CN105135873B - Dynamic pressure electric pulse double-field control sintering furnace and sintering method - Google Patents

Abstract

The invention relates to a dynamic pressure electric pulse double-field control sintering furnace and a sintering method, which includes a furnace body, a dynamic pressure system, a pulse current generator and a sintering controller; the furnace body is connected with the dynamic pressure system and the pulse current generator, and the dynamic pressure Both the system and the pulse current generator are connected to the sintering controller. There is a mold in the furnace body; the dynamic pressure system includes an upper pressure head electrode, a lower pressure head electrode, an upper pressure head, a lower pressure head, a constant pressure control module, a dynamic pressure control module and a pressure master control module; the dynamic pressure system is connected to the sintering controller The pulse current generator is connected to the upper and lower pressure head electrodes, and is connected to the sintering controller. The sintering controller controls the dynamic pressure system and the pulse current generator to generate adjustable dynamic pressure and plasma pulse current sintering for the material to be sintered. The invention provides a dynamic pressure electric pulse double-field control sintering furnace and a sintering method capable of preparing high-quality performance materials, which can be widely used in the sintering of high-performance materials.

Description

A dynamic pressure electric pulse double field control sintering furnace and sintering method

technical field

The invention relates to a sintering furnace and a sintering method, in particular to a dynamic pressure electric pulse double field control sintering furnace and a sintering method.

Background technique

The sintering process in the preparation of advanced materials is a critical step to achieve particle densification and endow materials with mechanical strength. Ceramics and some metal materials have high melting points, and it is often difficult to achieve sintering densification, so higher requirements are put forward for sintering equipment and technology.

Currently commonly used sintering methods include atmospheric pressure sintering, hot pressing sintering and spark plasma sintering. Atmospheric pressure sintering is a simple high-temperature sintering method, which promotes the densification of materials by heating under atmospheric pressure, and the degree of densification of materials is not high. Hot press sintering is to apply unidirectional or bidirectional pressure to the powder at the same time of sintering, which accelerates the densification process. Compared with normal pressure sintering, hot press sintering has a lower temperature and shorter sintering time, which can effectively promote the sintering of materials. Densification and inhibition of grain growth, the current application fields include advanced ceramics, hard alloys, powder metallurgy and composite materials. Spark plasma sintering is a new type of material sintering preparation method developed in recent years, also known as pulse current sintering. The main feature of this technology is that a DC pulse current is applied to the electrode to generate discharge plasma instantaneously, and the surface activation effect generated by the pulse current and the self-heating of the particles is effectively used to realize ultra-fast densification and sintering of the material, which greatly shortens the sintering time and reduces the Sintering temperature, but the pulse current has strong directionality and polarity, resulting in uneven performance distribution of the sintered material along the electric field direction of the current, which affects the use of the material. Studies have shown that the pressure provided by the current sintering equipment is constant pressure. Under constant pressure, it is difficult for particles to slide and rearrange, and it is difficult to discharge pores. During the sintering process, "hard agglomeration" is easy to occur between particles, which easily leads to uneven microstructure. Therefore, the degree of densification of the sintered body and the improvement of mechanical properties are restricted. Moreover, the shrinkage of the powder and the densification of the material during the sintering process cannot be grasped in time, thus restricting the sintering of high-performance materials.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a method that can effectively improve the inhomogeneity of electric field and temperature field in spark plasma sintering, so that the electric field and dynamic pressure field are in controllable changes, reducing and eliminating "hard agglomeration" , to achieve rapid densification of materials at lower temperatures, increase powder bulk density, and promote pore discharge, thereby preparing high-density, low-defect, high-strength and other high-quality performance materials. Dynamic pressure electric pulse double field control sintering furnace and sintering method .

In order to achieve the above object, the present invention adopts the following technical solutions: a dynamic pressure electric pulse double field control sintering furnace, characterized in that it includes a furnace body, a dynamic pressure system, a pulse current generator and a sintering controller; the furnace body Connecting the dynamic pressure system and the pulse current generator, both the dynamic pressure system and the pulse current generator are connected to the sintering controller;

A mold is arranged inside the furnace body, and the mold adopts a cylindrical structure with a hollow cavity;

The dynamic pressure system includes an upper pressure head electrode, a lower pressure head electrode, an upper pressure head, a lower pressure head, a constant pressure control module, a dynamic pressure control module and a pressure master control module; the upper pressure head electrode, the lower pressure head The head electrodes are respectively fixed on the upper part of the furnace body and the lower part of the furnace body; one end of the upper indenter is connected to the bottom of the upper indenter electrode, and the other end is inserted into the upper part of the hollow inner cavity of the mold; one end of the lower indenter is connected to The other end of the lower indenter electrode is inserted into the bottom of the hollow cavity of the mold, and the end of the upper indenter and the end of the lower indenter in the hollow cavity of the mold have a material to be sintered. space; the top of the upper pressure head electrode is connected to the constant pressure control module and the dynamic pressure control module, and both the constant pressure control module and the dynamic pressure control module are connected to the pressure master control module; The pressure master control module is connected to the output end of the sintering controller, the sintering controller sends the dynamic pressure control signal to the pressure master control module, and the pressure master control module controls the The constant pressure generated by the constant pressure control module and the dynamic pressure generated by the dynamic pressure control module are superimposed into a dynamic pressure with adjustable frequency and amplitude that acts on the upper pressure head electrode, and then controlled by the upper pressure head electrode The above-mentioned upper pressure head generates adjustable dynamic pressure on the material to be sintered.

The output end of the pulse current generator is connected to the upper indenter electrode and the lower indenter electrode, the input end of the pulse current generator is connected to the output end of the sintering controller, and the sintering controller will The pulse current control signal is sent to the pulse current generator, and the pulse current generator performs plasma pulse current sintering on the upper indenter electrode and the lower indenter electrode according to the received pulse current control signal, and the plasma pulse current The material to be sintered is acted on by the upper pressing head electrode, the lower pressing head electrode, the upper pressing head and the lower pressing head.

The dynamic pressure electric pulse double field control sintering furnace also includes a cooling water system, the cooling water system includes a water cooling channel and a cooling water control system, the water cooling channel is located inside the furnace body and close to the wall of the furnace body, so The water outlet of the water cooling channel is arranged at the upper end of the furnace body, the water inlet of the water cooling channel is arranged at the lower end of the furnace body, and the water inlet of the water cooling channel is connected to the sintering controller through the cooling water control system, The sintering controller sends a cooling water control signal to the cooling water control system, and the cooling water control system controls the inflow and outflow of cooling water in the water cooling channel according to the received cooling water control signal.

The dynamic pressure electric pulse double field control sintering furnace also includes a magnetic grid line displacement measurement system, and the magnetic grid line displacement measurement system includes a magnetic head, a magnetic grid line displacement sensor and a displacement display, and the magnetic head is placed on the upper head electrode The axial displacement signal is collected at the pressure point, and the obtained axial displacement signal is transmitted to the magnetic grid line displacement sensor, and the magnetic grid line displacement sensor transmits the collected axial displacement data to the displacement display for real-time show.

The dynamic pressure electric pulse dual-field control sintering furnace also includes a vacuum control system, the furnace body is connected to the sintering controller through the vacuum control system, and the sintering controller sends a vacuum control signal to the vacuum control system , the vacuum control system adjusts the vacuum degree in the furnace body according to the received vacuum control signal; the vacuum control system includes a mechanical pump, a Roots pump, a vacuum pressure gauge and an electromagnetic valve.

The mold is made of carbon/carbon composite material.

The dynamic pressure generated by the dynamic pressure control module ranges from 0 to 5 MPa, and the adjustable frequency ranges from 0 to 3 Hz.

A sintering method using a dynamic piezoelectric pulse double-field control sintering furnace, comprising the following steps:

1) Detect the power supply, water source and vacuum degree, and place the material to be sintered in the cavity of the hollow part of the mold in the furnace body;

2) Control the vacuum degree in the furnace body through the vacuum control system to reach the vacuum degree required by the process requirements of the material to be sintered;

3) The sintering controller controls the dynamic pressure system to act on the dynamic pressure of the required frequency and amplitude of the material to be sintered, and the dynamic pressure promotes the particle rearrangement of the material to be sintered, thereby increasing the green density of the material to be sintered;

4) While the dynamic pressure is acting on the material to be sintered, the pulse current generator is controlled by the sintering controller to perform plasma pulse current sintering on the material to be sintered, so that the material to be sintered is simultaneously subjected to the dual field control comprehensive effect of dynamic pressure and plasma pulse current;

5) According to the required temperature of the material to be sintered and the time required by the process, when the material to be sintered reaches the required temperature, keep the time required by the process of the material to be sintered;

6) After the time required by the sintering material process is reached, the cooling water system is used to control the entry and discharge of cooling water in the water cooling channel, and then the furnace body is slowly cooled; at the same time, the pressure master control module is controlled by the sintering controller to slowly reduce the dynamic pressure until Dynamic pressure is zero;

7) When the temperature in the furnace cools down to room temperature, the sintering is completed, and the sintered body is taken out of the furnace.

Because the present invention adopts the above technical scheme, it has the following advantages: 1. The present invention uses a pulse current generator to carry out plasma pulse current sintering on the material to be sintered, and applies a dynamic pressure to the material to be sintered through the dynamic pressure system, dynamic pressure and plasma pulse The comprehensive effect of double field control of current can greatly reduce the sintering temperature and sintering time required by the material to be sintered, promote the particle rearrangement, particle migration and pore discharge of the material to be sintered, accelerate the volume shrinkage of the material to be sintered, reduce and eliminate "hardness". Reunion" enables rapid densification, eliminates pores, micro-cracks and other defects, and greatly improves the sintered density and performance of the product. 2. Since the present invention adopts the superimposition of constant pressure and dynamic pressure to generate dynamic pressure, the frequency and magnitude of the dynamic pressure obtained by the material to be sintered can be adjusted, and the process requirements of the material to be sintered can be met. In summary, the present invention can be widely used in the sintering process of preparing high-performance materials.

Description of drawings

Fig. 1 is the schematic diagram of the dynamic pressure electric pulse dual field control sintering furnace of the present invention

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in FIG. 1 , the present invention provides a dynamic pressure electric pulse dual field control sintering furnace, which includes a furnace body 1 , a dynamic pressure system 2 , a pulse current generator 3 and a sintering controller 4 . The furnace body 1 is connected to a dynamic pressure system 2 and a pulse current generator 3 , and both the dynamic pressure system 2 and the pulse current generator 3 are connected to a sintering controller 4 .

A mold 11 is arranged inside the furnace body 1, and the mold 11 adopts a cylindrical structure with a hollow inner cavity, and the material to be sintered is placed in the hollow inner cavity of the mold 11.

The dynamic pressure system 2 includes an upper pressure head electrode 21 , a lower pressure head electrode 22 , an upper pressure head 23 , a lower pressure head 24 , a constant pressure control module 25 , a dynamic pressure control module 26 and a pressure master control module 27 . The upper indenter electrode 21 and the lower indenter electrode 22 are respectively fixed on the upper and lower parts of the furnace body 1. One end of the upper indenter 23 is connected to the bottom of the upper indenter electrode 21, and the other end is inserted into the upper part of the hollow inner cavity of the mold 11; one end of the lower indenter 24 is connected to The other end of the lower pressing head electrode 22 is inserted into the bottom of the hollow cavity, and there is a space between the end of the upper pressing head 23 and the end of the lower pressing head 24 in the hollow inner cavity of the mold 11 to accommodate the material to be sintered. The top of the upper head electrode 21 is connected to a constant pressure control module 25 and a dynamic pressure control module 26 , both of which are connected to a pressure master control module 27 . The pressure master control module 27 is connected to the output end of the sintering controller 4, and the sintering controller 4 sends the dynamic pressure control signal to the pressure master control module 27, and the pressure master control module 27 controls the constant pressure control module 25 according to the received dynamic pressure control signal The constant pressure generated and the dynamic pressure generated by the dynamic pressure control module 26 are superimposed to form a dynamic pressure with adjustable frequency and amplitude that acts on the upper indenter electrode 21, and then controls the size of the upper indenter 23 to be sintered by the upper indenter electrode 21 Adjustable dynamic pressure.

The output end of the pulse current generator 3 is connected to the upper pressing head electrode 21 and the lower pressing head electrode 22, the input end of the pulse current generator 3 is connected to the output end of the sintering controller 4, and the sintering controller 4 sends the pulse current control signal to The pulse current generator 3, the pulse current generator 3 performs plasma pulse current sintering on the upper indenter electrode 21 and the lower indenter electrode 22 according to the received pulse current control signal, and the plasma pulse current passes through the upper indenter electrode 21, the upper indenter 23. The lower pressing head electrode 22 and the lower pressing head 24 generate discharge plasma instantaneously when they reach the material to be sintered, so that the material to be sintered itself generates Joule heat and activates the surface particles of the material to be sintered, and the energy generated in the material to be sintered The transfer between particles accelerates the diffusion of energy between the materials to be sintered, so that the materials to be sintered are simultaneously subjected to the dual field control comprehensive effect of dynamic pressure and plasma pulse current.

In the above embodiment, the dynamic pressure electric pulse double field control sintering furnace also includes a cooling water system, the cooling water system includes a water cooling channel 51 and a cooling water control system 52, the water cooling channel 51 is located inside the furnace body 1 and close to the wall of the furnace body 1, and the water cooling The water outlet 53 of the passage 51 is arranged at the upper end of the furnace body 1, the water inlet 54 of the water cooling passage 51 is arranged at the lower end of the furnace body 1, and the water inlet 54 of the water cooling passage 51 is connected to the sintering controller 4 through the cooling water control system 52, and the sintering controller 4 The cooling water control signal is sent to the cooling water control system 52, and the cooling water control system 52 controls the inflow and outflow of cooling water in the water cooling channel 51 according to the received cooling water control signal.

In the above-mentioned embodiment, the dynamic pressure electric pulse double-field control sintering furnace also includes a magnetic grid line displacement measurement system 6, and the magnetic grid line displacement measurement system 6 includes a magnetic head 61, a magnetic grid line displacement sensor 62 and a displacement display 63, and the magnetic head 61 is directly on the The axial displacement signal is collected at the pressure point of the upper indenter electrode 21, and the obtained axial displacement signal is transmitted to the magnetic grid line displacement sensor 62, and the magnetic grid line displacement sensor 62 transmits the collected axial displacement data to the displacement display 63 for real-time display.

In the above-mentioned embodiment, the dynamic pressure electric pulse double-field control sintering furnace also includes a vacuum control system 7, the furnace body 1 is connected to the sintering controller 4 through the vacuum control system 7, and the sintering controller 4 sends the vacuum control signal to the vacuum control system 7, The vacuum control system 7 adjusts the vacuum degree in the furnace body 1 according to the received vacuum control signal, and the vacuum control system 7 includes a mechanical pump, a Roots pump, a vacuum pressure gauge and an electromagnetic valve.

In the above embodiments, the mold 11 is made of a carbon/carbon composite material with higher toughness and strength, which can withstand continuous impact of high-frequency dynamic pressure and has a long service life.

In the above embodiments, the dynamic pressure generated by the dynamic pressure control module 26 ranges from 0 to 5 MPa, and the adjustable frequency ranges from 0 to 3 Hz.

The present invention also provides a dynamic pressure electric pulse dual-field controlled sintering method, comprising the following steps:

1) Detect the power supply, water source and vacuum degree, and place the material to be sintered in the cavity of the hollow part of the mold 11 .

2) The vacuum degree in the furnace body 1 is controlled by the vacuum control system 7 to reach the vacuum degree required by the process requirements of the material to be sintered.

3) The sintering controller 4 controls the dynamic pressure system 2 to act on the dynamic pressure of the required frequency and amplitude of the material to be sintered. The dynamic pressure promotes the particle rearrangement of the material to be sintered, thereby increasing the green density of the material to be sintered.

4) While the dynamic pressure is acting on the material to be sintered, the pulse current generator 3 is controlled by the sintering controller 4 to perform plasma pulse current sintering on the material to be sintered, so that the material to be sintered is simultaneously subjected to the dual field control comprehensive effect of dynamic pressure and plasma pulse current .

5) According to the required temperature of the material to be sintered and the time required by the process, when the material to be sintered reaches the required temperature, keep the time required by the process of the material to be sintered.

6) After the time required by the sintering material process is reached, the cooling water system is used to control the entry and discharge of cooling water in the water cooling channel 51, and then the furnace body 1 is slowly cooled; at the same time, the pressure master control module 27 is controlled by the sintering controller 4 to slowly Decrease the dynamic pressure until the dynamic pressure is zero.

7) When the temperature in the furnace body 1 cools down to room temperature, the sintering is completed, and the sintered body is taken out from the furnace body 1 .

The above-mentioned embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component can be changed to some extent, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not excluded from the protection scope of the present invention.

Claims (10)

1. sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse, it is characterised in that：It includes body of heater, dynamic pressure system, pulse Current feedback circuit and sintering controller；The body of heater connects the dynamic pressure system and the impulse current generator, described Dynamic pressure system and the impulse current generator all connect the sintering controller；

The furnace interior is provided with mould, and the mould is using the column structure with hollow cavity；

The dynamic pressure system include seaming chuck electrode, push tip electrode, seaming chuck, push-down head, constant pressure control module, Dynamic pressure control module and pressure top control module；The seaming chuck electrode, the tip electrode that pushes are separately fixed at the stove Body top and the lower portion of furnace body；Described seaming chuck one end connects the seaming chuck electrode base, and the other end inserts the mould Hollow cavity top；Tip electrode is pushed described in push-down head one end connection, the other end inserts the mould hollow cavity bottom, And the seaming chuck end in the mould hollow cavity and it is described push between cephalic par have accommodate it is to be sintered The space of material；The seaming chuck top of electrodes connects with the constant pressure control module and the dynamic pressure control module Connect, the constant pressure control module and the dynamic pressure control module are connected to the pressure top control module；The pressure The outfan of the power top control module connection sintering controller, the sintering controller sends dynamic pressure control signal to institute Pressure top control module is stated, the pressure top control module controls the constant pressure control according to the dynamic pressure control signal for receiving The dynamic pressure that the constant pressure and the dynamic pressure control module that molding block is produced is produced is superposed to a frequency and amplitude Adjustable dynamic pressure acts on the seaming chuck electrode, and then treats burning by the seaming chuck electrode control seaming chuck Knot material produces the adjustable dynamic pressure of size.

2. sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse as claimed in claim 1, it is characterised in that：The pulse current The outfan of generator connect the seaming chuck electrode and it is described push tip electrode, the input of the impulse current generator connects The outfan of the sintering controller is connected to, the sintering controller sends pulse current control signal to the pulse current Generator, the impulse current generator according to the pulse current control signal for receiving to the seaming chuck electrode and it is described under Pressure head electrode carries out plasma pulse electric current sintering, and plasma pulse electric current is by the seaming chuck electrode, push-down head electricity Pole, the seaming chuck and the push-down head act on material to be sintered.

3. sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse as claimed in claim 1 or 2, it is characterised in that：The dynamic The double field control sintering furnaces of pressure electric pulse also include cooling water system, and the cooling water system includes water-cooling channel and cooling water control System, the water-cooling channel is located at the furnace interior and near the body of heater wall, and the outlet of the water-cooling channel is arranged In the body of heater upper end, the water inlet of the water-cooling channel is arranged on the body of heater lower end, the water inlet Jing of the water-cooling channel The cooling water control system connects the sintering controller, and the sintering controller sends cooling water control signal to described Cooling water control system, the cooling water control system is controlled in the water-cooling channel according to the cooling water control signal for receiving Cooling water is flowed in and out.

4. sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse as claimed in claim 1 or 2, it is characterised in that：The dynamic The double field control sintering furnaces of pressure electric pulse also include magnetic grid linear movement measuring system, and the magnetic grid linear movement measuring system includes magnetic Head, magnetic grid linear movement pick-up and displacement display, the magnetic head gathers axial position on the pressure spot of the seaming chuck electrode Shifting signal, by the axial displacement signal of acquisition the magnetic grid linear movement pick-up is transferred to, and the magnetic grid linear movement pick-up will The axial displacement data for collecting are delivered to institute's displacement display and are shown in real time.

5. sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse as claimed in claim 3, it is characterised in that：The dynamic pressure The double field control sintering furnaces of electric pulse also include magnetic grid linear movement measuring system, and the magnetic grid linear movement measuring system includes magnetic head, magnetic Grid line displacement transducer and displacement display, the magnetic head gathers axial displacement letter on the pressure spot of the seaming chuck electrode Number, the axial displacement signal of acquisition is transferred to into the magnetic grid linear movement pick-up, the magnetic grid linear movement pick-up will be gathered To axial displacement data be delivered to institute's displacement display and shown in real time.

6. a kind of double field control sintering furnaces of dynamic pressure electric pulse as described in claim 1 or 2 or 5, it is characterised in that：It is described dynamic The double field control sintering furnaces of state pressure electric pulse also include vacuum-control(led) system, and vacuum-control(led) system connection is described described in the body of heater Jing Sintering controller, the sintering controller sends vacuum control signal to the vacuum-control(led) system, the vacuum control system System adjusts the vacuum in the body of heater according to the vacuum control signal for receiving；The vacuum-control(led) system include mechanical pump, Lobe pump, pressure vacuum gauge and electromagnetic valve.

7. sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse as claimed in claim 3, it is characterised in that：The dynamic pressure The double field control sintering furnaces of electric pulse also include vacuum-control(led) system, the sintering control of vacuum-control(led) system connection described in the body of heater Jing Device processed, the sintering controller sends vacuum control signal to the vacuum-control(led) system, the vacuum-control(led) system according to The vacuum control signal for receiving adjusts the vacuum in the body of heater；The vacuum-control(led) system include mechanical pump, lobe pump, Pressure vacuum gauge and electromagnetic valve.

8. a kind of double field control sintering furnaces of dynamic pressure electric pulse as described in claim 1 or 2 or 5 or 7, it is characterised in that：Institute State mould and adopt carbon/carbon compound material.

9. a kind of double field control sintering furnaces of dynamic pressure electric pulse as described in claim 1 or 2 or 5 or 7, it is characterised in that：Institute The dynamic pressure magnitude range for stating the generation of dynamic pressure control module is 0～5MPa, and adjustable frequency scope is 0～3Hz.

10. the sintering side of sintering furnace is controlled in a kind of double fields of dynamic pressure electric pulse using as any one of claim 1～9 Method, comprises the following steps：

1) power supply, water source and vacuum are detected, material to be sintered is positioned over into intracavity in the hollow bulb of body of heater inner mold；

2) vacuum controlled in body of heater by vacuum-control(led) system reaches the vacuum during material technology to be sintered is required；

3) dynamic pressure of dynamic pressure systemic effect frequency and amplitude needed for material to be sintered is controlled by sintering controller, Dynamic pressure promotes the particle re-arrangement of material to be sintered, so as to improve the green density of material to be sintered；

4) while sintered material effect dynamic pressure is treated, by sintering controller control impulse current generator burning is treated Knot material carries out plasma pulse electric current sintering so that material to be sintered is subject to dynamic pressure and plasma pulse electric current simultaneously Double control comprehensive functions；

5) according to material to be sintered is temperature required and its technological requirement time, after material to be sintered reaches temperature required, keep Material technology to be sintered wants seeking time；

6) after material technology to be sintered wants seeking time to reach, by cooling water system control water-cooling channel in cooling water entrance and Discharge, and then slow cooling is carried out to body of heater；It is slow to reduce dynamic pressure simultaneously by sintering controller control pressure top control module Power is until dynamic pressure is zero；

7) after the temperature cooling in body of heater reaches room temperature, sintering is completed, and sintered body is taken out from body of heater.