CN104902603B - A kind of method and device of quick heating Al2O3 - Google Patents

Abstract

_The invention relates to a method and device for rapidly heating _Al2O3 . Al ₂ O ₃ is a substance that absorbs microwaves weakly. When the temperature is lower than 800°C, the heating rate of the method and device using microwave direct heating is very slow, but when the temperature is higher than 800°C, it becomes easy to absorb microwaves, and microwaves can be directly heated. According to This feature of Al ₂ O ₃ , the method and device of the present invention are characterized in that there is an auxiliary electric field generating circuit and an intelligent temperature control circuit, the auxiliary electric field generating circuit is composed of an auxiliary electric field control circuit and positive and negative metal electrode plates, and the intelligent temperature control The circuit is composed of a temperature measuring device and an intelligent switch. The auxiliary electric field generation circuit generates an auxiliary electric field in the microwave energy applicator through the positive and negative metal electrode plates, which plays the role of polarizing Al ₂ O ₃ molecules, and the electric dipole moment of the polarized Al ₂ O ₃ molecules increases, which can It is rapidly heated by the microwave generated by the microwave generator, and the temperature measuring device monitors the temperature of Al ₂ O ₃ in the microwave energy applicator in real time. When the temperature is higher than 800°C, the intelligent switch automatically turns off the auxiliary electric field. The invention can directly and rapidly heat Al ₂ O ₃ , and is energy-saving and environment-friendly.

Description

A method and device for rapidly heating Al2O3

technical field

_The invention relates to a method and device for rapidly heating _Al2O3 , belonging to the field of microwave heating.

Background technique

Microwave heating is a new heating method, which has the advantages of internal heating, fast heating, clean and hygienic, easy automatic control, and energy saving. However, due to the selective heating characteristics of microwave, the heating speed of weak absorbing substances is slow, which limits the heating treatment of these substances by microwave technology.

Al ₂ O ₃ is a material that absorbs microwaves weakly. When it is heated with microwaves at a certain power for 4.5 minutes, the temperature only rises to 78°C. However, Fe ₃ O ₄ , a material that absorbs microwaves strongly, is only heated for 2.75 minutes with microwaves. up to 1258°C [1]. Therefore, in the microwave industry, only the auxiliary heating method can be used for Al ₂ O ₃ at present.

There are five auxiliary heating methods commonly used in industry [1]:

1. Add strong microwave-absorbing substances: WHSutton et al. added Fe ₃ O ₄ , a strong microwave-absorbing substance, to Al ₂ O ₃ , a weakly absorbing microwave substance, so that Al ₂ O ₃ with Fe ₃ O ₄ can be significantly absorbed Microwave. Use 6KW microwave power to heat pure Al ₂ O ₃ material, the temperature of Al ₂ O ₃ is about 100°C after 10 minutes; heat the mixture of 10% Fe ₃ O ₄ +90% Al ₂ O ₃ , the temperature of the mixture is about 200°C after 10 minutes °C; the mixture of 50% Fe ₃ O ₄ +50% Al ₂ O ₃ is heated, and the temperature of the mixture exceeds 600 °C after 6 minutes.

2. Picket fence method: Janney et al. and Smith et al. used the Picket fence method for microwave-assisted heating of zirconia. The sintered zirconia was wrapped with zirconia fiber insulation material, and silicon carbide rods were arranged around it. At low temperature, silicon carbide absorbs the main microwave energy and transfers heat to zirconia. When the temperature reaches a certain critical point, zirconia begins to absorb heat and is easily heated by microwaves to the required sintering temperature. This method basically eliminates local overheating Phenomenon.

3. Microwave absorber lined with silicon carbide: This method was designed by Clark of Florida State University in the United States. When microwave heating is performed, the microwave absorber lined with silicon carbide is placed on the weak absorbing sample. It is a strong microwave-absorbing substance, which can quickly absorb microwave energy and then transfer heat to the sample to be heated through heat conduction. This method can also be used to heat Al2O3.

4. Patterson method: a microwave-assisted heating and sintering method of silicon nitride invented by Patterson et al. They regularly inserted 90 knives made of silicon nitride into an alumina crucible, which was filled with a mixture of silicon carbide, boron nitride and silicon nitride. These powders were used to support the knives, and microwave heating In the initial stage, it can be used as a strong absorbing material to heat silicon nitride, and it can also prevent silicon nitride from reacting with the surrounding environment, and at the same time play a role of heat preservation.

5. Adjustable microwave coupling window for single-mode cavity: Shi Jianlin, Shanghai Institute of Ceramics, Chinese Academy of Sciences, etc. used adjustable microwave coupling window in single-mode cavity, and adjusted microwave output power, short-circuit piston, etc. to maintain cavity Internal resonance and optimal coupling conditions, so as to keep the sample heating up at a certain rate and reach a stable final temperature.

As can be seen from the above description, the disadvantages of using microwave-assisted heating: 1. The process is relatively complicated; 2. The energy loss is large, and it is necessary to do useless work to heat the strong absorbing material, which is not energy-saving enough; 3. The weak absorbing material is easily separated from the Strong absorbing substances are mixed, and new impurities may be generated.

There are many variants of Al ₂ O ₃ , which belong to the transition type compound, which is mainly ionic compound, and contains some covalent type. In the microwave-assisted heating method, we found that Al ₂ O ₃ is a weak absorbing substance, but when the temperature of Al ₂ O ₃ is higher than 800°C, it begins to absorb microwaves easily and can be directly heated by microwaves[ 1].

references:

[1] Peng Jinhui, Liu Bingguo. Microwave calcination technology and its application [M]. 2013:106-111.

Contents of the invention

The technical problem to be solved in the present invention is to overcome the shortcomings of the microwave-assisted heating of Al ₂ O ₃ , and to be able to rapidly heat Al ₂ O ₃ , combined with the microwave heating characteristics of Al ₂ O ₃ , the present invention starts from the microstructure of the substance, Using the dielectric polarization principle and microwave heating mechanism, a method and device for heating Al ₂ O ₃ rapidly, directly, and energy-saving are provided.

_The technical solution of the present invention is: a method for rapidly heating _Al2O3 , characterized in that it comprises the following steps:

_{The Al2O3} material is placed in the microwave energy applicator of the microwave heating device; after power-on, an auxiliary electric field is provided in the microwave energy applicator for polarizing the molecules of _{Al2O3 ;} after that, the magnetron The microwave is emitted, and the microwave energy applicator is introduced through the waveguide to act on the polarized Al ₂ O ₃ molecules to heat the Al ₂ O ₃ .

During the heating process, the auxiliary electric field is always turned on to continuously polarize the Al ₂ O ₃ molecules, until the Al ₂ O ₃ reaches the specified temperature, the auxiliary electric field is turned off.

The specified temperature is 800°C.

The auxiliary electric field generated by the auxiliary electric field generating circuit is a steady electric field.

The electric field strength of the auxiliary electric field is between 0.5 and 0.6 times of the maximum electric field strength of the microwave field generated by the magnetron.

_A device for rapidly heating _Al2O3 , comprising a main control circuit, a transformer circuit, a magnetron, a waveguide and a microwave energy applicator, characterized in that it also includes: an auxiliary electric field generating circuit; the auxiliary electric field generating circuit includes The auxiliary electric field control circuit and the positive and negative metal electrode plates are used to generate an auxiliary electric field in the microwave energy applicator to polarize the molecules of the material.

The device also includes an intelligent temperature control circuit for intelligently controlling the on and off of the auxiliary electric field according to the temperature; the intelligent temperature control circuit includes a temperature measuring device and a switch; the temperature measuring device measures and controls the microwave energy in real time The temperature of Al ₂ O ₃ in the applicator is fed back to the intelligent temperature control circuit, and the intelligent temperature control circuit controls the on-off of the auxiliary electric field through the switch.

The auxiliary electric field generated by the auxiliary electric field generating circuit is a steady electric field; the electric field strength of the auxiliary electric field is between 0.5 times and 0.6 times of the maximum electric field strength of the microwave field generated by the magnetron.

The positive and negative metal electrode plates of the auxiliary electric field generating circuit are symmetrically placed on the two opposite sides of the microwave energy applicator, close to the inner surface of the microwave energy applicator; the metal electrode plates are close to but not in contact with the cavity of the microwave energy applicator, and Insulating ceramics are filled between the metal electrode plate and the inner cavity of the microwave energy applicator, and the positive and negative metal electrode plates are isolated from the inner surface of the microwave energy applicator by insulating ceramics with a thickness not exceeding 2.5mm.

The positive and negative metal electrode plates of the auxiliary electric field generating circuit are stainless steel electrode plates with a thickness between 6 mm and 12 mm. The higher the temperature, the larger the volume of the microwave energy applicator, and the thicker the positive and negative metal electrode plates.

The beneficial effects of the present invention are:

The auxiliary electric field generation circuit controls the voltage in the circuit through the auxiliary electric field control circuit, and emits an auxiliary electric field in the microwave energy applicator through the positive and negative metal electrode plates. The function of the auxiliary electric field is to make the microwave energy applicator The Al ₂ O ₃ is polarized. Al ₂ O ₃ is a kind of weak absorbing substance, and its molecular electric dipole moment is small. Put it into a microwave energy applicator, and the auxiliary electric field will cause it to undergo electron displacement polarization, ion displacement polarization, and ion relaxation polarization. and space charge polarization, the total polarization is the synthesis of these four polarizations. _The electric dipole moment of the molecule increases after polarization, which is ready for the rapid heating of _Al2O3 by microwaves.

According to the mechanism of microwave heating and the absorbing characteristics of materials, Al ₂ O ₃ with increased electric dipole moment can obtain a larger combined electric field force and larger moment under the irradiation of microwave field, and the collision between molecules , extrusion, and friction increase, and the efficiency of converting microwave energy into heat energy is further improved, that is, the microwave heating speed is increased.

According to the microwave-absorbing characteristics of Al ₂ O ₃ , when its temperature exceeds 800°C, Al ₂ O ₃ begins to absorb microwaves easily, and no auxiliary heating method is needed, and the auxiliary electric field contributes little to the heating at this time. In order to save energy, the temperature measuring device of the present invention measures and controls the temperature of Al ₂ O ₃ in real time, and feeds back the temperature data to the intelligent temperature control circuit. If the measured temperature of Al ₂ O ₃ is lower than 800°C, the intelligent temperature measuring circuit closes the switch , the auxiliary electric field is turned on, if the measured temperature of Al2O3 is higher than 800°C, the intelligent temperature measurement circuit will turn off the switch, and the auxiliary electric field will be turned off, so as to achieve the effect of energy saving and environmental protection.

_In summary, the method and device of the present invention heat _Al2O3 under the joint action of the auxiliary electric field generated by the auxiliary electric field generating circuit and the microwave field generated by the magnetron, and the auxiliary electric field mainly plays a role in polarization. It is used to increase the electric dipole moment of Al ₂ O ₃ molecules. The microwave electric field plays a heating role. The two fields work together. Al ₂ O ₃ can quickly absorb microwave energy and convert it into its own heat energy, and the temperature increases rapidly. At the same time, the intelligent temperature control circuit monitors the temperature of Al ₂ O ₃ in real time, and uses the temperature rise characteristics of Al ₂ O ₃ to control the on-off of the auxiliary electric field. The microwave device can quickly heat Al ₂ O ₃ which cannot be heated quickly by conventional microwave devices, and avoids the disadvantages of complex devices, large energy loss, and possible introduction of new impurities in the conventional auxiliary heating process, and has the advantages of simple operation, energy saving, and high degree of intelligence. characteristics, and can expand the industrial application of microwave heating Al ₂ O ₃ at the same time.

Description of drawings

The temperature rise curve figure of the alumina in the crucible of Fig. 1 in the microwave field;

The flowchart of Fig. 2 method of the present invention;

The block diagram of the circuit principle of the embodiment of the present invention of Fig. 3;

FIG. 4 is a schematic diagram of the installation of the auxiliary electric field metal electrode plate and the temperature measuring device 7 of the microwave oven according to the embodiment of the present invention.

In the figure: 200-microwave device for rapidly heating Al ₂ O ₃ , 201-main display window, 202-control panel, 203-heated Al ₂ O ₃ , 204-positive and negative metal electrode plates, 205-insulating ceramics, 206 - Temperature measuring device.

detailed description

The present invention will be further described below in combination with the accompanying drawings and specific embodiments.

Firstly, starting from the microstructure of matter, the microwave absorption characteristics of different molecules and the principle of microwave heating are described. In the microwave field, dielectrics can generally be divided into non-polar dielectrics, weakly polar dielectrics, and polar dielectrics with large electric dipole moments. The non-polar dielectric is composed of non-polar molecules. When there is no electric field, the molecules or atoms that make up the dielectric, in which the center of the positive charge of the nucleus coincides with the center of the negative charge of the electrons distributed around the nucleus, and is neutral to the outside. Because there is no electric dipole moment, the electric field in the microwave field can not produce a resultant external force and moment when it acts on it, and the molecules will not squeeze, rub, rotate and vibrate, so they do not absorb microwave energy. We call it difficult to absorb waves or Non-absorbing substances. The weakly polar dielectric is composed of polar molecules with a small electric dipole moment. When there is no external electric field, the positive and negative centers of the molecules or atoms that make up the dielectric do not coincide, that is, the electric dipole moment of the molecule is small. In the microwave field When the electric field acts on it, it can only produce a small combined external force and moment, and the molecular extrusion, friction, rotation and vibration are relatively small, so it can absorb a small amount of microwave energy and convert it into its own heat energy. When heated in a microwave field The heating rate is very slow, we call this kind of material weak absorbing material, such as Al ₂ O ₃ . Due to the large electric dipole moment, polar molecules with large electric dipole moment can quickly dissipate microwave energy in the microwave field, and the temperature rises quickly in the microwave field. We call it easy-to-absorb material. Such as Fe ₃ O ₄ . Therefore, the electric dipole moment can be used as a parameter to judge whether the microwave absorbs rapidly.

Based on the above principles, the method of the present invention is to increase the distance between the equivalent positive and negative charges of the substance molecules, that is, to increase the electric dipole moment.

According to the principle of dielectric polarization and the material properties of Al ₂ O ₃ , Al ₂ O ₃ is a weak absorbing substance, and the electric dipole moment of the molecule is small. If it is placed in an electric field, it will have the following Form of polarization: 1. Electronic displacement polarization: the relative displacement of positive and negative charge centers in each molecule or atom; 2. Ion displacement polarization: positive and negative ions produce relative displacement, positive ions move along the direction of the electric field, and negative ions move against The direction of the electric field moves, this type of polarization is only positive for ionic compounds, and Al ₂ O ₃ is a transitional compound, which is mainly ionic compounds, but contains some covalent compounds, so ion displacement polarization will also occur; 3. Ion relaxation polarization: This polarization occurs in a medium composed of ions or containing ionic impurities. It is caused by some weakly connected ions in the dielectric, which are caused by the transition movement along the direction of the electric field under the action of an electric field; 4 1. Space charge polarization: under the action of an electric field, the chaotically arranged positive and negative free charges tend to move towards regularity, resulting in the accumulation of more negative charges near the positive plate and the redistribution of space charges. , which actually forms the space charge polarization of the medium. It occurs in heterogeneous media and crystals with defects. For the actual Al ₂ O ₃ crystal media, the internal free charges move under the action of an electric field, which may be eliminated by the unavoidable defects in the crystal (such as lattice vacancies , impurity centers, dislocations, etc.) are captured and accumulated to cause local accumulation of charges, which makes the charge distribution uneven, thereby causing polarization. Most of the Al ₂ O ₃ used in engineering is uneven and defective. The total polarization is the vector sum of the above polarizations. The distance between the equivalent positive and negative charges of the polarized Al ₂ O ₃ molecules increases, and the electric dipole moment increases. This is a must for rapid and direct heating _{of Al2O3} by microwaves.

Then introduce the heating characteristics of microwave heating Al ₂ O ₃ . Figure 1 shows the temperature rise characteristic curve of Al ₂ O ₃ collected in our laboratory. Al ₂ O ₃ is placed in a crucible and heated in a microwave device with a certain power. The abscissa represents the time in minutes, and the ordinate _The coordinates represent the temperature of _Al2O3 in degrees Celsius. Although the crucible is used for auxiliary heating, we can see that in the first 22 minutes of heating, the temperature of Al ₂ O ₃ rises from room temperature to about 400°C, and the temperature rise rate is relatively slow, indicating that Al ₂ O ₃ completely depends on the heat transfer of the crucible ; From the 22nd to 30th minute, the temperature of Al ₂ O ₃ rose from about 400°C to about 800°C, and the temperature rise rate in this range was relatively fast, indicating that Al ₂ O ₃ not only relied on the heat transfer of the crucible, but also gradually absorbed the wave absorbing ability of Al 2 O 3 From 30 minutes to 33 minutes, the temperature of Al ₂ O ₃ increased from about 800°C to about 1200°C. The temperature rise rate in this range was very fast, indicating that Al ₂ O ₃ became easy to absorb microwaves. Therefore, 800°C is the cut-off point for Al ₂ O ₃ to absorb waves easily, which is consistent with what was reported in literature [1].

Introduce the concrete implementation process of the present invention at last:

As shown in Figure 2, it is a flowchart of the method of the present invention. Include the following steps:

_{The Al2O3} material is placed in the microwave energy applicator of the microwave heating device;

After electrification, an auxiliary electric field is provided in the microwave energy applicator for polarizing _Al2O3 molecules _;

Afterwards, the magnetron emits microwaves, which are introduced into the microwave energy applicator through the waveguide to act on the polarized Al ₂ O ₃ molecules to heat the Al ₂ O ₃ .

During the heating process, the auxiliary electric field is always turned on to continuously polarize the Al ₂ O ₃ molecules, until the Al ₂ O ₃ reaches the specified temperature, the auxiliary electric field is turned off.

The specified temperature is 800°C. After the Al ₂ O ₃ reaches 800°C, the auxiliary electric field is turned off, but the magnetron continues to work, and the Al ₂ O ₃ continues to be heated until it reaches the expected temperature.

The auxiliary electric field generated by the auxiliary electric field generating circuit is a steady electric field.

The electric field strength of the auxiliary electric field is between 0.5 and 0.6 times of the maximum electric field strength of the microwave field generated by the magnetron.

As shown in Fig. ₃ , it is a kind of circuit schematic block diagram of the microwave device that can be used for directly heating _Al2O3 of the present invention, specifically includes:

Main control circuit 1, transformer circuit 2, magnetron 3, waveguide 4, microwave energy applicator 9, auxiliary electric field generation circuit 5 and intelligent temperature control circuit 6. The auxiliary electric field generating circuit ₅ is used to generate an auxiliary electric field in the microwave energy applicator, and the heated _Al2O3 material in the microwave energy applicator can be rapidly heated under the joint action of the auxiliary electric field and the microwave field generated by the magnetron 3 , while the intelligent temperature control circuit 6 is used to control the on-off of the auxiliary electric field according to the temperature.

The auxiliary electric field generating circuit 5 includes: an auxiliary electric field control circuit and positive and negative metal electrode plates. The auxiliary electric field generated by the auxiliary electric field generating circuit 5 is a steady electric field.

The auxiliary electric field control circuit of the auxiliary electric field generation circuit 5 is also used to control the intensity of the auxiliary electric field to be smaller than the electric field intensity of the microwave field generated by the magnetron.

The field strength of the auxiliary electric field is between 0.5 and 0.6 times the maximum value of the microwave electric field. If the field strength of the auxiliary electric field is too small, the polarization effect on the weak polar molecules is insufficient, and it is difficult to significantly increase the electric dipole moment of the molecules; if the strength of the auxiliary electric field is too large, the microwave heating time in a single microwave cycle is insufficient. According to the molecular characteristics and polarization type of Al ₂ O ₃ , the magnification is selected between 0.5 and 0.6.

The positive and negative metal electrode plates of the auxiliary electric field generating circuit 5 are symmetrically placed on two opposite sides of the microwave energy applicator 9 , close to the inner surface of the microwave energy applicator 9 .

The positive and negative metal electrode plates are close to but not in contact with the cavity of the microwave energy applicator 9, and insulating ceramics are filled between the metal electrode plates and the microwave energy applicator 9, in order to prevent a small part of the microwave from going out from the insulating ceramics. The positive and negative metal electrode plates are separated from the surface of the microwave energy applicator 9 by insulating ceramics with a thickness of no more than 2.5mm.

The positive and negative metal electrode plates of the auxiliary electric field generating circuit 5 are stainless steel electrode plates. In order to ensure that it can reflect microwaves at high temperatures, the thickness is between 6 mm and 12 mm. The higher the temperature, the larger the volume of the microwave energy applicator. The thickness of the positive and negative metal electrode plates is thicker.

The cavity of the microwave energy applicator 9 is grounded.

The intelligent temperature control circuit 6 includes: a temperature measuring device 7 and a switch 8 . The temperature measuring device 7 extends from the top of the microwave device of the present invention into the cavity of the microwave energy applicator 9, and the switch 8 is used to control the on-off of the auxiliary electric field generating circuit 5.

The temperature measuring device 7 measures and controls the temperature of _Al2O3 in the microwave energy applicator ₉ in real time, and feeds back the temperature data to the intelligent temperature control circuit 6, and the intelligent temperature control circuit 6 controls the switching of the auxiliary electric field generating circuit 5 through the switch 8. broken.

When the temperature measuring device ₇ measures that the temperature of _Al2O3 in the microwave energy applicator 9 is lower than 800°C, the switch 8 is closed, the auxiliary electric field generating circuit 5 works, and there is an auxiliary electric field in the microwave energy applicator 9; When the temperature measuring device 7 detects that the temperature of Al ₂ O ₃ in the microwave energy applicator 9 is higher than 800° C., the switch 8 is turned off, and the auxiliary electric field generating circuit 5 stops working.

The 220V, 50Hz alternating current flows into the microwave oven through the socket, first passes through the main control circuit 1, and supplies it to the microprocessor, timing and power regulator, turntable circuit, lighting circuit, fan, main display window, etc. (non-core components, not shown in the figure) shown), then flows through the primary coil of the transformer and returns to the socket. The transformer circuit 2 divides the 220V, 50Hz alternating current into three parts. The first part is the auxiliary electric field generating circuit 5. The constant voltage emits an auxiliary electric field in the microwave energy applicator 9 through the positive and negative metal electrode plates; the second part of the commercial power is transformed into an alternating current of about 4V and applied to the cathode of the magnetron 3 to heat the filament of the magnetron 3 , so that the cathode can emit electrons; the third part of the mains is boosted again to a high voltage of about 4000V through high-voltage transformation, and after rectification, it is loaded on the anode of the magnetron 3, which is used to receive electrons. Under the joint action of the second part of the input and the third part of the input, after the hot electrons overflow from the cathode, under the combined action of the magnetic field force and the electric field force, they fly to the anode at high speed in a spiral shape, and also have the function of a resonant cavity, and the electrons oscillate into The microwave is finally input into the microwave energy applicator through the waveguide 4 . The heated Al ₂ O ₃ is placed in the microwave energy applicator, and under the double action of the microwave field generated by the magnetron 3 and the auxiliary electric field generated by the auxiliary electric field generating circuit 5, the microwave energy is quickly absorbed and turned into itself heat energy, the temperature rises rapidly. Considering the microwave heating characteristics of _Al2O3 , the present invention extends and installs a temperature measuring device ₇ (such as a thermocouple _{) on} the top of the microwave device to monitor the temperature of _Al2O3 in real time, according to the temperature of _Al2O3 The data controls the on-off of the auxiliary electric field generating circuit 5 through the switch, so as to realize the purpose of energy saving.

As shown in FIG. 4 , a schematic diagram of the installation of the positive and negative metal electrode plates and the temperature measuring device 7 of the microwave device according to the embodiment of the present invention. The microwave device 200; the main display window 201 is located in the upper right corner, which can display the temperature of Al ₂ O ₃ , heating time, power, heating mode, etc.; the control panel 202 is located in the lower right side, connected with the main control circuit, and can adjust the heating power, Heating mode, etc.; the heated Al ₂ O ₃ material 203 is placed in the middle of the microwave energy applicator, which is a weak absorbing material; the positive and negative metal electrode plates are marked as 204, and the constant voltage is emitted into the microwave cavity through it. The inner cavity of the microwave cavity and the positive and negative metal electrode plates are filled with insulating ceramics 205, and the temperature measuring device 7 is marked as 206, which extends from the top of the microwave device of the present invention and is used for real _- time monitoring of the surface of _Al2O3 temperature.

When the microwave oven is powered on, Al ₂ O ₃ is in a double _- field environment (auxiliary electric field and microwave field ₎ . Space charge polarization, etc. After polarization, the distance between the equivalent positive and negative charges of Al ₂ O ₃ molecules increases, and the electric dipole moment increases, which is a necessary condition for rapid heating of Al ₂ O ₃ in a microwave oven. The role of the microwave field is heating. When the microwave electric field acts on the polarized Al ₂ O ₃ material, the molecules constituting the Al ₂ O ₃ are subject to a greater resultant electric field force and a greater moment, and these resultant forces and moments will provide more Large extrusion force, rotational power and rotational inertia, and when the direction of the microwave electric field changes billions of times per second, the friction, extrusion and collision between the molecules in the polarized load are more intense, and the microwave energy conversion In order to further increase the efficiency of thermal energy, the heating rate of the load is increased. At the same time, considering that Al2O3 becomes easy to absorb waves when the temperature exceeds 800°C, the auxiliary electric field will no longer function and will only consume more electric energy. Therefore, the intelligent temperature control circuit 6 is used to control the on-off of the auxiliary electric field generation circuit to achieve energy saving and environmental protection. Effect.

The positive and negative metal electrode plates of the auxiliary electric field generating circuit 5 can not only generate a steady electric field, play the role of polarized molecules, but also reflect microwaves like a microwave cavity.

The auxiliary electric field generated by the auxiliary electric field generating circuit is a steady electric field, which acts on the heated substance together with the microwave electric field generated by the magnetron, and works synchronously without interfering with each other.

When the microwave field acts on these polarized Al ₂ O ₃ substances, when the angle between the auxiliary electric field vector generated by the auxiliary electric field generating circuit and the microwave electric field vector is 0, the auxiliary electric field does not contribute to the heating of the microwave electric field, but The direction of the microwave field changes hundreds of millions of times per second, so this state exists for a very short time and does not have much impact on the heating of the microwave oven, which can be ignored.

The temperature measuring device 7 is a common temperature measuring element in the market.

Therefore, the microwave device in the present invention can not only overcome the shortcomings of the traditional auxiliary heating Al ₂ O ₃ technology, but also can directly and rapidly heat the Al ₂ O ₃ load, and can also play a role in energy saving.

It can be understood that the changes made to the auxiliary electric field generating circuit and the intelligent temperature measuring circuit, such as the auxiliary electric field power supply circuit mechanism and the size, shape, and position of the positive and negative metal electrode plates, temperature measuring devices, switches, etc., should all belong to the present invention The scope of the claims.

The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Variations.

Claims (9)

1. a kind of quick heating Al₂O₃Method it is characterised in that：Comprise the following steps：

By Al₂O₃Material be placed in the Pulse width device of microwave heating equipment；

After energising, provide an auxiliary electric field in described Pulse width device, for the Al that polarizes₂O₃Molecule；

Afterwards, magnetron microwave, by waveguide import Pulse width device, act on polarized after material molecule, with Heated material；

In heating process, always on auxiliary electric field, persistently polarize material molecule, until after material reaches the temperature specified, Auxiliary electric field is closed.

2. quick heating Al according to claim 1₂O₃Method it is characterised in that：Described assigned temperature is not less than 800 ℃.

3. quick heating Al according to claim 1 and 2₂O₃Method it is characterised in that：Described auxiliary electric field is steady Sustained field.

4. according to the quick heating Al described in claim 1,2 any one₂O₃Method it is characterised in that：Described auxiliary electricity The electric field intensity of field is between 0.5 times to 0.6 times of the electric field intensity maximum of microwave field that described magnetron produces.

5. a kind of quick heating Al for claim 1 methods described₂O₃Device, including main control circuit, transforming circuit, Magnetron, waveguide and Pulse width device it is characterised in that：Also include auxiliary electric field and produce circuit；Described auxiliary electric field occurs Circuit includes auxiliary electric field control circuit and positive and negative metal electrode board, for producing an auxiliary electric field in Pulse width device, With the Al that polarizes₂O₃Molecule.

6. quick heating Al according to claim 5₂O₃Device it is characterised in that：Also include intelligent temperature control circuit, use Carry out Based Intelligent Control in the break-make to auxiliary electric field by temperature height；Described intelligent temperature control circuit includes temperature measuring equipment and opens Close；Al in described temperature measuring equipment real-tune TT ＆ C Pulse width device₂O₃Temperature, feed back to intelligent temperature control circuit, intelligent temperature control Circuit passes through the break-make of on-off control auxiliary electric field.

7. quick heating Al according to claim 5₂O₃Device it is characterised in that：Described auxiliary electric field produces circuit institute The auxiliary electric field producing is steady electric field；The electric field intensity of auxiliary electric field is the electric field intensity of the microwave field that described magnetron produces Between 0.5 times to 0.6 times of maximum.

8. quick heating Al according to claim 5₂O₃Device it is characterised in that：Described auxiliary electric field produces circuit Positive and negative metal electrode board is symmetrically positioned two offsides of Pulse width device, near the inner surface of Pulse width device；Metal electricity Pole plate is close with Pulse width device inner chamber but does not contact, and in described metal electrode board and described Pulse width device inner chamber Between fill insulating ceramics, with less than 2.5mm thickness between described positive and negative metal electrode board and Pulse width device inner surface Insulating ceramics isolation.

9. quick heating Al according to claim 5₂O₃Device it is characterised in that：Described auxiliary electric field produces circuit Positive and negative metal electrode board is stainless steel electrode plate, and between 6mm to 12mm, temperature higher Pulse width body amasss more thickness Greatly, the thickness of described positive and negative metal electrode board is thicker.