CN210952312U - Heating cavity for metal powder forming microwave composite sintering equipment - Google Patents

Abstract

The utility model discloses a heating cavity for metal powder forming microwave composite sintering equipment, which comprises a microwave cavity, a carrier installed inside the microwave cavity, a heat-insulating wave-transparent cavity arranged on the carrier, a waveguide installed on the microwave cavity and used for heating, and a sintering carrier plate arranged inside the heat-insulating wave-transparent cavity and used for carrying a metal powder embryo. The heat-insulating wave-transparent cavity is provided with a plurality of evenly distributed wave-absorbing auxiliary heating layers, and a gap is formed between two adjacent wave-absorbing auxiliary heating layers. The microwave heating efficiency of the wave-absorbing auxiliary heating layer arranged inside the microwave cavity of the utility model is extremely high at low temperature, so that the heat-insulating wave-transparent cavity is quickly heated, so that the metal powder embryo can be radiated and heated to achieve auxiliary heating, and achieve a composite heating function, thereby effectively solving the microwave sintering problem of metal powder, so as to achieve the effects of fast heating speed, short sintering time, and low energy consumption, and greatly improve the efficiency and quality of metal powder microwave sintering.

Description

Heating cavity for metal powder molding microwave composite sintering equipment

Technical field:

The utility model relates to the technical field of metal powder molding microwave sintering, in particular to a heating cavity for metal powder molding microwave composite sintering equipment.

Background technique:

Microwave is an electromagnetic wave in the band between radio waves and infrared, with a wavelength of 1mm-1m and a frequency of 00MHZ-300GHZ. It is also called ultra-high frequency electromagnetic waves. Compared with electromagnetic waves in other bands, microwaves have shorter wavelengths and higher frequencies. , strong penetrating ability, obvious quantum characteristics and so on. Its wavelength range is in the same order of magnitude or smaller than the size of general objects on Earth. Like other visible light, except for lasers, microwaves are polarized and coherent waves that follow the laws of light and interact with matter according to Substances have different properties and can be transmitted, absorbed or reflected, that is, selective. At the same time, microwave has transit time effect, radiation effect and skin effect.

According to the principle of microwave heating, the volume heating method of microwave can make the temperature distribution of the sample uniform. However, if the sample is directly exposed to the atmosphere, the radiation and convective heat loss on the surface will make the surface temperature lower than the internal temperature, resulting in uneven temperature distribution of the sample. For the sample, the temperature measurement will be inaccurate and cause Deformation and cracking of specimens.

Therefore, how to keep the temperature inside the sintered sample uniform becomes a key link in the microwave sintering process. Due to the particularity of microwave sintering, the temperature gradient direction of the sintered sample is from the inside to the outside, and the temperature rises and falls rapidly, which is easy to crack the alloy sample, so it is necessary to choose a suitable thermal insulation material. In addition, the thermal insulation layer also plays multiple roles in the sintering process, such as reducing heat loss, preheating low-loss materials, and preventing microwave ignition in the heating cavity. Therefore, the selection of thermal insulation materials in the microwave sintering system becomes the decisive factor for microwave sintering. One of the key factors for success.

Metal powder molding methods include powder metallurgy (PM), metal injection molding (MIM), 3D printing (3DP), etc., but only through the important process of metal powder sintering to obtain metal products. Compared with the traditional electric heating method, microwave sintering has obvious advantages due to its special electromagnetic wave: overall heating; selective heating; no thermal inertia; negative temperature gradient; fast heating speed, short sintering time; low energy consumption; sintered products show better Good microstructure and properties. Due to the skin effect on the metal surface, microwave sintering of metal powders was not discovered and put into practice until 1999 by Penn State University et al. The experimental results show that metal powder is a low-loss medium at low temperature (<600°C), and has a weak effect on microwaves, and its ability to absorb microwaves is poor, and individual metals are even difficult to absorb microwaves. , can also achieve microwave sintering. How to achieve rapid heating at low temperature, mixing absorbing material into metal powder is an implemented method, but this method is not good for the performance of the final sintered product.

In view of this, the inventors propose the following technical solutions.

Utility model content:

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a heating cavity for metal powder molding microwave composite sintering equipment.

In order to solve the above-mentioned technical problems, the utility model adopts the following technical scheme: the heating cavity for the metal powder molding microwave composite sintering equipment comprises: a microwave cavity, a carrier installed inside the microwave cavity, a heating cavity arranged on the carrier A heat-insulating wave-transmitting cavity, a waveguide installed on the microwave cavity and used for heating, and a sintering carrier plate arranged inside the heat-insulating wave-transmitting cavity and used for carrying metal powder green embryos, the heat-insulating wave-transmitting cavity Several uniformly distributed wave-absorbing auxiliary heating layers are arranged inside, and a space is formed between two adjacent wave-absorbing auxiliary heating layers.

Further, in the above technical solution, the heat-insulating wave-transmitting cavity includes a wave-transmitting and temperature-resistant ceramic ring body with a circular cross-section, a bottom plate arranged at the lower end of the wave-transmitting and temperature-resistant ceramic ring body, and a The cover plate on the upper end of the wave-transmitting and temperature-resistant ceramic ring body, and the wave-absorbing auxiliary heating layer is arranged on the inner wall of the wave-transmitting and temperature-resistant ceramic ring body.

Further, in the above technical solution, the area of the wave-absorbing auxiliary heating layer accounts for 1/2-1/3 of the inner wall area of the wave-transmitting and heat-resistant ceramic ring.

Further, in the above technical solution, the area of the wave-absorbing auxiliary heating layer accounts for 1/2 of the inner wall area of the wave-transmitting and heat-resistant ceramic ring.

Further, in the above technical solution, the thickness of the wave-absorbing auxiliary heating layer is 2-10 mm; the thickness of the wave-transmitting and heat-resistant ceramic ring body is 10-35 mm.

Further, in the above technical solution, the wave-absorbing auxiliary heating layer is a silicon carbide coating fixed on the inner wall of the wave-transmitting and temperature-resistant ceramic ring by coating, which forms a whole with the wave-transmitting and temperature-resistant ceramic ring. .

Further, in the above technical solution, the carrier is fixed inside the microwave cavity.

Further, in the above technical solution, the lower end of the carrier is provided with a rotating shaft, the lower end of the rotating shaft passes through the lower end of the microwave cavity, and is connected to a rotary drive device, so that the carrier is rotatably installed inside the microwave cavity.

Further, in the above technical solution, the microwave cavity is a stainless steel tank, and a cooling water channel is provided in the interlayer of the stainless steel tank.

Further, in the above technical solution, the microwave cavity is provided with an observation window, an air inlet, an exhaust pipe and a thermometer, and the thermometer extends into the heat-insulating wave-transmitting cavity.

After adopting the above-mentioned technical scheme, the present utility model has the following beneficial effects compared with the prior art: when the utility model works, the waveguide conducts microwaves, and the microwaves heat the gas inside the microwave cavity, and the heated gas will cause the insulation The heat wave-transmitting cavity is heated, and the microwave can also pass through the heat-insulating wave-transmitting cavity to heat the metal powder green embryo inside the heat-insulating wave-transmitting cavity. The microwave-absorbing auxiliary heating layer arranged in the microwave-to-microwave cavity of the utility model has extremely high microwave heating efficiency at low temperature, so that the inside of the heat-insulating wave-transmitting cavity can be heated rapidly, so that the metal powder green embryo can be radiated and heated to realize auxiliary heating. , to achieve the composite heating function, so as to effectively solve the problem of microwave sintering of metal powder, so as to achieve the effect of fast heating speed, short sintering time and low energy consumption, and the sintered product shows better microstructure and performance, which greatly improves the metal powder. Efficiency and quality of powder microwave sintering.

Description of drawings:

Fig. 1 is the structural representation of the present utility model;

Fig. 2 is the structural schematic diagram of the heat-insulating wave-transmitting cavity in the present utility model;

Figure 3 is a schematic diagram of a metal powder molding microwave composite sintering equipment.

Detailed ways:

The present utility model will be further described below with reference to specific embodiments and accompanying drawings.

As shown in Figure 3, it is the schematic diagram of the metal powder molding microwave composite sintering equipment, in which the microwave source is 1-4 3KW industrial magnetrons, the main frequency is 2450±50MHZ, and the power is continuous between 0-12KW Adjustable. The microwave transmission and measurement system in the metal powder molding microwave composite sintering equipment includes many devices, mainly including microwave generator 101, circulator 102, water load 103, waveguide 104, directional coupler 105 and impedance adjuster 106, heating Cavity 107, etc., but each device plays a different role. The waveguide is a square copper tube that transmits microwaves. The function of the circulator is to transmit the reflected microwave generated when the load is seriously mismatched to the water load, so as to protect the microwave generator. The directional coupler can detect the microwave signal obtained from the waveguide after attenuation with a microammeter to monitor the matching of the load and the absorption of microwave energy by the material, and to detect the forward and reverse power. Impedance matcher is a device that makes the system achieve the best matching state, which can be adjusted within a certain range. Heating cavity is the core part of the whole system, which can be traveling wave cavity, mixed cavity, multi-mode cavity and single-mode cavity. Compared with other cavities, the multi-mode cavity has a simple mechanical structure and can be adapted to various heating loads. Among them, the multi-mode cavity microwave heater is the most widely used microwave heater. Generally speaking, the multi-mode cavity heater is to couple a certain power microwave from a microwave source to a sealed metal box by a certain method. The structure and size of the box are designed according to certain theoretical methods, and the size is at least two Each direction should have a length of several wavelengths, maintaining many resonant modes in a given frequency band in the cabinet. The main problem of the multi-mode cavity is that the intensity of the electromagnetic field in the local area is not as high as that of the single-mode cavity, so the heating rate of the heating cavity will be lower.

Referring to FIGS. 1 and 2 , it is a heating cavity for metal powder molding microwave composite sintering equipment, which includes: a microwave cavity 1 , a carrier 2 installed inside the microwave cavity 1 , a heating cavity arranged on the carrier 2 A heat-insulating wave-transmitting cavity 3, a waveguide 4 installed on the microwave cavity 1 and used for heating, and a sintering carrier plate 5 disposed inside the heat-insulating wave-transmitting cavity 3 and used for carrying metal powder green embryos 7, the A plurality of uniformly distributed wave-absorbing auxiliary heating layers 6 are arranged inside the heat-insulating wave-transmitting cavity 3 , and a space is formed between two adjacent wave-absorbing auxiliary heating layers 6 . When the utility model works, the waveguide 4 conducts microwaves, the microwaves heat the gas inside the microwave cavity 1, the heated gas will heat the heat-insulating wave-transmitting cavity 3, and the microwaves can also pass through the heat-insulating cavity 3. The wave-transmitting cavity 3 is used to heat the metal powder green embryo 7 inside the heat-insulating wave-transmitting cavity 3. Since the microwave heating efficiency is low under the low temperature of the metal powder, the present invention uses the microwave to absorb the waves arranged inside the microwave cavity 1. The auxiliary heating layer 6 has extremely high microwave heating efficiency at low temperature, so that the inside of the heat-insulating wave-transmitting cavity 3 can be heated rapidly, so that the metal powder green embryo 7 can be radiantly heated to achieve auxiliary heating and achieve a composite heating function, thereby effectively solving the problem of metal powder. The problem of microwave sintering of powder, so that the effect of fast heating speed, short sintering time and low energy consumption is achieved, and the sintered product shows better microstructure and performance, which greatly improves the efficiency and quality of microwave sintering of metal powder.

The heat-insulating wave-transmitting cavity 3 includes a wave-transmitting and temperature-resisting ceramic ring 31 with an annular cross-section, a bottom plate 32 arranged at the lower end of the wave-transmitting and temperature-resisting ceramic ring 31, and a bottom plate 32 arranged on the wave-transmitting and temperature-resisting ceramic ring 31 . The cover plate 33 at the upper end of the ring body 31 and the wave-absorbing auxiliary heating layer 6 are arranged on the inner wall of the wave-transmitting and temperature-resistant ceramic ring body 31 . The area of the wave-absorbing auxiliary heating layer 6 accounts for 1/2-1/3 of the inner wall area of the wave-transmitting and heat-resistant ceramic ring body 31 . As a preferred embodiment, the area of the wave-absorbing auxiliary heating layer 6 accounts for 1/2 of the inner wall area of the wave-transmitting and heat-resistant ceramic ring body 31 .

The thickness of the wave-absorbing auxiliary heating layer 6 is 2-10 mm; the thickness of the wave-transmitting and heat-resistant ceramic ring body 31 is 10-35 mm.

The wave-absorbing auxiliary heating layer 6 is a silicon carbide coating that is fixed on the inner wall of the wave-transmitting and temperature-resistant ceramic ring body 31 by coating, and forms a whole with the wave-transmitting and temperature-resistant ceramic ring body 31, so as to achieve thermal insulation and permeability. For the purpose of integrating the wave material and the auxiliary heating material, it is more convenient to use. Of course, the wave-absorbing auxiliary heating layer 6 may also be other material layers such as silicon carbide.

The carrier 2 is fixed inside the microwave cavity 1 . Alternatively, the lower end of the carrier 2 is provided with a rotating shaft 21, the lower end of the rotating shaft 21 passes through the lower end of the microwave cavity 1, and is connected to a rotary drive device, so that the carrier 2 is rotatably installed inside the microwave cavity 1, At this time, the microwave cavity 1 and the metal powder green embryo inside it rotates with the rotation of the carrier 2, so that the heating is more uniform, and the efficiency and quality of the metal powder microwave sintering are further improved.

The microwave cavity 1 is a stainless steel tank, and a cooling water channel 11 is arranged in the interlayer of the stainless steel tank. After the heating work is completed in the later stage, cooling water is passed through the cooling water channel 11 to achieve rapid cooling of the stainless steel tank. , to ensure the quality of sintered products.

The microwave cavity 1 is provided with an observation window 12 , an air inlet 15 , an exhaust pipe 13 and a thermometer 14 , and the thermometer 14 extends into the heat-insulating wave-transmitting cavity 3 .

The inventor has done the following three kinds of tests, which are as follows:

In test 1, when there is no wave-absorbing auxiliary heating layer in the wave-transmitting and heat-resistant ceramic ring body 31, it takes 125 minutes for the iron powder green body to rise from normal temperature to 600°C.

Test 2, when the duty ratio of the wave-absorbing auxiliary heating layer in the wave-transmitting and temperature-resistant ceramic ring body 31 is 1/2, that is, when it occupies half of the area of the inner surface of the wave-transmitting and temperature-resistant ceramic ring body 31, the iron powder green body will change from normal temperature. Raised to 600°C took 28 minutes.

Test 3, when the duty ratio of the wave-absorbing auxiliary heating layer in the wave-transmitting and temperature-resistant ceramic ring body 31 is 1/3, that is, when the area of the inner surface of the wave-transmitting and temperature-resistant ceramic ring body 31 is 1/3, the iron powder green body It took 33 minutes to go from room temperature to 600°C.

From the above test, it can be concluded that adding a wave-absorbing auxiliary heating layer in the wave-transmitting and temperature-resistant ceramic ring body 31 can greatly reduce the working time and improve the working efficiency, and the wave-absorbing auxiliary heating layer in the wave-transmitting and temperature-resistant ceramic ring body 31 can be occupied. When the ratio is 1/2, the effect is better.

To sum up, when the utility model works, the waveguide 4 conducts microwaves, the microwaves heat the gas inside the microwave cavity 1, and the heated gas will heat the heat-insulating wave-transmitting cavity 3, and the microwaves also The heat-insulating wave-transmitting cavity 3 can be used to heat the metal powder green embryo inside the heat-insulating wave-transmitting cavity 3. Since the microwave heating efficiency of metal powder is low at low temperature, the present invention is used in the microwave-to-microwave cavity 1. The provided wave-absorbing auxiliary heating layer 6 has extremely high microwave heating efficiency at low temperature, so that the inside of the heat-insulating wave-transmitting cavity 3 can be heated rapidly, so that the metal powder green embryo can be radiated to achieve auxiliary heating and achieve the composite heating function, thereby Effectively solve the problem of microwave sintering of metal powders, so as to achieve the effects of fast heating rate, short sintering time and low energy consumption, and the sintered products show better microstructure and properties, which greatly improves the efficiency and quality of microwave sintering of metal powders .

Of course, the above are only specific embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. Any equivalent changes or modifications made in accordance with the structures, features and principles described in the scope of the patent application of the present invention are not intended to limit the scope of the present invention. It should be included in the scope of the patent application of this utility model.

Claims (10)

1. The heating cavity for the metal powder molding microwave composite sintering equipment is characterized in that: it includes: the microwave cavity comprises a microwave cavity (1), a carrier (2) arranged inside the microwave cavity (1), a heat-insulating wave-transmitting cavity (3) arranged on the carrier (2), a waveguide tube (4) arranged on the microwave cavity (1) and used for heating, and a sintering support plate (5) arranged inside the heat-insulating wave-transmitting cavity (3) and used for bearing a metal powder green body, wherein a plurality of wave-absorbing auxiliary heating layers (6) which are uniformly distributed are arranged inside the heat-insulating wave-transmitting cavity (3), and a gap is formed between every two adjacent wave-absorbing auxiliary heating layers (6).

2. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 1, wherein: the heat-insulation wave-transparent cavity (3) comprises a wave-transparent temperature-resistant ceramic ring body (31) with a circular ring-shaped cross section, a bottom plate (32) arranged at the lower end of the wave-transparent temperature-resistant ceramic ring body (31) and a cover plate (33) arranged at the upper end of the wave-transparent temperature-resistant ceramic ring body (31), and the wave-absorbing auxiliary heating layer (6) is arranged on the inner wall of the wave-transparent temperature-resistant ceramic ring body (31).

3. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 2, wherein: the area of the wave-absorbing auxiliary heating layer (6) accounts for 1/2-1/3 of the area of the inner wall of the wave-transmitting temperature-resistant ceramic ring body (31).

4. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 3, wherein: the area of the wave-absorbing auxiliary heating layer (6) accounts for 1/2 of the area of the inner wall of the wave-transmitting temperature-resistant ceramic ring body (31).

5. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 3, wherein: the thickness of the wave-absorbing auxiliary heating layer (6) is 2-10 mm; the thickness of the wave-transparent temperature-resistant ceramic ring body (31) is 10-35 mm.

6. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in any one of claims 2 to 5, wherein: the wave-absorbing auxiliary heating layer (6) is a silicon carbide coating fixed on the inner wall of the wave-transparent temperature-resistant ceramic ring body (31) in a coating mode, and the wave-absorbing auxiliary heating layer and the wave-transparent temperature-resistant ceramic ring body (31) form a whole.

7. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 6, wherein: the carrier (2) is fixed inside the microwave cavity (1).

8. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 6, wherein: the lower end of the carrier (2) is provided with a rotating shaft (21), and the lower end of the rotating shaft (21) penetrates through the lower end of the microwave cavity (1) and is connected with a rotation driving device, so that the carrier (2) can be rotatably arranged in the microwave cavity (1).

9. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 6, wherein: the microwave cavity (1) is a stainless steel tank body, and a cooling water channel (11) is arranged in an interlayer of the stainless steel tank body.

10. The heating cavity for the metal powder forming microwave composite sintering equipment as claimed in claim 6, wherein: an observation window (12), an air inlet (15), an exhaust pipeline (13) and a temperature measuring instrument (14) are arranged on the microwave cavity (1), and the temperature measuring instrument (14) extends into the heat-insulating wave-transmitting cavity (3).

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