DE102015015254A1 - Device for cooling - Google Patents

Abstract

The device for cooling has a tissue. The fabric is made of at least one fiber having electrical conductivity. The fiber material is formed by a base material of at least one polymer. Elements are embedded in the base material. The elements have an order of magnitude of a maximum of one micrometer in diameter and overlap at least in regions with their electron clouds. At least a part of the elements may consist of at least one ceramic material.

Description

The invention relates to a device for cooling, which comprises a fabric which is made of at least one fiber with electrical conductivity, wherein the fiber material is formed by a base material of at least one polymer, which elements are incorporated.

It has been known for some time prior art to use plastics or plastic composite materials for various technical applications, for example as a base material for garments, as insulation material, etc. One of these widely used types of plastic is polyethylene terephthalate (PET). This PET plastic is a thermoplastic produced by polycondensation of the polyester family.

PET has a polar basic structure and strong intermolecular forces. PET molecules are also linear, d. H. built without networking. Due to the polar-linear structure, PET is characterized by semi-crystalline regions and fibers which cause high resistance to breakage and dimensional stability even in temperature ranges above 80 ° C. Thus, PET is generally suitable as a material for these temperature ranges.

PET materials are made from monomers such as terephthalic acid or benzene dicarboxylic acid and ethylene glycol or dihydroxyethane or ethanediol. In order to produce quantities that are relevant for industrial application, industrial production takes place by transesterification of dimethyl terephthalate with ethanediol. In the context of this equilibrium reaction produces an undesirable increase in amount of ethanediol, or it is necessary for the reaction that this substance is distilled off again by the reaction, in order to influence the equilibrium favorable.

The alternative possible melt phase polycondensation is unsuitable for the production of large quantities, because this form of production takes too long periods of time. In order to achieve a high PET quality, a solid state polycondensation is connected downstream, depending on the intended use, in order to achieve a further condensation. Another known production possibility of PET is the esterification of ethanediol with terephthalic acid.

In general, the PET molecules are long-chain structures that consist predominantly of carbon, hydrogen and some other atoms. The molecules have a spiral to tangled arrangement. This leads to a large number of free spaces in the atomic region between the molecules, especially in the amorphous state. By axial or biaxial orientation of the material, these clearances can be reduced, which leads for example to a higher strength of the material and to a reduced gas permeability.

In addition to the use of PET in pure form, the material modification of the prior art is also known. As a base material for composite materials, other elements can be added to the thermoplastic resin. In its pure state, PET is essentially an electrical non-conductor. By incorporating, for example, metallic atoms into the free spaces between the molecules or by attaching, for example, metallic atoms to the PET molecules, the material can be imparted to a certain extent with electrically conductive properties. Correspondingly metallically doped PET fibers thus conduct an electric current when a voltage is applied.

Furthermore, it is known that various, mainly metallic materials such. As alloys with gadolinium or other rare earth metals, have a magnetocaloric effect. The magnetocaloric effect heats the material when it is exposed to a magnetic field, and it cools down when the magnetic field influence stops. The cause of this heating reaction is the alignment of the magnetic moments of the material by the magnetic field and their dependence on the magnetic field strength. The alignment speed of the magnetic moments creates heat. A possible application could be use as a coolant, thereby periodic magnetization and simultaneous removal of the resulting heat, a cooling effect can be achieved.

The magnetocaloric effect is heavily hysteresis-dependent depending on the alloy. In order to realize the magnetocaloric effect also in connection with applications, which means a possibly additive mechanical load, alloys are sought, which combine these physical effects and properties. Another problem of the technical application of this effect in addition to the undesirable Hysteresis behavior is the fact that so far this effect is relatively weak in known alloys and material compositions.

The skin effect, also known as current displacement, is an effect in electrical conductors through which higher-frequency alternating current flows, which makes the current density inside a conductor lower than in external areas. It occurs in relation to the skin depth thick conductors and also in electrically conductive shields and cable shields. The skin effect favors the transfer impedance of shielded lines and the screen attenuation of conductive shields with increasing frequency, but increases the resistance of an electrical line. This practically means that the skin depth, d. H. the Leitschichtdicke, material-dependent decreases with increasing AC frequency. As a result of high alternating current frequencies of more than 100 kHz, a skin depth of 0.21 mm is present within a copper line.

It is also already known to provide polymer fibers by the incorporation of metallic particles with electrically conductive property. According to this prior art, it is exploited that the polymeric material, due to the spatial arrangement and arrangement of the molecules, has extremely small cavities into which small metallic particles can be incorporated. With regard to practical applications, however, the electrical properties of these fibers prove to be not manufacturable with sufficiently high reproduction accuracy and the electrical properties are not usable in the desired manner.

Various devices are currently used to carry out cooling. The most common are using a compressor working evaporator or absorber. But are also purely electrical cooling devices based on polymer elements.

The known cooling devices absorb heat or heat radiation extremely broadband. A narrow-band absorption, however, presents difficulties. In addition, at present, absorption of electromagnetic radiation in general can not be sufficiently precisely realized with known materials.

The type of plastic polyethylene terephthalate (PET) is an electrical non-conductor and thus initially not suitable to generate by means of conversion of electrical energy, a heat energy. PET materials are made from monomers such as terephthalic acid or benzene dicarboxylic acid and ethylene glycol or dihydroxyethane or ethanediol. In order to produce quantities that are relevant for industrial application, industrial production takes place by transesterification of dimethyl terephthalate with ethanediol.

The object of the present invention is to provide a device of the aforementioned type such that a precisely defined absorption of radiant energy and that a cost-effective production is possible.

According to the invention the object is achieved in that the elements have a size of at most one micrometer in diameter and are provided with a distance such that overlap electron clouds at least partially.

As a polymeric material, for example, PET or aramid can be used. Optionally, it is possible to form at least part of the indoctrinated or doped elements of at least one ceramic material.

The doping elements may additionally impart the ability to at least partially conduct electrical energy to the polymeric material. The doping elements, on the one hand generate properties as an absorber for radiant energy, on the other hand, they can generate properties as electrical conductors. By incorporating, for example, metallic atoms into the free spaces between the molecules or by attaching metallic atoms, for example, to the polymeric molecules, the polymeric material can be given, to a certain extent, electrically conductive properties.

Correspondingly metallically doped polymeric fibers thus conduct an electric current when a voltage is applied. Depending on the electrical resistance of this composite material, this generates radiation or absorbs it as a function of the applied current. The effects are supported as a function of the previously described skin effect and by additive absorption of radiant energy. This means that the polymeric composite material according to the invention represents a new material alternative for the radiation absorption or radiation generation to the known metal fiber materials.

In addition, the mechanical properties of the polymeric material in terms of breaking strength and dimensional stability are also used in temperature ranges above 80 ° C in order to open up the absorber material application areas with these increased mechanical requirements.

Another property of the material according to the invention consists in its property, which is dependent on the respective doping elements, of being at least partially electrically conductive. In particular, when the polymeric composite material is a base material for any heat source, the physical effects of absorbability and electrical conductivity for increasing the amount of heat to be delivered can be combined and thus increased by adding, in addition to the emitted heat radiation due to the radiation absorption by means of a polymer Composite material applied voltage due to the electrical resistance of the material in addition to electrical energy heat energy is generated.

A further interesting application of the polymeric composite material is opened by its property to realize the magnetocaloric effect and at the same time have the polymer's own improved mechanical material properties. By means of suitable doping elements, it is thus also possible to impress cooling effect properties on the material according to the invention.

The teaching according to the invention recognizes that the elements which are suitable for doping the polymer are, in particular, MnFe phosphorus compounds, MnFe (As, PwGexSiz) s; FeMn-phosphorus compounds with As, Si-phosphorus substitution possibly combined with La (FeMnP) AlCo; Compounds with Mn-Zn are.

A preferred application is the use of the doping structural formula MnFe (As, PwGexSiz) s. This compound has high cooling capabilities at temperatures of 200 to 600 K, especially at 280 to 500 K. This compound shows a very strong magnetocaloric effect. The use of this compound is environmentally friendly due to the fact that the environmentally problematic substances, in particular the Mn molecules, are bound in the basic polymer matrix. Very efficient results are achievable when x = 0.3-0.7 and / or w less than 1 - x and z = 1 - x - w in its structural connection. Preferably, in this specific setting, the material is realized in a hexagonal structuring of the Fe2P.

The preparation of the various material compositions can be carried out in a ball mill and under a protective gas atmosphere.

For example, an alloy of 5 g of FeMnPO, 7GeO, 3 having a critical temperature of about 350 K can be prepared by mixing the pure elements having a quality of 3N in the following amounts: FeMnP 0.7 GaO 3. In a closed ball mill, these elements are milled under a protective atmosphere until an amorphous or microcrystalline product is obtained. Depending on the properties of the mill, such a product can be obtained within 20 minutes to a few hours. The powder is then heated in a closed ampule in a protected atmosphere until a temperature of about 800 to 1050 degrees C is reached. Thereafter, this is tempered to a temperature of about 650 degrees C. The alloy crystallizes in a hexagonal Fe2P structure.

An alloy of 5 g FeMnP 0.5 Ge 0.5 having a critical temperature of about 600 K is prepared by mixing the pure elements having a quality of 3 N in the following amounts: Fe = 1.72 g, Mn = 1.69 g, P = 0.476 g and Ge = 1.12 g. In a closed ball mill, these elements are milled under a protective atmosphere until an amorphous or microcrystalline product is obtained. Depending on the properties of the mill, such a product can be obtained within 20 minutes to a few hours. The powder is then heated in a closed ampule in a protected atmosphere until a temperature of about 800 to 1050 degrees C is reached. Thereafter, this is tempered to a temperature of about 650 degrees C.

The alloy also crystallizes in a hexagonal Fe2P structure.

An alloy of 5 g FeMnP 0.5 Ge 0.1 Si 0.4 having a critical temperature of about 300 K is prepared by mixing the pure elements having a quality of 3 N in the following amounts: Fe = 1.93 g, Mn = 1 , 90 g, P = 0.535 g, Ge = 1.251 g and Si = 0.388 g. In a closed ball mill, these elements are milled under a protective atmosphere until an amorphous or microcrystalline product is obtained. Depending on the properties of the mill, such a product can be obtained within 20 minutes to a few hours. The powder is then protected in a closed ampule Atmosphere heated until a temperature of about 800 to 1050 degrees C is reached. Thereafter, this is tempered to a temperature of about 650 degrees C. The alloy also crystallizes in a hexagonal Fe2P structure.

An alternative embodiment is obtained by modifications of alloys of the starting materials rather than the pure elements - this is particularly advantageous when Si is used in the alloy. This is based on the fact that FeSi alloys are very stable and are obtained when pure Fe and Si are available in the mill.

An alloy of 10 g of FeO, 86MnI, 14PO, 5Si0.35GeO, 15, which has a critical temperature of 390 K, is obtained by mixing the pure elements having a quality of 3N and the alloy Fe2P having a quality of 2N (Alpha Aesar 22951) in the following amounts: Fe2P = 4.18g, Mn = 4.26g, P = 0.148g, Si = 0.669g and Ge = 0.742g.

In a closed ball mill, these elements are milled under a protective atmosphere until an amorphous or microcrystalline product is obtained. Depending on the properties of the mill, such a product can be obtained within 20 minutes to a few hours. The powder is then heated (sintered) in a sealed ampule in a protected atmosphere until a temperature of about 800 to 1050 degrees C is reached. Thereafter, this is tempered to a temperature of about 650 degrees C. The present invention is not limited to the exemplary embodiment. The quantities can vary in many ways.

The teaching according to the invention provides, in particular, for the doped PET material to be used in one embodiment as a fiber for a heating foil. The fibers of the polymer base material have at least one doping with one of the above-described noble metal particles in order to be able to use the described physical effects in each case individually or arbitrarily in summary for a temperature increase. Preferably, the fibers are integrated into a membrane-like or sheet-like semifinished product in order to support the assembly. In addition, the film is directly equipped with the desired, temperature-increasing properties by the integration.

In the drawings, the underlying effects of the invention and embodiments of the internal structure of the material are shown schematically. Show it:

1 the physical skin effect on the basis of a diagram, ie the equivalent conductive layer thickness δ in mm of different metals over the alternating current frequency f in kHz,

2 in a summarized representation the absorption behavior of different atmospheric gases as a function of the wavelength,

3 the microstructure of FeMnP0.5Si0.5,

4 in a perspective view the structure of Mn (CO) 5J anions,

5 in a perspective view the structure of [Mn3Se2 (CO) 9],

6 in a perspective view in the upper figure the structure of the compound [Fe3Se2 (CO) 9] and in the lower figure the structure of the compound [Mn3Se2 (CO) 9] 2-anion. It was waived the representation of the CO groups. The planes that span the carbon atoms of each Mn atom are indicated by solid lines,

7 in a perspective view part of an alternating chain of trinuclear [Fe352 (CO) 9] and dinuclear [Fe2 (52) (CO) 6],

8th in a perspective representation, the superposition of the structures of [Mn3Se2 (CO) 9] 2- (shown in bold) and [Mn3Se2 (SeMe3) (CO) 9] 2- (shown as a dashed line) ( 9 ), which form a complete 2-my carbon bridge,

9 1H NMR absorption behavior of Ph protons in [Ph4P] 2 [Mn3Se2 (CO) 9] (in the left part of the figure A) and [Ph4P] 2 [Mn3Se2 (CO) 9] in the right part of the figure B,

10 a diagram illustrating the particle size and the grain size of sintered particles,

11 a diagram for illustrating phase states,

12 a diagram illustrating grain sizes and particle sizes,

13 a diagram to illustrate the modulus of elasticity of material groups,

14 a diagram for illustrating the fracture toughnesses of zirconia-reinforced ceramics,

15 a diagram illustrating the dependence of the bending stiffness on the temperature,

16 a diagram for illustrating thermal expansion coefficients,

17 a diagram illustrating the flexural strength,

18 a diagram illustrating the course of temperature values in a cooling and

19 a schematic representation of a fiber with metal particles and ceramic portions,

20 a perspective view of a foil-like cooling device,

21 a schematic representation of a fiber with symbols to illustrate doping elements,

22 one opposite 21 modified schematic representation of the fiber and

23 a schematic representation of a constructed of fibers microstructure.

1 shows the physical effect of current displacement in near-surface edge layers of a current-carrying conductor based on a diagram, ie, the equivalent Leitschichtdicke δ in mm of different metals over the AC frequency f in kH.

2 Illustrates in an assembled representation the absorption behavior of different atmospheric gases as a function of the wavelength.

3 shows the known microstructure of FeMnP 0.5 Si 0.5.

4 shows in a schematic diagram the structure of Mn (CO) 5J anions. In the crystalline structure of [Ph4P] [Mn (CO) 5], the charges of the mononuclear ionic complex [Mn (CO) 5] are compensated by tetraphenylphosphonium cations. The crystal complex consisting of a central Mn particle, which has five compounds to each a C and an O particles, is of tetrahedral arrangement. Typical bond lengths and bond angles between the particles are summarized in the following table: Table 15.1B. Distances [A] and angles [*] in a [Mn (CO) 5] anion Distances: Angles: Mn - C (1) 102.6 (1) 1.809 (2) C (1) - Mn - C (2) Mn - C (2) 154.7 (1) 1.794 (3) C (1) - Mn - C (1a) C (1) - Mn - C (1b) 87.3 (1) C (1) - O (1) 179.5 (2) 1.159 (2) Mn - C (1) - O (1) C (2) - O (2) 180.0 (1) 1.155 (4) Mn - C (2) - O (2) * Symmetry transformation: (a), ½-X, ½-y, z (b), 1/2-y, x, z (c), 3/2-xs, ½-y, z (d), 1/2 + y, 1 - y, 1 - z

The structural similarities of Mn (CO) 5J anions and [HMn (CO) 5] are observed. The synthesis and structural analysis of the Mn (CO) 5J anions confirms that the energy barrier between square-pyramidal and trigonal-bipyramidal arrangements of the ligands in MLS complexesis are very low. This type of complex stereochemically non-rigid geometry, whereby, for example, another counterion is present, may account for a change in the arrangement of the ligands. Remarkably, despite the low energy barrier, only the [Mn (CO) 5] anions are the only example of the presence of two geometric isomers of the [M (CO) 5] n complex. Also, the angles within the [Mn (CO) 5] anion arrangement are in o. G. Table listed.

5 shows in a perspective view the structure of [Mn3Se2 (CO) 9]. X-ray diffraction results indicate that crystals of [Ph4P] 2 [Mn3Se (CO) 9] contain, in addition to the mixed-valent trinuclear [Mn3Se2 (CO) 9] 2 ion in the complex, 2: 1 THF molecules.

The heavy atom structure of [Mn3Se2 (CO) 9] is a slightly distorted square pyramid with an alternating arrangement of Mn and Se atoms in the surface region and a third Mn atom at the tip. Here, the environment for each of the Mn atoms is composed of the two Se atoms and three carbon ligands. A peculiarity in the arrangement of the carbon groups has the Mn atom at the top of the pyramid.

One of the Mn ... C distances are unexpectedly long, while in the corresponding carbon group the bonds are particularly inclined in the direction of the neighboring Mn atoms. In this feature, a new type of asymmetric carbon bridges is realized. While the heavy atom skeleton [M3Se2] in the same compound has an isoelectronic iron complex [Fe3Se2 (CO) 9], the two compounds differ in the arrangement of the carbon ligands on the metal atom M3Se2 in the apex of the pyramid.

Obviously, an electronic antivalence of Mn (1) and Mn (2) leads to the fact that an asymmetric carbon bridge C (7) is formed between Mn (2) and M (3). The electronic mismatch of Mn atoms is particularly evident when one considers the corresponding Mn-Se bond lengths (Mn (1) 2.458 (2) or 2439 (2), Mn (2): 2407 (2) and 2.402 (2) Angstrom ) considered. This can be explained by the different oxidation states of manganese atoms, the common mean of which is 0.67.

Turning now to the observed bond lengths and coordination numbers, the atoms Mn (2) and Mn (3) have the oxidation state 1 and are assigned, while results for Mn (1) give a value of ± O. The molecule has a point symmetry, with the manganese centers lying in the mirror plane. Neglecting the weak interaction of the asymmetric bridge (Mn (2) -C (7) 2726 (7)) results in all three Mn atoms surrounding a square-pyramidal geometry of three carbon and selenium two ligands. In this analysis, Mn (2) has a distorted-octahedral ligand environment.

In contrast to the square-pyramidal coordination of the manganese centers, the coordination of Fe (3) in 6-trigonal bipyramidal form.

The arrangement of the carbon ligands to Fe (3) is such that Fe (1) and Fe (2) are surrounded. They are chemically equivalent and have approximately the same length of iron-selenium bonds (Fe (1): 2.351 (1) 2.359 (1), Fe (2): 2.354 (1) 2.358 (1) angstroms). The molecular symmetry Cs with the mirror plane now passes through the two selenium atoms and Fe (3). In mixed-valence compound 6, Fe (3) has the oxidation state +2, while Fe (1) and Fe (2) formally +1.

The material presented here starts from the assumption that in complexes of the type [M3X2 (CO) 9] z (X = S, Se, Te, z = -2, -1,0, +1) / 5a -e / an asymmetric carbon bridge is formed when the two metal atoms at the base of the pyramidal M3X2 are not equivalent electronically. Here, the higher oxidized metal center is stabilized by the bridge, optionally through an interaction. The transition is non-equivalent. Here, the higher oxidized metal center is stabilized by the bridge, possibly through an interaction.

The transition from the non-bridged to the bridged form is associated with a 30 degree rotation of the apical M (CO) 3 of its symmetry axis followed by a tilt of 15 degrees towards M (2). At the same time, a change from trigonal pyramidal to quadratic pyramidal coordination occurs.

6 shows in a perspective view in the upper figure the structure of the compound [Fe3Se2 (CO) 9] and in the lower figure the structure of the compound [Mn3Se2 (CO) 9] 2-anion. It was waived the representation of the CO groups. The planes that span the carbon atoms of each Mn atom; are indicated by solid lines. Selected bond lengths and bond angles between the particles of the [Mn3Se2 (CO) 9] 2 anion are listed in the following table: Distances: Angle: Mn (1) - Se (1) 2.407 (2) Se (1) - Mn (1) - Se (2) 82.5 (1) Mn (1) - Se (2) 2.402 (2) Se (1) - Mn (2) - Se (2) 80.7 (1) Mn (2) - Se (1) 2.458 (2) Se (1) - Mn (2) - Se (2) 80.9 (1) Mn (2) - Se (2) 2.439 (2) Middle figures 81.3 Mn (3) - Se (1) 2.446 (2) Mn (3) - Se (2) 2.444 (2) Average: 2432 Mn (1) - Mn (2) 3.647 (2) Mn (1) - Mn (3) - Mn (2) 82.6 (1) Mn (1) - Mn (2) 2,803 (3) Mn (1) - Mn (2) - Mn (3) Mn (1) - Mn (2) 2.724 (2) Mn (2) - Mn (1) - Mn (3) Se (1) ... s (2) 3.171 (2) Mn (2) - C (4) 1.805 (8) Mn (2) - C (4) - O (4 176.8 (1) Mn (2) - C (5) 1.803 (6) Mn (2) - C (4) - O (4 176.6 (1) Mn (2) - C (6) 1.769 (9) Mn (2) - C (4) - O (4 176.0 (1) Mn (3) - C (7) 1.783 (8) Mn (3) - C (7) - O (7) 176.5 (1) Mn (3) - C (9) 1.794 (7) Mn (3) - C (9) - O (9) 171.0 (1) Mn (2) - C (7) 2.726 (7) [MnFe25e2 (CO) 9] - compared to [Mn35e2 (CO) 9] 2

A related compound with mixed metal complex [MnFe25e2 (CO) 9] - / 3e / was synthesized and used as isostructural with [Fe35e2 (CO) 9] / Sb /. Structural analysis was conducted on the basis of a disordered model in which two of the three metal centers are statistically occupied by Mn and Fe. The problem of Fe / Mn distribution in the complex anion [MnFe25e2 (CO) 9] - is the task to achieve the results described above. This compound should be isostructural with 6.

The structure can be better described by assuming the presence of an asymmetric carbon bridge. The [MnFe25e2 (CO) 9] anion carbon bridge is therefore not found as 6, but rather built like [Mn3Se2 (CO) 9].

Taking into account the individual metal selenium whose distances show that the positions of the metal atoms in the base of the M35e2 pyramid in all probability not statistically, but in an orderly manner of manganese (position M (1)) and iron (position M (2)) , Here, the formally higher oxidized metal atom (here Mn) is stabilized by the asymmetric carbon bridge in accordance with the hypothesis formulated above.
[Fe352 (CO) 9] [Fe2 (52) (CO) 6] compared with [Mn35e2 (CO) 9] 2

Although asymmetric carbon bridges are very common in chemistry, very few examples of the [MnFe25e2 (CO) 9] 2 anion have an unexpectedly long-term Mn-identified form. An essential, as yet undiscovered, asymmetric bridge of this type can be found in the [Fe352 (CO) 9] unit complex. The property can also be found in [Fe352 (CO) 9] [Fe2 (52) (CO) 6]. This is surprisingly typical for a long M ... C contact, although the two Fe atoms in the base of the pyridine Fe352 are chemically equivalent. The unusual location of the apical Fe (CO) 3 is known as an alternative conformation. According to previous findings, however, the presence of an asymmetric carbon bridge must also be assumed. The explanation for the unexpected behavior of [Fe352 (CO) 9] in the complex adduct is found high in the arrangement of the two components in the crystal. These are packaged so that the complexes are present, in fact, like charge-transfer adducts.

7 Figure 3 shows in a perspective view part of an alternating chain of trinuclear [Fe352 (CO) 9] and bidentate [Fe2 (52) (CO) 6]. When trinuclear [Fe352 (CO) 9] and bidentate [Fe2 (52) (CO) 6] molecularly alternate to 3.15 Angstrom, intermolecular SS bridges to infinite one-dimensional junctions. It is probably due to the disulfide group of the dinuclear complex and the resulting electron deficiency [Fe352 (CO) 9] and is compensated by the asymmetric carbon bridge and transferred into an electron density in a thetrinuclear component. This explains why the coexisting Mössbauer spectrum of [Fe352 (CO) 9] (Fe2 (52) (CO) 6] significantly differs from that of isolated complexes.
[Mn3Se2 (CO) 9] 2 compared to [Mn3Se2 (SeMe3) (CO) 9] 2

It is observed - in the system [Mn2 (CO) 10] / Na25e / [Ph4P] Cl, the promotion of the reaction [Mn35e2 (CO) 9] 2- () [Mn35e2 (5eMe3) (CO) 9] 2. This complex is formed under solvothermal conditions in methanol formally by the addition of a Methanselenolat ligands and the removal of an electron from the manganese structure. Here's the my-2-5eMe3 bridge between Mn (1) and Mn (3) is attached. (3) For the asymmetric carbon bridge between Mn (2) and Mn.

8th shows in a perspective view the superposition of the structures of [Mn3Se2 (CO) 9] 2- (shown in bold) and [Mn3Se2 (SeMe3) (CO) 9] 2- (shown as a dashed line) ( 9 ), which form a complete 2-my carbon bridge and illustrates these differences. The position of the carbon ligand to Mn (1) and Mn (2) changes only slightly, while Mn (3) has an octahedral coordination consisting of two terminal CO ligands, the 2-my-carbon bridge composed of 2 my -SeMe3 bridges and the two my-3 selenide ligands.

The introduction of the 2-my-SeMe3 bridges and the associated change in geometry, ie the formation could be fixed by magnet holding forces. The complex is diamagnetic 9a with its even number of 50 valence electrons. While the complex ion 9a with an odd number of valence electrons shows the expected paramagnetism (= 1.8 myB for myeff [Mn3Se2 (CO) 9) 2] 2 - at 100 K). This is also reflected in the significant scattering of the phenyl resonances in the IH-NMR spectrum.

9 Figure 1 is a diagrammatic representation of the 1H NMR absorption behavior of Ph protons in [Ph4P] 2 [Mn3Se2 (CO) 9] (in the left part of the figure A) and of [Ph4P] 2 [Mn3Se2 (CO) 9] (in the right part of the figure B) ). These Heusler alloys often undergo a martensitic transition between the martensitic and austenitic phases, which generally occurs due to temperature induction and is first order. Ni2MnGa arrangements are ferromagnetic with a Curie temperature of 376 K and a magnetic moment of 4.17 IIB, which is largely confined to the Mn atoms and associated with the Ni atoms with a small momentum of about 0.3 ILB , As can be expected from its cubic structure, the initial phase has a low magnetocrystalline anisotropy energy (Ha = 0.15 T). However, in its martensitic phase, the compound has much greater anisotropy (Ha = 0.8 T).

The martensitic transformation temperature is close to 220 K. This martensitic transformation temperature can be easily varied to about room temperature by changing the composition of the alloy to a stoichiometric alloy. The low-temperature phase evolves from the initial phase by a diffusionless, position-changing transformation towards a tetragonal structure, a = b = 5.90 A, c = 5.44 A. A martensite phase generally accommodates the stem associated with transformation (that is 6.56% of c for Ni2MnGa), through the formation of twin variants.

This means that a cubic crystal splits into two tetragonal crystallites that share a contact plane. These twins are packed together in matching orientations to the strain energy (much like the magnetization of a ferromagnet on different orientations by breaking up into domains to minimize the magnetostatic energy). The alignment of these twin variants by the movement of the twin boundaries leads to large macroscopic trunks.

In the tetragonal phase with higher magnetic anisotropy, an applied magnetic field can cause a change in strain, and therefore these materials can be used as actuators. In addition to this ferromagnetic shape memory effect, one can observe very close to the martensitic transition temperature that there is a large change in magnetization for low-level magnetic fields. This change in magnetization is also related to the magnetocrystalline anisotropy.

This change in magnetization, which results in a moderate magnetic entropy change of a few J / molK, is enhanced when implemented on a single crystal. If the composition is present in this material in such a way that the magnetic and structural transformation occurs at the same temperature and is tuned to the greatest magnetic entropy, changes are observed.

For magnetic applications, extremely large changes in length in the martensitic transition will lead to aging effects. It is known in magnetic shape memory alloys that often only single crystals are driven while polycrystalline materials spontaneously pulverize after several cycles. One can increase the temperature effects by pressure on the crystalline formations, but also aging effects and declination of the polycrystallines are then observed.

Fe2P-based compounds provide the opportunity to prevent ionization processes, the binary intermetallic compound Fe2Ph can be considered as a base alloy for a workable mixture of materials. This compound crystallizes in the hexagonal, non-point symmetric FeMn-phosphorus compound, and has all the positive properties to be used as a transponder for home refrigeration systems.

Substitutions of Fe and / or Mn are conceivable with AS, Zi, Ni, Ge, Si. Fe occupies the 3g and 3f sides and p the Ib and 2c sides. This results in a stack of alternating P-rich and low-P-layers. The neutron diffraction reveals that the magnetic moment of the Fe on the 3g side is about 2my-B, while the momentum on the 3f side is about 1my-B. The hexagonal shape has poor opportunities to be recovered by aging as a magnetic source.

A significant reason for the electrically conductive properties of the polymeric fibers by the doping is that in the dielectric support structure of the polyester, the metal particles are spatially separated from each other, but that the electron clouds of the metal particles overlap each other. The embedding of the doping elements in the polyester prevents decomposition processes and prevents external influences.

In particular, reoxidation, friction decomposition are avoided and flexibility is improved.

It can be achieved with respect to the radiation exactly fixed, sharply delimited and reproducible frequency responses.

In particular, with regard to the radiation absorption, it is possible to achieve a suitable doping by the generation of infrared radiation in the frequency range of 4.5 μm to 11.5 μm.

As an alternative to using PET polymeric fibers, it is also possible to use aramids. The production of the fibers can be carried out by electrospinning.

A typical diameter of the fibers is in the range 2 μm to 6 μm. The doping with the metal particles is preferably carried out in a gas plasma.

A typical fiber length is in the range of 2 cm to 4 cm.

Particularly suitable doping elements are the following chemical elements, either in the pure state or as an alloy. Especially thought is the use of rare earth metals. It is also possible to use, for example, iron, manganese, phosphorus, silicon, lanthanum, germanium, sodium, zinc, fluorine or arsenic. In addition, aluminum, copper and / or nickel are also usable.

Also contemplated is the use of earth metals or alkali elements, for example, magnesium, calcium, sodium or potassium.

The integration of the ceramic material in the polymeric base material is carried out at a respective size dimensioning in a molecular range, depending on the material and a corresponding order of magnitude in an atomic range is possible. The diameters of the stored elements thus amount to a maximum of 1 micrometer, preferably a maximum of 1 nanometer. In general, these diameters can be between the diameters of a hydrogen atom and the diameter of a uranium atom.

In a ceramic cooling wire in micrometer structure, the metal particles in gas plasma form, arranged amorphously in a coordinate system separately inhomogeneous one. This has the consequence that in a dielectric support structure, in the x, y, z-axis spatially separated metal particles, but are interconnected via their electron clouds. The advantage of this technical procedure, in comparison with the existing coating and wire-entangling methods, is firstly that there are no decomposition processes from diffraction of the individual crystals and metal particles, secondly the individual particles are isolated from one another and isolated from one another by the amorphous spatial separation integrated into one of the electrical conductors of their own and external influences and show isolated properties on the interface / surface in the x, y, z-direction; which considerably increases the service life, durability and longevity in safety and functional efficiency. Reoxidation, friction degradation and flexibility characteristics are improved in favor of increased efficiency and effectiveness of use.

One advantage of this technique lies in the specific usability of precisely fixed emitting frequency responses to radiating bodies or metal particles.

Thus, the individual work areas and modes of operation can be modularly elaborated.

The resulting "filters" allow accurate spectral absorbers, which absorb only in the range of IR-C ranges from 4.5 microns to 11.5 microns of visible light. It can also be defined that absorptions of light, sound and electromagnetic fields as well as pressure on materials can be made specifically in defined range frequencies.

A first film or web-like embodiment has the following characteristics: properties unit value total thickness mm 0.38 tolerance mm ± 0.025 breaking strength kN / mm 12 strain % 20 hardness Shore A 90 tensile strenght N / mm ² - Continuous operation Temperature ° C -60- + 200

This foil has a diameter of 38 μm, width of choice, max. 1600 mm. Glass fiber reinforced polyamide fabric, with 40% ceramic content.

According to a second embodiment, the following characteristics are present: properties unit value filler - thermally conductive Polyimiddicke microns 25 material thickness microns 150 tensile strenght MPa 46 tear strength kN / m 60 hardness Shore C 90

The second foil has a diameter of 25 μm, width of your choice, max. 1600 mm, cellulose (paper) and polymide substrate, mixed with graphene powder to 15% in mixing ratio.

The wire made of the fibers can be used as a cooling element.
Wire made of PET or aramid, fiber by electro-spinning method, diameter 2 μm to max. 6 μm, filled with gas plasma metal particles. Length 2 cm to max. 4 cm, for cooling foil, sheet resistance 0.4 mil ohms per cm ² .
In textile fabric: cooling wire according to customer specification in diameter and length.

Hybrid cooling elements offer enormous potential for miniaturization because they absorb heat precisely where it needs to be dissipated.

Energy savings, since the heat loss to uninvolved components is minimal (energy efficiency).

Reduction of process time, because on the one hand the heat is absorbed in the shortest possible time due to the low thermal mass of the ceramic heaters.

The ceramic can be used in special applications.

Hybrid cooling elements are infinitely variable over the entire temperature range. Due to the linear temperature dependence of the resistance, the platinum cooling conductor can simultaneously assume the function of a temperature sensor and thus measure and regulate the temperature of the cooling element. The lifetime and resilience (thermal shock resistance, constant heating and cooling) is very high.

Highest mechanical strength, even at high temperatures, electrically conductive, highest fracture toughness, high Weibul modulus. Barely wetting with EDM machinable. Excellent wear resistance, good sliding properties, very good thermal conductivity, small mass (density 3.9 g / cm3) extruded. Color: brown to golden brown.

For conductivity, ions are responsible as charge carriers. Their mobility is low but by incorporation into the crystal structure. The proportion of different ions in the total conductivity of a material is documented by the transfer coefficients of cations, anions and electrons or voids. Such cooling elements can survive a temperature of about 1,000 ° C in continuous operation or up to 1,300 ° C for short-term temperature peaks. Typical designs are tubular (tubular) cooling elements, so-called tube coolers, rod coolers or lamella coolers or flat cooling plates.

CaO-Al2O3-SiO2 melt is the base material, combined with PA molecules in a mixing ratio of 40% to 60%.

Preferred materials are silicon nitride and carbide, oxide ceramics and graphite.

The fibers are used to form a wire and conductor training.

Electron conduction, as it has great importance in metallic materials, can be explained with the band model. Even in the single atom, an electron can only take on an energy state described by corresponding quantum numbers (Pauli principle). The discrete energy levels of the electrons of the individual atoms widen in the atomic union in each case to an energy band in which the electrons can occupy the same quantum state of extremely many atoms very close to each other but different energy states. The atoms take their equilibrium distance r0 to each other, only the energy levels of the interrelated bonding electrons are expanded into a band.

Typical achievable densities for metal oxide ceramics are> 99.7%.

• – Reaktionssintern
• – Vakuumsintern
• – Drucksintern (axiales und isostatisches Heißpressen, Nachhippen)

In addition to pressureless conventional sintering, the following sintering technologies are also used in ceramics:

• - Reaction sintering
• - Vacuum internally
• - Pressure sintering (axial and isostatic hot pressing, Nachhippen)

Reaction sintering is used primarily for special silicon carbide and silicon nitride materials. The advantage lies in the low shrinkage of the components (<5% to 0%). The vacuum and pressure sintering technology allows the production of almost pore-free materials with practically 100% theoretical density. In the sintering process of multiphase materials, a dense structure consisting of several crystalline phases or a mixture of crystalline and glassy phases arises at high temperatures.

As the coefficients of thermal expansion of the different phases differ, they contract differently as they cool, creating stresses and microcracks between individual grains. The resulting coefficient of expansion of the composite material can be calculated if it is assumed that only pure tensile and compressive stresses occur and no cracks are formed.

For example, in the conversion of electrical energy into mechanical / thermal energy. The pure deformation is used when applying electrical voltages to actuators.

For crystals, crystal symmetry is another criterion for the occurrence of piezoelectricity. The piezoelectric polarization does not occur when the crystal has an inversion center. For all 21 non-centrosymmetric point groups, piezoelectricity may occur with the exception of the cubic point group 432. In other words, an elementary cell may not have a center of symmetry (= a point at which point reflection transforms the crystal into itself).

The best known material with piezo properties is quartz (SiO ₂ ). Quartz crystals have the non-centrosymmetric point group 32. Each Si atom sits in the middle of a tetrahedron of four oxygen atoms. A force acting in the direction of the base-surface peak (crystallographic direction) now deforms these tetrahedra in such a way that the compressed tetrahedra are electrically polarized and thus a net voltage occurs on the surfaces of the crystal (in the direction).

Piezoelectric thin films are increasingly being used as active sensor materials. With the help of semiconductor technologies, it is possible to deposit these active piezoelectric thin films on silicon. These are usually zinc oxide (ZnO) or aluminum nitride (AlN).

The plastic polyvinylidene fluoride (PVDF) can be - similar to piezoelectric ceramics - polarize and is then piezoelectric. Applications for this are hydrophones.

The materials which are suitable for use as heating elements / heating conductors ("active", current-carrying components which are heated) are, in addition to special high-temperature and oxidation-resistant metals (NiCr, FeCrAl, Pt; in an inert atmosphere also W and Mo) also conductive ceramic materials, so-called ceramic matrix composites (CMC, eg ATN = Al2O3 / TiN mixed ceramics, Al2O3 / MoSi2 mixed ceramics, Si3N4 / MoSi2, etc.) and hybrid heating elements. Depending on the maximum operating temperature and the ambient atmosphere, the appropriate material is selected for each application.

• – Hohe Temperaturbeständigkeit (höher als die maximale Ableittemperatur),
• – Elektrische Isolationsfestigkeit auch bei hohen Temperaturen,
• – Chemische Beständigkeit und Korrosionsbeständigkeit in der geforderten Atmosphäre,
• – Gute Temperaturwechselbeständigkeit.

Carrier materials for heating conductors, so-called. Heizleiterträger have compared to "active" heating elements, the task of the heating heating coils that are pulled over the Heizleiterträger or suspended from it to wear even at very high annealing temperatures permanently. The prerequisites for the ceramics used for this purpose are:

• - high temperature resistance (higher than the maximum discharge temperature),
• - electrical insulation strength even at high temperatures,
• Chemical resistance and corrosion resistance in the required atmosphere,
• - Good thermal shock resistance.

The ideal material here is cordierite. Cordierite is a magnesium aluminum silicate mineral characterized by a very low coefficient of linear expansion. Accordingly good is the thermal shock resistance or in other words the resistance to thermal shock. Cordierite ceramics are available in both porous and dense form. It is used where pores have no negative impact on the application. This can be z. B. penetrating moisture, which can lead to electrical flashovers over time. Here dense cordierite (C410) can be used. Depending on the type, cordierite can be used up to a maximum temperature of approx. 1,240 ° C (C 520) or 1300 ° C (C 530). Specialties with high alumina or mullite content can be used up to 1700 ° C. However, these special types also have a lower thermal shock resistance.

• a) Fe und Zr in das Gitter einzubauen. Fe³⁺ wird auf Zr⁴⁺-Plätzen eingebaut, die entsprechend der Oxidationszahlen gegenüber dem ungestörten Gitter eine negative Ladung trägt. Zur Ladungskompensation gehen für ein eingebautes Fe³⁺-Kation ¼Zr⁴⁺ auf Zwischengitterplätze.

According to a first variant, it is possible

• a) Install Fe and Zr in the grid. Fe ³⁺ is incorporated on Zr ⁴⁺ sites, which carries a negative charge according to the oxidation numbers compared to the undisturbed lattice. For charge compensation, a built-in Fe ³⁺ cation ¼Zr ^{4+ is placed} on interstitial sites.

• b) xFe'_Zr, 1/2 × V •• / 0 Es sei angemerkt, dass auch bei dem Beispielen 1 und 2 prinzipiell andere Fehlordnungen möglich wären

Another possibility would be that oxygen vacancies are formed:

• b) xFe _'Zr, 1/2 × V •• / 0 It should be noted that also in Examples 1 and 2, in principle, other dislocations would be possible

At first, a distinction is made between the electron and ion conductors due to the charge carriers. In the case of the electron conductors, a further distinction is generally made on the basis of the size of the specific resistances, ρ: superconductors ρ <10 ^-10 Ωcm Metallic ladder 10 ^-10 < ρ <10 ^-4 Ωcm semiconductor 10 ^-4 < ρ <10 ^{+ 5} Ωcm insulators ρ> 10 ⁺⁵ Ωcm

When the temperature increases, the resistivities change as follows:

In polycrystalline polyphase materials, these criteria are sometimes misleading because the assignment due to resistivity may be different than that due to the temperature dependence of the resistivity.

For example, the specific resistance of graphite decreases with increasing temperature, while that of TiN, TaC and some oxide ceramics increases (thus show metallic conductivity).

The preparation of a ceramic can, as described below, take place.

Production of ZrO ₂ ceramics

ZrO ₂ powder for the production of ionic conductors or mechano-ceramics is today mainly produced by coprecipitation. Here, ZrCl _{3 is} mixed with YCl ₃ and then hydrolyzed.

In this case, a precipitation of Zr (OH) ₄ and Y (OH) _{3 is achieved} in finely divided form. The subsequent thermal treatment produces extremely sintered doped ZrO ₂ powder. This is commercially available and allows complete sintering at sintering temperatures> 1400 ° C through a solid-state sintering process. It should be noted that a sintering temperature of 1400 ° C for a phase with a melting point> 2700 ° C is exceptionally low.

The chosen structure of the order of magnitude as well as the particle density, have considerable effects on the expansion and shrinkage capabilities of the cooling wire, but also on the molecular elongation at break within the ionic tracks between the metal atoms. Materials on which a tension acts expand. Rigid materials (such as steel) stretch only slightly, yielding materials (such as polyethylene) more. This fact is expressed in the modulus of elasticity. But before we can give this, we first define what stretching is.

Aluminum titanate ceramic is not high-strength and therefore a rather atypical mechanoceramics. Fig. 3.26. shows the flexural strength of an Al ₂ TiO ₅ ceramic compared to ZrO ₂ and Al ₂ O ₃ .

For ZrO ₂ ceramics, highest strengths are achieved at room temperature, but they drop rapidly at temperatures above 500 ° C. For Al ₂ O ₃ ceramics, a significant drop is observed only from 1000 ° C. In contrast, the strength of Al ₂ TiO ₅ ceramic increases from about 30 MPa at room temperature to about 80 MPa at 1000 ° C.

This has effects on the thermal properties and expansion coefficients: The specific volume of a crystal increases with increasing temperature, and the crystal tends to become more symmetrical. The general increase in volume with temperature is essentially determined by the increase in the amplitude of vibrations of the lattice units about their average position. The repulsive force between atoms changes faster than the attractive force as the distance between two atoms increases. The consequence of this is that the energy distribution is asymmetric as a function of the atomic distance (Figure 3.2.1). As the lattice energy increases, the increasing amplitude of the lattice vibrations results in a larger atomic distance, which equals lattice expansion.

From a thermodynamic point of view, the energy of the structure increases and the entropy decreases. The change in volume caused by lattice vibrations is thus closely related to an increase in internal energy. Consequently, changes in the coefficient of thermal expansion with increasing temperature run parallel to changes in the specific heat.

(In the case of anisotropic crystals, the coefficient of thermal expansion differs in the direction of the different crystallographic axes.) Crystals almost always tend to have a higher symmetry at higher temperatures, whereas in tetragonal crystals, for example, the ratio of the crystallographic axes c / a (at the crystal) increases with increasing temperature The ratio of the expansion coefficients αc / αa also decreases as a rule with increasing temperature).

3.6. non-oxide ceramics

3.6.1. General about non-oxide ceramics

Non-oxide ceramics are ceramics that contain little or no oxygen. Non-oxide ceramics, which are currently of technical importance, are: nitrides: Si ₃ N ₄ AlN BN TiN Carbide: SiC B ₄ C WC TiC borides: TiB ₂ ZrB ₂ silicides: MoSi ₂

The subgroup carbides, nitrides, borides and silicides are metallically conductive, have metallic luster, but much higher hardness than metals. They are also referred to as hard metals (or hard materials). Tungsten and titanium carbide as well as TiN are mainly used as cutting materials. Here, tungsten carbide is the classic material ("Widia"). Titanium nitride is golden yellow and of much higher hardness than tungsten carbide. It is used as a coating for tungsten carbide tools ("Goldmaster"). In addition to the above-mentioned Nebengruppencarbiden and nitrides, others are used, for. Niobium or tantalum carbide and nitride. Titanium boride and zirconium boride are mainly used as materials for armor because of their high impact strength. Molybdenum silicide, and also mixtures or solid solutions with tungsten silicide, are used for high temperature heating elements (up to 1850 ° C).

4. Silicon-Infiltrated SiC (SiSiC)

Produced like RBSiC, just without expelling excess SiC. SiSiC shows strengths of about 350 MPa, which are essentially retained up to 1300 ° C, but then fall off quickly. SiSiC continues to show a high thermal conductivity.

5. Pressure-sintered silicon carbide (SSiC)

The finest sinter-active silicon carbide powder is sintered at 1900-2200 ° C with the addition of 2% B + C (as a sintering aid). This is where complete compaction occurs. SSiC has a very uniform microstructure with small crystallite sizes. It has strengths up to 500 MPa, which are preserved up to 1400 ° C.

6. Hot pressed silicon carbide (HPSiC)

Hot isostatically pressed silicon carbide (HiPSiC)

Again, the finest sinter-active powders and B + C as a sintering aid, but only about 1% d. H. less than used in the production of SSiC. The moldings are compacted under uniaxial pressure (HPSiC) or isostatic pressure (HiPSiC) of about 40 MPa. The porosity is less than 2%, the structure is very even with the smallest crystallites. This results in best mechanical properties with strengths of about 550 MPa, which are only slightly lower at 1400 ° C.

The mechanical properties of various silicon carbide ceramics at 20 and 1400 ° C are shown in Tab. 3.4. shown. Tab. 3.4. Density and mechanical properties of silicon carbide ceramics Density in g / cm Strength in MPa 20 ° C 1400 ° C Tied SiC 2.6 30 15 Recrystallized SiC 2.5 100 100 RBSiC 3.0 350 200 SSiC 03.01 400 400 HPSiC 3.2 550 500

1) Reaction-bound silicon nitride (RBSN)

Silicon powder is plasticized. After shaping, the mixture is heated to about 1200 ° C. under a nitrogen atmosphere (ie, below the melting point of elemental silicon). Here, the silicon reacts on the surface to silicon nitride. If nitridation has occurred for some time, the Si ₃ N ₄ layer only grows slowly. Then the temperature is raised (also beyond the melting point of silicon).

The porosity is about 15-20%. The partially nitrided molded body is easily machinable. RBSN shows good high temperature properties (no oxide phases).

2) Pressure-sintered silicon nitride (SSN)

Fine sintered silicon nitride powder is mixed with a high proportion of sintering aids (~ 10%) Y ₂ O ₃ and / or MgO. After shaping, the sintering takes place at about 1800 ° C. in a powder bed of Si ₃ N ₄ . SSN has high strengths (about 650 MPa), which, however, rapidly decrease above 1000 ° C.

3) Hot-pressed silicon nitride (HPSN)

Hot isostatically pressed silicon nitride (HiPSN)

Production similar to SSN but with less sintering aid (~ 5%). The sintering takes place under pressure. The microstructure is finer grainy than SSN, the mechanical properties even better (strength about 600 MPa).

Fig. 3.34. Bending strengths of some silicon nitride ceramics as a function of temperature.

Similar to silicon carbide, numerous polymer routes have been developed for the production of silicon nitride, which can be used to produce powders of higher sintering activity.

The formed chain polysilazane can further crosslink. Upon heating under NH ₃ , it is converted into nanocrystalline Si ₃ N ₄ .

• – Partikel (Partikelverstärkung)
• – Faserverstärkung Langfasern: SiC, Kohle oder Al₂O₃. Kurzfasern
• – Whisker (kleine nadelförmige Einkristalle): vor allem SiC. Problem: Whisker sind lungengängig und nicht abbaubar daher: krebserregend.
• – Platelets (kleine plättchenförmige Einkristalle): SiC, Al₂O₃.
• – Einlagerung von Metallteilchen.

In principle, the following reinforcing elements can be used

• - Particles (particle reinforcement)
• - Fiber reinforcement Long fibers: SiC, coal or Al ₂ O ₃ . short fibers
• - Whiskers (small needle-shaped single crystals): mainly SiC. Problem: Whiskers are respirable and non-degradable therefore: carcinogenic.
• - Platelets (small platelet-shaped single crystals): SiC, Al ₂ O ₃ .
• - Storage of metal particles.

• – Rissablenkung
• – Rissverzweigung
• – „Fibre Pull-out”

The effect of reinforcing elements is ideally as follows:

• - Crack deflection
• - Crack branch
• - "Fiber pull-out"

Fig. 3.35. shows schematically the three effects.

This only changes with the use of micrometer wires.

The modulus of elasticity is a measure of the resistance of a material to elastic deformation. Low modulus materials have low stiffness; when weighted, they give way severely (feathers, upholstery material, pole vault bar). Atoms within the molecule, d. H. an elastic oscillation of the atoms against each other, corresponding to a continuous storage of kinetic and potential energy.

Ceramic materials have a very high modulus of elasticity, but under load they show very little elastic deformation. Only in the composite material of PA fibers with ceramic particles, in powder mixture is a material produced. which has both strength and tensile and compressive properties, which in turn meets the requirements of a heating wire with high temperature component.

This means that the longevity of the micrometer wire as a cooling element, without histeresis and molecular decompositions possible. This means that the faster movement of the gas molecules, which requires the heating of one kilomole of a gas by 1 K at constant volume, requires an energy input of 0.993 kcal per excited degree of freedom.

• – Der innere Strahlungstransportanteil nimmt mit steigender Temperatur wesentlich schneller zu als der Leitungsanteil. Bei hohen Temperaturen findet der Wärmetransport weitgehend durch innere Wärmestrahlung statt.
• – Der Leitungsanteil wird bei konstanter Temperatur mit steigender Gesamtporosität geringer.
• – Der Strahlungsanteil wird bei gleicher Temperatur mit kleinerem mittlerem Porendurchmesser geringer. Er wird wesentlich von der Porengrößenverteilung beeinflusst.
• – Bei gleicher Ausgangsporosität wird ein feuerfester Werkstoff mit kleinerem mittlerem Porendurchmesser einen geringeren Anstieg der effektiven Wärmeleitfähigkeit in Abhängigkeit von der Temperatur zeigen.
• – Bei Anisometrien bzw. Texturen, besonders bei der Porenvolumenstruktur, kann die effektive Wärmeleitfähigkeit richtungsabhängig sein.

For porous (refractory) materials the following essential statements apply:

• - The internal radiation transport component increases with increasing temperature much faster than the line share. At high temperatures, the heat transfer takes place largely by internal heat radiation.
• - The proportion of pipe decreases at constant temperature with increasing overall porosity.
• - The radiation fraction is lower at the same temperature with a smaller average pore diameter. It is significantly influenced by the pore size distribution.
• - For the same initial porosity, a refractory with a smaller average pore diameter will exhibit a smaller increase in effective thermal conductivity as a function of temperature.
• - For anisometries or textures, especially in the pore volume structure, the effective thermal conductivity may be directional.

• – Die Porosität ist auf die Einsatztemperatur bzw. das zu dämmende Temperaturgefälle abzustimmen. Die für die minimale Wärmeleitfähigkeit erforderliche Porosität sinkt mit steigender Einsatztemperatur.
• – Die Poren sollen möglichst klein sein.
• – Das Feststoffgerüst soll aus locker gepackten Kristallstrukturen aus Atomen mit hoher relativer Atommasse aufgebaut sein, komplizierte Verbindungen enthalten, feinkristallin sein, eine hohe Fehlstellendichte, großen Brechungsindex und geringe Transparenz aufweisen.
• – Risse und Grobporen, die einen konvektiven Wärmetransport ermöglichen, sind zu vermeiden.
• – Den Wärmedämmstoffen können Stoffe zugesetzt werden, die den Strahlungstransport behindern. Diese Maßnahme hat erfahrungsgemäß nur bis zu Temperaturen von unter 1000°C einen Effekt.

Summarizing all the statements presented, one can formulate the requirements for a refractory material with minimum or maximum thermal conductivity. A thermal insulation material with optimum properties is obtained by the following measures:

• - The porosity must be adjusted to the operating temperature or the temperature gradient to be insulated. The porosity required for the minimum thermal conductivity decreases with increasing service temperature.
• - The pores should be as small as possible.
• The solid skeleton should be composed of loosely packed crystal structures of atoms with a high relative atomic mass, contain complicated compounds, be finely crystalline, have a high defect density, high refractive index and low transparency.
• - Cracks and coarse pores that allow convective heat transport should be avoided.
• - Substances that hinder the transport of radiation can be added to the thermal insulation materials. This measure has experience, only up to temperatures of less than 1000 ° C an effect.

• – Der feuerfeste Werkstoff soll weitgehend porenfrei sein.
• – Die Feststoffphase soll aus einer dichtgepackten Kristallstruktur aus Atomen mit einer geringen relativen Atommasse aufgebaut sein, aus möglichst großen Kristallen mit einer hohen Ordnung im Gitter, ohne Mikrorisse oder amorphe Anteile bestehen, möglichst einphasig sein und eine hohe Transparenz besitzen.
• – Der Zusatz von Graphit oder SiC erhöht die Wärmeleitfähigkeit üblicher feuerfester Verbund-keramiken.

A refractory material with maximum thermal conductivity is achieved by the following measures:

• - The refractory material should be largely free of pores.
• The solid phase should be composed of a densely packed crystal structure of atoms with a low relative atomic mass, consisting of crystals as large as possible with a high order in the lattice, without microcracks or amorphous fractions, be as single phase as possible and have high transparency.
• - The addition of graphite or SiC increases the thermal conductivity of conventional refractory composite ceramics.

The addition of PA or PET fractions substantially increases the elasticity and elongation of the micrometer fiber.

• A. PET wird mit Metallstrukturen FeMnCu substituiert, zusammen mit CaO Nanopartikeln.
• B. Durch Reibungen bei Nano-Draht Spinning werden die einzelnen überschüssigen Anteile an Partikeln entfernt.
• C. Die einzelne Faser wird immer homogener in der äußeren Struktur.
• D. Die einzelnen Metallpartikel zeigen bereits unter Einfluss des Elektronen Raster Mikroskopes, magnetisches Verhalten, indem die Metallpartikel Ladungswolken ausbilden (dicke Körner), über diese Ladungswolken/Elektronen-Wolken wird der Strom geleitet, und durchfliest den gesamte Faser sowohl in Längs- als auch in Querachse.

The following steps in the production of the fibers are appropriate:

• A. PET is substituted with metal structures FeMnCu, together with CaO nanoparticles.
• B. Friction in nano-wire spinning eliminates any excess particulate matter.
• C. The single fiber becomes more and more homogeneous in the outer structure.
• D. The individual metal particles already show under the influence of the electron microscope grid, magnetic behavior in that the metal particles form charge clouds (thick grains), over these charge clouds / electron clouds, the current is passed, and traverses the entire fiber in both longitudinal and in transverse axis.

The ceramic particles according to 19 are used for rapid absorption of high temperatures to increase the internal melting point of a PET / PA fiber.

20 shows a perspective view of the structure of a cooling foil ( 10 ). The invention provides that fibers ( 1 ) of a doped polymeric material in the interior of a cooling foil ( 10 ) are integrated in a non-directional litter deposition. The fibers ( 1 ) may have a round cross section similar to a wire shape, which is small relative to the fiber length. These can be of such small diameter that values of 2-4 μm are present. The surface ( 2 ) of the fibers ( 1 ) is plastic insulated.

Shown schematically at the end-side fiber end are the doping elements ( 3 ), which may comprise metal atoms and / or all compounds described above. The cooling foil ( 10 ) is preferably made of two Kühlleitfolien ( 11 ), which have the electron conductor property and lie on one another in such a way that the preferably each one-sidedly acted upon fiber deposition ( 1 ) on the mutually facing side of the Kühlleitfolien ( 11 ) is located. The two slides ( 11 ) may be fixed in their congruent position to each other, for example by gluing.

Depending on the selected doping component ( 3 ) or their combination for the polymeric fibers ( 1 ) absorption abilities and / or electrical conductivity properties can be imprinted with at least one of the described physical properties of the doping elements ( 3 ) correspond. This makes it possible to generate heat energy in a particularly efficient manner.

21 shows a doped with metal components and ceramic components fiber that absorbs infrared radiation.

22 illustrates the superposition of the respective electron clouds of the doping elements. To generate the radiation, a low-voltage pulse is preferably applied in the longitudinal direction of the fibers. The respective electron clouds are thereby influenced and superimposed controllable.

23 illustrates a textile-like mesh of doped polymeric fibers. It is simplified here shown a microstructure of individual fibers. From the fibers, however, threads can first be produced in a first production step, and then textile-like base structures can be produced from these doped polymeric threads.

Claims (18)

Device for cooling, comprising a fabric made of at least one fiber with electrical conductivity, wherein the fiber material is formed by a base material of at least one polymer, in which elements are embedded, characterized in that the elements have a size of at most one micrometer Have diameter and are provided with a distance such that overlap electron clouds at least partially. Apparatus according to claim 1, characterized in that at least some of the induced elements have current-conducting properties, so that the fiber is at least partially electrically conductive. Apparatus according to claim 1 or 2, characterized in that the induced elements have magnetocaloric effects, so that the fiber at least partially undergoes an increase in temperature by the action of a magnetic field. Device according to one of the preceding claims, characterized in that the induced elements are incorporated within the polymeric base material in an unequal density distribution. Apparatus according to claim 4, characterized in that the induced elements are less densely arranged in material cross-sectional areas with Stromverdrängungseffekt as in material cross-sectional areas with current compression effect. Apparatus according to claim 4 or 5, characterized in that the induced elements in near-surface material cross-sectional areas of the equivalent conductive layer thickness δ one induced in a higher density than outside this range. Device according to one of the preceding claims, characterized in that the induced elements are introduced by doping in the polymeric base material. Device according to one of the preceding claims, characterized in that the induced elements are formed by MnFe phosphorus compounds. Device according to one of the preceding claims 1 to 7, characterized in that the induced elements by MnFe (As, PwGexSiz) s are formed. Apparatus according to claim 9, characterized in that the induced elements have the following values: x = 0.3-0.7 and, or w less than 1 - x and z = 1 - x - w. Device according to one of the preceding claims 1 to 7, characterized in that the induced elements are formed by FeMn-phosphorus compounds with As, Si-phosphorus substitution and combined with La (FeMnP) AlCo. Device according to one of the preceding claims 1 to 7, characterized in that the induced elements are formed by compounds with Mn-Zn. Device according to one of the preceding claims 1 to 7, characterized in that the induced elements are formed by an alloy with FeMnPO, 7GeO, 3. Device according to one of the preceding claims 1 to 7, characterized in that the induced elements are formed by an alloy with FeMnP0.5Ge0.5. Device according to one of the preceding claims 1 to 7, characterized in that the induced elements by an alloy with FeO, 86MnI, 14PO, 5Si0,35GeO, 15 are formed. Device according to one of the preceding claims 1 to 7, characterized in that at least a part of the elements consists of at least one ceramic material. Device according to one of the preceding claims 1 to 16, characterized in that the polymer is formed as PET. Device according to one of the preceding claims 1 to 17, characterized in that at least some of the elements are formed of metal.

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