CN105622111A - Sintering technology of high-performance permanent magnetic ferrite - Google Patents
Sintering technology of high-performance permanent magnetic ferrite Download PDFInfo
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Abstract
A sintering technology of a high-performance permanent magnetic ferrite is disclosed. A green body in a kiln undergoes sintering successively in a warming area, a thermal insulation area and a cooling area. The warming area comprises a drainage area and a warming heating area. The drainage area is provided with a hot air inlet. Part of hot air in the cooling area passes through the hot air inlet and enters the warming area. The technology is characterized in that a 1000-650 DEG C temperature zone of the cooling area is provided with 3-5 air outlets. One of the air outlets is arranged above a 1000-950 DEG C temperature zone. The final air outlet is arranged above a 680-650 DEG C temperature zone. Several hot air inlets are arranged in the feeding direction of the drainage area. Part of hot air in the cooling area is drawn out through the air outlets and enters the drainage area via the hot air inlets to heat the green body. Total hot air flow entering respectively from a kilneye and the cooling area is gradually increased in the heading direction of the product. The formula of Q=30+5*K*V*t is satisfied. Hot air flow is controlled by a flow controller.
Description
Technical field
The present invention relates to the manufacture method of a kind of permanent-magnet ferrite, especially relate to the sintering process of a kind of high-performance permanent-magnet ferrite.
Background technology
Permanent-magnet ferrite is with iron sesquioxide for primary raw material, it is fabricated by by ceramic processing methods, there is the features such as strong anti-demagnetization capability, high residual magnetic flux density and good chemical stability, the permanent magnet material be that a class cost performance is high, range of application is the widest, having the call. The industries such as it is widely used in automobile, household electrical appliance, industrial automation. Known hexagonal crystal system M type (Magnetoplumbate-type) Sr ferrite or Ba ferrite, its traditional processing technology route has the production links such as pre-burning, coarse pulverization, finely divided, molding, sintering, mill processing, cleaning, detection, packaging.
Application number is the Chinese patent of CN201220398077, it is noted that a kind of sintering magnetic materials system, as it is shown in figure 1, this system includes feeding area, preheating zone, sintering zone, cooling zone, discharging area, is provided with a prebake district between feeding area and preheating zone; Air-introduced machine it is provided with in cooling zone, air-introduced machine is connected to ventilation shaft, ventilation shaft is divided into two branch roads, article one, branch road leads to preheating zone, another branch road leads to prebake district, together with (1) this system is disadvantageous in that, discharging area is not attached to feeding area, generally respectively need 24 hours upper and lower products of 1 people; (2), together with prebake district is not attached to preheating zone, by hot product by, in the process of entrance preheating zone, prebake district, there is the phenomenon of heat losses; (3), this patent does not mention the concrete control method of heating-cooling curve and sintering atmosphere; (4), the not impact with regard to the sintering process microstructure on product and product magnetic property of this patent is discussed; (5) this patent is not discussed with regard to the common band residual magnetism phenomenon after product sintering.
Application number is the Chinese patent of CN201210232628, it is noted that a kind of method increasing magneto tile-shaped magnet comprcssive strength, and the method is disadvantageous in that, (1) the sintering period of product is longer, production efficiency is relatively low.
Application number is the Chinese patent of CN200910098603, refer to a kind of high-performance permanent magnet ferrite arch magnet and sintering method, refer to its magnetic shoe in embodiment is the sintering being incubated 2 hours through the double; two push pedal electrical kiln 1210 DEG C of 30m, then cool down with kiln, the technology of existing pushed bat kiln sintered permanent ferrite, the easy band residual magnetism of product after its sintering, and the sintering period is longer, production efficiency is not high, arch bar phenomenon easily occurs, product solid state reaction degree is not high, and magnetic property is undesirable, and energy consumption is higher.
Application number is the Chinese patent of CN201210034434, refer to a kind of sintering process producing permanent-magnet ferrite shoe-shaped product, this technique is disadvantageous in that: (1), utilize heat energy that 1100 DEG C of electrical kiln natural cooling district locates and electrical kiln afterbody waste heat that green compact are heated, as started to take out thermal current near 1100 DEG C, the flowing that the steam causing most high sintering temperature (namely 1200 DEG C near) flows to kiln caudal directions is accelerated, heat near most high sintering temperature declines, make product solid state reaction complete, the magnetic property of product meets requirement, most high sintering temperature must be properly increased, the power of most hyperpyrexia knot temperature area heating body increases, cause unnecessary energy waste, (2) about its temperature reduction technology, this patent is mentioned, and above 1100 DEG C of positions of electrical kiln cooling zone, the heat energy part in this district is guided to insulating tube and needs, with electrically heated electrical kiln porch low-temperature space, to make the electrical kiln temperature dramatic decrease about 200 DEG C in this region, the method does not take into account cooling area near Curie temperature and lowers the temperature the too fast problem that will appear from product residual magnetism phenomenon, and affects the process control method of the cooling area (in product cooling area, Curie temperature to kiln tail) of product mechanical strength, (3), guide to the thermal current in cryopumping district and from up to down blow to and wait to burn on product, this mode, it is easy to occur that the upper strata product of load bearing board and lower floor's product are heated uneven phenomenon.
Summary of the invention
The present invention provides the sintering process of a kind of high-performance permanent-magnet ferrite, purpose is to solve prior art problem, the sintering process of a kind of energy-conservation permanent-magnet ferrite is provided, be provided in particular in a kind of efficient, energy-conservation, sintering atmosphere is effectively controlled, product microstructure is excellent, mechanical strength is high, the limit bears that load is strong, the sintering process of the permanent-magnet ferrite of product nothing left magnetic phenomenon after sintering.
The problem of this invention address that the technical scheme is that
The high-performance permanent-magnet ferrite green compact that ceramic process obtains routinely, it is 2.9��3.2g/cm that its green density controls3, its sintering process controls as follows:
A kind of sintering process of high-performance permanent-magnet ferrite, green compact are sintered through heating zone, heat preservation zone, cooling area successively in kiln, heating zone includes catchment and the intensification thermal treatment zone, and catchment is provided with thermal current import, and the part steam of cooling area flows through thermal current import and enters in heating zone. Being provided with 3��5 exhaust outlets between 1000 DEG C��650 DEG C warm areas of cooling area, wherein first exhaust outlet is arranged on above 1000 DEG C��950 DEG C warm areas, and last exhaust outlet is arranged on above 680��650 DEG C of warm areas. Array thermal current import is arranged along catchment feedstock direction, the part thermal current of cooling area is extracted out by exhaust outlet and is entered into catchment through thermal current import and green compact are heated, the total thermal current flow wherein entered in heating zone is gradually increased along the direction of advance of product, and meets following equation:
Q=30+5 �� K �� V �� t,
Q, the flow of thermal current, m3/ 3600,
K, for coefficient, its value is 1.5-3.5,
V, the speed that green compact advance, meter per second;
T, the time that green compact advance, the second;
Thermal current flow is controlled by flow controller, whole sintering process is automatically controlled by PLC system, air is in flow regime at whole kiln intracavity, this flow regime, be conducive to the microstructural improvement of magnet, thus further improving mechanical strength and the magnetic property of product, especially improve Br and the H of productCJDeng magnetic parameter.
Further, the thermal current import of catchment, from entering kilneye, is 1 group every 400mm, totally 30 groups.
Total thermal current in described heating zone enters in sintering oven by three kinds of modes simultaneously, a kind of is extracted out the thermal current of cooling area by exhaust outlet to enter (main), one enters (secondary) from kiln tail, a kind of is enter (trace by the bypath valve of heat exchanger, in order to regulate by the temperature of gas in heat exchanger, as this temperature meets technological requirement, then bypath valve is closed, and does not enter air herein).
First exhaust outlet is arranged on above 1000 DEG C��950 DEG C warm areas and has two purposes: be (1) remote from most high sintering temperature place, the steam avoiding most high sintering temperature flows to the flowing of kiln caudal directions to accelerate, making the heat near most high sintering temperature decline, temperature quickly reduces. And to make product solid state reaction complete, the magnetic property of product meets requirement, it is necessary to properly increase most high sintering temperature, and the power of most hyperpyrexia knot temperature area heating body increases, and will cause unnecessary energy waste. (2) the thermal current extraction with higher temperature can be delivered to catchment, effectively utilize heat, save the energy, reduce the time of workpiece cooling. And last exhaust outlet is arranged on 680��650 DEG C of warm areas, it is therefore an objective to slowly reduce temperature near permanent-magnet ferrite Curie temperature (450 DEG C). The near Curie temperature too fast problem that will appear from product residual magnetism phenomenon of cooling, and then affect product mechanical strength. Slowly workpiece is lowered the temperature, prevent the appearance of the bad products such as residual magnetism. Other exhaust outlets offered between first and last exhaust outlet, purpose is extract out the thermal current with higher temperature to deliver to catchment equally, effectively utilizes heat, saves the energy, reduces the time of workpiece cooling.
Being additionally provided with heat exchanger, the thermal current of cooling area needs through heat exchanger heat exchange before entering into catchment, controls its temperature at 260 DEG C��350 DEG C after heat exchange. The purpose that entrance catchment hot stream temperature is controlled is to prevent the product cracking phenomena occurred because of temperature too low (lower than 260 DEG C), or the product crack performance occurred because of temperature too high (lower than 350 DEG C).
Further, for better controlling to be entered into the temperature of the thermal current of catchment by cooling area, devise an automatic temp controller, when lower than the temperature set, automatically controlled by PLC and start heater, thermal current is heated, when temperature is higher than the temperature set, bypath valve automatically turns on, and the cold air under room temperature enters the pipeline of thermal current, reduces the temperature of thermal current.
Further, for better controlling to be entered into the temperature of the thermal current of catchment by cooling area, being additionally provided with autoalarm in kiln, thermostat is connected with autoalarm. Time when the temperature of the thermal current after heat exchanger heat exchange does not meet 260 DEG C��350 DEG C more than 2 minutes, autoalarm is reported to the police. Be conducive to check that to scene the reason caused of reporting to the police also quickly is got rid of technologist's very first time that production scene is maked an inspection tour.
The draining head of district in heating zone 12 meters, arranges a passage getting rid of steam every 2 meters. The intensification thermal treatment zone is divided into slow heating zone and the district that is rapidly heated, and slow heating zone is long 12 meters, and be rapidly heated the head of district 6 meters. Wherein tail point temperature in catchment controls in 260��350 DEG C, and slow heating zone tail point temperature controls at 550��600 DEG C, and the district's tail point temperature that is rapidly heated controls at 1190 DEG C��1230 DEG C. Above-mentioned catchment tail point is also slow heating zone head-end, and slow heating zone tail point is also the district's head-end that is rapidly heated, and catchment head-end is kilneye.
Described heat preservation zone is 3 meters. Temperature in whole heat preservation zone will not change in theory, and the temperature of its head-end and tail point is identical, but in practical operation, temperature has a small amount of change (within 2 DEG C), and its variations in temperature does not affect sintering. Described heat preservation zone head-end is also the district's tail point that is rapidly heated.
Described cooling area includes fast cooling district and slow cooling area, the fast cooling head of district 5.2 meters; The slow cooling head of district is 5.8 meters, and wherein fast cooling district tail point temperature controls at 620��550 DEG C, and the temperature of slow cooling district tail point controls at 120 DEG C��60 DEG C. Above-mentioned fast cooling district tail point Ye Shi slow cooling district head-end, slow cooling district tail point is kiln tail, and namely fast cooling district head-end is heat preservation zone tail point.
It is blown into respectively in kiln from the thermal current of cooling area extraction from load bearing board with above green compact.
End points and each exhaust outlet at each warm area are equipped with a temperature-detecting device.
Having four exhaust outlets, second exhaust outlet is arranged on above 860 DEG C��800 DEG C warm areas, and the 3rd exhaust outlet is arranged on above 760��720 DEG C of warm areas. Offering exhaust outlet above the two temperature range respectively, purpose is extract out the thermal current with higher temperature to deliver to catchment equally, effectively utilizes heat, saves the energy, reduces the time of workpiece cooling.
In slow cooling district, workpiece is with stove natural cooling.
Beneficial effects of the present invention: by the control to the control of thermal current flow and sintering atmosphere, make whole sintering process efficient, energy-conservation, and product microstructure is excellent, mechanical strength is high, the limit bears that load is strong, the sintering process of the permanent-magnet ferrite of product nothing left magnetic phenomenon after sintering, is specifically mainly reflected in following several respects:
(1) steam flows into the flow of kilneye, with automatically controlling gas flowmeter, by formula " Q=30+5 �� K �� V �� t ", thermal current is effectively controlled, catchment in heating process and time catchment, make the design of green compact thermally equivalent, abundant draining, effective for permanent-magnet ferrite sintering atmosphere controls, and lays a good foundation for its Fast Sintering.
(2) between 1000 DEG C of cooling area��650 DEG C warm areas, it is provided with 3��5 exhaust outlets, wherein first exhaust outlet is arranged on above 1000 DEG C��950 DEG C warm areas, last exhaust outlet is arranged on 680��650 DEG C of warm areas, it is conducive to: 1. temperature is reaching at 680��650 DEG C of (near permanent-magnet ferrite Curie temperature (450 DEG C)) front slow coolings, therefore prevents the appearance of the bad products such as residual magnetism; 2. higher heat is drawn out of, and is conducive to temperature in cooling area to decline faster, it is achieved Fast Sintering; Green compact are heated by the heat suction being 3. beneficial to kiln aft section to row district water, have saved the energy; 4. strengthening the mobility of kiln furnace gas, in kiln, oxygen content is high, and this is conducive to the microstructural improvement of magnet, thus improving mechanical strength and the magnetic property of product, especially improves Br and the H of productCJDeng magnetic parameter.
(3) the thermal current of cooling area controls its temperature at 260 DEG C��350 DEG C through heat exchanger before entering into catchment. Prevent the product cracking phenomena occurred because of temperature too low (lower than 260 DEG C); Prevent the product crack performance occurred because of temperature too high (lower than 350 DEG C).
Accompanying drawing explanation
Fig. 1 is each warm area schematic diagram and gas flow direction in existing sintering magnetic materials system
Fig. 2 is three operation break-down schematic diagrams of sintering circuit;
Fig. 3 is each warm area and product and gas flow direction schematic diagram in the present invention;
Fig. 4 is the typical sintering temperature curve of embodiment 1;
Fig. 5 is the typical control climate curve of heating zone;
Fig. 6 be the obtained product of embodiment 1 bear load chart;
Fig. 7 be the obtained product of comparative example 1 bear load chart;
Fig. 8 is the microstructure photograph of the obtained product of embodiment 1;
Fig. 9 is the microstructure photograph of the obtained product of comparative example 1.
Detailed description of the invention
Research finds, band magnetic phenomenon after sintering, show as the many polar forms of one side more, number of poles be a little pole to tens poles not etc., and pole-face very irregular, with magnetic displaying instrument it will be clear that multiple irregular small circle, inside and outside circle, it is not homopolarity, different polarity and intensity (a few mT �� 60��70mT) can be measured with hall probe. With magnetic phenomenon can the phenomenon of imposite product tape magnetic, or under similarity condition sometimes band magnetic and sometimes without magnetic. Roller kilns in commercial production, pushed bat kiln etc. is likely to occur band magnetic after sintering, the sintering for multi-layer magnet, there is also the possibility of overall demagnetization, the top of scheduling product, the bottom middle serious possibility with magnetic without magnetic substantially occurs. , when multi-layer sintering, often there is this phenomenon in anisotropy, particularly premium quality product. Product once band magnetic phenomenon after sintering occurs, by the mill of product process, cleans, class wrapping and installation operation bring many troubles, hence it is evident that reduction product comprehensive qualified rate, reduction production efficiency.
Research shows, if during molding, orientation is incomplete, then magnetic is from being distributed as a minizone, and when demagnetization is unclean, then the number of forward and reverse magnetic moment is unequal, and macroscopic view has certain magnetic. During sintering, mainly magnet is played compaction, substantially do not change the arrangement of magnetic domain, and the magnetic moment of magnetic domain can be done random change by the impact of warm-up movement, declining with temperature, warm-up movement weakens, after cooling, finally fix on positive direction or the opposite direction of magnetic domain easy magnetizing axis. Generally, the arranged anti-parallel minimum in free energy, forward and reverse magnetic moment is uniformly distributed, and numerical value is equal, and macroscopic magnetization is zero. Heating demagnetization is exactly such.
When cooling, too short by air blast or body of heater or heat radiation is too fast etc. affects, lowered the temperature play, the state that the warm-up movement overall demagnetization when also more acute, energy is not also preferably minimized or entirety are not demagnetized can be fixed, just there is the unequal phenomenon pockety of positive and negative magnetic moment in result, a part is in N pole, and another part is S pole. Former differently-oriented directivity presents the multipole magnetized situation that pole-face is irregular, intensity is uneven.
By examine high-performance permanent-magnet ferrite product sintering after band residual magnetism phenomenon, and through many experiments, the invention provides a kind of efficient, energy-conservation, sintering atmosphere is effectively controlled, product microstructure is excellent, mechanical strength is high, the limit bears that load is strong, the sintering process of the permanent-magnet ferrite of product nothing left magnetic phenomenon after sintering.
Below in conjunction with the drawings and specific embodiments, the present invention is described in further details.
Embodiment 1
Prepare commercially available iron oxide red, its main constituent Fe2O3Mass fraction be more than 99.2%, prepare mass fraction be the SrCO of more than 98.5%3Powder, is the CaCO of more than 98.5%3Powder, is the La of more than 99%2O3Powder, the mass fraction of Co is the cobalt oxide powder of more than 72%; To permanent-magnet ferrite accessory ingredient SrmMpBzOm+p+2zPreparation: taking m=0.9, p=2.7, z=0.3, adopt dry or wet to be mixed uniformly, in atmosphere insulation 2 hours at 950 DEG C, then fine powder is broken to the powder that particle mean size is 1.5 ��m.
Main constituent to permanent-magnet ferrite, (Ca0)X��(R2O3)Y��(Fe2O3)n, wherein x=0.4, y=0.55, n are the addition of the 5.9 each main materials of calculating. And be 2.3% weigh Sr by the mass fraction of Preburning material to be generatedmMpBzOm+p+2z, each raw material of wet-mixed. Its incorporation time is 4 hours, and then, by each raw material stoving of mix homogeneously, insulation 2 hours at 1295 DEG C, by gained Preburning material dry type coarse crushing to 2 ��m, take this ground product some in atmosphere, in parts by weight, and the respectively CaCO of 1%3, the SiO of 0.4%2With known dispersant sorb sugar alcohol 0.5%, and in material, ball, water the ratio that mass ratio is 1:6:1.5, material, steel ball (cleaning up), water being put into and carry out finely divided in the ball mill (cleaning up) of �� 2000 �� 1980, measuring its particle mean size with WLP-208 is 0.80 ��m. By the water content control of gained slip 38%, then at the action of a magnetic field compacted under, the magnetic field of magnetizing during molding is 12000Oe, the green compact obtained after molding, and green density is 2.9��3.2g/cm3The whole sintering circuit of this kind of high-performance permanent-magnet ferrite green compact be divided into heating process 1., insulation operation 2., cooling process 3., as in figure 2 it is shown, be sintered through heating zone, heat preservation zone, cooling area successively in kiln, wherein heating zone includes catchment and the intensification thermal treatment zone. Green compact are heated by catchment by the thermal current brought from cooling area, long 12 meters, arrange a passage getting rid of steam every 2 meters. Green compact are heated by the intensification thermal treatment zone by heater, and the intensification thermal treatment zone includes time catchment (i.e. slow heating zone) and the district that is rapidly heated, the slow intensification head of district 12 meters, and be rapidly heated the head of district 6 meters. The insulation head of district 3 meters. Cooling area is divided into fast cooling district and slow cooling area, and the fast cooling head of district is 5.2 meters; The slow cooling head of district is 5.8 meters. Wherein 1000 DEG C, cooling area, 860 DEG C, 760 DEG C, above 680 DEG C of these four temperature ranges, offer an exhaust outlet respectively, cooling area part thermal current enters heating zone by exhaust outlet the thermal current import through being located at kiln internal drainage district, and air is in flow regime at whole kiln intracavity. In its whole kiln, the division of each warm area and structure are as shown in Figure 3. Exhaust outlet and each warm area end points place are provided with temperature-detecting device, in order to control variations in temperature. When temperature exceedes predetermined temperature range value, automatic control system carries out temperature adjustment automatically, makes temperature meet the requirements, the prior art that the automatic regulating system of the temperature in the present embodiment adopts.
Its concrete sintering process is as described below:
Workpiece enters in sintering oven, it is introduced into catchment, 25 DEG C��260 DEG C, catchment, the thermal current import of catchment, from entering kilneye, is 1 group every 400mm, totally 30 groups, often group is all blown into kiln intracavity respectively from the top of the lower section of load bearing board and green compact, so can make the green compact of each position, thermally equivalent in kiln body. Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, for better controlling to be entered into the temperature of the thermal current of catchment by cooling area, devise an automatic temp controller, when lower than the temperature 260 DEG C set, automatically controlled by PLC and start heater, thermal current is heated, and when temperature is higher than the temperature set, bypath valve automatically turns on, cold air under room temperature enters the pipeline of thermal current, reduces the temperature of thermal current. For better controlling to be entered into the temperature of the thermal current of catchment by cooling area, being additionally provided with autoalarm in kiln, when the temperature of the thermal current after heat exchanger heat exchange is unsatisfactory for the technological requirement of 260 DEG C, during more than 2 minutes, autoalarm is reported to the police. Be conducive to check that to scene the reason caused of reporting to the police also quickly is got rid of technologist's very first time that production scene is maked an inspection tour.
Workpiece, behind catchment, sequentially enters slow heating zone 260 DEG C��550 DEG C, and be rapidly heated 550 DEG C��1200 DEG C of district, 1200 DEG C, heat preservation zone, 1200 DEG C��620 DEG C of fast cooling district, behind 620 DEG C��120 DEG C of slow cooling district, and kiln discharge. Wherein workpiece is taked in slow cooling district to lower the temperature with stove natural cooling mode, and namely in this warm area, the air inlet bottom kiln is closed.
In fast cooling district, first exhaust outlet is opened in 1000 DEG C of tops, there are two purposes: (1) is remote from most high sintering temperature place, the steam avoiding most high sintering temperature (namely 1200 DEG C near) flows to the flowing of kiln caudal directions to accelerate, making the heat near most high sintering temperature decline, temperature quickly reduces. And to make product solid state reaction complete, the magnetic property of product meets requirement, it is necessary to properly increase most high sintering temperature, and the power of most hyperpyrexia knot temperature area heating body increases, and will cause unnecessary energy waste. (2) the thermal current extraction with higher temperature can be delivered to catchment, effectively utilize heat, save the energy, reduce the time of workpiece cooling. And last exhaust outlet is arranged on 680 DEG C of warm areas, it is therefore an objective to slowly reduce temperature near permanent-magnet ferrite Curie temperature (450 DEG C). The near Curie temperature too fast problem that will appear from product residual magnetism phenomenon of cooling, and then affect product mechanical strength. Slowly workpiece is lowered the temperature, prevent the appearance of the bad products such as residual magnetism. And at 860 DEG C, above 760 DEG C of the two temperature ranges, offer exhaust outlet respectively, purpose is extract out the thermal current with higher temperature to deliver to catchment equally, effectively utilizes heat, saves the energy, reduces the time of workpiece cooling.
Except the above-mentioned control to sintering temperature, the control of sintering kiln atmosphere is important too. Air-flow enters in sintering oven by three kinds of modes simultaneously, a kind of is extracted out the thermal current of cooling area by exhaust outlet to enter (main), one enters (secondary) from kiln tail, a kind of is enter (trace by the bypath valve of heat exchanger, in order to regulate by the temperature of gas in heat exchanger, as this temperature meets technological requirement, then bypath valve is closed, and does not enter air herein. Whole heating zone steam flows into the flow of kilneye, with automatically controlling gas flowmeter control, adjusts. Total thermal current flow of heating zone, starts from kilneye and is gradually increased along the direction of advance of product, and meeting following equation:
Q=30+5 �� K �� V �� t,
Q, the flow of thermal current, m3/ 3600,
K, for coefficient, its value is 1.5,
V, the speed that green compact advance, meter per second,
T, the time that green compact advance, the second.
The load bearing board of dress green compact is 370 �� 370mm, enters plate speed and is every 5 points and within 30 seconds, enters 1 and push away (technique initialization, fine-tuning), then V=0.37/330=1.12 �� t/10-3(meter per second)
Q=30+5 �� 1.5 �� 1.12 �� t/10-3(m3/hr)��
The amount of Q changes with the change of t (green compact advance the time), such as the 1st group of air inlet (from kiln hood 400mm), t=0.4/V=356.7 second, Q=30+5 �� 1.5 �� 1.12 �� t/10-3=33m3/hr��
Product needs the time of cost to be 10.9 hours from kilneye to kiln tail, and 44 meters double; two push away roller kilns, have 237.82 plates, fill blank 24kg by every plate and calculate in kiln, the blank 12.56 tons that can go out after sintering for every 24 hours.
Green compact are when sintering, and as shown in Figure 4, at heating zone, its typical control climate curve is as shown in Figure 5 for its typical sintering temperature curve. Green compact after the sintering, the product obtained, carry out magnetic property detection with the NIM-2000F permanent-magnet ferrite measuring instrument of China National Measuring Science Research Inst., the test of gas product porosity: first measure apparent density d and the x light solid density d of materialX, the porosity of product is then asked for by equation below:
Carry out the apparent density of measuring samples with buoyancy method, concretely comprise the following steps:
1. the aerial quality W of tested drying sample is weighed out in the balance1; Then, after sample is soaked 10 minutes (purpose is the gap allowing moisture immerse sample top layer), take out sample, with filter paper by after the water wiping of sample surfaces, with fine rule or hairline, sample is fastened.
2. take half cup water (can be good at flooding sample, it is ensured that sample does not contact beaker and is as the criterion) with 50ml beaker, balance weighs up the quality W of cup+water2;
3. the sample fastened is suspended on support (or with portable live), allows sample be immersed in the water in beaker (noting: will completely flood, but object can not contact the side of beaker bottom and cup);
4. the quality W of cup+water+sample at this moment is weighed up3, W3With W2Difference equal to the volume of sample.
5. calculate: the mode calculating �� presses following formula execution.
With open up instrument Science and Technology Ltd. TF-212 product pressure testing machine test product bear load limit, obtained product bear load chart as shown in Figure 6, it is 254.5kgf that its limit bears load, the microstructure of obtained magnet is as shown in Figure 8, the product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Embodiment 2
Except some difference following, other are all identical with the sintering process of embodiment 1:
It is 25 DEG C��300 DEG C that catchment temperature controls, it is 300 DEG C��580 DEG C that slow heating zone temperature controls, the district's temperature that is rapidly heated controls to be 580 DEG C��1230 DEG C, it is 1230 DEG C that heat preservation zone temperature controls, it is 1230 DEG C��560 DEG C that fast cooling district temperature controls, and it is 560 DEG C��80 DEG C that slow cooling district temperature controls.
Four exhaust outlets are opened in 980 DEG C, 820 DEG C, 720 DEG C, 650 DEG C tops successively.
Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, after heat exchange, temperature controls is 300 DEG C.
In formula Q=30+5 �� K �� V �� t, K is 2.0.
The product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Embodiment 3
Except some difference following, other are all identical with the sintering process of embodiment 1:
It is 25 DEG C��350 DEG C that catchment temperature controls, it is 350 DEG C��600 DEG C that slow heating zone temperature controls, the district's temperature that is rapidly heated controls to be 600 DEG C��1190 DEG C, it is 1190 DEG C that heat preservation zone temperature controls, it is 1190 DEG C��550 DEG C that fast cooling district temperature controls, and it is 550 DEG C��60 DEG C that slow cooling district temperature controls.
Four exhaust outlets are opened in 950 DEG C, 800 DEG C, 740 DEG C, 670 DEG C tops successively.
Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, after heat exchange, temperature controls is 350 DEG C.
In formula Q=30+5 �� K �� V �� t, K is 3.5.
The product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Embodiment 4
Except some difference following, other are all identical with the sintering process of embodiment 1:
Four exhaust outlets are opened in 1000 DEG C, 840 DEG C, 760 DEG C, 680 DEG C tops successively.
Embodiment 5
Except some difference following, other are all identical with the sintering process of embodiment 1:
Four exhaust outlets are opened in 950 DEG C, 800 DEG C, 720 DEG C, 650 DEG C tops successively.
Embodiment 6
Except some difference following, other are all identical with the sintering process of embodiment 1:
Most high sintering temperature is 1200 DEG C, and four exhaust outlets are opened in 980 DEG C, 830 DEG C, 740 DEG C, 660 DEG C tops successively.
Embodiment 7
Except some difference following, other are all identical with the sintering process of embodiment 1:
Most high sintering temperature is 1195 DEG C, and four exhaust outlets are opened in 980 DEG C, 830 DEG C, 740 DEG C, 660 DEG C tops successively.
Embodiment 8
Except some difference following, other are all identical with the sintering process of embodiment 1:
Five exhaust outlets are opened in 1000 DEG C, 950 DEG C, 800 DEG C, 720 DEG C, 650 DEG C tops successively.
Embodiment 9
Except some difference following, other are all identical with the sintering process of embodiment 1:
Three exhaust outlets are opened in 1000 DEG C, 860 DEG C, 650 DEG C tops successively.
Comparative example 1
The green compact that molding obtains are identical with embodiment 1, during sintering, in traditional pushed bat kiln, adopt conventional sintering process that product is sintered: the catchment heater heating of temperature rise period, sintering atmosphere Artificial Control by rule of thumb, enter plate speed, often push away 12 minutes, the dou-ble-pusher kiln of 44 meters, have 237.82 plates in kiln, fill blank 24kg by every plate and calculate, the blank 5.76 tons that can go out after sintering for every 24 hours.
Obtained product bear load chart as shown in Figure 7, it is 190.2kgf that its limit bears load, the microstructure of obtained magnet as it is shown in figure 9, the qualification rate of obtained product, magnetic property, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Contrast experiment finds, steam flows into the flow of kilneye, with automatically controlling gas flowmeter, by formula " Q=30+5 �� K �� V �� t ", thermal current is effectively controlled, catchment in heating process and time catchment, making the design of green compact thermally equivalent, abundant draining, effective for permanent-magnet ferrite sintering atmosphere controls, and lays a good foundation for its Fast Sintering.
Comparative example 2
Except some difference following, other are all identical with the sintering process of embodiment 1:
It is 25 DEG C��350 DEG C that catchment temperature controls, it is 350 DEG C��550 DEG C that slow heating zone temperature controls, the district's temperature that is rapidly heated controls to be 550 DEG C��1200 DEG C, it is 1200 DEG C that heat preservation zone temperature controls, it is 1200 DEG C��550 DEG C that fast cooling district temperature controls, and it is 550 DEG C��60 DEG C that slow cooling district temperature controls
Four exhaust outlets are opened in 1000 DEG C successively, 860 DEG C, 760 DEG C, 680 DEG C of tops.
Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, after heat exchange, temperature controls is 350 DEG C.
In formula Q=30+5 �� K �� V �� t, K is 1.
The product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Comparative example 3
Except some difference following, other are all identical with the sintering process of embodiment 1:
It is 25 DEG C��350 DEG C that catchment temperature controls, it is 370 DEG C��600 DEG C that slow heating zone temperature controls, the district's temperature that is rapidly heated controls to be 600 DEG C��1200 DEG C, it is 1200 DEG C that heat preservation zone temperature controls, it is 1200 DEG C��550 DEG C that fast cooling district temperature controls, and it is 550 DEG C��60 DEG C that slow cooling district temperature controls
Four exhaust outlets are opened in 1000 DEG C successively, 860 DEG C, 760 DEG C, 680 DEG C of tops.
Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, after heat exchange, temperature controls is 350 DEG C.
In formula Q=30+5 �� K �� V �� t, K is 4.
The product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Comparative example 4
Except some difference following, other are all identical with the sintering process of embodiment 1:
It is 25 DEG C��230 DEG C that catchment temperature controls, it is 230 DEG C��500 DEG C that slow heating zone temperature controls, the district's temperature that is rapidly heated controls to be 500 DEG C��1200 DEG C, it is 1200 DEG C that heat preservation zone temperature controls, it is 1200 DEG C��500 DEG C that fast cooling district temperature controls, and it is 500 DEG C��150 DEG C that slow cooling district temperature controls.
Four exhaust outlets are opened in 1000 DEG C successively, 860 DEG C, 760 DEG C, 680 DEG C of tops.
Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, after heat exchange, temperature controls is 230 DEG C.
In formula Q=30+5 �� K �� V �� t, K is 2.0.
The product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
Comparative example 5
Except some difference following, other are all identical with the sintering process of embodiment 1:
It is 25 DEG C��360 DEG C that catchment temperature controls, it is 360 DEG C��650 DEG C that slow heating zone temperature controls, the district's temperature that is rapidly heated controls to be 650 DEG C��1200 DEG C, it is 1200 DEG C that heat preservation zone temperature controls, it is 1200 DEG C��640 DEG C that fast cooling district temperature controls, and it is 640 DEG C��150 DEG C that slow cooling district temperature controls
Four exhaust outlets are opened in 1000 DEG C successively, 860 DEG C, 760 DEG C, 680 DEG C of tops.
Before the thermal current of cooling area sends into heating zone, first through heat exchanger heat exchange, after heat exchange, temperature controls is 370 DEG C.
In formula Q=30+5 �� K �� V �� t, K is 2.0.
The product obtained, its qualification rate, the magnetic property of product, the porosity with bear the isoparametric typical data of load limit, be shown in Table 1.
The contrast table of the qualification rate of product and each parameter under table 1 different technology conditions
Contrast experiment shows: be provided with 3��5 exhaust outlets between 1000 DEG C��650 DEG C warm areas of cooling area, wherein first exhaust outlet is arranged on above 1000 DEG C��950 DEG C warm areas, last exhaust outlet is arranged on above 680��650 DEG C of warm areas, be conducive to: 1. temperature is reaching 680��650 DEG C of (near permanent-magnet ferrite Curie temperature (450 DEG C)) front slow coolings, prevents the appearance of the bad products such as residual magnetism; 2. higher heat is drawn out of, and is conducive to temperature in cooling area to decline faster, it is achieved Fast Sintering; 3. the heat being beneficial to kiln aft section enters leading portion to green compact heating, has saved the energy; 4. strengthening the mobility of kiln furnace gas, in kiln, oxygen content is high, and this is conducive to the microstructural improvement of magnet, thus improving mechanical strength and the magnetic property of product, especially improves Br and the H of productCJDeng magnetic parameter.
Contrast experiment further demonstrates that at fast cooling district tail point (620��550 DEG C) front beginning slow cooling, and substantially reducing production efficiency, slow down fltting speed, as from starting thereafter slow cooling, will caused the appearance of the bad product phenomenons such as residual magnetism.
Contrast experiment also shows: the thermal current of cooling area controls its temperature at 260 DEG C��350 DEG C through heat exchanger before entering into catchment. Prevent the product cracking phenomena occurred because of temperature too low (lower than 260 DEG C); Prevent the product crack performance occurred because of temperature too high (lower than 350 DEG C).
Although the present invention being made that detailed description, and describe some specific embodiments, but embodiment is the illustration to technical scheme, the understanding to the present invention program, it is not limited to embodiment.
Claims (10)
1. the sintering process of a high-performance permanent-magnet ferrite, green compact are sintered through heating zone, heat preservation zone, cooling area successively in kiln, heating zone includes catchment and the intensification thermal treatment zone, catchment is provided with thermal current import, the part steam of cooling area flows through thermal current import and enters in heating zone, it is characterized in that: between 1000 DEG C��650 DEG C warm areas of cooling area, be provided with 3��5 exhaust outlets, wherein first exhaust outlet is arranged on above 1000 DEG C��950 DEG C warm areas, and last exhaust outlet is arranged on above 680��650 DEG C of warm areas; Array thermal current import is arranged along catchment feedstock direction, the part thermal current of cooling area is extracted out by exhaust outlet and is entered into catchment through thermal current import and green compact are heated, wherein total in heating zone thermal current flow is gradually increased along the direction of advance of product, and meets following equation:
Q=30+5 �� K �� V �� t,
Q, the flow of thermal current, m3/ 3600,
K, for coefficient, its value is 1.5��3.5,
V, the speed that green compact advance, meter per second;
T, the time that green compact advance, the second;
Thermal current flow is controlled by flow controller, and whole sintering process is by PLC system control.
2. the sintering process of a kind of high-performance permanent-magnet ferrite as described in claim 1, it is characterised in that: being additionally provided with heat exchanger, the thermal current of cooling area through heat exchanger heat exchange, controls its temperature at 260 DEG C��350 DEG C before entering into catchment and needing after heat exchange.
3. the sintering process of a kind of high-performance permanent-magnet ferrite as described in claim 2, it is characterised in that: being additionally provided with autoalarm, when the hot stream temperature after heat exchanger heat exchange does not meet 260 DEG C��350 DEG C, autoalarm is reported to the police.
4. the sintering process of a kind of high-performance permanent-magnet ferrite as described in claim 1, it is characterised in that: the draining head of district in heating zone 12 meters, every 2 meters, a passage getting rid of steam is set; The intensification thermal treatment zone is divided into slow heating zone and the district that is rapidly heated, slow heating zone is long 12 meters, be rapidly heated the head of district 6 meters, wherein tail point temperature in catchment controls in 260��350 DEG C, slow heating zone tail point temperature controls at 550��600 DEG C, and the district's tail point temperature that is rapidly heated controls at 1190 DEG C��1230 DEG C.
5. the sintering process of high-performance permanent-magnet ferrite as described in claim 1, it is characterised in that: described heat preservation zone is 3 meters.
6. the sintering process of high-performance permanent-magnet ferrite as described in claim 1, it is characterized in that: described cooling area includes fast cooling district and slow cooling area, the fast cooling head of district 5.2 meters, the slow cooling head of district is 5.8 meters, wherein fast cooling district tail point temperature controls at 620��550 DEG C, and the temperature of slow cooling district tail point controls at 120 DEG C��60 DEG C.
7. the sintering process of high-performance permanent-magnet ferrite as described in claim 1, it is characterised in that: it is blown into respectively in kiln from the thermal current of cooling area extraction from load bearing board with above green compact.
8. the sintering process of high-performance permanent-magnet ferrite as described in claim 1, it is characterised in that: end points and each exhaust outlet at each warm area are equipped with a temperature-detecting device.
9. the sintering process of high-performance permanent-magnet ferrite as described in claim 1, it is characterised in that: having four exhaust outlets, second exhaust outlet is arranged on above 860 DEG C��800 DEG C warm areas, and the 3rd exhaust outlet is arranged on above 760��720 DEG C of warm areas.
10. the sintering process of high-performance permanent-magnet ferrite as described in claim 6, it is characterised in that: in slow cooling district, workpiece is with stove natural cooling.
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| CN109448981A (en) * | 2018-11-13 | 2019-03-08 | 中磁电科有限公司 | A kind of magnet ring processing method |
| CN109494069A (en) * | 2018-11-13 | 2019-03-19 | 中磁电科有限公司 | A kind of full-automatic magnet ring system of processing |
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