CN1203946C - Plasma technology for activating sintered material - Google Patents
Plasma technology for activating sintered material Download PDFInfo
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- CN1203946C CN1203946C CN 01107084 CN01107084A CN1203946C CN 1203946 C CN1203946 C CN 1203946C CN 01107084 CN01107084 CN 01107084 CN 01107084 A CN01107084 A CN 01107084A CN 1203946 C CN1203946 C CN 1203946C
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Abstract
The present invention relates to a new technology of using plasma to activate a sintered material, a preparation and processing technology of a powder metallurgical material. A sintering process is carried out in a plasma activated sintering furnace, and completed in four stages: (1). slightly supplying coaxial pressure to materials; (2). keeping constant pressure, supplying a pulse voltage so as to generate the plasma and activating the surfaces of powder particles; (3). switching off the pulse voltage, continuing to supply the pressure, switching on a direct current under the constant pressure and heating the materials to a required temperature for required time; (4). stopping resistance heating and eliminating the pressure to obtain a finished product. The technology has the advantages of low sintering temperature and inhibited grain growth, and the activation of the surfaces of the particles enhances the performance of the sintered material in nature.
Description
One, technical field: a kind of powdered metallurgical material preparation, processing technology.
Two, background technology: sintering is one of operation the most basic in the powder metallurgy production process.Sintering is a high temperature action, generally will also suitable protective atmosphere will be arranged through the long time.Therefore, consider from economic angle that the consumption of sintering circuit is the pith that constitutes product cost, improves operation and agglomerating plant, reduces the consumption of material and energy, as reducing sintering temperature, shortening sintering time etc., meaning economically is very big.
Known sintering method has: traditional pressureless sintering method, hot pressing sintering method, microwave sintering method, plasma sintering method (as microwave plasma, direct-current plasma) but all have outside its deficiency.No matter long, poor, the energy consumption height of properties of product of tradition pressureless sintering method process time adopts the fuel heating still to adopt electrical heating, all makes cost up, is therefore replaced by some novel sintering methods gradually.Though hot pressing sintering method has adopted pressure, in the sintering process activation degree (being dynamic process) of sample still needed and further improve, and apparatus expensive and process-cycle are long.And microwave sintering method and plasma sintering method are improved aspect activation, shortened sintering time, reduced sintering temperature, suppressed growing up of dusty material particle, but experimental condition such as temperature is difficult to control in the sintering process, particularly cause the thermal runaway effect easily in the microwave sintering process, dusty material is produced inhomogeneous heating, thereby influenced the various performances of sintered products, thereby a kind of new method that can improve above-mentioned sintering process shortcoming of in the preparation of dusty material and process, still needing.
Plasma activated sintering dusty material technology, abroad start to walk since the nineties, because it melts plasma-activated, hot pressing, resistance heated is an one, have advantages such as sintering time weak point, temperature precise control, the relative theory density that only in minutes just makes dusty material is near 100%, and can effectively improve the various performances of material, thereby the research of plasma activated sintering and being applied in abroad emerges rapidly, becomes the new focus of dusty material research.
What essential distinction do plasma activated sintering and plasma sintering have so? plasma sintering is placed on material in the plasma atmosphere and carries out, and mainly contains the discharge of direct current cathode cavity, high-frequency induction, three kinds of methods that produce high-temperature plasma of microwave-excitation at present.The device that these three kinds of methods adopt all has a cover to keep the system of vacuum and control gas pressure and flow, and different mainly is the power mode that produces plasma.The essence of this technology is that the high-temperature plasma of utilize producing heats material, and the heat exchange by material and high-temperature plasma realizes sintering, promptly plasma as thermal source, material is carried out sintering.But shortcoming is: sample is easy to generate cracking, and along with the rising of temperature, the volatilization of material also aggravates, and technology and theory are all immature.
And the plasma activated sintering method is the micro discharge phenomenon of utilizing between powder particle that the gap produced, by the plasma strike and the intergranular contact portion of heating powder of discharging and being produced, can make the material of contact portion produce evaporation, thereby reach the purpose of purification and activated powder particle, have advantages such as sintering time weak point, temperature precise control, easy industrialization.
Three, summary of the invention: the present invention is needing to impose pulse voltage on the dusty material of sintering, produce plasma with activated powder material granule surface, by direct current the dusty material Fast Heating is heated up, exert pressure again with sintering and curing powder material, it is even to reach that sintering time is short, the temperature precise control is sintered material granule, improves the purpose of material property.
Fig. 1 is the installation drawing of plasma activated sintering of the present invention, and 1 is Pulased power supply unit among the figure, the 2nd, and resistive heating device, the 3,4,5,6,11, the 12nd, the axial pressure device, the 10th, the sintering mould, 9 and 13 is upper and lower drifts.The dusty material that needs sintering is placed the sintering mould and imposes homoaxial pressure, in dusty material, produce the particle surface of plasma with pulse voltage with activated material, be heated by resistive device then and impose direct current, material is carried out Fast Heating, to finish activated sintering to dusty material.(the plasma activated sintering device is described in the utility application that the applicant proposes on January calendar year 2001 13).
Fig. 2 is temperature, the pressure schematic diagram of above-mentioned sintering process four-stage.Sintering divides four-stage to carry out: the phase I, the dusty material that is sintered is slightly executed homoaxial pressure; Second stage keeps constant pressure, and adds pulse voltage, produces plasma, and particle surface is activated, and supervenes a spot of heat; Phase III, close pulse power supply circuit, continue to improve pressure, under the constant voltage effect, be heated to temperature required and the time to material with direct current; The quadravalence section stops the D.C. resistance heating, eliminates pressure.Applied pressure, temperature and pulse voltage need to decide according to the dusty material and the sintered products performance that are sintered.
Fig. 3 is Pulased power supply unit and resistive heating device circuit theory diagrams
Become Rectified alternating current, obtain HVDC after by capacitor filtering through three-phase bridge rectification by the three phase sine alternating current, this high voltage direct current is sent into the power switch inverter, become the square wave alternating current, transfer grand to required voltage through intermediate-frequency transformer, behind switching and rectifying, inductor filter, can obtain working direct current again.It is that a kind of contravariant external characteristics is that voltage falls suddenly, the constant-current type electric current.
For guaranteeing the constant set-point of direct current of resistive heating device output, in Circuits System, be provided with current regulation control circuit and Current Feedback Control circuit in technological requirement; For the pulse direct current that guarantees Pulased power supply unit output satisfies technological requirement, be provided with the modulator loop that pulse frequency modulation and pulse-width modulation circuit constitute especially, in order to the low frequency dc pulse voltage is modulated on the direct current of output.
Pulased power supply unit, resistive heating device, desired parameters will generally can be controlled in according to the difference of agglomerated material and sintered products performance requirement is set during the work of axial pressure device: (1) pulse voltage 5～100V, pulse current 100～250A, pulse turn-on time 10～90ms, pulse 10～80ms breaking time, overall pulse time 20～100s; (2) resistance heated voltage 5～120V, electric current 100～1200A, power-efficient are greater than 80%, and power factor (PF) is greater than 0.9; (3) temperature range is 200～1600 ℃.
Compare advantage and good effect that the present invention has with known technology:
(1) to the dusty material pressurization accurately, steadily controlled;
(2) Pulased power supply unit and resistive heating device stability is high, continuity is good, and adjustable extent is big, and dynamic response is fast;
(3) owing to the activation of plasma, new technology can realize low-temperature sintering, has so just suppressed growing up of crystal grain, from having improved the performance of sintered body in essence.
(4) sintering time is short, compares with the several hrs of conventional sintering, has saved the energy, has reduced the loss of equipment.
This technology also can make up configuration respectively with Medium frequency induction or AC resistance stove, also can carry out plasma-activated-Medium frequency induction sintering, plasma-activated-indirect resistance heat-agglomerating etc.
This technology also can be used for exploring the activated sintering of different types of dusty material or the different process process of preferred dusty material of the same race, also can adopt first activation, after the technical process such as knot of pressurizeing, reburn.
Four, description of drawings: Fig. 1 is an installation drawing of the present invention, and 1 is Pulased power supply unit among the figure, the 2nd, and resistive heating device, the 3,4,5,6,11, the 12nd, the axial pressure device, the 10th, the sintering mould, 9 and 13 is upper and lower drifts.Fig. 2 is temperature, the pressure schematic diagram of sintering process quadravalence section.Fig. 3 is Pulased power supply unit and resistive heating device circuit theory diagrams.
Five, the specific embodiment:
Embodiment 1: the plasma activated sintering of alumina in Nano level
Packed in the sintering mould in the nano-alumina powder end, at first powder is activated with pulse current, be rapidly heated subsequently and powder exerted pressure and carry out sintering, pulse current 850A wherein, pulse turn-on time 60ms, breaking time 30ms, plasma-activated time 90s, pressure 40Mpa, 1250～1300 ℃ of heating-up temperatures.
Embodiment 2: the plasma activated sintering of Hardmetal materials WC+Co
With purity is that 99.9% WC powder and purity are to pack into after 99.8% Co powder evenly mixes in proportion in the sintering mould, at first powder is activated with pulse current, be rapidly heated subsequently and powder exerted pressure and carry out sintering, the process conditions of sintering need be followed according to the percentage composition of Co powder in the alloy and be set.
(a), to the optimum process condition of WC-6%Co dusty material sintering: pulse current 600A, pulse turn-on time 40ms, plasma-activated time 30s, pressure is 30.5Mpa, 1350 ℃ of following sintering 5 minutes, hardness reached HRA92, and the relative theory density value is 99.83%.
(b), to the optimum process condition of WC-10%Co dusty material sintering: pulse current 500A, pulse turn-on time is 40ms, be 60ms breaking time, the plasma-activated time is 25s, pressure is 26.3Mpa, and heating-up temperature 300-1350 ℃, sintering time is 4 minutes, relative theory density reaches 99.65%, and Rockwell hardness reaches 91.
(c), to the optimum process condition of WC-15%Co dusty material sintering: pulse current 450A, pulse turn-on time is 40ms, be 60ms breaking time, the plasma-activated time is 20s, pressure is 21.6MPa, 1300 ℃ of following sintering 5 minutes, hardness reached HRA90, and the relative theory density value is 99.90%.
(d), to the optimum process condition of WC-20%Co dusty material sintering: pulse current 400A, pulse turn-on time is 20ms, be 80ms breaking time, the plasma-activated time is 30s, heating-up temperature 1250-1300 ℃, pressure was 17.6Mpa, 1300 ℃ of following sintering 5 minutes, hardness reaches HRA89, and the relative theory density value is 99.93%.
Embodiment 3: nanoscale ZrO
2High beta plasma activated sintering
With nanoscale ZrO
2Powder is packed in the sintering mould, at first with pulse current powder is activated, be rapidly heated subsequently and powder exerted pressure and carry out sintering, optimum process condition is: pulse current 700A, pulse turn-on time 45ms, breaking time 30ms, plasma-activated time 60s, pressure 30Mpa, heating-up temperature 1300-1400 ℃, sintering time is 7 minutes, and Vickers hardness reaches 15.4Gpa, and relative theory density is near 100%.
The plasma activated sintering of embodiment 4:Cu powder
Technological parameter is: pulse current 2500A, pulse turn-on time are that 40ms, breaking time are 60ms, adopt D.C. resistance heat-agglomerating to 600 ℃ again, total activated sintering time is 15s, reduce to room temperature subsequently, institute's applied pressure is 5MPa in the process, after activated sintering, the solid density of sample reaches 99.6%, and the process time only is 15s.
Claims (1)
1, a kind of method of plasma activated sintering material, sintering divide four-stage to carry out, and the phase I, the dusty material particle are slightly granted its homoaxial pressure; Second stage keeps constant pressure, and adds pulse voltage, produces plasma, and the dusty material particle surface is activated; Phase III, close pulse power supply circuit, continue to improve pressure, under the constant voltage effect, be heated to temperature required and the time to material with direct current; The quadravalence section stops the D.C. resistance heating, eliminates pressure, it is characterized in that:
With purity is that 99.9% WC powder and purity are to pack into after 99.8% Co powder evenly mixes in proportion in the sintering mould, at first with pulse current powder is activated, be rapidly heated subsequently and powder exerted pressure to carry out sintering,
(a), to the process conditions of WC-6%Co dusty material sintering: pulse current 600A, pulse turn-on time 40ms, plasma-activated time 30s, pressure is 30.5Mpa, 1350 ℃ of following sintering 5 minutes, hardness reached HRA92, and the relative theory density value is 99.83%.
(b), to the process conditions of WC-10%Co dusty material sintering: pulse current 500A, pulse turn-on time is 40ms, be 60ms breaking time, the plasma-activated time is 25s, pressure is 26.3Mpa, and heating-up temperature 1300-1350 ℃, sintering time is 4 minutes, relative theory density reaches 99.65%, and Rockwell hardness reaches 91.
(c), to the process conditions of WC-15%Co dusty material sintering: pulse current 450A, pulse turn-on time is 40ms, be 60ms breaking time, the plasma-activated time is 20s, pressure is 21.6MPa, 1300 ℃ of following sintering 5 minutes, hardness reached HRA90, and the relative theory density value is 99.90%.
(d), to the process conditions of WC-20%Co dusty material sintering: pulse current 400A, pulse turn-on time is 20ms, be 80ms breaking time, the plasma-activated time is 30s, pressure is 17.6Mpa, 1300 ℃ of following sintering 5 minutes, hardness reached HRA89, and the relative theory density value is 99.93%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 01107084 CN1203946C (en) | 1996-07-12 | 2001-01-20 | Plasma technology for activating sintered material |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO962936 | 1996-07-12 | ||
| CN 01107084 CN1203946C (en) | 1996-07-12 | 2001-01-20 | Plasma technology for activating sintered material |
Related Child Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100520914A Division CN1292864C (en) | 2001-01-20 | 2001-01-20 | Method for copper powder plasma activated sintering |
| CNB200510052090XA Division CN1292863C (en) | 2001-01-20 | 2001-01-20 | Nano zirconium oxide plasma activation sintering method |
| CNB2005100520929A Division CN1292865C (en) | 2001-01-20 | 2001-01-20 | Nano aluminium oxide plasma activation sintering method |
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| CN1302707A CN1302707A (en) | 2001-07-11 |
| CN1203946C true CN1203946C (en) | 2005-06-01 |
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| CN 01107084 Expired - Fee Related CN1203946C (en) | 1996-07-12 | 2001-01-20 | Plasma technology for activating sintered material |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| SI22048A (en) | 2005-06-02 | 2006-12-31 | Institut "Jozef Stefan" | Method and device for local functionalization of polymer materials |
| CN102464494A (en) * | 2010-11-16 | 2012-05-23 | 中国科学院合肥物质科学研究院 | Microwave pressure sintering device |
| CN102139371B (en) * | 2011-05-04 | 2013-01-23 | 佛山市钜仕泰粉末冶金有限公司 | Tungsten alloy target material and preparation method thereof |
| CN102703869A (en) * | 2012-05-30 | 2012-10-03 | 深圳市华星光电技术有限公司 | Method for preparing target for copper conductor of thin film transistor (TFT)-liquid crystal display (LCD) array substrate, and target |
| CN103567440A (en) * | 2013-08-15 | 2014-02-12 | 厦门虹鹭钨钼工业有限公司 | Preparation method for tungsten carbide target material for film coating of oil exploration drill bit |
| CN104630524A (en) * | 2013-11-15 | 2015-05-20 | 核工业西南物理研究院 | Method for preparing beryllium-titanium alloy by carrying out spark plasma sintering |
| ES2738627T3 (en) * | 2016-02-19 | 2020-01-24 | Fundacion Tecnalia Res & Innovation | Method for sintering electrically conductive powders |
| CN116655380A (en) * | 2023-05-26 | 2023-08-29 | 香河昆仑新能源材料股份有限公司 | Garnet type solid electrolyte and preparation method and application thereof |
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