WO2004033135A1

WO2004033135A1 - Moulded soft magnetic part produced by metal powder processing technique and exhibiting high maximum permeability, related manufacturing methods and uses

Info

Publication number: WO2004033135A1
Application number: PCT/EP2003/005209
Authority: WO
Inventors: Johannes Tenbrink; Robert Brand; Burkhard Kraus; Georg-Werner Reppel
Original assignee: Vacuumschmelze Gmbh & Co. Kg
Priority date: 2002-09-27
Filing date: 2003-05-17
Publication date: 2004-04-22
Also published as: DE10245088B3

Abstract

The invention concerns a moulded magnetic part consisting of layers of powder particles of a ferromagnetic material. An insulation arranged between said powder particles electrically isolate them at least partly from one another. The moulded part is reinforced by annealing. The invention also concerns a related production method and use of same comprising the following steps: treating a ferromagnetic material powder with a phosphate constituent; treating same with another constituent containing organofunctional silanes or a constituent containing both phosphates and organofunctional silanes; optionally adding compressing additives, binders, resins or lubricants; pressing the resulting compressed powder to form a green compact; annealing said green compact at a temperature exceeding the decomposition temperature of the organofunctional silanes to produce a mechanically reinforced moulded part.

Description

description

Powder-metallurgically produced soft magnetic molded part with high maximum permeability, process for its production and its use

The invention relates to a powder-metallurgically produced soft-magnetic molded part with high maximum permeability, and a method for producing this molded part from metallic powder particles, the powder particles being provided with an electrical insulation layer, so that when the molded part is used as a magnetic core in alternating fields, as described, for example, in Fast switching solenoid valves can occur, the eddy current losses are low. Furthermore, the invention relates to the use of this molded part in dynamic applications, such as, for example, as magnetic cores in magnetic valves in injection systems of motor vehicles, as cores of ignition coils, as yokes in magnetic systems for valve control or as a rotor or stator in engine applications.

When developing soft magnetic powder composite materials of the type mentioned above, the following properties are optimized at the same time:

1. a maximum specific resistance, from which minimal eddy current losses result;

2. a minimal coercive field strength, by means of which minimal hysteresis losses are brought about;

3. maximum permeability; 4. a maximum degree of filling with magnetic material, ie a high density, from which a maximum saturation polarization results. In particular, the demands on the specific resistance and the coercive field strength are generally difficult to reconcile with one another, since the annealing required to reduce the coercive field strength generally also leads to a reduction in the specific resistance.

However, studies show the best resistance level at given coercive field strengths if at the same time relatively large values for permeability and density are required. It ensures a reduction in the coercive force while maintaining a high level of resistance.

No. 2,601,212 proposes a process for the production of soft magnetic powder composite materials for applications in the high-frequency range in which phosphated carbonyl iron is mixed with 1 to 6% by weight of organosilanes as a binder. After pressing, the molded parts are cured at temperatures around 150 ° C. Annealing and thus decomposition of the organosilanes does not take place, which means that the organosilanes are polymerized and are in the finished product

Molding as a binder polymer. The molded parts produced are Usage frequencies below 10 kHz are unsuitable.

A method which takes this fact into account is described in DE 34 39 397. According to this process, powder particles which are provided with a phosphate insulation are subjected to annealing in an oxidizing atmosphere at a temperature of at most 600 ° C. The annealing treatment leads to a reduction in the coercive field strength of the iron and increases due to the formation of iron oxide between the

Powder particles the strength of the molded part. A similar process with subsequent annealing is described in German patent application 39 070 950.5. The application shows that protection of the powder particles, which are provided with phosphate insulation, is possible during the pressing by means of an organic resin layer.

These powder-metallurgically produced molded parts known from the prior art are still significantly inferior to conventional soft magnetic alloy materials with regard to the maximum permeability, which is determined at 50 Hz and H = 10 A / cm. In general, maximum permeabilities of up to 200 are achieved. However, a maximum permeability of at least 275, preferably greater than 300, is often desired for certain applications of the molded parts, for example as core material in magnetic valves in motor vehicle technology.

The object of the present invention is therefore to provide a molded part with soft magnetic properties, high maximum permeability, which is determined at 50 Hz and H = 10 A / cm, and at the same time high mechanical strength. A further object of the present invention is to provide a soft magnetic powder-metallurgically produced molded part with fast response behavior, whereby a good response behavior means according to the invention that the frequency-dependent maximum permeability of a core made of this material in the entire frequency band from 0 to 4 kHz is preferably at least 200 ,

According to the invention, the object is achieved by a powder-metallurgically produced molded part from compressed and annealed soft-magnetic phosphate-coated powder particles, the phosphate-coated powder particles having been coated with organofunctional silanes prior to annealing where the weight fraction of the organofunctional silanes is between 0.1 and 3% by weight of the unannealed molded part and after the annealing the molded part contains no polymerized organosilanes, characterized by a specific resistance p ≥ 10 μΩm, a coercive field strength H _c ≤ 3 .0 A / cm, hysteresis losses W _H ≤ 0.1 J / kg with a modulation of B = 1 Tesla, a maximum permeability (measured at f = 50 Hz)> 275 and a density γ ≥ 7.1 g / cm ³ .

The essential idea of the present invention lies on the one hand in the insulating effect of the material and on the other hand in the lubricating effect of the silane layer. The latter results from the fact that the organofunctional silane is not polymerized out to siloxane, as is the case in the above-mentioned US Pat. No. 2,601,212. This would take place at temperatures of approx. 100 - 150 ° C, but the powder is only dried at approx. 50 ° C in the coating process. The subsequent annealing of the pressed parts then leads to polymerization, but the resulting siloxanes are not very temperature-resistant, so that they are destroyed above approx. 200 ° C. It essentially remains Si0 ₂ in the material.

Overall, it has been shown that annealing, in which the organosilanes are decomposed, after pressing is suitable for reducing the losses mentioned. In order to heal crystalline defects as effectively as possible and to promote grain growth, the highest possible temperatures in the range of approximately 1100 ° C. would be desirable. At this temperature, however, the phosphate insulation on the surface of the powder particles would be destroyed. Due to the lubricating effect of the unpolymerized silane layer of the powder before pressing, the proportion of the pressing aid can be significantly reduced. Typically, pressing aids are added in an amount of approximately 0.5% by weight. This proportion can be reduced to 0.25 or 0.125% by weight or even 0% by weight using the silane. This is advantageous for the resulting density of the material and for the specific total power loss (in W / kg).

This consists of the hysteresis losses and the eddy current losses:

A proportional dependence of the hysteresis loss power on the frequency applies:

P _H = W „.f (2)

The eddy current losses in turn contain two parts. On the one hand, the eddy currents flow within the powder particles, on the other hand also over the entire part volume:

The following generally applies to the calculation of the eddy current power loss:

(geometry-dependent pre-factor z, diameter d, specific resistance p _e ι, density y, induction B with exponent g, frequency f ⁾

In the eddy current power loss within the powder particles (mean diameter d) of the prefactor ² shall z = π / 20 (according to K. N. Honma and Hirano, R & D 2, 40-42 (1980)). The values for pure iron should be used for the resistance and density (γ _Fe = 7.87 g / cm ³ and p _Fe = 0.1 μΩm).

For the calculation of the eddy current power loss over the entire part volume, the examined ring geometry is approximated with a toroidal shape. One obtains the prefactor z = π ^2/16 (RM by Bozorth, Ferromagnetism, IEEE Press, New York, 1993). You also need the iron diameter D of the toroid and the macroscopic density. If the measured hysteresis losses and resistances are taken as a basis, the following equation results for the total power loss (with a modulation of B = IT):

p _Fe ≤ W _H xf + 627 (Ws ² ) / (kgm ² ) xd ² xf ² + cx ∑fxf ²

with the upper limit for the hysteresis losses W _H ≤ 0.14 J / kg.

During the annealing treatment, the organofunctional silanes react in the reaction products that are produced under the corresponding reaction conditions. Examples of such reaction products are silicon oxides and silicon carbides.

It has surprisingly been found that molded parts which contain powder particles isolated in a known manner, for example powder particles isolated by means of phosphates, are further improved by using organofunctional silanes can. The properties of the molded part according to the invention also improve compared to an insulation layer formed exclusively by the use of a substance containing silicon.

The molded parts according to the invention have a higher maximum permeability than all known molded parts with a comparably high mechanical strength.

The maximum permeability is determined according to the invention at H = 10 A / cm and f = 50 Hz.

Description of the method for determining the maximum permeability:

A primary winding with 100 turns and a secondary winding with 20 turns are applied to an insulated ring of the sample with the dimensions 33 x 20 x 6 mm ² (outer / inner diameter / height). The field is excited by means of a sine voltage with an adjustable frequency. The induction voltage on the secondary winding is determined with a voltmeter.

The maximum permeability is generally determined by varying the strength of the applied field and looking for the maximum permeability on the new curve. As a rule, however, the maximum permeability of the molded part according to the invention is approximately H = 10 A / cm, so that the specification of the permeability in this magnetic field corresponds to the maximum permeability with sufficient agreement. The values according to the invention for the maximum permeability at 50 Hz essentially correspond to the value of the maximum permeability in the static field.

The maximum permeability of the molded parts according to the invention in the quasi-static field at f = 50 Hz is preferably at least 275, in particular at least 300. Molded parts with maximum permeabilities of more than 400, in particular 480, are particularly preferred.

In the entire frequency band from 0 and up to 4 kHz, the maximum permeability is preferably at least 200. It is particularly preferred if the maximum permeability between 0 and 4 kHz is above 300, in particular 350. Moldings whose maximum permeability is between 0 and 4 kHz above 400 are very particularly preferred.

For certain applications, it is desirable if the frequency-dependent permeability of the molded parts according to the invention is as large as possible in the range from 0 to 4 kHz with a higher modulation of W = 1 T (H> 10 A / cm).

The frequency-dependent permeability at high modulation (1 T) for the molded parts according to the invention is preferably at least 200, in particular 250.

The flexural strength of the molded parts according to the invention, which is determined by the method described below, is preferably at least 30 N / mm ² . Values of more than 50 N / mm ² , in particular 60, are particularly preferred

N / mm ² . Those molded parts according to the invention which have a bending strength of more than 80 N / mm ² are very particularly preferred. The ferromagnetic material used according to the invention is preferably iron, cobalt iron, nickel iron or silicon iron, which is used in the form of a powder. Although the highest possible level of purity is preferred for the ferromagnetic material, minor impurities due to manufacturing technology are practically unavoidable. The ferromagnetic material according to the invention therefore contains small amounts of impurities such as nitrogen, oxygen, sulfur or carbon. The carbon content is preferably below 0.1%, in particular below 0.03%. The nitrogen content is preferably below 0.01%, in particular below 0.003%. Examples of commercially available iron powders which can be used according to the invention are those with the designations "AT40.29", "ASC100.29" and "ABC100.30" from Höganäs AB, Sweden.

A value of at least about 50 μm is preferably expedient for the particle size (d ₅₀ ) of the powder particles. In general, larger particles also lead to higher maximum permeabilities. An upper limit can expediently be specified at 400 μm.

When optimizing the molded parts according to the invention for a high permeability with a modulation of approximately B = 1 T, a range from 50 to 200 μm is particularly preferred since there is an upper limit due to the eddy current losses occurring in the alternating field. In order to achieve a high maximum permeability, a range from more than 200 to about 400 μm is particularly preferred.

The coercive field strength of the molded parts according to the invention is preferably 1 to 3 A / cm. In the magnetic alternating field, electrical losses occur in the molded part according to the invention, which essentially consist of hysteresis losses and eddy current losses. As a rule, the losses increase at higher frequencies. Losses in the sense of the invention are understood to mean the total losses from all measured losses.

The losses at B = 1 T and f = 1 kHz of the molded parts according to the invention are preferably in a range from 80 to 450 W / kg. Those molded parts according to the invention which have losses of less than 250 W / kg at B = 1 T and f = 1 kHz are particularly preferred. Molded parts whose losses are below 160 W / kg are very particularly preferred.

The losses are measured on a toroidal core measuring 33 x 20 x 6 mm ² with n _x = 170 and n ₂ = 20.

The specific resistance of the molded parts is preferably greater than 500 μΩm.

The invention also relates to a method for producing a magnetizable molded part comprising the steps:

- Treatment of a powder made of a ferromagnetic material with a phosphate component

Treatment with a further component containing organofunctional silanes or treatment of the powder with a component which contains both phosphates and organofunctional silanes,

Possibly. Add pressing aids, binders, resins or

lubricants,

Pressing the treated powder into a green compact and Annealing the green body to a mechanically solidified molded part.

The organofunctional silanes which can be used are substances which are preferably building blocks of the general formula

X R {CHι) n - Si - X (l)

X

where X is an easily hydrolyzable group and R represents an organic radical.

Examples of easily hydrolyzable groups are Cl, OCH ₃ , OCH ₂ H ₅ or OCH ₂ CH ₂ OCH ₃ .

Suitable organic radicals are, for example, hydrogen or aliphatic or aromatic radicals having 2 to 10 carbon atoms, which can either be unsubstituted or partially substituted. Suitable substituents are, for example, F, Br, I or preferably chlorine. Unsubstituted organic radicals are preferably used.

The organofunctional silanes containing substances used are, for example, vinyl silanes, such as vinyl trichlorosilane, vinyl triethoxysilane, vinyl trimethoxysilane, vinyl tris (β-metoxyethoxy) silane or vinyl triacetoxysilane, aminosilanes, such as γ-aminopropyl-triethoxysilane, γ-trimethoxysilane, γ N-ß- (aminoethyl) -γ-aminopropyltrimethoxysilane or N-ß- (aminoethyl) -γ-aminopropyltrimethoxysilane or N-ß- (aminoethyl) -N- (ß-aminoethyl) -γ-aminopropyltrimetoxysilane, Ureisosalkylsilane, Epoxyalkylsi- lanes, such as ß-glyxidyloxypropyl-trimethoxysilane, methacrylalkylsilanes, such as γ-methacryloxypropyl-trimetoxysilane or γ-methacryloxypropyl-tris (ß-methoxyethoxy) -silane or mercaptoalkysilanes, such as γ-mercaptopropyl-trimethoxysiloxysiloxysiloxysilane ,

The proportion by weight of the organofunctional silanes is preferably in the range from 0.1 to 3% by weight, in particular 0.25 to 2% by weight.

Conventional lubricants for improving the pressing density are preferably present in the molded parts. Examples of suitable lubricants are calcium, lithium, magnesium, zinc stearate and stearic acid. In principle, however, other lubricants are also conceivable as long as they have a supporting effect on the pressing process and do not have a disadvantageous effect on the pourability of the powder.

Lithium stearate, stearic acid or Ca stearate is preferably used as a lubricant in an amount which on the one hand sufficiently supports the pressing process, but on the other hand still leads to high maximum permeabilities. The proportion by weight is preferably in the range from 0 to 5% by weight, in particular between 0 and 0.6% by weight.

The powders which can be used according to the invention can be used annealed (pretreated) or unannealed. If the powders are used in an annealed state, a reducing atmosphere, in particular a hydrogen-containing atmosphere, is preferred.

The powder is treated in a manner known per se, as described, for example, in W. Rausch et. al, "The phosphating tion of metals ", 2nd edition, Eugen Leuze Verlag, Saulgau (1988).

A thermoplastic or thermosetting plastic can be applied to the powder particles as an outer layer

Presses is hardened to a green body, but preferably no thermoplastic or thermoset is applied.

The pressing process can take place either at room temperature or at a temperature above room temperature (hot pressing). When hot pressing, temperatures of at least 80 ° C are preferred.

The green body is preferably annealed in an oxidizing atmosphere, such as, for example, air or humidified hydrogen.

The green body is preferably annealed at a temperature of at least 500 ° C. The temperature is limited by the temperature at which the insulation layer becomes ineffective. For the insulation means used, this limit is preferably around 680 ° C. To increase the strength, it can be advantageous to carry out the annealing at different temperature levels.

It is possible to carry out the silane treatment before or after the phosphating treatment. However, the phosphating is preferably carried out before the silane treatment. The phosphates can be used in aqueous or non-aqueous solution.

In a further preferred embodiment it is also possible to coat the phosphate and silane to be carried out in one operation. It has been shown that the powder particles can be coated analogously to the method described in DE-Al-4 403 876 for the passivation of metallic surfaces of screws. In this method, the silane or polysiloxane contains built-in phosphorus-oxygen assemblies, which can preferably be built in as intermediate links in polysiloxane chains (SI-0-Si-OPP-Si ...). The atomic ratio P: SI in the siloxane layer is preferably greater than 0.01.

Depending on the production conditions, the moldings according to the invention can have an open residual porosity, which can have a disadvantageous effect on the corrosion resistance. To improve corrosion protection, the molded part is preferably subjected to vacuum impregnation with liquid resins and subsequent hardening after annealing. Suitable resins are crosslinking or thermoplastic resins known per se, such as, for example, anaerobic methacrylate resins. The penetration of the resin into the molded part can be promoted with the help of gas under pressure. Suitable pressures are advantageously in the range from 3 to 30 bar. In this way, oil and gasoline resistant molded parts with good temperature resistance up to about 250 ° C can be produced.

Furthermore, the present invention includes the use of the molded part according to the invention in solenoid valves, as cores of ignition coils or as yokes in magnet systems for valve control or as a rotor or stator in motor applications or other electrical machines.

The invention is explained in more detail below with reference to exemplary embodiments shown in the drawing figures. It shows : FIG. 1 shows the frequency dependence of the maximum permeability of samples according to the production according to Examples 1,

3, 4, 6, 7, and 8,

2 shows the frequency dependence of the maximum permeability of samples according to the production according to Examples 1 and 10-19 and

Figure 3 shows the frequency dependence of the maximum permeability of samples according to the manufacture according to Examples 20 and 21 with a varied control of the toroid.

Example 1 (comparison)

Manufacture of cores with phosphate insulation in aqueous solution

200 g of iron powder (AT 40.29, Höganäs) with an average particle size d ₅₀ = 265 μm and a C content or N content of about 0.003% and an O content of about 0.081% was etched onto HCl and with an aqueous solution Solution treated for phosphating.

To prepare the solution, the commercially available phosphating Novaphos F 2311 (from Novamax) was dissolved in water (15 g F 2311 per liter of water) and the solution was adjusted to a pH of 5.0 at 57 ° C. using sodium hydroxide solution. The iron powder was then mixed with 1 l of the solution. After 5 minutes the reaction was stopped by rinsing with water and the powder was dried in air at 130 ° C. Mixed: (. L / cm ³ density 19d softening temperature of 90-95 ° C, Epikote ^® EP 1055, from Shell) connecting the powder with a flexible after curing epoxy resin. The resin was used in the form of a 20% acetone solution and added to the powder in an amount of 2.5 g per 100 g powder (0.5% EP 1055). The mixing time was 30 minutes. The solvent was then evaporated in vacuo.

Before pressing, 0.5% by weight of calcium stearate was added as a lubricant and mixed in for about 30 minutes.

The powder thus produced was pressed in a non-directional press with a pressure of 600MPa into rings with an outer diameter of 33 mm, inner diameter of 20 mm and a height of 6 mm. Finally, annealing was carried out in two stages, first 1 h at 600 ° C in alternating air / vacuum and then 1 h at 520 ° C in air.

Example 2 (comparison)

Non-aqueous phosphating

The production corresponds to Example 1 with the following difference:

1000 g of iron powder as in Example 1 are mixed reaction ₂ 0 30 min with 80 g of acetone and 3.37 g of H ₃ P0 and lg H, and dried at room temperature under vacuum. The maximum permeability over the frequency of this sample is plotted in FIG. 1 (AT 40.29 OF) and 2 (AT 40.20 OF / 0.5% EP 1055 = .5% Ca RT).

Examples 3 to 5 Phosphate and silane treatment

According to Example 2, iron powder was provided with a phosphate layer and then coated with different organofunctional silanes.

Silane compounds used:

Various solutions with the composition 4 g of silane, 95 g of isopropanol and 1 g of distilled water were prepared from these silane compounds.

To form the silane layer, the phosphated Fe powder was mixed with the silane solution in a ratio of 0.5 g of silane per 100 g of iron powder and reaction mixed for 1 hour. The mixtures were then dried in vacuo at 150 ° C. for 1.5 h. The powders were then further processed into cores in accordance with Example 1.

The measured maximum permeability is shown in Fig. 1 shown,

Examples 6 to 8

Variat ion of the silane content

Cores according to Examples 3 to 5 with different silane contents were produced.

FIG. 1 shows the maximum permeability of the cores produced as a function of the frequency of the magnetic field compared to. Samples without the addition of organofunctional silanes (AT 40.29 OF).

Examples 10 to 19

Variations in lubricant and press temperature

Cores were produced in accordance with Examples 3 and 9, in which 0.5% of a lubricant was added to the powders before pressing. The powders were pressed either at room temperature (RT) or at 150 ° C.

The maximum permeability of the cores as a function of the frequency of the applied field is shown in FIG. 2.

Table 1 summarizes the measured values of the maximum permeability at a frequency of the applied field of f = 50 Hz for Examples 10, 11, and 13-19.

Example 20

5 kg of the powder AT 40.29 (Höganäs) with d ₅₀ = 265 μm were phosphated in a mixer with 15 g H ₃ P0 and acetone. The acetone was then pumped off. After adding 50 g of silane A187 with isopropanol and water, the mixture was mixed again and pumped off. The powder obtained was mixed with 0.5% Li stearate in a tumble mixer. Rings were produced in accordance with Example 1. The maximum permeability (H = 10 A / cm) was 440. The frequency dependence of the maximum permeability and the permeability at B = 1 T is shown in FIG. 3.

Example 21

According to Example 20, further rings were produced, but by using a powder with d ₅₀ = 120 μm (ABC100.30, Höganäs).

At f = 3 kHz and an induction B = 1 T (higher modulation compared to example 20), a permeability of 304 is achieved. The frequency dependence of the maximum permeability and the permeability at B = 1 T is shown in FIG. 3.

Flexural strength measurement

In order to determine the bending strength of the cores, parallelepiped-shaped bars with dimensions l _s = 40 mm, b = 10 mm, h = 4 mm were pressed analogously to the examples above. The measurement was carried out in the usual way by placing the rod at two points at a distance of 15 mm and applying a downward force in the middle between these points. From the measured bending force F _B is the bending strength _B s is calculated by the following formula:

S _B = 1.5 x (F _B xl _s ) / (wxh ')

The flexural strength was measured on 3 identical samples and the mean value was determined from the values for s _B. The results of the measurements are shown in Tab. 2. The examples show that the permeability of powder cores can be increased by using organofunctional silanes. Especially in the frequency range up to 4 kHz and above there is a significant improvement compared to known powder cores (AT 40.29 OF).

Furthermore, three further groups of implementation examples are presented. Two exemplary embodiments are listed below for each group. All powders (partially pre-annealed) were coated, pressed and annealed in accordance with the present invention. The manufacturing parameters and the resulting properties are listed in the tables below.

, group

, group

, group

25

All data of the three groups listed above refer to the mean values of measurements on three rings or five rods.

The resistances were measured on rods with an oxidized surface. The oxidation results from the annealing, but due to the very low porosity of the material (high density) there is only a thin oxide layer.

The oxide layer is a better electrical conductor than the actual powder composite. When measuring resistance across the length of the rod, there is therefore a parallel connection of a thin oxide layer (low specific resistance) and powder composite material (high specific resistance). The measured values of the spec. Resistance for the entire bar is therefore smaller than the spec. Resistance for the actual powder composite.

Claims

claims

1. Powder metallurgically produced molded part from pressed and annealed soft magnetic phosphate-coated powder particles, the phosphate-coated powder particles having been coated with organofunctional silanes prior to annealing, the weight fraction of the organofunctional silanes being between 0.1 and 3% by weight of the unannealed molded part and the molded part does not contain any polymerized organofunctional silanes after annealing, characterized by a specific resistance p ≥ 10 μΩm, a coercive field strength H _c ≤ 3.0 A / cm, hysteresis losses W _H ≤ 0.14 J / kg (with a modulation of B = 1 T), a maximum permeability (measured at f = 50 Hz)> 275 and a density γ ≥ 7.1 g / cm ³ .

2. Molding according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the specific resistance is p ≥ 200μΩm.

3. Molding according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the specific resistance is p ≥ 750μΩm.

Shaped part according to one of claims 1 to 3, characterized in that the hysteresis losses W _H ≤ 0.115 J / kg with a modulation of 1 Tesla.

5. Molding according to claim 4, characterized in that the hysteresis losses W _H ≤ 0.110 J / kg with a modulation of 1 Tesla.

6. Molding according to one of claims 1 to 5, characterized in that the loss factor c ≤ 1.00 (Ws ² ) / (kgm ² ).

7. Molding according to claim 6, characterized in that the loss factor c ≤ 0.50 (Ws ² ) / (kgm ² ).

8. Molding according to one of claims 1 to 7, that the frequency-dependent maximum permeability at 10 A / cm in the entire frequency band from 0 to 4 kHz is at least 200.

9. Shaped part according to one of claims 1 to 8, d a d u r c h g e k e n n z e i c h n e t that the bending strength is at least 30 MPa.

10. Molding according to one of claims 1 to 9, characterized in that the powder particles consist of iron, nickel iron, cobalt iron or silicon iron with an average particle size d ₅₀ > 50 microns.

11. Molding according to one of claims 1 to 10, characterized in that the powder particles consist of water-atomized iron.

12. Shaped part according to one of claims 1 to 8, characterized in that the particle size d _{50 of} the powder particles is in the range from about 50 to about 400 microns.

13. A method for producing a magnetizable molded part comprising the steps:

Treatment of a powder made of a ferromagnetic material with a phosphate component, treatment with a further component containing organofunctional silanes or treatment of the powder with a component which contains both phosphates and organofunctional silanes, optionally adding pressing aids, binders, resins or lubricants, pressing the treated powder to a green body and - annealing the green body above the decomposition temperature of the organofunctional silanes to a mechanically solidified molded part.

14. The method according to claim 13, d a d u r c h g e k e n n z e i c h n e t that the organofunctional silanes building blocks of the general formula

X R (CH2) n-Si-X (D

X where x is an easily hydrolyzable group and R represents an organic radical.

15. The method according to claim 13 or 14, so that the annealing is carried out in an oxidizing atmosphere or under a protective gas.

16. The method according to any one of claims 13 to 15, so that the green body is annealed at a temperature of at least 400 ° C.

17. The method according to any one of claims 13 to 16, so that the phosphating is carried out before the silane treatment.

18. The method according to any one of claims 13 to 16, so that the phosphating and silane treatment is carried out in one operation.

19. The method according to any one of claims 13 to 18, that the molded part is subjected to a vacuum impregnation with liquid resins after the annealing.

20. Use of the molded part according to claim 1 in solenoid valves as cores of ignition coils or as yokes in magnet systems for valve control or as a stator or rotor in electrical machines.