KR20050085871A - Soft magnetic powder composition comprising insulated particles and a lubricant selected from organo-silanes, -titanates, -aluminates and zirconates and a process for their preparation - Google Patents

Abstract

The present invention concerns a new ferromagnetic powder composition comprising soft magnetic iron-based core particles wherein the surface of the core particles are surrounded by an insulating coating, and a lubricating amount of a compound selected from the group consisting of silanes, titanates, aluminates, zirconates, or mixtures thereof. The invention also concerns a process for the preparation of soft magnetic composite materials using the new powder composition.

Description

SOFT MAGNETIC POWDER COMPOSITION COMPRISING COMPOSING INSULATED PARTICLES AND A LUBRICANT SELECTED FROM ORGANO-SILANES, -TITANATES, -ALUMINATES AND ZIRCONATES AND A PROCESS FOR THEIR PREPARATION}

The present invention relates to a novel metal powder composition. More specifically, the present invention relates to novel iron-based powders useful for producing soft magnetic materials having improved properties when used at both high and low frequencies. The present invention also relates to a process for producing soft magnetic composite materials made from novel iron-based powders.

Soft magnetic materials are used in applications such as core materials in inductors, stators and rotors of electrical devices, actuators, sensors and transformer cores. Typically, soft magnetic cores, such as rotors and stators in electrical devices, are made of laminated steel laminates. Soft magnetic composite (SMC) materials are generally based on iron-based soft magnetic particles, each of which is electrically insulating coated. SMC parts are manufactured by compressing insulated particles with optional lubricants and / or binders using conventional powder metallurgical processes. By using such powder metallurgical techniques, the three-dimensional shape can be obtained by the compression process and the SMC material can support three-dimensional magnetic flux, so that SMC parts can be prepared more than with steel sheets. It is possible to produce materials with high degrees of freedom in design.

Two main features of iron core parts are the permeability and core less characteristics of the core part. The permeability of a substance is a measure of its ability to support flux or to be magnetized. Permeability is defined as the ratio of induced magnetic flux to magnetic force or magnetic field strength. When a magnetic material is exposed to a changing magnetic field, energy losses occur because of the loss of magnetic history and eddy currents. The hysteresis loss is caused by the consumption of energy required to overcome residual magnetic forces inside the iron core part. Vortex losses are caused by current being generated in the iron core part because of the changing flux caused by the alternating current (AC) state. The high electrical resistance of the component is desirable to minimize eddy currents.

Research in powder metallurgical manufacture of magnetic core parts using coated iron-based powders has been developed towards the development of iron powder compositions that enhance certain physical and magnetic properties without adversely affecting other properties of the final part. Preferred part properties include, for example, high permeability, low iron core loss, high saturation induction, and high strength over an extended frequency range. In general, the increased density of the component improves all these properties under the condition that sufficient electrical resistance can be maintained. Preferred powder properties include the suitability of compression molding techniques, which means that the powder can be easily molded into high density parts, and also can be easily discharged from the molding apparatus without damage on the part surface.

The present invention relates to a novel ferromagnetic powder composition suitable for compression into high density composite parts. More specifically, the invention relates to powder compositions comprising soft magnetic iron or iron-based core particles, wherein the surface of the particles is surrounded by an electrically insulating inorganic coating, and the composition is silane, titanate, aluminate, or Lubricants selected from zirconates.

The present invention includes a method of making compacts that can be selectively heat treated at high density from the composition. Such a method can be heat treated after providing the composition, optionally mixing the composition with additives such as binders and conventional lubricants (ie, certain lubricants) as well as flow enhancing agents. Compressing and ejecting the molded body in a uniaxial direction in a die under high pressure.

The ferromagnetic powders used in the present invention are made of iron or an iron containing alloy and optionally contain up to 20% by weight of one or more elements selected from the group consisting of aluminum, silicon, chromium, niobium, molybdenum, nickel and cobalt as alloying elements. . Preferably, the novel powders of the present invention are based on a base powder consisting essentially of pure iron. The powder may be, for example, a commercially available water-atomised or gas-sprayed iron powder or reduced iron powder, such as sponge iron powder. The powder particles may be round, irregular, or flat.

Preferred electrically insulating coatings that can be used according to the invention are thin phosphorus containing coatings of the type described in US Pat. No. 6,348,265, herein incorporated by reference. Other coatings, preferably inorganic coatings, can also be used, for example coatings based on Cr, Mg, Mo, Zn, Ni, or Co.

Lubricants used according to the invention are in the form of organo-silanes, organo-titanates, organo-aluminates or organo-zirconates. Materials of this kind are often referred to as surface modifiers, coupling agents, or cross-linking agents, depending on the chemical functionality of the linked groups. Particular forms of organo-silanes, organo-titanates, organo-aluminates or organo zirconates which may be referred to as compounds of organo-metals and which are used according to the invention are those of at least one hydrolyzable group and at least one lubricious organic moiety. It is distinguished by its existence. Compounds of this type have the following general formula:

M (R ₁ ) _n (R ₂ ) _m

Wherein M is a central atom selected from Si, Ti, Al, and Zr; R ₁ is a hydrolyzable group; R ₂ is a group consisting of lubricious organic moieties; The sum of m + n must be equal to the coordination number of the central atoms, where n is an integer greater than or equal to 1 and m must be an integer greater than or equal to 1.

In particular R ₁ is an alkoxy group having less than 12 carbon atoms. Preferred are alkoxy groups having less than 6 carbon atoms, most preferred are alkoxy group groups having 1 to 3 carbon atoms. R ₁ may be a chelate group such as a residue of hydroxyacetic acid (—OC (O)) — CH ₂ O— or a residue of ethylene glycol (—OCH ₂ CH ₂ O—).

R ₂ is an organic group containing 6 to 30 carbon atoms, preferably 10 to 24 carbon atoms, and optionally including one or more hetero atoms selected from the group consisting of N, O, S and P. R ₂ is a group consisting of organic moieties, which are not readily hydrolyzed and are often lipophilic and are alkyl, ether, ester, phospho-alkyl, phospho-alkyl, phospho-lipid Or chains of phospho-amines. The phosphorus may be present as a phosphato, pyrophosphato or phosphito group. Furthermore R ₂ may be linear, branched, cyclic, or aromatic.

Preferred lubricant silane groups according to the invention are alkyl-alkoxy silanes and polyether-alkoxy silanes. Moreover, the promised results are hexadecyl-trimethoxy silane, isopropyl-triisostearyl titanate, isopropyl-tri (dioctyl) phosphato titanate, neopentyl (diallyl) oxy-tri (dioctyl) force Patho zirconate, neopentyl (diallyl) oxy-trineodecanoyl zirconate, and diisobutyl-acetoacetyl aluminate have been obtained.

The amount of the compound is preferably present in a substantial amount of at least 0.05% by weight, such as 0.05 to 0.5% by weight, preferably 0.07 to 0.45% by weight, and more preferably 0.08 to 0.4% by weight of the composition. Too little lubricant can result in high densities but can result in poor drainage and, therefore, can result in poor surface conditions of the tool and / or SMC parts. However, too much lubricant may result in good drainage, but may result in low density of parts. It is also preferred that the compound be present as a lubricating layer on the insulating particles. However, it should be noted that not only the material but also the shape of the part and the quality of the tool have a great influence on the surface condition of the SMC part after ejection.

The use of compound organo-silanes, organo-titanates, or organo-aluminates is known from US Pat. Nos. 4,820,338 and 6,537,389. U.S. Patent No. 4820338 silanes, titanates or aluminates according to the call carbonate is used to facilitate the coupling between the magnetic powder particles and the electrically insulating organic binder polymer claim. The powder particles do not have an inorganic coating.

US Pat. No. 6,537,389 describes a wide range of silicon-containing, aluminum-containing, or boron-containing compounds as molecular precursors for producing electrically insulating ceramics on soft magnetic powders. The precursor compound is converted into a ceramic, metal, and intermetallic end product by heat treatment to improve temperature resistance and solvent resistance. US Pat. No. 6,537,389 differs from the present invention in that the organo-metal compound is used as a precursor for making chemical and thermally resistant coatings, not as a major component that facilitates the manufacture of high density parts. Furthermore, the precursor compounds described in the examples of US Pat. No. 6,537,389 do not include a lubricious moiety.

The lubricious compounds used according to the invention can be used in such a way that they are dissolved or dispersed in a suitable solvent, for example an organic solvent such as acetone or ethanol. The obtained solution or dispersion is subsequently added to the iron-based powder during mixing and optional heat treatment. The solvent is finally evaporated, optionally under vacuum.

The powder used according to one embodiment of the invention has coarse particles. In other words, the powder is essentially free of fine particles. The term “essentially free of fine particles” means that less than about 5% of iron powder or iron-based powder particles have a size of 45 μm or less, as measured by the method described in SS-EN 24 497. The most interesting results so far have been achieved by powders consisting essentially of particles of at least about 106 μm, in particular at least about 212 μm. The term “consisting essentially of” means that at least about 40% and preferably at least about 60% of the particles have a particle size of at least 106 and 212 μm, respectively. So far the best results have been achieved with powders having an average particle size of about 250 μm and only less than 3% of the particles having a particle size of 106 μm or less. The maximum particle size may be about 5 mm. For iron-based powders used in PM manufacturing, the particle size distribution is generally distributed in a Gaussian distribution with an average particle diameter in the range of 30 to 100 μm and 10 to 30% of less than 45 μm. Iron based powders that are essentially free of fine particles are free of fine particles that may be obtained by preparing a powder with the desired particle size distribution or by removing a finer fraction of powder.

Contrary to the common practice in powder metallurgy, according to a preferred embodiment of the present invention in which conventional PM lubricants are used in the iron powder mixture or in combination with a binder and / or surface treatment agent, the iron powder or iron-based powder It should not be mixed with a separate (specific) lubricant before being transferred. There is no need to use external lubrication (die wall lubrication) where lubricant is provided to the walls of the die before compression is performed. However, the present invention also does not exclude the possibility of using conventional internal lubrication (in amounts up to 0.5% by weight), external lubrication, or a combination thereof. The powder to be compacted may also comprise an additive selected from the group consisting of binders, lubricants, and flow-enhancing agents. Examples of inorganic lubricants that may also be used as organic PM lubricants are hexagonal boron nitride, and MoS ₂ .

In accordance with the present invention a soft magnetic composite material having a density of about 7.45 g / cm 3 or greater can be prepared by compressing the novel powder composition in one direction without die wall lubrication in the die under high compression pressure. When the molded body is ejected from the compression tool, the molded body may be heat treated at a temperature of about 700 ° C.

The term "high compression pressure" means a pressure of about 800 MPa or more. More interesting results are achieved at pressures above 900 MPa, more preferably above 1000 MPa, and most preferably at high pressures such as 1100 MPa. Conventional compression at high pressures, ie pressures above about 800 MPa, typically for particles containing finer particles, results in the high force required to discharge the molded body from the die, thus high wear properties of the die, and It is considered unsuitable because of the fact that the surface tends to be less shiny or deteriorated. High electrical resistance can be achieved even if high compressive forces are used to achieve high density. It has been unexpectedly found that by using the powders according to the invention the ejection force is reduced at high pressures of about 1000 MPa and that parts which can be accommodated or even have a perfect surface can be produced.

The compression can be performed with standard equipment, which means that the new method can be carried out without costly investment. Compression is performed uniaxially and preferably in a single step at ambient temperature or above ambient temperature. Alternatively, the compression may be carried out with the aid of a percussion machine (model HYP 35-4 from Hydropulsor) as described in patent publication WO 02/38315.

The heat treatment is carried out at temperatures commonly used in various forms of air or reduced pressure and optionally in the presence of steam, for example up to about 700 ° C. Compressed parts prior to heat treatment may optionally be green processed and / or green cleaned.

The main object of the present invention is to achieve a high density product, for which it is preferred to use coarse powder as described above. However, it has been found that this lubricating effect may also be produced with a combination of powders containing a larger amount of fine particles, for example, in the form typically used in the PM industry today. Examples 3 and 5 below illustrate the lubricating effect of the compounds of organo-metals according to the invention on conventional powders and coarse powders. As can be observed, high density can be obtained with conventional powders containing larger amounts of fine particles. Lubricants according to the invention and compositions comprising iron powders or iron-based powders having a particle size distribution generally used today are particularly suitable for certain applications and are therefore also within the scope of this invention.

The term "high density" means a shaped body having a density of at least about 7.45 g / cm 3. "High density" is not an absolute value. For a single heat treated and single compressed part, the density that can typically be achieved according to the prior art is about 7.2 g / cm 3. An increased density of 0.2 g / cm 3 may be reached by using warm compaction. As used herein, the term "high density" means a shaped body having a density of about 7.45 to 7.65 g / cm 3, depending on the amount and form of the additive used and the form of the iron-based powder used. Parts with lower densities may also be produced but are believed to have less advantage.

In short, the advantage obtained by using the process and powder according to the invention is that high density SMC parts can be manufactured cost-effectively. SMC parts with significantly higher levels of magnetic induction with lower iron losses can be obtained. Another advantage is that the mechanical strength is increased after the heat treatment, and despite the high density, compressed parts with high electrical resistance without the negative impact on the finish of the die wall and / or on the surface of the SMC part are Can be successfully discharged from the die. Thus, it is possible to obtain a component having excellent surface finish. This result can be obtained in a single compression step. Examples of products which are particularly advantageous for the novel powder compacts are inductors, stators and rotors for machines, actuators, sensors, and transformer cores.

The invention is further illustrated by the following examples. However, it should be understood that the present invention is not limited to such subsequent examples.

Example 1

Iron-based water spray powder (Somaloy 550 ™, made available from Hoganagas Avesa, Sweden) was used as the starting material. The powder has an average particle size of 212 μm to 425 μm and less than 5% of the particles have a particle size of 45 μm or less. The powder is a pure iron powder electrically insulated by a thin phosphorus-containing thin barrier, which powder is treated with 0.2% by weight of hexadecyl-trimethoxy silane as a lubricant. The addition of lubricant was carried out as follows: Hexadecyl-trimethoxy silane was diluted in 20% by weight ethanol solution and the solution was stirred for 60 minutes. The solution in an amount corresponding to 0.2% by weight was added during mixing in a mixer of iron powder previously heat treated at 75 ° C. Intensive mixing was performed in the same mixer during the vacuum to evaporate the solvent and for 3 minutes after the slow mixing for 30 minutes. Corresponding powders mixed with conventional lubricants were used as comparisons. The powder was mixed with Kenuolube ™ before compaction. The amount of lubricant used is 0.5% of the composition This is generally considered to be a small amount of lubricant for parts compressed at high pressures.

Rings with an inner diameter of 47 mm, an outer diameter of 55 mm and a height of 4 mm were compressed in one axial direction in a single step at different compression pressures 800, 1000 and 1200 MPa. Despite the small amount of organo-metallic lubricant and high compression pressure, the surface of the part showed no signs of deterioration.

After compression the parts were heat treated at 500 ° C. for 30 minutes in air. The heat-treated ring is subjected to 25 senses and 112 drive turns. It was. Magnetic properties were determined on LDJ 3500 Hysteresigraph. Table 1 summarizes the maximum relative permeability and magnetic induction at 1500 A / m and 6900 A / m, respectively, measured under DC conditions. Iron loss / cycle has also been measured at 1 T and 50 Hz and 1 T and 400 Hz respectively.

Table 1 below shows the results obtained:

Sample Compression Pressure MPa Density g / cm 3 μ _max B ₁₅₀₀ (T) B ₆₉₀₀ (T) Iron core loss / cycle 1T and 50 Hz (J / Kg) Iron core loss / cycle 1T and 400 Hz (J / Kg) Sample of the present invention 800 7.45 720 1.08 1.53 0.134 0.178 1000 7.59 790 1.15 1.59 0.126 0.163 1200 7.64 820 1.18 1.62 0.124 0.165 Sample of Comparative Example 800 7.39 620 0.95 1.46 0.142 0.200 1000 7.47 590 0.95 1.49 0.140 0.198 1200 7.49 550 0.92 1.48 0.140 0.193

As can be seen from Table 1, the green density in the powder according to the invention is considerably high and the magnetic properties are also improved compared to the materials used in the comparative examples. It can be seen from the comparative examples that the magnetic pressure is slightly or hardly improved by increasing the compression pressure to 1000 MPa and 1200 MPa.

Despite the high density samples obtained, iron loss was maintained at low levels, even at 400 Hz, indicating that the electrical insulation layer was maintained.

Samples prepared according to Example 1 were tested for transverse rupture strength (TRS) after heat treatment at 500 ° C. for 30 minutes in air. The pull strength was tested according to ISO 3995. 1 shows the drag force at different density levels. In the material according to the invention, it should be noted that the strength is unexpectedly high even at the same compacted density.

Example 2

Ultra high purity water spray iron-based powder, the particles of which have a thin insulating coating, which has an average particle size of at least 212 μm and treated with 0.1% and 0.2% hexadecyl-trimethoxysilane, respectively, according to the procedure of Example 1. It became. The same iron-based powder was used as reference without lubricant.

Cylindrical samples having a diameter of 25 mm and a height of 4 mm were compressed by uniaxial press movement at a compression pressure of 1000 MPa.

Table 2 shows the emission energy and green density obtained to discharge the part. Emission energy is expressed as a percentage of the emission energy for the sample without lubricant.

Amount of silane Green density (g / cm 3)  Comparative emission energy% Surface finish characteristics 0 % 7.66 100 fixation 0.1% 7.67 58 Good 0.2% 7.66 48 Good

From Table 2, it can be seen that according to the present invention the surface finish is improved by the addition of a small amount of organic-metal lubricating agent and the energy required to discharge is significantly reduced. It can also be observed that an increase in lubricant from 0.1% by weight to 0.2% by weight has a positive effect on the emission energy.

Example 3

This example shows the effect of the chain length of the compound hydrolyzable group or group R ₂ of the organo-metal on lubricating properties when discharged after being compressed to high pressure. Various forms and amounts of alkyl-alkoxy silanes (center atom Si) in this example are used as lubricants. Two kinds of high purity water spray iron based powders have a thin insulating coating and two different particle size distributions were used to show the effect of particle size. The S-powder has about 14% of the particles less than 45 μm and a weight average particle size of about 100 μm. The C-powder has a weight average size of about 250 μm and a fairly coarse particle size distribution with less than 3% having a size of 106 μm or less.

Five kinds of organo-silanes (A-E) were used:

A methyl-trimethoxy silane

B propyl-trimethoxy silane

C octyl-trimethoxy silane

D hexadecyl-trimethoxy silane

E Polyethylene-trimethoxy silane with 10 ethylene ether groups

Five alkyl-alkoxy silanes were added to the insulated iron powder in the range of 0.05% to 3.0% by weight and the resulting mixture was compressed to 1100 MPa by uniaxial press movement into slugs with a diameter of 25 mm and a height of 12 mm. . As shown below in Table 3, the dynamic ejection force per unit slide area during ejection was measured, the painted surface finish characteristics were evaluated and the density was measured after ejection.

Powder C Powder C Powder C Powder S Powder C Powder S Powder C Powder C Silane 0.05% 0.1% 0.2% 0.2% 0.4% 0.4% 1.0% 3.0% A fixation B fixation C fixation 58 N / mm2 poor7.60g / cm3 D 89 N / mm2 poor7.70g / cm3 69 N / mm2 OK7.70g / cm3 38 N / mm 2 OK7.68g / cm 3 63N / mm2 poor7.65g / cm3 47N / ㎡OK7.57g / cm3 54N / mm2 OK7.54g / cm3 E 80N / ㎡ Poor 7.70g / cm3 35 N / ㎡ OK 7.69 g / cm 3 75N / mm2 poor7.64g / cm3 32N / mm2 OK7.59g / cm3 49 N / mm 2 OK7.60 g / cm 3

As can be seen from Table 3, the chain length of up to 8 carbon atoms in the alkyl chain was unsatisfactory despite the large amount of additives. Therefore, about eight or more atoms are needed to successfully eject a part from a lubricated (alkyl, or polyethyleneether) chain group or group. Since the density of the green part will have a negative effect, it is believed that more than 0.5% added amount will be less beneficial. The table shows that when the organo-silane content is less than 0.05%, the emission without surface damage of parts and dies is impossible in the case of silane "D" comprising 16 atoms in the lubricating alkyl group. However, not only the quality of the device but also the geometry of the part has a great influence on the surface condition of the part after ejection. Thus amounts of lubricants less than 0.05% conventionally used, ie, optionally mixed with a particular lubricant, may be beneficial in some applications.

It can also be concluded from Table 3 that extremely high densities can be obtained. Coarse particles show better emissions than standard powders. Even powders having a standard particle size distribution can be compressed at high densities (at least about 7.60 g / cm 3). As mentioned above, ejectability is also highly dependent on component combination and device material and quality. Thus, powders with standard particle distributions can be beneficial in some applications.

Example 4

This example illustrates the lubricating effect of compounds of organo-metals having different central atoms. The lubricating effects of four different lubricants in this example were each tested with Si, Ti, Zr and Al as central atoms, ie silane, titanate, zirconate and aluminate. Various central atoms have different coordination numbers and chemical properties. However, the chemical structure of the compound of organo-metal was chosen because of the chain length of the lubricity group or group R ₂ , which would show comparable properties with those obtained with hexadecyl-trimethoxy silane (D).

High purity water spray iron based powders with a thin insulating coating were treated with 0.2% by weight of each organo-metal compound as a lubricant. The resulting mixture was compressed to 1100 MPa by uniaxial press movement into a slug having a diameter of 25 mm and a height of 12 mm. As shown in Table 4 below, during discharge, the dynamic discharge force per unit sliding area was measured, the green surface finish after discharge was evaluated, and the density was measured.

Four different types of organo-metals were tested (A-D):

A isopropyl-triisostearoyl titanate

B neopentyl (diallyl) oxy-trineodecanoyl-zirconate

C diisobutyl (oleyl) -aceto-acetyl aluminate

D hexadecyl-trimethoxy silane

Organo-metallic compounds A B C D Discharge force [N / ㎡] 35 44 50 39 Density [g / cm 3] 7.68 7.68 7.68 7.68 Exhaust and part quality OK OK OK OK

As can be seen in Table 4 the lubricity of all compounds is satisfactory. Therefore, the shape of the central atom shows only a small effect on lubricity. According to the present invention the chain length of the hydrolyzable group or group in several ranges of chain length and chemical structure has been shown to provide lubricity.

Example 5

The influence of average particle size and particle size distribution was also investigated. All three insulated with thin phosphate based electrical insulation, three different high purity iron-based powders with different particle size distributions, were prepared according to Table 5. All samples were treated with 0.2% by weight of hexadecyl-trimethoxy silane according to the procedure described in Table 1.

Cylindrical samples having a diameter of 25 mm and a weight of 50 g were compressed by uniaxial press movement at a compression pressure of 1000 MPa and a green density of 7.6 g / cm 3 or more was obtained for all samples.

Particle size distribution Sample A (%) Sample B (%) Sample C (%) -45 μm 8.4 0.0 0.1 45-106 μm 52.7 15.5 1.0 106-212 μm 30.0 84.3 37.4 212-315 μm 0.1 0.2 51.0 +315 μm 0.1 0.0 10.5 Density [g / cm 3] 7.61 7.63 7.62 Surface finish Poor * OK Good

Higher lubricants improve surface finish.

It can be observed that the surface finish of sample C is superior to the surface finish of each of samples A and B.

Example 6

This embodiment illustrates the importance of inorganic insulation.

The particles of the powder, which are electrically insulated by high purity iron powder, a thin phosphorus-containing barrier, were compared with the same powder without phosphorus-based inorganic insulation. Both forms of powder were then treated with 2% by weight of hexadecyl-trimethoxy silane as lubricant according to the invention.

Rings with an inner diameter of 45 mm and an outer diameter of 55 mm and a height of 5 mm were uniaxially compressed in a single step at a compression pressure of 1100 MPa, after heat compression at 500 ° C. for 30 minutes in air after compression of the parts. Electrical resistance was measured by the four-point method.

Table 6 below shows the electrical resistivity and density of the composite parts produced from powder without insulated particles and with insulated particles.

Electrical resistivity [μOhm * m] Density [g / cm 3] According to the present invention 150 7.68 Comparative Example 0.5 7.68

Claims (23)

As a ferromagnetic powder composition, Soft magnetic iron core particles whose surface is surrounded by an insulating inorganic coating, and A lubricant comprising a compound selected from the group consisting of silanes, titanates, aluminates, zirconates, or mixtures thereof, Ferromagnetic powder composition. The method of claim 1, Wherein said compound has at least one hydrolyzable group and at least one lubricious organic moiety, Ferromagnetic powder composition. The method according to claim 1 or 2, Wherein the compound is present as a lubricating layer on the insulated particles, Ferromagnetic powder composition. The method according to any one of claims 1 to 3, The compound is of the general formula: M (R ₁ ) _n (R ₂ ) _m , M is a central atom selected from Si, Ti, Al, or Zr, R ₁ is a hydrolyzable group, R ₂ is a group consisting of lubricious organic moieties, The sum of m + n is the coordination number of the central atoms;  n is an integer greater than or equal to 1, and  m is an integer greater than or equal to 1, Ferromagnetic powder composition. The method of claim 4, wherein R ₁ is an alkoxy group having less than 12, preferably less than 6, most preferably less than 3 carbon atoms, Ferromagnetic powder composition. The method of claim 4, wherein R ₁ is a chelate group, Ferromagnetic powder composition. The method of claim 6, Wherein the chelate group is a residue of hydroxyacetic acid (-O (O = C) -CH ₂ O-) or a residue of ethylene glycol (-OCH ₂ CH ₂ O-) Ferromagnetic powder composition. The method according to any one of claims 4 to 7, R ₂ is an organic group comprising 6 to 30, preferably 10 to 24 carbon atoms, and optionally including one or more hetero atoms selected from the group consisting of N, O, S and P, Ferromagnetic powder composition. The method of claim 8, R ₂ is linear, branched, cyclic, or aromatic, Ferromagnetic powder composition. The method according to claim 8, wherein R ₂ is a chain selected from the group consisting of alkyl, ether, ester, phospho-alkyl, phospho- lipid, or phospho-amine, Ferromagnetic powder composition. The method of claim 10, R ₂ is selected from the group consisting of phosphato, pyrophosphato or phosphito, Ferromagnetic powder composition. The method according to any one of claims 1 to 10, Wherein said compound is selected from the group consisting of alkyl-alkoxy silanes and polyether-alkoxy silanes, Ferromagnetic powder composition. The method according to any one of claims 1 to 12, The compound is octyl-trimethoxy silane, hexadecyl-trimethoxy silane, polyethyleneether-trimethoxy silane, isopropyl-triisostearyl titanate, isopropyl-tri (dioctyl) phosphato titanate, neo Selected from the group consisting of pentyl (diallyl) oxy-trineodecanoyl zirconate, neopentyl (diallyl) oxy-tri (dioctyl) phosphato zirconate, and diisobutyl-acetoacetyl aluminate Ferromagnetic powder composition. The method according to any one of claims 1 to 13, Insulating inorganic coating of the iron-based particles is phosphorus-based, Ferromagnetic powder composition. The method according to any one of claims 1 to 14, Wherein the iron-based core particles consist essentially of pure iron, Ferromagnetic powder composition. The method according to any one of claims 1 to 15, Less than 5% of the iron-based core particles have a size of 45 μm or less, Ferromagnetic powder composition. The method according to any one of claims 1 to 16, At least 40%, preferably at least 60% of the iron-based core particles consist of particles having a particle size of at least about 106 μm, Ferromagnetic powder composition. The method according to any one of claims 1 to 17, At least 20%, preferably at least 40%, and most preferably at least 60% of said iron-based powder particles consist of particles having a particle size of at least about 212 μm, Ferromagnetic powder composition. The method according to any one of claims 1 to 18, The amount of the compound is present in an amount of 0.05 to 0.5% by weight, preferably 0.07 to 0.45% by weight, and more preferably 0.08 to 0.4% by weight, Ferromagnetic powder composition. The method according to any one of claims 1 to 19, The powder is optionally mixed with additives such as certain lubricants, binders or flow-enhancing agents, Ferromagnetic powder composition. A method of producing a soft magnetic composite material having a density of at least 7.45 g / cm 3, Providing an iron or iron-based powder composition according to any one of claims 1 to 20; Compressing the soft magnetic powder composition in one direction in a die at a compression pressure of at least about 800 MPa; Ejecting a compression molded body from the compression tool; And Selectively heat treating the molded body, Method for producing soft magnetic composite material. The method of claim 21, The compression is carried out at a pressure of at least about 900 MPa, more preferably at least 1100 MPa, and most preferably at least 1100 MPa, Method for producing soft magnetic composite material. The method of claim 21 or 22, The particle size of the iron-based powder is defined according to any one of claims 16 to 18, Method for producing soft magnetic composite material.