CN112276079A - Device and method for sintering tantalum briquette and removing binder - Google Patents
Device and method for sintering tantalum briquette and removing binder Download PDFInfo
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- CN112276079A CN112276079A CN202010571005.5A CN202010571005A CN112276079A CN 112276079 A CN112276079 A CN 112276079A CN 202010571005 A CN202010571005 A CN 202010571005A CN 112276079 A CN112276079 A CN 112276079A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
- B22F3/1021—Removal of binder or filler
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1003—Use of special medium during sintering, e.g. sintering aid
- B22F3/1007—Atmosphere
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Abstract
The invention discloses a device for debinding and sintering tantalum briquettes, which comprises a heating furnace, a binder recycling box, a conduit connecting the heating furnace and the binder recycling box, and a vacuum system. The invention also discloses a method for sintering the tantalum briquette by loading the tantalum briquette mixed with the binder into the heating furnace, evacuating and heating the tantalum briquette, recovering the volatilized binder through a binder recovery box, and then continuously heating the tantalum briquette. The capacitor tantalum briquette sintered by the device has low oxygen content, the tantalum anode manufactured by the device has low leakage current and high yield, and the bonding agent can be recycled, so that the device is kept free from pollution, and the environment is purified.
Description
Technical Field
The present invention relates to a method and apparatus for manufacturing tantalum electrolytic capacitors, and more particularly, to an apparatus and method for debinding and sintering compacts pressed from tantalum powder.
Background
A process for preparing electrolytic capacitor from tantalum powder includes such steps as adding adhesive/lubricant (paraffin wax, camphor, glycerin, polypropylene carbonate and stearic acid) in 1-5 wt% of tantalum powder, pressing to become tantalum block with embedded lead wire, removing adhesive, sintering to become porous sintered body, anodizing the porous sintered body with tantalum wire as anode to form dielectric oxide film on internal and external surfaces of said sintered body, and coating to form cathode. The binder is added into the tantalum powder to improve the flowability of the tantalum powder, so that the obtained sintered body has larger porosity; particularly, at the moment of forming and pressing, tantalum powder particles flow at a very high speed, the flowability of the tantalum powder is very important, and the pores at each part of a sintered body can be uniform due to good flowability, so that the phenomenon of closed pores cannot be generated. If the tantalum briquette with the binder is directly sintered by the existing heating furnace, the structure of the heating furnace is complex, a plurality of layers of heat preservation screens are arranged, the furnace shell is filled with cooling water, the temperature of the inner wall of the furnace shell and the heat preservation screens close to the furnace shell is low, the binder volatilized from the tantalum briquette when the briquette is heated is condensed on the furnace wall, the heat preservation screens and other components with low temperature, so that the sintered body is polluted, and if a vacuum pump is used for evacuating, gas containing binder particles passes through the vacuum pump, so that the vacuum pump oil is seriously polluted, even the components of the vacuum pump are damaged, and the vacuum degree of the system cannot be removed, therefore, the tantalum briquette is usually subjected to binder removal by special equipment and then is put into a high-vacuum sintering furnace for vacuum sintering after being taken out of the furnace. Thus, the material is wasted, and the oxide film on the surface of the tantalum powder particles is broken twice after the surface of the tantalum powder is subjected to vacuum high temperature to the atmospheric room temperature twice, so that a thicker oxide film is formed, the oxygen content of the tantalum powder sintered body is high, the leakage current of the manufactured capacitor is increased, and the voltage resistance is poor.
US5470525 discloses a technique for removing binder by washing tantalum briquettes with 50-200 ° f water and detergent, however, this technique cannot completely remove the binder in the tantalum briquettes (only 95%) and, in the process of removing the binder by washing the tantalum briquettes with water, some of the tantalum briquettes may lose their edges and corners and even break, and some of the tantalum wire leads may loosen, which affects the yield.
CN105931843 discloses placing a tantalum briquette into a vacuum drying oven filled with a degreasing agent; then carrying out low-temperature wet catalytic degreasing; and then the tantalum metal anode placed in the vacuum drying oven is circularly degreased for more than 3 times and then is subjected to vacuum drying to remove the binder, and the method needs to consume more degreasing agents and has long treatment time.
CN210435361U discloses a method for removing binder and sintering in the same furnace, however, when the binder in tantalum briquette is removed by heated circulating gas, under the condition of inert gas blowing, the device still deposits many pollutants generated by the binder on the furnace wall, heat-insulating screen, pipeline and other components in the furnace, so that the device is cleaned and replaced frequently, and the vacuum system is polluted; and the binder removal under the inert gas condition is not beneficial to the binder removal under the vacuum condition, the binder removal at low temperature is not clean, and carbon elements can permeate into tantalum lattices during high-temperature sintering, thereby seriously reducing the quality of tantalum sintered blocks.
Since the prior art has the problem that debinding and sintering of tantalum briquettes cannot be performed in the same furnace, it is desirable in the art to design an apparatus that allows debinding and sintering to be performed in one apparatus.
Disclosure of Invention
In view of the problems of the prior art, it is an object of the present invention to provide an apparatus and method for debinding and then sintering tantalum briquettes.
It is another object of the present application to provide a device and method for debinding adhesives more thoroughly.
Another object of the present invention is to provide a device and method that is less likely to contaminate the instrument.
It is an object of the present invention to provide a device that can recycle adhesive.
One or more of the above objects are achieved by the respective solutions described below.
The device for debinding and sintering the tantalum briquette of the present invention comprises:
heating furnace;
a binder recovery tank;
a conduit connecting the heating furnace and the binder recovery tank; and
the system is evacuated.
In one embodiment, the heating furnace includes: the furnace comprises a furnace barrel, a furnace bottom connected with the lower part of the furnace barrel, and a furnace cover connected with the upper part of the furnace barrel.
In one embodiment, the furnace cylinder comprises multiple concentric metal cylinders of different diameters, and the furnace cover and furnace bottom are multiple metal circular plates.
In one embodiment, the furnace barrel, the furnace bottom and the outermost layer of the furnace cover all comprise water-cooling jackets, and the water-cooling jackets are provided with a cooling water inlet pipe and a cooling water outlet pipe; the inner side of the water-cooling jacket is provided with at least two layers of communicated and evacuable sealed jackets, and the sealed jackets are provided with evacuation pipes.
In one embodiment, a heat-insulating screen, a heater and a material rack arranged in the heater are arranged in the furnace cylinder from outside to inside in sequence, the material rack is used for placing a crucible, tantalum briquettes are loaded into the crucible, and the crucible is evacuated, heated and debindered and sintered.
In one embodiment, the heater is selected from a cylindrical heater.
In one embodiment, said conduit connecting said heating furnace and said binder recovery tank is a sealed jacketed conduit consisting of multiple layers of concentric metal tubes, said conduit being provided with an evacuation conduit to the jacket; the outer side of the conduit is provided with a heat preservation sponge.
In one embodiment, the adhesive recovery tank includes:
a box body;
a heat exchanger;
a flow guide screen;
a binder collection tank; and
a lifting device.
The box body comprises a cylinder with a cooling water jacket, a box cover connected with the upper end of the cylinder, and a box bottom connected with the lower end of the cylinder and provided with the cooling water jacket. An exhaust pipeline is arranged on the side surface of the cylinder; the exhaust pipe can be respectively connected with a high vacuum pump and a low vacuum pump by valves. The box cover is provided with an opening which is connected with the heating furnace through the guide pipe.
In one embodiment, the base is removably attached to the tank.
Wherein, the heat exchanger is arranged in the cylinder and is selected from metal spiral tubes, two ends of the heat exchanger extend out of the box cover, the adhesive flows into the adhesive recovery box and contacts with the outer wall of the heat exchanger, and the adhesive is cooled and condensed.
The diversion screen extends downwards from the inner wall of the upper part of the box body, is large at the top and small at the bottom, and forms a horn shape.
In one embodiment, an upper portion of the deflector wraps around at least a portion of the heat exchanger.
In one embodiment, at least a portion of the lower portion of the deflector extends into the adhesive collection tank.
In one embodiment, a baffle ring is arranged on the inner wall of the box body close to the upper part, and the outer side surface of the upper edge of the flow guide screen is tightly attached to the baffle ring. And leading the airflow containing the adhesive to completely flow downwards from the inner side of the flow guide screen to the lower end, leading the airflow containing the adhesive to meet the heat exchanger and be rapidly condensed to flow into the adhesive collecting tank, and leading the residual gas to flow out of the exhaust pipe upwards from the slits on the outer side of the flow guide screen and the inner side of the collecting tank.
The lifting device supports the box bottom and the binder collecting tank, and after the tantalum briquette binder removal and sintering procedure is finished and the tantalum briquette is discharged from the furnace, the lifting device can be used for lowering the box bottom plate, taking out the collecting tank and recovering the binder.
In another aspect, the present application provides a binder apparatus for recovering a binder volatilized from a tantalum briquette during heating.
The binder recycling bin comprises:
a box body;
a heat exchanger;
a flow guide screen;
a binder collection tank; and
a lifting device.
The box body comprises a cylinder with a cooling water jacket, a box cover connected with the upper end of the cylinder, and a box bottom connected with the lower end of the cylinder and provided with the cooling water jacket. An exhaust pipeline is arranged on the side surface of the cylinder; and the exhaust pipeline is respectively connected with the high vacuum pump and the low vacuum pump through valves.
In one embodiment, the box cover is provided with an opening for connecting with a heating furnace.
In one embodiment, the base is removably attached to the tank.
Wherein, the heat exchanger is arranged in the cylinder and is selected from metal spiral tubes, two ends of the heat exchanger extend out of the box cover, the adhesive flows into the adhesive recovery box and contacts with the outer wall of the heat exchanger, and the adhesive is cooled and condensed.
The diversion screen extends downwards from the inner wall of the upper part of the box body, is large at the top and small at the bottom, and forms a horn shape.
In one embodiment, an upper portion of the deflector wraps around at least a portion of the heat exchanger.
In one embodiment, at least a portion of the lower portion of the deflector extends into the adhesive collection tank.
In one embodiment, a baffle ring is arranged on the inner wall of the box body close to the upper part, and the outer side surface of the upper edge of the flow guide screen is tightly attached to the baffle ring. And leading the airflow containing the adhesive to completely flow downwards from the inner side of the flow guide screen to the lower end, leading the airflow containing the adhesive to meet the heat exchanger and be rapidly condensed to flow into the adhesive collecting tank, and leading the residual gas to flow out of the exhaust pipe upwards from the slits on the outer side of the flow guide screen and the inner side of the collecting tank.
The lifting device supports the box bottom and the binder collecting tank, and after the tantalum briquette binder removal and sintering procedure is finished and the tantalum briquette is discharged from the furnace, the lifting device can be used for lowering the box bottom plate, taking out the collecting tank and recovering the binder.
In another aspect, the present invention provides a method of debinding and sintering a tantalum briquette comprising the steps of:
1) loading a plurality of discs of crucibles filled with tantalum briquettes and a material rack into a heating furnace, closing a cooling water path of a furnace cylinder, a furnace bottom and a furnace cover of the heating furnace, and starting to evacuate a heating furnace system; starting to evacuate a sealed jacket of a furnace barrel, a furnace bottom, a furnace cover and a guide pipe of the heating furnace;
2) when the pressure in the furnace is lower than 5 x 10－2Pa; opening a box bottom and a box body cooling water valve of the binder recovery box, opening a heat exchanger cooling water circulation, closing a high vacuum valve, opening a low vacuum valve to evacuate, starting a heating furnace to electrify and heat up to 350 +/-50 ℃ (for example, 350 +/-40 ℃, 350 +/-30 ℃, 350 +/-20 ℃, 350 +/-10 ℃ and any temperature value in the ranges), preserving heat for 60-150 minutes, closing the low vacuum valve, opening the high vacuum valve to evacuate, and continuing to heat up;
3) when the temperature reaches 600 ℃. + -. 50 ℃ (for example 600 ℃. + -. 40 ℃, 600 ℃. + -. 30 ℃, 600 ℃. + -. 20 ℃, 600 ℃. + -. 10 ℃, and any temperature value within these ranges)), the cooling water valves of the furnace tube, the furnace bottom and the furnace cover of the heating furnace are opened to circulate the cooling water until the pressure in the heating furnace is lower than 5X 10－2Pa, heating to 1000-2100 ℃, and preserving heat for 10-120 minutes;
4) cutting off power and cooling to 30 ℃ or below, and passivating the tantalum sintered body;
5) opening the heating furnace, and taking out the material rack filled with the tantalum billets;
6) and (4) opening the box bottom of the binder recovery box, lowering the lifting device, and taking out the binder in the binder collection tank.
In the present invention, the binder is selected from one or more of paraffin, camphor, glycerin, polypropylene carbonate and stearic acid.
Effects of the invention
The device for debinding and sintering the tantalum briquette provided by the invention has the advantages that the sintered body obtained by the method has lower oxygen content, the leakage current of the capacitor is lower, and the yield is high.
2. The invention carries out binder removal and sintering on the tantalum briquette in the same furnace, thereby saving energy; the adhesive is recycled, so that the production cost is saved.
3. The invention can recover the binder component released during heating, thus reducing the pollution to the vacuum system and the environment.
Drawings
FIG. 1 is a schematic diagram of an apparatus for debinding and sintering tantalum briquettes in accordance with a preferred embodiment of the present invention.
Description of the reference numerals
100 heating furnace 110 hearth 111 hearth cooling water inlet pipe 112 hearth cooling water outlet pipe 113 hearth sealing type jacket evacuation pipe 114 argon gas inlet pipe 115 hearth sealing type jacket 116 air inlet pipe 118 hearth water cooling jacket 120 barrel 121 hearth cooling water inlet pipe 122 hearth cooling water outlet pipe 123 hearth sealing type jacket evacuation pipe 125 hearth sealing type jacket 128 hearth cooling water jacket 130 hearth cooling water inlet pipe 132 hearth cooling water outlet pipe 133 hearth sealing type jacket 135 hearth cooling water inlet pipe 132 hearth cooling water outlet pipe 133 hearth sealing type jacket 136 pressure gauge 138 hearth water cooling jacket 139 air release valve 170 cylinder type heat preservation screen 171 upper heat preservation screen 13 heater 15 temperature probe 16 rack 18 tantalum billet 19 crucible 200 conduit 210 heating furnace and conduit connection flange 230 binder recovery box and conduit connection flange 23 conduit jacket evacuation pipe 24 heat preservation sponge 25 conduit sealing type jacket 300 conduit Lifting device for adhesive 38 in adhesive recovery tank 310, tank bottom 311, tank bottom cooling water inlet pipe 312, tank bottom cooling water outlet pipe 320 cylinder 321 cylinder cooling water inlet pipe 322 cylinder cooling water outlet pipe 324 high vacuum valve 325 low vacuum valve 326 adhesive recovery tank exhaust pipe 330, tank cover 331, heat exchanger coolant inlet pipe 332, coolant outlet pipe 333 heat exchanger 328 baffle ring 329 flow guide screen 35, adhesive collection tank 36
Detailed Description
The effectiveness and advantages of the present invention and method are further illustrated by the following non-limiting examples. The invention is further illustrated by the following preferred examples.
In this application, the unit ppm refers to "parts per million" expressed in terms of mass ratio, unless explicitly stated otherwise.
In the present application, "about" is about 5% above or below the range value.
In this application, the singular forms "a", "an" and "the" are intended to include the plural forms as well.
In this application, when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. Or connected in some state, e.g., contact, and unconnected in some state, e.g., no contact; or always connected.
In the present application, the terms "vertical", "up", "down", "left", "right" and the like are used for illustrative purposes and do not represent unique embodiments.
In this application, expressions "greater than", "less than", "lower", "above", "below" or similar ranges encompass the instant numbers.
In the present application, when an element is referred to as being "secured to," "disposed on," or "disposed on" another element, it can be directly on the other element or intervening elements may also be present.
In the application, the oxygen content of tantalum powder was analyzed using an LECO oxygen determinator.
In the method of the present application, known techniques, such as various method techniques disclosed in chinese patent nos. CN106955996, CN107052329 and CN106964772, which are incorporated herein by reference in their entirety, can be used.
Fig. 1 is an apparatus for debinding and sintering tantalum briquettes, according to an exemplary embodiment of the present invention, comprising a heating furnace 100, a binder recovery tank 300, a duct 200 connecting the heating furnace 100 and the binder recovery tank 300, and an evacuation system (not shown in the drawings) having a high vacuum pump and a low vacuum pump for evacuating the heating furnace, the duct, and the binder recovery tank, and a sealed jacket evacuation low vacuum pump for the furnace vessel, the furnace bottom, the furnace lid, and the duct. High vacuum pumps such as diffusion pumps, booster pumps, and the like, plus low vacuum pumps; the low vacuum pump comprises a mechanical pump, a roots pump and the like.
The heating furnace 100 mainly includes: a furnace tube 120 with a water-cooling jacket, a furnace bottom 110 connected with the lower part of the furnace tube 120 and a furnace cover 130 connected with the upper part of the furnace tube 120; the furnace tube 120 is composed of a plurality of layers of concentric metal cylinders with different diameters, the outermost edge is a furnace tube water-cooling jacket 128, and the furnace tube water-cooling jacket 128 is provided with a furnace tube cooling water inlet pipe 121 and a furnace tube cooling water outlet pipe 122; the inner side of the furnace cylinder water-cooling jacket is provided with at least two layers of furnace cylinder sealing jackets 125 which are communicated and can be evacuated, and the furnace cylinder sealing jackets 125 are provided with furnace cylinder sealing jacket evacuation pipes 123; the furnace bottom 110 consists of a plurality of layers of metal round plates, the outermost edge of the furnace bottom is provided with a furnace bottom water-cooling jacket 118, at least two layers of furnace bottom sealed jackets 115 which are communicated and can be evacuated are arranged in the furnace bottom water-cooling jacket 118, and the furnace bottom sealed jackets 115 are provided with furnace bottom inner sealed jacket evacuation pipes 113; the furnace cover 130 is composed of a plurality of layers of metal round plates, the outermost edge is a furnace cover water cooling jacket 138, and the furnace cover water cooling jacket 138 is provided with a furnace cover cooling water inlet pipe 131 and a furnace cover cooling water outlet pipe 132; at least two communicated furnace cover sealing type jackets 135 which can be evacuated are arranged in the furnace cover water cooling jacket 138; the furnace cover sealing type jacket 135 is provided with a furnace cover sealing type jacket evacuation pipe 133; the jacket has good heat insulating effect, and only the innermost layer is exposed to the heating furnace, and the temperature of the jacket is not so low during heating, so that the adhesive is not easily deposited thereon.
A cylindrical heat preservation screen 170, a lower heat preservation screen 171 of the furnace bottom and an upper heat preservation screen 172 covering the upper part of the cylindrical heat preservation screen 170 are arranged in the furnace cylinder 120 and on the furnace bottom, the heat preservation screens are close to the heater 13, have higher temperature, are generally respectively provided with two or more layers and are made of refractory metals; a cylindrical heater 13 (preferably cylindrical) is provided in the furnace tube 120, and is generally made of refractory metal sheet or wire, and is a resistance heater, electrically insulated from the furnace bottom, and cooled by cooling water; a rack 16 and a crucible 19 are placed in the heater 13, the crucible 19 is generally made of tantalum material to avoid contamination, the tantalum briquette 18 is loaded into the crucible 19, and the crucible 19 is evacuated to remove the binder and sinter the briquette. At least one temperature probe 15, such as a thermocouple, is provided in the furnace vessel to measure the temperature of the tantalum briquette, preferably a plurality of temperature probes to measure the temperature of the tantalum briquette at different locations, preferably near the tantalum briquette to measure the true temperature of the tantalum briquette. The furnace cylinder water-cooling jacket is provided with a furnace cylinder cooling water inlet pipe 121 and a furnace cylinder cooling water outlet pipe 122 for introducing circulating water for cooling when the tantalum capacitor is sintered; the furnace cylinder sealing type jacket evacuation pipe 123 is arranged on the outer side of the furnace cylinder and is used for evacuating the furnace cylinder sealing type jacket 125; a furnace bottom cooling water inlet pipe 111 and a furnace bottom cooling water outlet pipe 112 are arranged on the outer side of the furnace bottom 110, and circulating water is introduced for cooling when the tantalum capacitor is sintered; the furnace bottom 110 is provided with a furnace bottom sealed jacket evacuation pipe 113 for evacuating the furnace bottom sealed jacket 115; a furnace cover cooling water inlet pipe 131 and a furnace cover cooling water outlet pipe 132 are arranged on the outer side of the furnace cover 130, and circulating water is introduced to cool the furnace cover 130 when the tantalum capacitor is sintered; the furnace cover 130 is provided with a furnace cover sealing type jacket evacuation pipe 133 for evacuating the furnace cover sealing type jacket 135. The furnace cover 130 is provided with a pressure gauge 136 for measuring the pressure in the system. A vent valve 139 is preferably provided in the furnace lid 130.
The size and shape of the furnace is not particularly limited, and generally depends on the amount of material to be treated.
The invention tantalum briquette binder removing and sintering device, wherein a guide pipe 200 and the heating furnace 100 are connected with a heating furnace and guide pipe connecting flange 210, and the binder recycling box 300 is connected with a binder recycling box and guide pipe connecting flange 230, the guide pipe is bent downwards in an arc shape, the guide pipe 200 is a sealed jacket consisting of two layers of concentric metal pipes and is provided with a guide pipe jacket evacuation pipe 23; the insulating sponge 24 is provided outside the connecting duct 200 so that the adhesive component in the air flow is hardly deposited on the duct wall.
According to a preferred embodiment of the present invention, the adhesive recovery tank 300 comprises a tank body, a spiral tubular heat exchanger 333, a trumpet-shaped baffle 329 having a large upper part and a small lower part, an adhesive collection tank 35, a lifting device 38; the box body comprises a cylinder 320 with a cooling water jacket, a box cover 330 connected with the upper end of the cylinder 320 and a box bottom 310 with a cooling water jacket connected with the lower end of the cylinder 320 through screws; the side of the cylinder is provided with a binder recovery box exhaust pipe 326; the binder recycling box exhaust pipe 326 is respectively connected with a high vacuum pump or a low vacuum pump through a high vacuum valve 324 and a low vacuum valve 325; the heat exchanger 333 is a metal spiral pipe arranged in the cylinder, the heat exchanger coolant inlet pipe 331 and the heat exchanger coolant outlet pipe 332 extend out of the box cover 330, preferably made of metal with good heat conductivity, such as red copper, pure nickel or stainless steel, and the like, and have a certain length, the solenoid has a large surface area, the shape is large at the top and small at the bottom, the distance between the outer contour and the inner wall of the flow guide screen is about 3-8 cm, and the coolant flows through the heat exchanger to cool the binder and condense; a baffle ring 328 is arranged on the inner wall of the cylinder 320 close to the upper part, the upper edge of the flow guide screen 329 is tightly attached to the baffle ring 328, the flow guide screen has a taper of about 10-15 degrees, the outer side surface of the baffle ring is welded on the inner side of the cylinder, and the inner side of the baffle ring has the same taper as the flow guide screen; the baffle plate makes the air flow containing the adhesive all flow downwards from the inner side of the baffle plate 329 to the lower end, and then flows out from the exhaust pipe 326 of the adhesive recovery box from the slit between the outer side of the baffle plate 329 and the inner side of the adhesive collecting tank 35 upwards, so that the adhesive steam volatilized from the vacuum heating furnace is rapidly condensed and flows into the adhesive collecting tank 35, and the side surface of the adhesive collecting tank has a taper of about 8-15 degrees; the lifting device 38 supports the box bottom 310 and the binder collection tank 35, and after the tantalum briquette binder removal and sintering procedure is completed and the tantalum briquette is discharged from the furnace, the lifting device 38 can be used for lowering the box bottom plate, taking out the binder collection tank 35 and recovering the binder 36.
Example 2
Performing an experiment by using tantalum powder with the oxygen content of 2200ppm and the nominal specific volume of 30000 mu FV/g, using stearic acid as a binder, dissolving the stearic acid in ethanol, adding a stearic acid binder solution with the mass of 3 percent of the tantalum powder into the tantalum powder, uniformly stirring, drying in a vacuum box, embedding tantalum wires with the diameter of 0.19mm into the tantalum wires with the weight of 150mg of each briquette powder, and pressing into the tantalum wires with the diameter of about 3mm and the height of about 4.25mmThe briquette of (1), the briquette density being about 5.0g/cm3The tantalum briquettes thus obtained were divided into two parts, one part was used in example 1 and the other part was used in comparative example 1.
According to the apparatus shown in FIG. 1, a part of the above-mentioned pressed tantalum briquette is loaded into a crucible 19, the crucible together with the tantalum briquette is loaded on a rack 16, the rack 16 is placed on a furnace bottom 110 at the center of a heating furnace, a temperature measuring thermal probe 15 such as a thermocouple is placed so that the probe is close to the tantalum briquette, a heat insulating screen 172 is covered, a furnace lid 130 is covered, and the measuring electrode is well insulated from the furnace body; the argon inlet pipe 114 is closed, the air inlet pipe 116 is closed, and the air release valve 139 is closed; closing the valve of the furnace cooling water inlet pipe 121; closing a valve of the furnace bottom cooling water inlet pipe 111; closing a valve of the furnace cover cooling water inlet pipe 131; opening the valve of the cylinder cooling water inlet pipe 321 of the binder recovery tank 300; opening a valve of a cooling water inlet pipe 311 at the bottom of the box; opening the furnace cylinder sealed jacket valve 123, and evacuating the furnace cylinder sealed jacket 125 of the heating furnace; opening a valve of the furnace bottom sealed jacket 113, and evacuating the furnace bottom sealed jacket 115; opening a furnace cover sealing type jacket valve 133, and evacuating a furnace cover sealing type jacket 135; the catheter clamp evacuation tube 23 is opened and the catheter seal clamp 25 is evacuated. The roughing pump is started and the roughing valve 325 is opened to evacuate the furnace system (at which time the high vacuum diffusion pump is preheated in advance).
When the pressure in the furnace is lower than 8 x 10－1Pa, opening high vacuum valve 324, closing low vacuum valve 325, and continuing to evacuate when the pressure is lower than 8X 10－3Pa, closing the high vacuum valve 324, opening the low vacuum valve 325, electrifying the heating furnace to raise the temperature, and immediately raising the pressure in the furnace along with the temperature rise, wherein the temperature rise speed is not particularly limited, generally 10 ℃/min-30 ℃/min, the time is not too long in the low temperature, and the temperature is raised to 350 ℃ for 120 minutes.
When the pressure in the furnace is lower than 8 x 10－1Pa, opening a high vacuum valve, closing a low vacuum valve, and continuing to heat;
when the temperature reaches 600 ℃, a valve of the furnace barrel cooling water inlet pipe 121 is opened; opening a valve of the furnace bottom cooling water inlet pipe 111;opening a valve of a furnace cover cooling water inlet pipe 131 to circulate cooling water; heating to 1460 deg.C, maintaining for 20 min, and stopping heating; finally the vacuum degree reaches 5 multiplied by 10－2Pa。
The power cut cooling and passivation can be performed according to the prior art, for example, when the temperature in the furnace is reduced to 200 ℃, the furnace cavity is stopped from being evacuated, the valve of the argon inlet pipe 114 at the bottom of the furnace is opened, the pressure in the furnace is slightly greater than 0.1MPa, for example, the pressure is 0.101MPa, the vent valve 139 on the furnace cover is opened, and the argon is circulated to cool the tantalum sintered body. Preferably, the argon gas introduced into the sintering furnace is cooled to 0 ℃ to-40 ℃ before entering the furnace body.
At this time, the evacuation of the furnace bottom sealing type jacket 115, the furnace shell sealing type jacket 125, the furnace lid sealing type jacket 135 and the guide pipe sealing type jacket 25 is stopped. The high vacuum valve 324 is closed and the evacuation pump is turned off.
When the temperature of the tantalum sintering compact in the furnace is reduced to 30 ℃, a valve of an air inlet pipe 116 at the bottom of the furnace is opened for passivation treatment.
And after the passivation treatment is finished, opening a heating furnace cover, taking out the material rack containing the tantalum billets, and screening the material rack without finding damaged tantalum billets.
And (4) opening the box bottom of the binder recovery box, lowering the lifting device, and taking out the binder in the binder collection tank.
At this time, all the cooling water valves, such as the valves of the furnace bottom cooling water inlet pipe 111, the furnace cover cooling water inlet pipe 121, the furnace cover cooling water inlet pipe 131, the tank bottom cooling water inlet pipe 311, the cylinder cooling water inlet pipe 321, and the heat exchanger coolant inlet pipe 331, are closed.
Subjecting the sintered cake to oxygen content analysis and electrical property detection respectively, wherein the electrical property detection is to anodize at 100V constant voltage for 2 hours in 0.1% (Vol) phosphoric acid solution at about 80 ℃ to form an electrolytic capacitor anode, the anode is obtained by applying 70V voltage in 10 (Vol)% phosphoric acid solution at about 21 ℃, and the charging time is 120 seconds to measure the leakage current; at 18% H2SO421 ℃, 2.5V DC bias, 120HZ capacity and loss; the breakdown voltage was measured at a voltage increase rate of 80mA/g in a 0.1 (vol)% aqueous phosphoric acid solution, and the results of the electrical properties are shown in TableIn 1, the reject ratio in the table means the sum of the numbers of rejected capacity and leakage current divided by the total number of rejected capacity and leakage current.
Comparative example 1
The tantalum briquettes pressed simultaneously under the same conditions as in example 1 were first heated to 350 ℃ under vacuum and then heat-preserved for 2 hours to remove the binder, taken out of the furnace, and then charged into a vacuum sintering furnace, heated to 1460 ℃ and heat-preserved for 20 minutes, and then cooled, passivated as in example 1, and then discharged, and the tantalum briquettes were simultaneously subjected to oxygen content analysis and electrical property detection under the same conditions as in example 1, and the results are shown in table 1.
TABLE 1 tantalum briquette electrical results
As can be seen from the data in Table 1, the sintered compacts obtained according to the present invention have lower oxygen content, lower leakage current, better voltage resistance and higher yield than those obtained by the prior art.
In the method for removing the adhesive and sintering the tantalum briquette by adopting the device or the method, the furnace barrel, the furnace bottom and the furnace cover are not communicated with cooling water before 600 ℃, the innermost layer of the sealed jacket is exposed in the furnace atmosphere, the temperature is higher, adhesive volatile matters are not easy to deposit on the surface of the sealed jacket under the evacuation condition, even a little adhesive is deposited, when the temperature is continuously increased, the temperature is over 600 ℃, even the cooling water of the furnace is opened, the little deposited adhesive is evacuated and taken away along with the temperature increase, and the device or the method is different from the prior device, and the adhesive can be deposited on the inner wall of the furnace, a heat insulation screen close to the cooling water and other parts.
It should be noted that the sintering furnace provided in the embodiments of the present application may not only be used for sintering tantalum briquettes, but also be used for sintering various briquettes containing a binder of tantalum alloy, niobium, tungsten, or an alloy thereof, such as a biological implant, where the binder is removed in another device and then the biological implant is transferred to the sintering furnace for sintering; it is also suitable for the heat treatment of tantalum powder added with a binder.
Claims (10)
1. An apparatus for sintering and debinding tantalum briquettes, comprising:
heating furnace;
a binder recovery tank;
a conduit connecting the heating furnace and the binder recovery tank; and
the system is evacuated.
2. The apparatus of claim 1, wherein said furnace comprises: a furnace barrel, a furnace bottom and a furnace cover;
the furnace cylinder comprises a plurality of layers of concentric cylinders with different diameters, and the furnace cover and the furnace bottom are both multilayer circular plates;
preferably, the outermost layers of the furnace barrel, the furnace bottom and the furnace cover comprise water-cooling jackets; more preferably, the water-cooling jacket is provided with a cooling water inlet pipe and a cooling water outlet pipe;
preferably, at least two layers of sealing type jackets which can be evacuated are communicated with each other and arranged at the inner side of the water-cooling jacket; preferably, the sealed jacket is provided with an evacuation pipe;
preferably, a heat preservation screen, a heater and a material rack are arranged in the furnace cylinder.
3. The device of claim 2, wherein said catheter is selected from the group consisting of a sealed jacketed catheter consisting of multiple layers of concentric tubes;
preferably, the sealed jacket conduit is provided with an evacuation tube;
preferably, the outside of the catheter is covered with a heat-insulating sponge.
4. The apparatus of claim 1, wherein the adhesive recovery tank comprises a housing, a heat exchanger, a baffle, an adhesive collection tank, and a lifting device.
5. The apparatus of claim 4, wherein the housing comprises a housing cover, a cooling water jacketed cylinder, and a housing bottom with a cooling water jacket;
preferably, the tank bottom is detachably connected with the cylinder;
preferably, the side surface of the cylinder is provided with an exhaust pipe; the exhaust pipe can be respectively connected with a high vacuum pump and a low vacuum pump through valves;
preferably, the box cover is provided with an opening which can be connected with the heating furnace through the conduit.
6. The apparatus of claim 4, wherein said heat exchanger is a spiral coil having opposite ends extending from said cover;
preferably, the flow guide screen is in a horn shape with a large upper part and a small lower part;
preferably, the upper portion of the deflector screen wraps at least a portion of the heat exchanger;
preferably, at least a portion of the lower portion of the flow guide screen extends into the adhesive collection tank;
preferably, a baffle ring is arranged on the inner wall of the cylinder close to the upper part, and the upper edge of the flow guide screen is tightly attached to the baffle ring;
preferably, the lifting device supports the tank bottom.
7. A binder recycling box comprises a box body, a heat exchanger, a flow guide screen, a binder collecting tank and a lifting device.
8. The adhesive recovery tank of claim 7, wherein the tank body comprises a tank cover, a cylinder with a cooling water jacket, and a tank bottom with a cooling water jacket;
preferably, the tank bottom is detachably connected with the cylinder;
preferably, the side surface of the cylinder is provided with an exhaust pipe; the exhaust pipe can be respectively connected with a high vacuum pump and a low vacuum pump through valves;
preferably, the box cover is provided with an opening which can be connected with the heating furnace through a conduit.
9. The adhesive recovery bin of claim 7, wherein said heat exchanger is a helical coil having opposite ends extending from said lid;
preferably, the flow guide screen is in a horn shape with a large upper part and a small lower part;
preferably, the upper portion of the deflector screen wraps at least a portion of the heat exchanger;
preferably, at least a portion of the lower portion of the flow guide screen extends into the adhesive collection tank;
preferably, a baffle ring is arranged on the inner wall of the cylinder close to the upper part, and the upper edge of the flow guide screen is tightly attached to the baffle ring;
preferably, the lifting device supports the tank bottom.
10. A method for sintering a tantalum briquette using the apparatus of any one of claims 1 to 6, comprising the steps of:
1) the crucible filled with the tantalum briquette and the material rack are loaded into a heating furnace, a cooling water path of a furnace cylinder, a furnace bottom and a furnace cover of the heating furnace is closed, and the sealed jackets of the furnace cylinder, the furnace bottom, the furnace cover and the guide pipe are evacuated; starting to evacuate the heating furnace system;
2) when the heating furnace system is pumped down to the pressure lower than 5 x 10 < -2 > Pa; opening a box bottom and a box body cooling water valve of a binder recovery box, opening a heat exchanger cooling water inlet valve and a heat exchanger cooling water outlet valve, closing a high vacuum valve, opening a low vacuum valve to evacuate, opening a heating furnace to be electrified and heated, heating to 350 +/-50 ℃, preserving heat for 60-150 minutes, closing the low vacuum valve, opening the high vacuum valve to evacuate, and continuing heating;
3) when the temperature reaches 600 +/-50 ℃, opening cooling water valves of a furnace barrel, a furnace bottom and a furnace cover of the heating furnace to circulate cooling water until the pressure in the heating furnace is lower than 5 multiplied by 10 < -2 > Pa, and then heating to 1000-2100 ℃ for heat preservation for 10-120 minutes;
4) cutting off power and cooling to 30 ℃ or below, and passivating the tantalum sintered body;
5) opening the heating furnace, and taking out the material rack filled with the tantalum billets;
6) and (4) opening the box bottom of the binder recovery box, lowering the lifting device, and taking out the binder in the binder collection tank.
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| CN202010571005.5A CN112276079B (en) | 2020-06-22 | 2020-06-22 | Device and method for sintering tantalum briquette and removing binder |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114589306A (en) * | 2021-11-20 | 2022-06-07 | 蓝山县金山川粉末冶金有限公司 | Powder metallurgy degreasing and oil discharging system |
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| CN210632944U (en) * | 2019-07-30 | 2020-05-29 | 上海富驰高科技股份有限公司 | Vacuum sintering waste gas treatment device for metal powder injection molding product |
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| US4059442A (en) * | 1976-08-09 | 1977-11-22 | Sprague Electric Company | Method for making a porous tantalum pellet |
| CN202072753U (en) * | 2011-03-23 | 2011-12-14 | 宁夏东方钽业股份有限公司 | Tantalum metal surface inactivating equipment with argon forced cooling device |
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| CN114589306B (en) * | 2021-11-20 | 2023-08-29 | 蓝山县金山川粉末冶金有限公司 | Powder metallurgy degreasing and oil discharging system |
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