WO2014175555A1

WO2014175555A1 - High-performance sendust powder core and method for production thereof

Info

Publication number: WO2014175555A1
Application number: PCT/KR2014/002439
Authority: WO
Inventors: 김현철
Original assignee: 배은영
Priority date: 2013-04-25
Filing date: 2014-03-24
Publication date: 2014-10-30
Also published as: KR20140127565A

Abstract

The present invention provides a high-performance sendust powder core and a method for the production thereof. The core is produced by using fine powder with a low apparent density prepared by high pressure water atomization without grinding and heat treatment of the powder, coating with a polyimide-based binder as an insulator between powders, and automatic compression molding in the temperature range of 300˚C to 600˚C using MoS₂ powder, which can be lubricated at high temperatures, as a lubricant, thereby providing a sendust powder core having high molding density and molding strength, low iron loss and improved direct current bias characteristics with inexpensive manufacturing costs compared to typical sendust powder cores.

Description

High performance sendust powder core and core manufacturing method

The present invention relates to a high-performance Sendust powder core core and a method for producing the same having excellent molding strength and soft magnetic properties by warm automatic molding, and more particularly, a fine alloy manufactured by high pressure water spraying or gas spraying. Automatic compression molding in the temperature range of 300 ~ 600 ℃ by using powder, coating with polyimide and phenol as binder between powders, and using MoS ₂ as lubricant for powder lubrication at high temperature Through the above, the molding strength of the dust core powder core is improved by 2 times or more, and the DC overlapping characteristics are improved by 5% to 10% or more, and the iron loss is low. It is about manufacture.

The present invention relates to a high-performance Sendust powder core core and a method for manufacturing the same for improving impurity incorporation, core strength, direct current overlapping characteristics and iron loss value during the grinding of powder, which has been a problem of the sender powder core core.

Previously, the production of sendust alloy powders was dissolved in several centimeters of the composition of sendust alloys (eg Fe 84.5wt%, Si 9.7wt%, Al 5.8wt%) in order to increase the apparent density of the powder. The ingot is manufactured to a size of ˜cm and undergoes a crushing process, followed by an annealing process for at least 1 hour in a reducing atmosphere near 800 ° C. to remove stress in the powder. As a result, the apparent density of the powder is higher than 3.0 g / cm ³ , but a large amount of impurities are generated during prolonged grinding, and a large amount of fine cracks are generated in the powder internal structure, thereby decreasing the effective permeability. Also, since the dust powder itself is brittle, the core strength is low even after the binder coating between the powders is formed and heat treated, so that the process of impregnating the epoxy solution to increase the strength after heat treatment of the core is essential. In order to omit the impregnation process, when the binder coating amount is 2wt% at the time of insulation between powders, the strength of the core is improved to some extent, but the effective permeability is more than 125, making it difficult to increase the coating amount.

In general, it is possible to produce fine powders by high pressure water spraying and gas spraying, but the apparent density is lower than 2.6g / cm ³ , so the molding density required for molding does not come out. Therefore, it is not applied to the use of a powder core core.

In order to solve this problem, in the present invention, by developing a manufacturing technology to form a warm forming in the temperature range of 300 ~ 600 ℃ by directly using the fine powder with a low apparent density of 2.6g / cm ³ or less without grinding the powder for Sendust The grinding and powder heat treatment process can be omitted, and the effective permeability of 125 or more, which was impossible to manufacture by the addition of a binder of 2 wt% or more, can be manufactured. A breakthrough method was developed in which the superposition properties and iron loss values could be improved by several percent over the prior art.

The present invention was devised to solve the above problems, and first, 100 mesh classification manufactured by a gas injection method using a water spray of 100 bar or more of water pressure or an inert gas of 20 bar or more of high pressure so as not to undergo a grinding process. A finely ground sandust powder is used which has not been subjected to heat treatment and which has not been heat treated.

Next, in order to provide insulation between powders and to increase core forming strength, a composite powder is prepared by coating 0.5 to 5.0 wt% of a polyimide-based or phenolic resin on the surface of the powder, and then a metal oxide-based powder that maintains lubricity even at high temperatures. After mixing MoS ₂ powder, and automatically compression molding at a speed of 5 to 15 strokes per minute in a temperature range of 300 to 600 ° C, a high performance sender powder can be produced in a molding press used in a conventional room temperature molding. It is to provide a method for producing a sim core.

Another object of the present invention is the molding density and the molding strength is higher than the conventional molding at room temperature according to the manufacturing method, while the effective permeability is 50% or more higher than the conventional sender powder green core, the DC overlap characteristics and iron loss It is to provide a high-performance sendust powder core core with improved value.

By using the fine powder prepared by the high pressure water injection method and the gas injection method directly without heat treatment according to the present invention, the pulverization and heat treatment processes applied at the time of the manufacture of the sendest powder are omitted, and the temperature of 300 to 600 ° C. It is possible to increase the forming strength and density of the core by warm molding in the area, and the manufacturing process can be reduced by shortening the manufacturing process by eliminating the impregnation process, and the high-performance sender powder core core according to the present invention is conventionally The effective permeability can be dramatically increased to 50% or more compared to the normal-temperature forming sandblast core cores, and the molding strength is more than two times higher than that of conventional molding at room temperature, and the DC overlap characteristic is 5% to 10% or more. It is possible to obtain an improved effect of the Sendust green powder core which has an improved and low iron loss.

1 is a change in the molding density of the molding core according to the molding temperature change for the powder prepared according to the conditions of Example 1

2 is a change in effective permeability according to the molding temperature change for the powder prepared according to the conditions of Example 1

In order to achieve the above object, a method for producing a high-performance sendust powder core core according to the present invention includes (a) fine particulate sandust powder that has passed 100 meshes prepared by a high pressure water spray method and a gas spray method. Performing liquid coating with a polyimide-based or phenol-based resin 0.5-5.0 wt% to produce a uniform and dense coated composite particle powder; (b) uniformly mixing the composite particles at 0.5-2.0 wt% by applying the fine powder of MoS ₂ as a lubricant; (c) molding the mixed powder at a speed of 5 to 15 strokes / minute at a pressure of 12 to 25 tons / cm 2 in a temperature range of 300 to 600 ° C .; And (d) heat treating the molded core at a temperature of 700 to 800 ° C. It includes.

Hereinafter, the present invention will be described in detail.

* The manufacture of the sender alloy powder used in the present invention can produce the fine powder by the water injection method of 100 bar or more and the gas injection method of the dissolved sender solution, in the present invention 100 bar to omit the grinding and heat treatment process The fine powder of the microthermal treatment which manufactured by the above water-jet method and passed through the 100 mesh classifier was used. The apparent density of the powder at this time may be 2.0 g / cm ³ or more. If it is less than this, the filling property of the powder will be poor at the time of molding the powder.

In order to increase the insulation of the powder and the bonding strength during molding, as a binder, a polyimide- or phenol-based resin softened at a temperature of 300 ° C. or higher is preferable, and an appropriate coating amount is suitably 0.5 to 5.0 wt% of the total mass of the powder. . In 0.5wt% or less, the insulation is inferior, and the iron loss value increases. In 5.0wt% or more, the viscosity between powders is strong, making the insulation coating difficult. On the other hand, water glass, which is conventionally applied as a binder, plays a role in improving insulation and molding strength, but it is not preferable to use water glass because it may cause surface damage to the molding die during molding as it is cured at 400 ° C. or higher. The above-mentioned "gross mass" means the sum of the masses of the coating agent and the sendust alloy powder constituting the core to be produced, and does not include the mass of the organic solvent.

In order to impart high temperature lubricity of the sender alloy powder prepared by coating a binder, MoS ₂ powder, which is a metal oxide that does not lose lubricity even at high temperatures, is suitable, and an average particle diameter of the powder to be used is suitably about 1 to 10 μm. The addition amount is preferably limited to 0.5 to 2.0 wt% of the total amount. If less than 0.5wt%, there is a lack of lubricity between powders, which causes damage to the punch for forming, and more than 2.0% of the soft magnetic properties deteriorate and economic efficiency is reduced.

At the time of core molding, a molding pressure of 12-25 ton / cm ² is appropriate. If the molding pressure is 12ton / cm ² or less, the molding density of the core is lowered and the soft magnetic properties are deteriorated. On the other hand, if the molding pressure is too high, problems such as abrasion and breakage of the molding die occur frequently, thereby increasing the production cost unit. As for the temperature at the time of shaping | molding, 300-600 degreeC temperature range is preferable. The optimum molding density is not realized below 300 ℃, and the higher the molding temperature, the higher the molding density of the core and the higher the density between powder particles, but the maximum molding temperature is 600 ℃ because it can affect the molding die above 600 ℃. It is preferable to set it as follows.

The heat treatment temperature of the molded core is different depending on the composition of the senddust alloy and the type of coating agent, but is suitable for 650 ~ 750 ℃. If the temperature is lower than 650 ° C., internal stresses generated in the core during molding may not be sufficiently removed. If the temperature is higher than 750 ° C., the used binder may be decomposed to damage insulation.

It is preferable that the heat treatment atmosphere is an inert gas or a reducing gas atmosphere, and the time is about 30 to 120 minutes. If the heat treatment time is too short, the stress in the core is not sufficiently removed, while if too long, productivity is reduced.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

1000g was prepared by classifying the unheated Sendust alloy powder (average particle size about 25㎛) prepared by 200bar high pressure water spraying into 100 mesh, and then 20g (2.0wt%) of polyimide was methylene chloride solution. After the coating treatment with a solution prepared by dissolving in, and then drying, a composite particle powder having a polyimide uniformly coated with a thickness of about 1 μm or less on the surface of the sender alloy powder having an average particle diameter of about 25 μm was prepared. After drying, 10 g (1 wt%) of MoS ₂ powder having an average particle diameter of 3 μm was uniformly mixed.

The mixed multiparticulate powder has an outer diameter of 12.7 mm and an inner diameter of 7.65 mm, and is automatically charged at about 2.40 g into a molding die maintained at 400 ° C., and then automatically molded at a speed of 10 strokes per minute at a pressure of 18 ton / cm ² to have an average height. A molded core of 4.75 mm was prepared. The molded core was heat-treated at 720 ° C. for 60 minutes in a nitrogen (N 2) gas atmosphere.

Magnetic properties such as molding density, core strength, effective permeability of various frequency bands, and core loss measured for cores manufactured are shown in Table 1, Figure 1, and Figure 2. Here, the core density is calculated by dividing the actual weight of the core by the volume of the core, and the core strength is expressed as compressive strength before and after heat treatment after forming by a tension meter, and the effective permeability is measured by an impedance analyzer. It is measured under the 10mOe external magnetic field in the frequency band of 100kHz, and the DC superposition characteristic is expressed as percentage by dividing the value measured under the external magnetic field of 20Oe in the frequency band of 100kHz by dividing it by 10mOe. . Iron loss values were measured by a magnetic analyzer (BH Analyzer) under a frequency of 50 kHz and an induction flux density of 1000 Gauss.

Example 2

The same procedure as in Example 1 was carried out except that the insulating coating was performed with 50 g (5.0 wt%) of polyimide. The properties of the molded core prepared are shown in Table 1 and FIGS. 1 and 2.

Example 3

The same procedure as in Example 1 was carried out except that the insulating coating was performed with 5 g (0.5 wt%) of polyimide. The properties of the molded core prepared are shown in Table 1 and FIGS. 1 and 2.

Example 4

It carried out similarly to Example 1 except having set molding temperature to 300, 500, and 600 degreeC.

The properties of the molded core prepared are shown in Table 1 and FIGS. 1 and 2.

Table 1

Condition number	Molding temperature (℃)	Apparent density (g / cm ³ )	Molding density (g / cm ³ )	Compressive strength (kgf)		Effective investment rate	DC overlap (%)	Iron loss (mW / cc)
Condition number	Molding temperature (℃)	Apparent density (g / cm ³ )	Molding density (g / cm ³ )	Before heat treatment	After heat treatment	Effective investment rate	DC overlap (%)	Iron loss (mW / cc)
Example 1	400	2.44	6.12	22	29	146	74.6	202
Example 2	400	"	6.05	39	45	95	86.5	215
Example 3	400	"	6.12	15	22	210	54.0	275
Example 4	300	"	6.00	15	29	125	76.2	220
	450	"	6.15	23	29	145	74.7	205
	500	"	6.16	25	29	156	74.1	202
Comparative Example 1	Room temperature	3.10	5.80	10	29	95	83.5	265
Comparative Example 2	400	2.44	6.16	5	26	195	53.0	317
Comparative Example 3	Room temperature	"	5.70	11	22	105	73.5	315
	100	"	5.71	11	24	105	73.5	316
	200	"	5.71	11	24	105	73.5	310

Here, referring to Table 1 and FIGS. 1 and 2, the molding temperature is almost no change in molding density and effective permeability up to 200 ° C., but increases linearly from 200 ° C. or higher, but gradually increases at 400 ° C. or higher. By molding at 300 ° C or more means that the effective coating rate of 125 or more, which was not possible in the conventional room temperature molding at 2 wt% or more, is possible. In addition, even when the insulation coating amount is 0.5wt%, the compressive strength is high, and the strength before heat treatment is several times higher than the forming core at room temperature, so that there is no fear of breakage during transport of the core, and after the heat treatment, the impregnation process is not required. In addition, it can be seen that the DC superposition characteristic is superior to the same permeability material at room temperature molding by more than 5%, and the iron loss value is also improved by 30% or more.

In addition, it can be seen that the present invention is superior to the conventional materials without the conventional grinding and heat treatment processes.

Hereinafter, the comparative example of this invention is demonstrated in detail.

Comparative Example 1

A centrifugal alloy ingot (average size of about 3 cm) manufactured by 1 bar low pressure water spraying method was pulverized with an Attrition Mill at 200 rpm for 20 minutes, and then classified into 100 mesh to obtain 1000 g of hydrogen at 800 ° C. It carried out similarly to an Example except having heat-processed under 1 hour. The characteristics of the prepared sender core are shown in Table 1 and FIGS. 1 and 2.

Comparative Example 2

The same procedure as in Example 1 was carried out except that 3 g (0.3 wt%) of polyimide was dissolved in methylene chloride to prepare a solution. The characteristics of the prepared sender core are shown in Table 1 and FIGS. 1 and 2.

Comparative Example 3

It carried out similarly to Example 1 except molding at normal temperature (25 degreeC) and 100 and 200 degreeC. The characteristics of the prepared sender core are shown in Table 1 and FIGS. 1 and 2.

Here, referring to Table 1, when the molding temperature is 200 ℃ or less, the molding density can not exceed 5.8g / cm ³ , and thus the permeability is not more than 110, when the coating amount is lower than 0.5wt% insulation in the core It can be seen that the iron loss is greatly increased and the molding strength of the core is significantly worsened.

Claims

(a) preparing a composite powder by coating a polyimide-based or phenolic-based powder using fine particulate sendust powder prepared by high-pressure water spraying and gas spraying, and omitting pulverized and heat-treated steps;

(b) mixing fine MoS 2 powder, which is a high temperature lubricant, into the multiparticulate powder;

(c) automatically molding the mixed powder at a high temperature;

(d) heat treating the molded composite particle powder; Method for producing a high performance sandust powder core containing a core
The method of claim 1,

At the time of coating the dust dust, the coating amount is 0.5 to 5.0wt% of the total mass, the amount of the lubricant is 0.5 to 2.0wt% of the total mass, the production method of high-performance sendust powder core core
The method of claim 1,

The molding is a method for producing a high-performance Sendust powder core core, characterized in that the automatic molding at a pressure of 12 to 25ton / ㎠ in the temperature range of 300 ~ 600 ℃
The method of claim 1,

The heat treatment is carried out at a temperature of 650 ~ 750 ℃ method for producing a high-performance senddust powder core core