JPS6017026B2 - Method for applying high-temperature sintering separation agent to grain-oriented electrical steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a dawn anchor separation agent powder film layer for the purpose of preventing collision of steel sheets during high-temperature sintering of grain-oriented electrical steel sheets.

Grain-oriented electrical steel sheets are cold-rolled and branded once or twice, and then subjected to secondary recrystallization to develop a (110)[001] orientation (C°Css orientation). It is sluggish at high temperatures above 0.

In this case, a high temperature fly hammer separating agent is applied to the surface of the steel plate to prevent the steel plates from colliding. This type of sintered anchor separation agent is generally applied on the outlet side of a continuous decarburizing annealing furnace by spraying a suspension with water or squeezing it with a rubber-coated roll, and after drying in a drying oven, it is It is something that is wound up.

Many techniques using various refractory metal compounds as phosphorus dull separators have been published (for example, Patent No. 179
No. 337 and No. 185395...CaC03, Muscle C
03, Special Publication No. 42-27533...AZ
203, Z no 2, Mg0, Ti02, Special Publication Showa 42-27
Publication No. 531...Aso203, Ca○, Special Publication No. 41
Publication No. 13726...Mg○, etc.). Among these, for grain-oriented electrical steel sheets, for example, Japanese Patent Publication No. 51-11
As described in Japanese Patent Publication No. 2451, Japanese Patent Publication No. 52-31296, etc., at the same time as preventing the seizure of steel sheets, glass is formed by a solid phase reaction at high temperatures with a scale layer mainly composed of SiO2 formed on the surface of the steel sheets. A dawn anchor separation agent containing magnesia as a main component is generally used because it tends to form a transparent film.
A glassy film is useful as a base for an insulating film to improve heat resistance and insulation. Magnesia that is industrially produced today can be roughly divided into two types, depending on the method of production: false magnesia and dead burnt magnesia. Kariyo magnesia is made by replacing Myojime2 (bitter) collected from seawater with Ca(OH)2 to obtain Mg(OH)2, which is calcined and crushed at 500 to 1000 qo, and is generally made from crabmeat. Also, something called flea magnesia belongs to this category. Shikyo magnesia is made by replacing M and ㆆ2 with Ca(OH)2 to produce Mg(OH)2, which is then fired and crushed at a high temperature of 1500 to 2100 qo, and is usually called magnesia clinker. be.
Table 1 and FIG. 1 show a comparison of the manufacturing methods and characteristics of both. Vertical or childish calcined magnesia is active and has strong hydration (moisture absorption) properties due to the low firing temperature, and most of the secondary particle diameters are less than 5 grains, and the primary particle diameter is On the other hand, non-hydratable magnesia is inert due to high temperature firing and hardly hydrates (absorbs moisture). Regarding the particle size distribution of non-hydratable magnesia, it is cemented for high-temperature firing, and is lumpy when fired, so it is crushed and classified into various particle size distributions depending on the actual purpose of use. , it is possible to use. In addition, the intermediate product magnesium hydroxide contains C
It includes evening and S04, and as shown in Figure 2, 15
These impurities cannot be removed by thermal decomposition unless heated above 00 qo, and since magnesia acts as a sulfur absorbent, refining is required in the production of calcined magnesia fired at low temperatures, and sulfur-free fuel is required. Magnesia is expensive to use. Among these magnesias, vertical or heavy temporary magnesia is generally used as a competitive separation agent.

In particular, light magnesia has good dispersibility in water and good adhesion to steel sheets, but on the other hand, it has high activity and requires primary soaking at temperatures of 500 to 70,000 to remove water due to hydration during high-temperature annealing. Moreover, the released water peroxidizes the surface of the steel sheet, which has a negative effect on the magnetic properties and the formation of a glassy film. Therefore, in order to eliminate these drawbacks, we used magnesia, which has a slightly lower quality of sailor 01, or Patent No. 600915, Japanese Patent Publication No. 52-3.
Attempts have been made to use a special magnesia as disclosed in Japanese Patent No. 1296, but the adhesion after drying was poor and it was very difficult to control the amount of hydration. Therefore, by suspending it in water,
In contrast to the method of coating and drying, the method described in Japanese Patent Publication No. 39-12211 and Japanese Patent Application Laid-Open No. 54-120215 is a method of directly and electrostatically adhering powder particles of a sintered anchor separation agent to a steel plate. Attempted.

The method described in Mochiko No. 39-12211 describes a method in which phosphorus dull separator powder is introduced between an electrode performing enteric corona discharge and the surface of a steel plate, and is electrostatically adhered to the surface. mentions the use of magnesia as this competitive anchor separating agent, but includes a wide range of substances such as calcium oxide, alumina, silica, or other refractory oxides, lime and the like; For purposes of the example presented herein, the invention will be described with respect to the use of magnesia, such as magnesia, although it will be clear that the invention is not so limited.

'', and as magnesia powder, ``1 inch 32
5 mesh or have a particle size of approximately 44 microns. ”. Furthermore, the method described in JP-A-54-106009 is characterized in that powder particles of the Akatsuki Separating Agent are charged and adhered to the surface of an electromagnetic steel sheet serving as a counter electrode. Also, annealing separators can be used without the constraints of conventional methods, such as heavy magnesia, alumina, zirconium oxide, silicic acid, titanium oxide, nickel oxide, manganese oxide, calcium oxide, chromium oxide, molybdenum oxide,
One type or a mixture of two or more types of oxidized shelving elements, or a composite oxide is used. "It has said. As shown in the cited example above, various oxides are used as a roasting hammer separation agent in the electrostatic coating method, but in the case of silicon-containing grain-oriented electrical steel sheets, they are used to prevent seizing of the steel sheet and at the same time desulfurize the hot rice bran hammer. S of steel plate surface
Magnesia was found to be the most preferable gun blunt separating agent based on its ability to form a glassy film through a solid phase reaction with a scale layer containing i02 as a main component.

However, when light or heavy pseudomagnesia, which has traditionally been used as a competitive separator, is used in electrostatic coating methods, the following problems hinder stable continuous operation over long periods of time. caused. '1} Due to agglomeration of magnesia powder, dispersibility decreases and adhesion to the steel plate becomes uneven.

0'2} Charging efficiency of magnesia powder particles is poor and adhesion to the steel plate is reduced.'3' Clogging occurs in the magnesia powder supply system.

■ Magnesia powder accumulates near the corona electrode, reducing chargeability. As a result of detailed investigation into these problems, the present inventors found that the hygroscopicity (hydration) and particle size distribution of magnesia powder were the dominant factors.

Generally, the powder used for electrostatic coating must have good charging properties, that is, it must have a large electrical resistance on the surface. Highly hygroscopic magnesia, such as scaly magnesia, absorbs moisture during use, and the electrical resistance of the surface of the powder particles decreases significantly, resulting in a gradual decrease in chargeability and deterioration of adhesion to steel plates.

In addition, moisture absorption increases cohesiveness and compressibility, resulting in poor dispersion and uniform adhesion to the steel plate surface, which can also cause clogging of the powder supply system and deposition near the corona electrode. . As a result of investigating the influence of fineness distribution,
It was found that the smaller the particle size of the powder, the stronger the agglomeration and the worse the dispersibility, making long-term continuous operation difficult. From the above research results, the characteristics of magnesia powder used in electrostatic coating method are: 1) It is non-hydratable.

■ Particle size distribution can be adjusted depending on the intended use.

It turns out that two points are necessary. However, calcined magnesia has strong hydration properties, and as mentioned above, the manufacturing method is characterized by the fact that extremely fine Mg(OH)2 produced and precipitated through a chemical reaction is calcined at a low temperature. The growth of the particles is small at 30 to 1000A, and the bonding of particles does not progress very much, making it brittle, as shown in Figure 3.
Most of the particles were smaller than 5 mm, and it was impossible to adjust the particle size distribution within the size range of 5 mm or larger. Therefore, it was found that magnesia was not suitable for electrostatic coating.

Therefore, the present inventors conducted tests on various types of magnesia powder, and found that the magnesia powder used in the electrostatic coating method was pulverized non-hydratable dead-burned magnesia clinker fired at a high temperature of 1,500 - 210,000. and particle size 5~
It has been found that the best material is one prepared so that 149 mountain surface accounts for 80% or more of the total surface.

If it contains more than 20% of powder with a grain size of 5rm or less, the fluidity will decrease, causing clogging of pipes and adhesion to the electrodes, and if the grain size is larger than 149, it will cause unevenness on the surface of the steel plate, making it unsuitable. understood. In order to clearly distinguish between hydratable and non-hydratable, parameters related to hydration rate were investigated.

As a result, citric acid activity is generally used as a parameter indicating the hydration (moisture absorption) rate of magnesia. Citric acid activity is expressed as the time required for a given weight of magnesia to provide hydroxyl ions that neutralize the required weight of citric acid. The test method was carried out under the same conditions as the method described in Tokukan Sho 54-3383 Publication. i.e.: '11 1% phenolphthalein indicator 2'
100' of an aqueous solution of 0.40% citric acid containing 0.40° C. is brought to 30° C. in an 8 ounce jar.

The bottle is equipped with a screw cap and an electromagnetic holder. '2'2
．． Pour 00 Yu's magnesia into the bottle and start the stopwatch at the same time.

Lake Place the lid immediately after adding the magnesia sample.

At 5 seconds, shake the bottle and contents vigorously.

The shaking ends at the point of 1 sand. '4' Place the sample on the electromagnetic wading device after one night.

If the inner diameter of the bottle is 6 mm, the mechanical azure should create a vortex about 2 mm deep in the center. ■ Stop the stopwatch when the suspension turns pink and record the time.

This time in seconds is the citric acid activity. As a result of research on various types of calcined magnesia,
The citric acid activity was 30-25 ash, whereas it was 1000-1000 ash in various dead scale magnesia clinkers with different firing temperatures and impurity contents.

Thus, it has been found that the activity of the conventionally used pseudomagnesia clinker is significantly different from that of the rival magnesia clinker. The non-hydratable magnesita aclinker used in the present invention is industrially produced in large quantities and commonly used in the manufacture of refractories, etc., and has a fineness distribution as shown in Figure 3, for example. However, as mentioned above, it can be adjusted depending on the purpose. In addition, regarding the technology of using non-water-challenged high-temperature calcined magnesia as a competitive hammer separation agent, there is a method of using it by suspending it in water and using a fine grinding mill.
An attempt was made in Japanese Patent Application No. 146101/1983 to improve the dispersibility in water by pulverizing it to less than rm, and adding Mg(OH)2 to improve adhesion to steel plates. However, according to the present invention, there is no need for pulverization using such a pulverizing mill or for additives, so it is extremely inexpensive. As an electrostatic coating method for non-hydratable magnesia clinker, for example, first, non-hydratable magnesia clinker powder is uniformly dispersed in a fluidized tank or a mixed tank, and then the powder is applied to a gas for transporting the powder. The powder particles are sent to the vicinity of the corona electrode of the electrostatic powder coating machine, and due to the corona discharge generated by the DC high voltage applied here, they collide with the ionized gas and come into contact with the non-hydratable magnesia clinker powder particles. can be positively or negatively charged and attached to the surface of a grounded steel plate serving as a counter electrode.

The positively or negatively charged non-hydrated dead-burned magnesia clinker powder particles are transported along the lines of electric force of the electric field formed by the potential difference between the corona electrode and the grounded steel plate, along with the air flow of the powder transporting gas. It flies toward the steel plate, attaches itself electrostatically, loses its charge, and becomes attracted to it. The polarity of the charge on the powder matches the polarity of the corona electrode, and it is possible to adhere to the steel plate even if it is charged to either a positive or negative polarity, but it is stronger when it is charged negatively. Adhesion was obtained. According to the present invention, when non-hydratable dead-burned magnesia clinker powder is electrostatically attached to a steel plate as a competitive separator, all of the prevention of adhesion of the steel plate, the desulfurization property, and the glass-like film formation property are good. However,
In order to form an even stronger glass-like film, for example, a suspension of a treatment agent containing calcined magnesia as a main component in water, which is described in Japanese Patent Publication No. 52-31296, is applied and dried. 0.5 to 3 evenings/day to form that lower layer film, and then 3 to 20 evenings/day to form an upper layer film by electrostatically adhering the non-hydratable dead burnt magnesia clinker powder of the present invention thereon. It is possible to use a method of applying

Also contains silicon, MnS, A〆N, B, Se, Sb
, Cu, Sn, etc. or one or more of these compounds,
In grain-oriented electrical steel sheets that are manufactured by adding them as inhibitors of normal grain growth, titanium, manganese, shelium, silicon, and niobium are added to the treatment agent whose main component is pseudomorphic magnesia, which is used as the lower layer coating. If one or more of oxides, nitrides, sulfides, sulfates, or thiosulfates of chromium, nickel, antimony, and strontium are added, the magnetic properties (iron loss, magnetic flux density, etc.) It is possible to improve the
With respect to the coating agent shown in Publication No. 2-31296,
There is a shelf element, and a compound containing a shelf element is 0.5 ~
2. A significant improvement in magnetic flux density is possible by adding a weight percent of (2.5 to 60 o/metre per steel plate). In the past, many patented inventions have been provided regarding the prevention of seizing of grain-oriented electrical steel sheets during high-temperature anchoring and glass-like coatings, but as in the present invention, the expensive temporary magnesia used in the past has been replaced, and it is extremely The use of a specific inexpensive non-hydrated magnesia has great industrial significance as it has become possible to operate the electrostatic coating method continuously for a long period of time.

Next, examples will be described.

Example 1 A non-hydratable magnesia clinker powder with a particle size of 5 to 149 and 90% of which is powder on the surface was negatively charged at a high pressure of 1 skin V using an electrostatic powder coating device, and a countermeasure was applied. It was electrostatically deposited on the upper surface of the steel plate of the electrode with a target accuracy of 9±1 min., and the amount of the deposit was measured.

Continuous coating was carried out for 3 hours, but no clogging of the powder supply system or accumulation of powder near the corona electrode was observed, and the adhesion of the powder to the steel plate was uniform.

Figure 4 shows the change in powder adhesion amount over time. Comparative Example 1 A steel plate was prepared under the same conditions as in Example 1 using light pseudomagnetic magnesia having 95% or more of the following powder particles and high-temperature calcined magnesia clinker having 70% or more of the powder with particle diameters of 5 mm or less. attached to the top surface.

Approximately 20 minutes after high voltage was applied, a thin deposited layer was observed around the corona electrode in both cases, and the adhesion to the steel plate became non-uniform. Figure 4 shows the change in powder adhesion amount over time. Example 2
When manufacturing grain-oriented electrical steel sheets of 0.3 sail thickness x 320 willow medium x 400 k9 containing Si: 3.16%, after finishing cold rolling, rolling oil was removed, and then 2:75% Si was applied. N
2: Non-hydratable dead-burned magnesia clinker powder with 95% particle size 5-149 grain powder as a competitive anchor separator after being continuously annealed for 4 minutes at 840 pm in a 25%, dew point 460 atmosphere. The body was negatively charged by applying a high voltage of 0,100 kV using an electrostatic powder coating device, electrostatically adhered to the upper surface of the steel plate of the counter electrode for 8.7 days, and immediately wound into a coil shape. Ta.

This was annealed at high temperature for 1200q0×10h in a hydrogen stream. After cooling, the coil was rewound, but no damage was observed.
After removing the unreacted magnetoraclinker, we observed the surface and found that a uniform gray glassy film had been formed in the middle, longitudinal direction, and upper and lower surfaces, and chemical analysis of the steel base revealed that desulfurization had completely progressed. I found out that The film properties are shown in Table 2. 0 Comparative Example 2 The same materials and continuous annealing as in Example 2 were used under the same conditions, and then a vertical pseudomorphic magnesia 10 base part containing 95% or more of the following powder with a particle size of 5 mm as a sintered anchor separation agent, titanium Mix 3 parts of oxide with 400 parts of water, apply it evenly while squeezing it with a rubber roll, and heat at 400°C x 3$ec. It was dried and immediately wound into a coil.

The powder adhesion amount after drying was 65 mm/day on each of the upper and lower surfaces, and 7.
It was midnight. Also, its hydration rate is (QO/Mg0)
×100=9.0%. This was heated for 60 minutes in a hydrogen stream.
0°C x 1 rule rs. First soak, then 1200℃ x 1M
e Dai. High temperature made the moth dull. After cooling, the coil was unwound and excess powder was removed by washing with water. Although no competition was observed in the steel plate, a fine, dark gray, glass-like film was formed at both ends of the coil in the middle direction of the coil, but in the center it was partially whitish. A rough, glassy film with poor adhesion was observed. The film properties are shown in Table 2. Comparative example
3 The same materials as in Example 2 were used, and they were subjected to continuous annealing under the same firing conditions, and then negative coating was performed at a high pressure of 100 kV using an electrostatic powder coating device using the same vertical magnesia used in Comparative Example 2 as a competitive anchor separating agent. The steel plate surface of the counter electrode is electrostatically charged to 10.
It was applied to the upper surface at 0.000 m/m and immediately wound into a coil.

This was heated at 1200oC x 10hers in a hydrogen stream. Fired at high temperature. The adhesion of the powder was uneven in many areas, and some peeling was observed when the powder was wound into a coil. After cooling, the coil was rewound and the excess powder was washed away with water, and it was found that some burning was observed at both ends of the steel plate, and poor formation of a glass-like film was observed in the longitudinal direction. Example 3 Si: 0.3 skin thickness containing 2.9% x 300 legs x
When manufacturing 350 kg of grain-oriented electrical steel sheets, after finish cold rolling, rolling oil was removed, and then the ratio: 75%, N2:2
5%, and 840 qo x 4 minutes in an atmosphere with a fog point of 4500, and then, first, 10 grains of vertical magnesia having 95% or more of powder with a particle size of 5 cm or less was used for forming a glassy film. Mix 3 parts of titanium oxide with 600 parts of water, stir, and apply evenly while squeezing with a rubber roll.
0℃×4$ec. Dry.

The amount of powder adhering after drying is 2.2 days per day on the top and bottom surfaces, respectively.
It was the 1.8th evening. In addition, the hydration rate is (ratio ○/M
g0)×100=11.0%.

Next, a particle size of 5 to 149 m was added to prevent steel sheets from colliding.
A non-hydrated magnesia clinker powder having a powder content of 85% or more is charged at a high voltage of 100 kV using an electrostatic powder coating device, and coated on the surface of the steel plate of the counter electrode at 8.0 μm/min. It was attached to the top surface and immediately wound into a coil. This was heated at 1200°C x 1 s in a hydrogen stream. High temperature competition slowed down. After cooling, the coil was rewound and excess powder was washed away with water, but no cracking of the steel plate was observed, and a uniform, dense, gray glassy film was formed in both the middle and longitudinal directions. The film properties are shown in Table 2. Example 4 When producing a grain-oriented electrical steel sheet containing 2.8% Si and 0.03% acid-soluble A, after finishing rolling to a thickness of 0.3 skin, the rolling oil was removed, and then Day 2: 75%, N2:
25%, dew point 45° C., for 4 minutes at 850 qox, and then mixed with 5 parts of titanium oxide and 10 parts of the coating agent shown in Jikko No. 52-31296 for the purpose of forming a glassy film. Add 1 part of magnesium oxide containing shelf elements as [B], mix with 600 parts of water, mix, apply evenly on the surface of the steel plate while squeezing with a rubber roll, and apply 400 pieces of C x 3 melons. ec. Dry.

The amount of powder attached after drying was 1.9/force on the top and bottom surfaces, 2
．． It was the third evening. In addition, its hydration rate is (20/M/day)
g○)×100=10.5%. Next, 95% of powder with a particle size of 5 to 149 mm was added to prevent rusting of steel plates.
% non-hydrated magnesia clinker powder was negatively charged at a high pressure of 100 kV using an electrostatic powder coating device, and deposited on the upper surface of the steel plate of the counter electrode for 7.5 days. 120,000 x 1 plate size in a hydrogen stream. The high temperature was dull. After cooling, excess powder was removed by washing with water, but no seizure was observed on the steel plate, and a uniform, dense, glossy, gray glassy film was formed on the entire upper and lower surfaces of the steel plate. The film characteristics are shown in Table 2, and the magnetic flux density (B.o) is shown in FIG. 1st
Table Comparison of magnesia manufacturing methods and properties Table 2 Comparison of film properties
cAmount of application: 4 evenings/final

[Brief explanation of drawings]

Figure 1 is a comparison diagram of the hygroscopicity of Figure 5 is a chart showing changes over time, and Fig. 5 is a chart showing magnetic flux density. Multi/Figure 2 Hair 3 Figure 4 Multi figure

Claims (1)

[Scope of Claims] 1. Electrostatically adhering non-hydratable dead-burned magnesia clinker powder whose particle size is adjusted so that 80% or more of the powder has a particle size of 5 to 149 μm on the surface of a grain-oriented electrical steel sheet. A method for applying a high-temperature annealing separator to a grain-oriented electrical steel sheet. 2 After forming a film on the surface of a grain-oriented electrical steel sheet by applying a suspension containing magnesia as a main component, a non-hydrated powder whose particle size is adjusted so that 80% or more of powder with a particle size of 5 to 149 μm is on this film. A method for applying a high-temperature annealing separator to a grain-oriented electrical steel sheet, the method comprising electrostatically adhering dead-burned magnesia clinker powder.