and average particle size of 0.1 ~ 4 μm with a compound of 0 rbs
An aqueous solution containing 5 to 30 parts by weight of at least one gold oxide selected from the group consisting of Al2O5, 8i0t, and MfO was applied to the surface of one electromagnetic iron plate by 0.5% by dry weight.
~3.5 A method for forming an insulating film on an electromagnetic iron plate, which is characterized by coating and baking.