CN103002612A - Built-in porous heater - Google Patents
Built-in porous heater Download PDFInfo
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- CN103002612A CN103002612A CN2011102788010A CN201110278801A CN103002612A CN 103002612 A CN103002612 A CN 103002612A CN 2011102788010 A CN2011102788010 A CN 2011102788010A CN 201110278801 A CN201110278801 A CN 201110278801A CN 103002612 A CN103002612 A CN 103002612A
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Abstract
The invention discloses a built-in porous heater. An integrated heating core is formed by circularly penetratingly winding a helical heating unit in a heating unit framework which is formed by closely arranging seven porous boron nitride tubes. The integrated heating core and a transitional leading out component are packaged in an armored casing and kept insulated from the shell. The heating body is connected with an outer lead line via a transition line, the transition line is in insulation protection with a joint of the outer lead line, and the joint, a thin tail end of a reducer tube and the outer lead line are fixedly sealed in a leading out section, so that integration between a heating element and a propelling chamber is realized. The built-in porous heater is applicable to heat control of an attitude and rail control propelling system for aerospace crafts, propellant medium utilized by an electric heating propeller passes through the built-in porous heater to directly contact with meshed porous electric heating materials so as to be heated up quickly, and the integrated heating core is high in heat exchange efficiency and low in power density. Electric heating performance, insulating performance and assembly performance of the built-in porous heater can meet requirements of the aerospace department.
Description
Technical field
The present invention relates to the heating element of electric heating thruster inside in the aerospace craft propulsion system, a kind of built-in porous heater that is placed in thruster inside specifically is when propellant medium can be heated rapidly during by the mesh structural porous thermo electric material in the heater.
Background technology
Thruster is the propulsion system actuator that keeps or change aerospace craft orbit and athletic posture.The heating element of electric heating thruster can promote the temperature of propellant on the one hand with the specific impulse of raising thruster, thereby improves the efficient of thruster; On the other hand, some propellant can directly be decomposed behind the electric heating in thruster, exempts to use catalyst, thereby improves the reliability of thruster.Therefore, in the world, no matter be military satellite or commercial satellite, the electric heating thruster all is widely used in miniature propulsion system; In China, the electric heating thruster also is in the development stage.
Heating element in the electric heating thruster is its critical component.A kind of electric heating thruster of Britain SSTL company development is used for lifting track, the heater of its heater that adopts is nickel filament, can be heated to 1000K to propellant medium, but power reaches 100W, volume is also larger, can not satisfy the needs of small electrothermal thruster.SSTL company also tests the heating properties of the integral heater of material with carbon element, when power is 30W, the propellant Xe of 0.09 Grams Per Second can be heated to 210 ℃ from normal temperature, but its heat resisting temperature only is 600 ℃.Built-in porous heater among the present invention, when power was 20W, the central temperature of heater can reach 700 ℃, and it is little to have a volume, and heating surface (area) (HS is large, and efficiency of heating surface advantages of higher can satisfy the requirement of compact low power electric heating thruster.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of built-in porous heater on the electric heating thruster in the aerospace craft propulsion system that is applied to is provided, this heater heat exchange area is large, and power density is low, and volume is little, insulation and good seal performance; Heating element is built-in and realized with thrust chamber integrated.
Technical scheme of the present invention is:
A kind of built-in porous heater comprises that integrated heating core, armouring housing, transition draw assembly, the section of drawing and outer lead;
Described integrated heating core comprises heater and heater skeleton; Heater is the bar shaped helical form, its material is mesh structural porous nichrome or mesh structural porous nichrome aluminum alloy, the heater skeleton is formed through solid matter by seven boron nitride tubes, and described solid matter is specially six roots of sensation periphery boron nitride tube symmetry arrangement centered by a center boron nitride tube; Center boron nitride tube inner axial tube is placed partition, and the two ends of peripheral boron nitride tube have notch, and heater back and forth installs into peripheral boron nitride tube successively through notch; Fix with inorganic glue between boron nitride tube;
Described armouring housing comprises stainless steel cylinder, ring flange and reducer pipe, and stainless steel cylinder and reducer pipe weld together by ring flange, and integrated heating core is encapsulated in the stainless steel cylinder, and the fairlead of transition wire is left at the ring flange center;
The insulating material part that assembly comprises transition wire and compound composition is drawn in described transition, and transition wire is the multiply nichrome wire, and its sectional area is 4～5 times of the true sectional area of heater; The insulating material part of compound composition comprises diplopore boron nitride disk, quartz ampoule, inorganic glue and fine magnesium oxide micro-powder; Diplopore boron nitride disk utilizes inorganic glue to be bonded between integrated heating core and the ring flange, after transition wire one end links to each other with the heater two ends from the porous boron nitride pipe of center the partition both sides draw (insulating between two transition wires guaranteeing), then two holes on diplopore boron nitride disk enter in the reducer pipe, transition wire links to each other with outer lead after drawing reducer pipe, transition wire overcoat quartz ampoule in the reducer pipe, filling inorganic glue and fine magnesium oxide micro-powder in the reducer pipe; Draw in two two holes of transition wire on diplopore boron nitride disk, to guarantee the insulation of heater and armour body.
Transition wire and outer lead tie point adopt high temperature resistant epoxy that it is enclosed in the stainless steel tube admittedly with the reducer pipe end after coating with heat-shrinkable T bush, consist of the section of drawing; Described transition wire is multiply nickel filament (the quality percentage composition 80% of nickel, the quality percentage composition 20% of chromium), and described outer lead is multiply silver-plated copper wire (polyimide film is wrapped).
Described heater is to consist of three-dimensional netted loose structure by the hollow and thin-walled metal rib that is interconnected, and its hole is interconnected, is evenly distributed; Porosity is 90～98%, and aperture size is 90～110PPI; The quality percentage composition of chromium is 18～35% in the described mesh structural porous nichrome; The quality percentage composition of chromium is 18～35% in the described mesh structural porous nichrome aluminum alloy, and the quality percentage composition of aluminium is 2～10%.
Described heater is after porous nickel mesh is processed as the spiral helicine nickel foam of bar shaped, to carrying out vacuum heat after the chromising of the spiral helicine nickel foam employing of bar shaped solid phase chromium implements, obtains mesh structural porous nichrome; Perhaps the spiral helicine nickel foam of bar shaped is adopted the solid phase chromising, carries out vacuum heat after the aluminising again, obtain mesh structural porous nichrome aluminum alloy.
Described boron nitride tube is to utilize laser drilling to make evenly intensive hole at every boron nitride tube wall, and pipe two ends fluting is made; The two ends otch of boron nitride tube is in order to install and fixing heater.
Its hole of described boron nitride tube evenly distributes on the circumference of pipe, and adjacent two round holes are spaced, and namely the center of circle of some holes is arranged on the perpendicular bisector of two hole circle center line connectings the neighbour; The hole gross area is greater than 50% of tube wall area;
The internal diameter of described peripheral boron nitride tube is 3～5mm, and wall thickness is 0.2～0.5mm, and length is 10～15mm; Described center its length of boron nitride tube be peripheral boron nitride tube 4/5ths to 1/2nd between, its thickness is that its internal diameter is identical with peripheral boron nitride tube between a times to two times of peripheral boron nitride tube;
Described partition is the bar shaped boron nitride, and length and the wall thickness with the center boron nitride tube is identical respectively with thickness for its length, and its width is identical with the internal diameter of center boron nitride tube;
Described reducer pipe is comprised of thin-walled reducer pipe and light-wall pipe, and thin-walled reducer pipe and light-wall pipe weld together by connecting ring; Described quartz ampoule is thick single hole quartz ampoule and thin single hole quartz ampoule, the thick single hole quartz ampoule of the part overcoat of transition wire in light-wall pipe, the thin single hole quartz ampoule of the part overcoat of transition wire in the thin-walled reducer pipe; Filling inorganic glue in the light-wall pipe, filling fine magnesium oxide micro-powder in the thin-walled reducer pipe.
After described transition wire is fixed in the light-wall pipe, transition wire is cut off at the place, fold point, every transition wire is split as two strands of transition wires; Connecting ring is enclosed within the joint of light-wall pipe and thin-walled reducer pipe, adopts pulse laser to weld to connecting ring and light-wall pipe lap-joint and connecting ring and thin-walled reducer pipe lap-joint; On four strands of transition wires, put respectively thin single hole quartz ampoule, filling fine magnesium oxide micro-powder in the thin-walled reducer pipe, fixing thin single hole quartz ampoule and transition wire; After transition wire is drawn from the thin-walled reducer pipe, utilize energy-accumulating spot welder that two strands of nickel filaments of every transition wire are welded again at gap.
Described inorganic glue is the silicate refractory inorganic adhesive, and its solid phase composition and liquid phase ingredient mass ratio are 2: 1; Liquid phase ingredient is potassium silicate solution, its modulus ratio SiO
2/ K
2O=4; The solid phase composition is that SiO 2 powder and alumina powder mix the mass ratio of SiO 2 powder and alumina powder 3: 1; The mass ratio of different-grain diameter silicon dioxide is 10 nanometers in the SiO 2 powder: 1000 orders: 600 orders: 400 orders: 200 orders=1: 2: 2.5: 2.5: 2; The mass ratio of different-grain diameter aluminium oxide is 1200 orders in the alumina powder: 40 orders=2: 8.
The boron nitride ring is placed in described integrated heating core lower end, and described ring flange is circular, and there is the step with the welding of stainless steel cylinder upper end in edge; Described stainless steel cylinder upper end open, the lower end has MEDIA FLOW to portal, and has the MEDIA FLOW hand-hole on the barrel.
Described high temperature resistant epoxy is that room temperature placement curing in 24 hours forms after being mixed by epoxy resin, curing agent and fine magnesium oxide micro-powder, and the part by weight of epoxy resin, curing agent and fine magnesium oxide micro-powder is 10: 10: 1, and described curing agent is diethylenetriamine; Described thick single hole quartz ampoule and light-wall pipe are isometric, and its material of described heat-shrinkable T bush is polytetrafluoroethylene.
Above-mentioned built-in porous heater is applied in the used thermal controls apparatus of aerospace craft appearance, rail control thruster.
The built-in porous heater of the present invention, the resistance value of its integrated heating core is determined by resistivity, sectional area and the length of mesh structural porous heater; Its power density is determined by helical form heater diameter, pitch and heater skeleton length, diameter; Its rate of heat exchange is determined by the specific area of mesh structural porous material and the volume of heater.
The stainless steel cylinder is the armour body of integrated heating core, also is the shell of electric heating thruster thrust chamber, and its tail end is that the MEDIA FLOW after heating or the decomposition is portalled, and leaves the technique step that is connected with Laval nozzle; Its front end and ring flange seam have tangential hole on its barrel, as the inflow entrance of propellant, integrated heating core is contained in the stainless steel cylinder, and tail end is separated with the boron nitride ring, is separated with diplopore boron nitride disk near the ring flange end, two transition wires are drawn through the hole, to guarantee the insulation of heater and armour body.With the stainless steel connecting ring light-wall pipe and thin-walled reducer pipe are welded together, transition is drawn assembly and is mounted in it.The design of armouring housing has realized that heating element and thrust chamber are integrated.
The encapsulation technology of the built-in porous heater of the present invention adopts high and low temperature to encapsulate respectively and lengthen the scheme of seal distance.In high temperature section, adopt the inorganic glue sealing between transition wire, diplopore boron nitride disk and armouring housing near the ring flange and filling inorganic glue in the light-wall pipe of stainless steel material; Filling fine magnesium oxide micro-powder in low-temperature zone, thin-walled reducer pipe, and adopt high temperature resistant epoxy that transition wire and thin-walled reducer pipe taper end are sealed admittedly.
Preparation technology's concrete steps of above-mentioned integrated heating core are as follows:
1) preparation of boron nitride tube and boron nitride sheet
Adopt chemical vapour deposition technique at the carbon-point of various outer diameter or the boron nitride tube of carbon plate deposition different-thickness and length, remove in the boron nitride tube or the carbon on the carbon plate with the method for machinery and calcining, obtain boron nitride tube or boron nitride partition;
2) boron nitride tube punching
Determine the parameters such as number, aperture, pitch of holes of length, the hole of peripheral boron nitride tube and center boron nitride tube, set pulse laser machining machine equipment parameter, by the designing requirement punching.
3) cutting of boron nitride tube and boron nitride sheet
The boron nitride tube and the boron nitride sheet that use scribing cut-off machine of many will accomplish fluently hole cut by design size, then clean up.
4) porous boron nitride end surfaces otch
With 7 boron nitride tube close-packed arrays, the center is slightly short boron nitride tube, and each manages the front end face alignment, then ties up fastening with fine wire; With miniature brill according to designing requirement at the upper and lower end face of heat generating core otch, slowly polish during operation, avoid large stretch of boron nitride to come off.Heater skeleton front end face between the first peripheral boron nitride tube to the six peripheral boron nitride tubes across in two the pipe tangent front end face double-walled notch three places that open, be respectively the first peripheral boron nitride tube and the tangent place of the second peripheral boron nitride tube, the 3rd peripheral boron nitride tube and the tangent place of 4th week limit boron nitride tube, the 5th peripheral boron nitride tube and the tangent place of the 6th peripheral boron nitride tube; Heater skeleton rear end face is opened rear end face double-walled notch two places at the second peripheral boron nitride tube and the tangent place of the 3rd peripheral boron nitride tube, 4th week limit boron nitride tube and the tangent place of the 5th peripheral boron nitride tube; Heater skeleton rear end face is opened single wall notch two places at the first peripheral boron nitride tube and the tangent extended spot of center boron nitride tube, the 6th peripheral boron nitride tube and the tangent extended spot of center boron nitride tube.
The preparation of 5) bar shaped helical form heater
Nickel foam sheet material is processed into the bar shaped of required size with numerically controlled wire cutting machine, then be wound up as helical form in thin ceramic tubes, cleaning-drying obtains the spiral helicine nickel chromium triangle of bar shaped or the nickel chromium triangle aluminium heater of three-dimensional netted porous by solid phase chromising (or again aluminising after the chromising), vacuum heat then.
6) heater wear around
Heater penetrates from the first peripheral boron nitride tube rear end, then passes through successively the second peripheral boron nitride tube to the six peripheral boron nitride tubes and front end face double-walled notch, rear end face double-walled notch, passes from the 6th peripheral boron nitride tube rear end at last; The heater two ends penetrate in the boron nitride tube of center through the single wall notch and are drawn by transition wire; Each bending place of bar shaped helical form heater must embed each notch; Be specially: the spiral helicine heater of bar shaped is put into from the first peripheral boron nitride tube rear end, after arriving the first peripheral boron nitride tube front end, enter from the second peripheral boron nitride tube front end again, after arriving the second peripheral boron nitride tube rear end, enter again the 3rd peripheral boron nitride tube, reciprocal successively, from the 6th peripheral boron nitride tube, pass at last, then the heater two ends in the first peripheral boron nitride tube and the 6th peripheral boron nitride tube and two transition wires are welded respectively, then transition wire is drawn from the boron nitride tube of center, guarantee that two pads are in the boron nitride tube of center; When heater entered another root boron nitride tube from a boron nitride tube, its bending place will embed each double-walled notch, and the heater two ends will enter via two single wall notches when entering the center boron nitride tube after transition wire is connected.
7) electricity of heater is drawn
Whole doubling of every transition wire, two end reciprocating folding types that close up the termination are as lap-joint, and the other end is as twining silk; The termination of heater and the lap-joint of transition wire mediate, and adopt impulsed spot welding with twining after silk is fixed; Two transition wires are drawn from the boron nitride tube of center, and partition with two transition wires separately prevents short circuit, and guarantee that tie point is in the boron nitride tube of center.
8) the heater skeleton is fixing
Peripheral six roots of sensation boron nitride tube and the center boron nitride tube worn around heater are cemented and place certain hour curing according to putting in order with the otch position with inorganic glue.
The preparation method of above-mentioned bar shaped helical form heater is: described porous nickel mesh is made through conductive treatment, plating and reduction sintering by polyurethane foam; After porous nickel mesh is processed as slice shape, according to structure and the technical indicator of built-in porous heater, determine coiling spiral shell footpath and pitch, it is wound in helical form, make bar shaped helical form nickel foam.
Nickel foam solid phase chromium implements is powder embedding chromium implements, powder embedding chromium implements is carried out in tube type high-temperature furnace, wherein: 950～1100 ℃ of temperature, temperature retention time 10～60min, form after penetration enhancer is mixed by alumina powder (1200 order), chromium powder (300 order) and ammonium chloride (analyzing pure) and through fully grinding, the weight percent of alumina powder, chromium powder and ammonium chloride is that content is (70～83): (15～25): (2～5).
Described solid phase alitizing is the pack aluminizing method, after the solid phase chromising, carry out again the solid phase aluminising in the spiral helicine nickel foam of bar shaped, the pack aluminizing method is carried out in tube type high-temperature furnace, wherein: 700～800 ℃ of temperature, temperature retention time 10～40min, form after penetration enhancer is mixed by alumina powder (1200 order), alumel (chemical pure) and ammonium chloride (analyzing pure) and through fully grinding, the part by weight of alumina powder, alumel and ammonium chloride is (80～83): 15: (2～5).
When the chromising of described powder investment and aluminising, at first vacuumize 30min with mechanical pump, remove the oxygen in tube type high-temperature furnace, pipeline and the penetration enhancer, pass into again protective gas (pure argon), simultaneously protective gas is carried out deoxygenation and removes water treatment.Adopt the active nickel oxygen scavenger to remove oxygen, adopt the 4A molecular sieve to remove water.When chromising or aluminising penetration enhancer and sample are loaded in quartz ampoule or the alumina tube, seal with high silica cloth or nickel foil at two ends.
Described vacuum heat-treating method is, the sample after chromising or the aluminising is put into vacuum furnace, and vacuum degree is (1～5) * 10
-3Pa, be heated to 1000～1100 ℃ after, the insulation 2～10h, then cool to room temperature with the furnace, obtain mesh structural porous thermo electric material, cooldown rate is determined by material requirements.
Described porous nickel mesh according to structure and the technical indicator of built-in porous heater, is determined its specification and size.
The present invention has following advantage:
1. to select the mesh structural porous electrothermal alloy of bigger serface be heating material in the present invention, increased the contact area of propellant medium and heater, thereby improve the efficient of heating element, makes the present invention can be applicable to the research and development of small size low-power consumption electric heating thruster.
2. the present invention adopts bar shaped helical form heater, can satisfy the required high resistance of built-in porous heater and small size requirement; It is the skeleton of heat generating core that the present invention adopts the porous boron nitride pipe, and it not only plays heater and supports and insulating effect, and can not hinder the circulation of propellant medium; The helical form heater back and forth is installed on being integrally formed heat generating core in the skeleton, is the basis that makes built-in heater.
3. the present invention adopts the Laser Welding technology that stainless steel cylinder, ring flange and thin-wall pipe welding are consisted of the armouring housing together, and the Laser Welding heat affected area is little, and fusion penetration is large, and weld seam is not revealed, and guarantees air-tightness;
4. to adopt light-wall pipe and thin-walled reducer pipe be the armour body that assembly is drawn in transition in the present invention, can greatly reduce the heat conduction, reduces the temperature of the built-in porous heater section of drawing.
5. the present invention adopts respectively self-control inorganic sealant and two kinds of encapsulant technology of high temperature resistant epoxy in high temperature section and the low-temperature zone of device, and by prolonging seal length, satisfies the requirement of electric heating thruster to guarantee air-tightness.
6. the present invention adopts inorganic glue and fine magnesium oxide micro-powder that the single hole quartz ampoule of transition wire and overcoat is fixed in the thin-walled reducer pipe, improves the impact resistance of device, in use can not break and affect the insulation of device.
7. integrated heating core and transition are drawn assembly and are installed in the armouring housing among the present invention, have realized that heating element and thrust chamber are integrated, are convenient to be combined with other assembly of thruster, improve integral installation and reliability.
In a word, the present invention adopts design and the reliable implementing process of unique exothermic material, novelty, develops the heating element that meets the requirement of electric heating thruster thermal controls apparatus---built-in porous heater.
Description of drawings
Fig. 1 is the built-in porous heater assembly of the present invention structural representation.
Fig. 2 is heater of the present invention and transition wire connection diagram.
Fig. 3 is heater skeleton structure schematic diagram of the present invention.
Fig. 4 is heater skeleton front end face structural representation of the present invention.
Fig. 5 is integrated heating core rear end face structural representation of the present invention.
Fig. 6 is integrated heating core front end face structural representation of the present invention.
Among the figure: 1 outer lead, 2 stainless steel tubes, 3 thin-walled reducer pipes, 4 connecting rings, 5 light-wall pipes, 6 ring flanges, 7 MEDIA FLOW hand-holes, 8 stainless steel cylinders, 9 high temperature resistant epoxies, 10 outer lead joints, 11 heat-shrinkable T bushs, 12 sub-thread transition wires, 13 thin single hole quartz ampoules, 14 fine magnesium oxide micro-powders, 15 bifilar transition wires, 16 thick single hole quartz ampoules, 17 inorganic glue, 18 diplopore boron nitride disks, 19 integrated heating cores, 20 heaters, 21 center boron nitride tubes, 22 transition contacts, 23 boron nitride rings, 24 partitions, 25 first peripheral boron nitride tubes, 26 second peripheral boron nitride tubes, 27 the 3rd peripheral boron nitride tubes, 28 4th week limit boron nitride tubes, 29 the 5th peripheral boron nitride tubes, 30 the 6th peripheral boron nitride tubes, 31 front end face double-walled notches, 32 rear end face double-walled notches, 33 is rear end face single wall notch; Identical numbering has same meaning among the figure.
Embodiment
Below by specific embodiment and accompanying drawing in detail the present invention is described in detail.
Take the required heating element of electric heating hydrazine thruster as example, and with reference to figure 1-6.
Foam nickel material is cut into the strip of 1.5mm * 1.2mm * 1000mm, standard coiled with pitch 0.5mm and spiral shell footpath 1.0mm, utilize solid phase to ooze again aluminising after technology chromising thereon or the chromising, the three-dimensional netted porous nickel chromium triangle that after vacuum heat, forms or the heater of nichrome aluminum alloy.
Utilize laser machine evenly to get thick and fast the hole of aperture Φ 1.0mm, pitch-row 1.8mm on for boron nitride tube (diameter 5mm, the wall thickness 0.5mm) tube wall of 25mm in length, make the porous boron nitride pipe; Slot with miniature being drilled on the tube wall of managing two ends simultaneously, width and the degree of depth of notch are 1.5～2.0mm.7 porous boron nitride Guan Liufang solid matters are consisted of the heater skeleton, and the center boron nitride tube 21 of skeleton is slightly short, is 20mm, assigns a boron nitride partition 24 in the pipe.Helical form heater 20 is back and forth worn in 6 porous boron nitride pipes of center boron nitride tube 21 peripheries, and fixing by the notch installation at boron nitride tube two ends, form integrated heating core.
With Φ 0.3mm length be the 80Ni20Cr B alloy wire of 200mm as transition wire, every transition wire must whole doubling, two end reciprocating folding types that close up the termination are as lap-joint, the other end is as twining silk; The termination of heater and the lap-joint of transition wire mediate, and adopt impulsed spot welding with twining after silk is fixed; Two transition wires are drawn through center boron nitride tube 21, must guarantee to insulate between two transition wires.Again transition wire is fixed in two Φ 0.6mm holes at diplopore BN disk 18 (diameter 25mm, thickness 0.5mm contact with skeleton) center with inorganic glue, puts thick single hole quartz ampoule 16 on the every bifilar transition wire 15, consist of transition and draw the assembly high-temperature section.
Utilize laser welder that ring flange 6 (there is the hole of Φ 4.5mm at the center for diameter 25mm, thickness 3mm) and light-wall pipe 5 (wall thickness 0.15mm, external diameter 4.5mm, length 20mm) are welded together; The recycling inorganic glue is drawn the inboard that diplopore BN disk 18 usefulness inorganic glue in the assembly high-temperature section are fixed on ring flange 6 with transition, allows cover have the bifilar transition wire 15 of thick single hole quartz ampoule 16 to pass from light-wall pipe 5.
First BN ring 23 is put into stainless steel cylinder 8 tail ends, again putting into stainless steel cylinder 8 with the integrated heating core of ring flange 6, then utilize laser welder with ring flange 6 and 8 seam of stainless steel cylinder.In the light-wall pipe 5 of the transition wire that overcoat single hole quartz ampoule is housed, be filled with inorganic glue 17; The transition wire that will stretch out is split into sub-thread transition wire 12 and is inserted in respectively thin single hole quartz ampoule 13, penetrates thin-walled reducer pipe 3 (wall thickness 0.15mm again; Thick section external diameter 4.5mm, length 5mm; Thin segment external diameter 2.5mm, length 35mm), and be filled with fine magnesium oxide micro-powder 14.Light-wall pipe 5 and thin-walled reducer pipe 3 are welded together by stainless steel connecting ring 4 with laser welder.
The again Split Down of transition wire of stretching out from thin-walled reducer pipe 3 taper ends, adopt mechanical grip, scolding tin reinforcing mode to be connected with the wrapped silver-plated copper outer lead 1 of polyimide film of 500mm length; After 11 coatings of transition wire outer lead joint 10 usefulness polytetrafluoro heat-shrinkable T bushs, adopt high temperature resistant epoxy 9 admittedly to be enclosed in the stainless steel tube 2 (diameter 3.4mm).
After built-in porous heater was made, measuring its resistance value was 36 Ω, and normal temperature insulate greater than 250M Ω/250VD.C.Examination in useful life condition is in the vacuum: rated power 20W, and central temperature is not less than 700 ℃, and each two minutes was a circulation for power on/off.Examination in useful life in vacuum, built-in porous heater is stablized power on/off circulation above 20,000, reaches the technical indicator of space flight department.
Claims (10)
1. built-in porous heater is characterized in that: comprise that integrated heating core, armouring housing, transition draw assembly, the section of drawing and outer lead;
Described integrated heating core comprises heater and heater skeleton; Heater is the bar shaped helical form, its material is mesh structural porous nichrome or mesh structural porous nichrome aluminum alloy, the heater skeleton is formed through solid matter by seven boron nitride tubes, and described solid matter is specially six roots of sensation periphery boron nitride tube symmetry arrangement centered by a center boron nitride tube; Center boron nitride tube inner axial tube is placed partition, and the two ends of peripheral boron nitride tube have notch, and heater back and forth installs into peripheral boron nitride tube successively through notch; Fix with inorganic glue between boron nitride tube;
Described armouring housing comprises stainless steel cylinder, ring flange and reducer pipe, and stainless steel cylinder and reducer pipe weld together by ring flange, and integrated heating core is encapsulated in the stainless steel cylinder, and the fairlead of transition wire is left at the ring flange center;
The insulating material part that assembly comprises transition wire and compound composition is drawn in described transition, and transition wire is the multiply nichrome wire, and its sectional area is 4～5 times of the true sectional area of heater; The insulating material part of compound composition comprises diplopore boron nitride disk, quartz ampoule, inorganic glue and fine magnesium oxide micro-powder; Diplopore boron nitride disk utilizes inorganic glue to be bonded between integrated heating core and the ring flange, transition wire one end link to each other with the heater two ends after from the porous boron nitride pipe of center the partition both sides draw, then two holes on diplopore boron nitride disk enter in the reducer pipe, transition wire links to each other with outer lead after drawing reducer pipe, transition wire overcoat quartz ampoule in the reducer pipe, filling inorganic glue and fine magnesium oxide micro-powder in the reducer pipe;
Transition wire and outer lead tie point adopt high temperature resistant epoxy that it is enclosed in the stainless steel tube admittedly with the reducer pipe end after coating with heat-shrinkable T bush, consist of the section of drawing; Described transition wire is the multiply nickel filament, and described outer lead is multiply silver-plated copper wire.
2. built-in porous heater according to claim 1, it is characterized in that: described heater is to consist of three-dimensional netted loose structure by the hollow and thin-walled metal rib that is interconnected, and its hole is interconnected, is evenly distributed; Porosity is 90～98%, and aperture size is 90～110PPI; The quality percentage composition of chromium is 18～35% in the described mesh structural porous nichrome; The quality percentage composition of chromium is 18～35% in the described mesh structural porous nichrome aluminum alloy, and the quality percentage composition of aluminium is 2～10%.
3. built-in porous heater according to claim 1, it is characterized in that: described heater is after porous nickel mesh is processed as the spiral helicine nickel foam of bar shaped, to carrying out vacuum heat after the chromising of the spiral helicine nickel foam employing of bar shaped solid phase chromium implements, obtain mesh structural porous nichrome; Perhaps the spiral helicine nickel foam of bar shaped is adopted the solid phase chromising, carries out vacuum heat after the aluminising again, obtain mesh structural porous nichrome aluminum alloy.
4. built-in porous heater according to claim 1 is characterized in that: described boron nitride tube is to utilize laser drilling to make evenly intensive hole at every boron nitride tube wall, and pipe two ends fluting is made;
Its hole of described boron nitride tube evenly distributes on the circumference of pipe, and adjacent two round holes are spaced, and namely the center of circle of some holes is arranged on the perpendicular bisector of two hole circle center line connectings the neighbour; The hole gross area is greater than 50% of tube wall area;
The internal diameter of described peripheral boron nitride tube is 3～5mm, and wall thickness is 0.2～0.5mm, and length is 10～15mm; Described center its length of boron nitride tube be peripheral boron nitride tube 4/5ths to 1/2nd between, its thickness is that its internal diameter is identical with peripheral boron nitride tube between a times to two times of peripheral boron nitride tube;
Described partition is the bar shaped boron nitride, and length and the wall thickness with the center boron nitride tube is identical respectively with thickness for its length, and its width is identical with the internal diameter of center boron nitride tube;
5. built-in porous heater according to claim 1, it is characterized in that: described reducer pipe is comprised of thin-walled reducer pipe and light-wall pipe, and thin-walled reducer pipe and light-wall pipe weld together by connecting ring; Described quartz ampoule is thick single hole quartz ampoule and thin single hole quartz ampoule, the thick single hole quartz ampoule of the part overcoat of transition wire in light-wall pipe, the thin single hole quartz ampoule of the part overcoat of transition wire in the thin-walled reducer pipe; Filling inorganic glue in the light-wall pipe, filling fine magnesium oxide micro-powder in the thin-walled reducer pipe.
6. built-in porous heater according to claim 5 is characterized in that: after described transition wire is fixed in the light-wall pipe, transition wire is cut off at the place, fold point, every transition wire is split as two strands of transition wires; Connecting ring is enclosed within the joint of light-wall pipe and thin-walled reducer pipe, adopts pulse laser to weld to connecting ring and light-wall pipe lap-joint and connecting ring and thin-walled reducer pipe lap-joint; On four strands of transition wires, put respectively thin single hole quartz ampoule, filling fine magnesium oxide micro-powder in the thin-walled reducer pipe, fixing thin single hole quartz ampoule and transition wire; After transition wire is drawn from the thin-walled reducer pipe, utilize energy-accumulating spot welder that two strands of nickel filaments of every transition wire are welded again at gap.
7. built-in porous heater according to claim 1, it is characterized in that: described inorganic glue is the silicate refractory inorganic adhesive, its solid phase composition and liquid phase ingredient mass ratio are 2: 1; Liquid phase ingredient is potassium silicate solution, its modulus ratio SiO
2/ K
2O=4; The solid phase composition is that SiO 2 powder and alumina powder mix the mass ratio of SiO 2 powder and alumina powder 3: 1; The mass ratio of different-grain diameter silicon dioxide is 10 nanometers in the SiO 2 powder: 1000 orders: 600 orders: 400 orders: 200 orders=1: 2: 2.5: 2.5: 2; The mass ratio of different-grain diameter aluminium oxide is 1200 orders in the alumina powder: 40 orders=2: 8.
8. built-in porous heater according to claim 1 is characterized in that: the boron nitride ring is placed in described integrated heating core lower end, and described ring flange be circular, and there is the step that welds with stainless steel cylinder upper end in edge; Described stainless steel cylinder upper end open, the lower end has MEDIA FLOW to portal, and has the MEDIA FLOW hand-hole on the barrel.
9. built-in porous heater according to claim 1, it is characterized in that: described high temperature resistant epoxy is that room temperature placement curing in 24 hours forms after being mixed by epoxy resin, curing agent and fine magnesium oxide micro-powder, the part by weight of epoxy resin, curing agent and fine magnesium oxide micro-powder is 10: 10: 1, and described curing agent is diethylenetriamine; Described thick single hole quartz ampoule and light-wall pipe are isometric, and its material of described heat-shrinkable T bush is polytetrafluoroethylene.
10. the application of a built-in porous heater as claimed in claim 1 is characterized in that: described built-in porous heater is applied in the used thermal controls apparatus of aerospace craft appearance, rail control thruster.
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| CN201110278801.0A CN103002612B (en) | 2011-09-19 | 2011-09-19 | Built-in porous heater |
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| CN201110278801.0A CN103002612B (en) | 2011-09-19 | 2011-09-19 | Built-in porous heater |
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| CN103002612B CN103002612B (en) | 2014-09-03 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105934007A (en) * | 2016-05-06 | 2016-09-07 | 武汉航空仪表有限责任公司 | Method for packaging armoured heater |
| CN110726320A (en) * | 2019-10-08 | 2020-01-24 | 沈阳工程学院 | Electric heating protective sleeve for solid electric heat storage furnace |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105934007A (en) * | 2016-05-06 | 2016-09-07 | 武汉航空仪表有限责任公司 | Method for packaging armoured heater |
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| CN110726320A (en) * | 2019-10-08 | 2020-01-24 | 沈阳工程学院 | Electric heating protective sleeve for solid electric heat storage furnace |
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|---|---|
| CN103002612B (en) | 2014-09-03 |
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