DE102013013401A1 - Use of silicon carbide (dielectric) as optional consumable material for heating thin material layers by means of microwave radiation - Google Patents

Abstract

The silicon carbide contained in the material layers absorbs three-dimensionally distributed in the materials to be heated, the microwave radiation to almost 100%, converts this radiation energy directly into heat and immediately returns this to its surroundings. Thus, the whole microwave energy is absorbed directly in the material layer (three-dimensional) and converted into heat. This means that even materials with a low dipole constant or microwave permeable material in joints / layers can be heated / melted / evaporated / ashed. Further, microwave transparent or low microwave absorbing rate, for example: high boiler liquids, can be efficiently vaporized / heated in a thin liquid layer mixed with silicon carbide. Applications: wood glue, chipboard, adhesives, plant construction, fuel evaporation, injection systems, recycling.

Description

It is known that silicon carbide, as a strongly polarizing dielectric, absorbs almost 100% of microwaves. It is also known that silicon carbide has extremely good thermal conductivity. Furthermore, it is known that the penetration depth of the microwave radiation in silicon carbide is about 0.7 mm. These properties are used, for example: as a reactor wall for chemical processes. Which corresponds to a two-dimensional heat transfer of the consisting of silicon carbide reactor wall. However, it is not known that when silicon carbide is mixed with other solids / liquids / gases or mixtures of these substance groups, ie there is a three-dimensional distribution of the silicon carbide in this mixture, an increase in temperature uptake upon exposure to microwaves (wavelengths 300 MHz to 300 GHz) done in these materials. In short: The silicon carbide contained in the material layers absorbs almost 100% of the microwave radiation, converts this radiation energy directly into heat and immediately returns it to its surroundings. Thus, the whole microwave energy is absorbed directly in the material layer (three-dimensional) and converted into heat. This means that even materials with a low dipole constant or microwave permeable material in joints / layers can be heated / melted / evaporated / ashed. Furthermore, microwave transparent or low microwave absorption rate, for example: high boiler liquids, can be efficiently vaporized / heated in a thin liquid layer mixed with silicon carbide. (Plant construction, fuel evaporation, injection systems).

Information about the technical and economic potential

Example 1 Gluing of Schichthölzem

Several layers of Holzbrettem be used with adhesive, here a wood glue based on a melamine-formaldehyde condensate, thermoset with reduced hardener system, coated / glued and pressed. Thereafter, the glued laminated timber was irradiated for 75 seconds of microwave radiation (2.45 GHz household microwave 900 watts). The finished hardened wooden board (dimensions: 5 layers of OSB boards 20 mm thick and 100 long and 100 mm wide or different material: 5 boards of unbreakable wood) was taken from the microwave.
Annotation:
At irradiation time of> 180 sec., The glue joints and parts of the adjacent wood were burned by the heat transfer of silicon carbide. By this method, for example, entire ceiling panels in timber house construction in a manufacturing process, be manufactured in a small amount of time.

Example 2 Production of wood / press clamping plates

Wood span or several types of wood chips are sprayed with wood glue based on urea / formaldehyde / harder, which has been treated with silicon carbide (> 0.001% silicon carbide content in wood glue), pressed into a household microwave oven (2.54 GHz and 900 watts) for 75 sec. Power) irradiated. The finished chipboard was then tested for application.
Technical benefits
Production of clamping plates thicker 50 mm possible, bent clamping plates, tubes made of wood span are machinable. Low technical investment due to direct heat input.

Example 3 Production / Bonding / Bonding of Material Associations

• • zwischen zwei Lagen Buchenholz wurde eine Lage Glasfaser, welche mit Holzleim/Härter und Siliciumcarbid getränkt ist, eingefügt verpresst und mit Mikrowellen (2,45 GHz, 900 Watt-Leistung) > 45 sec. bestrahlt. Danach wurde der Verbund der Mikrowelle entnommen. Einsatzgebiete > z. B: verstärkte Holzbauten, Brandschutz.
• • Mehrlagige Verbünde mit verschieden Material und Verbindungsschichten Eine Lage Holz, eine Lage Glasfser mit Holzleim, danach eine Holz eine Lage Epoxidkleber mit Siliciumcarbid dotiert, danach als Endlage eine Aluminiumschicht. Die Betrahlung erfolgt in der Mikrowelle, Zeitdauer und Mikrowellenfrequenz, sowie Mikrowellenleistung können je nach Verbund variabel sein. Anmerkung: Metalle reflektieren Mikrowellen, daher wurde dieser Verbund von der Holzschichtseite bestrahlt.

The following material dressings were produced in microwave irradiation as:

• • Between two layers of beech wood, a layer of glass fiber impregnated with wood glue / hardener and silicon carbide was pressed in and irradiated with microwaves (2.45 GHz, 900 watt power)> 45 sec. Thereafter, the composite was removed from the microwave. Applications> z. B: reinforced wooden structures, fire protection.
• • Multilayer composites with different material and bonding layers One layer of wood, one layer of glass fiber with wood glue, then one layer of wood Epoxy adhesive doped with silicon carbide, then an aluminum layer as end position. The irradiation takes place in the microwave, duration and microwave frequency, as well as microwave power can be variable depending on the composite. Note: Metals reflect microwaves, therefore this composite was irradiated from the wood layer side.

The material layers and their connecting layers are arbitrarily variable and are pressed in one irradiation cycle (several are possible) and then further processed. If these composites are produced in a microwave-permeable form, molded parts are also possible.

Example 4 Melting / heating of materials which are not or only slightly heated by microwave radiation (eg: polypropylene)

Powders or molten materials that absorb only low levels of microwaves may be melted by the addition of silicon car- den under microwave radiation. Example: it became polypropylene in an electric oven melted and mixed with> 0.0001% silicon carbide the melt was cooled. Thereafter, the not or only slightly heatable by microwave material for microwave radiation is heated, melted. Technical application in spray heads possible example in 3 D pressure, injection molding.

Example 5 Thin-film heating for the distillation of liquids

The evaporator section of a distillation column (various column separation types possible) has a heating floor (fillable tub) which has been irradiated by a microwave conductor which has a heat-resistant, microwave radiation-permeable window (for example glass) at the exit of the conductor. In this tub 8Verdampfererteil) is in the liquid to be distilled, the silicon carbide, three-dimensionally distributed, entwerden doped in the form of a floating in Destillait powder / granules / fibers or consists entirely of silicon carbide. or as spatially distributed silicon carbide in the form of a foam (doped with silicon carbide or silicon carbide foam) or a distillate-containing fabric which is dope-doped or entirely composed of silicon carbide. By irradiation, the liquid to be distilled is evaporated.

Laboratory Example:

Two samples of 100 g of distilled water are placed in a microwave (2.45 GHz, 900 watt power). One of the two samples is mixed with silicon carbide powder and the silicon carbide (> 1%) dispersed by stirring spatially (3D) in the water. Thereafter, both samples are simultaneously, 90 sec. Long, irradiated with the microwave. The sample without addition of silicon carbide did not come to the distillation and had after the irradiation a temperature of 67.5 ° C. The silicon carbide addition sample began to boil at the surface after 60 seconds. And has a temperature of 62 ° C after the end of the irradiation. In addition,> 2 g of water were evaporated. The reduced temperature compared to the sample without silicon carbide addition corresponds to the required evaporation energy of the water.

Conclusion:

Due to the three-dimensionally distributed addition of silicon in the liquid, evaporation already took place at the surface of the sample. (Total absorption of microwave energy by the silicon carbide and conversion to heat in a thin liquid layer on the sample surface). Advantages of the method. low hold up, distillation of liquids without / low dipole possible. lower Emergency weight of the column. Simple construction of Pressure columns. Higher security (microwave from no evaporation) etc

Example 6 Evaporation of Fuels for Gas Injections in Engines

The principle used in Example 5 can also be used to vaporize fuels. Here, the liquid to be evaporated, not separated / distilled as in Example 4, but the resulting gas is fed to a gas injection. The evaporator consists of a vessel (possibly pressure vessel) which has been provided with a microwave magnetron (waveguide with microwave-permeable window (eg: ceramic window / glass window).) Inlet and if necessary drain for the liquid to be evaporated, and a steam outlet for gas injection (if necessary Combi unit, gas, liquid injection).
In the pressure vessel, the silicon carbide is in dreidimesional distributed form.
as powder / granules or / and
as a fabric consisting of silicon carbide or doped with silicon carbide
or and
as an open-pore foam consisting of silicon carbide or doped with silicon carbide
The evaporator power or the Gaseinspitzstäuerung and or the operating pressure of the steam could be done via the timing of the microwave radiation

Example 7 Melting of splices doped with silicon carbide

Melt adhesives can be doped with silicon carbide, then materials of the prior art are adhered. Later, these spots can be remelted by precise microwave irradiation, possibly after which they are melt-glued again. Applications: repair of bonded components or recykling of bonded material.

Example 8 Heating of gases

Gas or gas mixtures are passed through a three-dimensionally distributed layer of fine-grained silicon carbide and / or one with silicon carbide coated carrier material and heated by irradiation of microwaves. The three-dimensional distribution can be carried out as a fluidized bed or in the form of random packings.

• 1 Das eine dreidimensionale Verteilung des Siliciumcarbid in dem zu erhitzenden Material/Materialien und oder Materialschicht/Materialschichten vorliegt. Der Agregatzustand des zu erwärmenden Material bzw. der Materialschicht kann flüssig, fest, gasförmig sein oder aus einer Mischungen der Agregatzustände bestehen.
• 2 Das Siliciumcarbid kann in den zu erwärmenden Materialen als Pulver auch in nano Verteilung, Granulat, dotiertem oder aus reinem Siliciumcarbid bestehendem offenporigen Schaum und oder als aus dotiertem oder reinem Siliciumcarbid beschaffenen Gewebe bestehen. Das Trägermaterial des dreidimensional verteilten Siliciumcarbid kann je nach Anwendung variabel sein.
• 3 das unter zu mischende Siliciumcarbid kann auch Reinheitsgrade unter 90 Gew.-% besitzen
• 4 das verwendete Siliciumcarbid muß keine vorgegebene Kristallgitterstruktur vorweisen.

The invention is characterized by

• 1 There is a three-dimensional distribution of the silicon carbide in the material / materials to be heated and / or material layer / material layers. The Agregatzustand of the material to be heated or the material layer may be liquid, solid, gaseous or consist of a mixture of Agregatzustände.
• The silicon carbide may also be present in the materials to be heated as a powder in nano distribution, granules, doped or pure silicon carbide open-pore foam, or as a fabric made of doped or pure silicon carbide. The support material of the three-dimensionally distributed silicon carbide can be variable depending on the application.
• 3, the silicon carbide to be mixed under can also have degrees of purity below 90% by weight
• 4 the silicon carbide used does not have to have a given crystal lattice structure.

Documents to be considered for the assessment

• Excerpt from a technical information search Patent Information Office PIZ-Kaiserslautern dated 24.01.2013

auditor classifications B01J 19/12 .. Application of electromagnetic waves C04B 35/64 .. burning or sintering process F27D 11/12 , Heating by acting directly on the material to be heated electromagnetic fields

1. Directly applicable documents

No directly applicable documents were determined.

2. Touching documents

• DE 102005018323 DE 19859292 DE 69720960 DE 4136416 DE 3936267 US 20060096977 US 5911941 US 5019680 WO 200000311

3. Technical background

• DE 102005049533 DE 69510541 DE 19648366 DE 4324606 DE 3737148 DE 3611141 US 4822966 US 4687895 US 4307277

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005018323 [0016]
• DE 19859292 [0016]
• DE 69720960 [0016]
• DE 4136416 [0016]
• DE 3936267 [0016]
• US 20060096977 [0016]
• US 5911941 [0016]
• US 5019680 [0016]
• WO 200000311 [0016]
• DE 102005049533 [0017]
• DE 69510541 [0017]
• DE 19648366 [0017]
• DE 4324606 [0017]
• DE 3737148 [0017]
• DE 3611141 [0017]
• US 4822966 [0017]
• US 4687895 [0017]
• US 4307277 [0017]

Claims (1)

The invention is characterized by 1 There is a three-dimensional distribution of the silicon carbide in the material / materials to be heated and / or material layer / material layers. The Agregatzustand of the material to be heated or the material layer may be liquid, solid, gaseous or consist of a mixture of Agregatzustände. The silicon carbide may also be present in the materials to be heated as a powder in nano distribution, granules, doped or pure silicon carbide open-pore foam, or as a fabric made of doped or pure silicon carbide. The support material of the three-dimensionally distributed silicon carbide can be variable depending on the application. 3, the silicon carbide to be mixed under can also have degrees of purity below 90% by weight 4 the silicon carbide used does not have to have a given crystal lattice structure.