CN113930898A - Manufacturing device and manufacturing method of polycrystalline alumina fiber liner - Google Patents
Manufacturing device and manufacturing method of polycrystalline alumina fiber liner Download PDFInfo
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- CN113930898A CN113930898A CN202111261469.7A CN202111261469A CN113930898A CN 113930898 A CN113930898 A CN 113930898A CN 202111261469 A CN202111261469 A CN 202111261469A CN 113930898 A CN113930898 A CN 113930898A
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/44—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling
- D04H1/46—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
- C04B35/62231—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on oxide ceramics
- C04B35/62236—Fibres based on aluminium oxide
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/44—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling
- D04H1/46—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres
- D04H1/48—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres in combination with at least one other method of consolidation
- D04H1/488—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres in combination with at least one other method of consolidation in combination with bonding agents
Abstract
The invention provides a manufacturing device of a polycrystalline alumina fiber gasket and a manufacturing method of polycrystalline alumina fibers, wherein the manufacturing device comprises: spinning shower nozzle module, the wind channel, set up in the collection net of wind channel below, connect the fibre areal density detection module who collects the net, and connect the system of collecting the web rear and fill up the module, wherein, spinning shower nozzle module contains a plurality of mobilizable spinning shower nozzles, the spinning colloid is collected the net through the wind channel after this spinning shower nozzle module blowout, form polycrystalline alumina precursor fiber aggregate, this fibre areal density detection module detects its areal density distribution, according to areal density distribution, the spinning shower nozzle is removed to corresponding position, polycrystalline alumina fiber liner is made to this polycrystalline alumina precursor fiber aggregate by the system pad module. The method can conveniently improve the surface density distribution uniformity of the polycrystalline alumina precursor fiber aggregate, and further improve the surface density distribution consistency, the peel strength and the aging surface pressure of the polycrystalline alumina fiber liner.
Description
Technical Field
The invention relates to a manufacturing device of a ceramic carrier supporting gasket, in particular to a manufacturing device of a polycrystalline alumina fiber gasket and a manufacturing method of the polycrystalline alumina fiber gasket.
Background
The air pollution prevention and control work in China faces unprecedented challenges, the control of tail gas pollution of mobile machinery and non-road mobile machinery has important significance for reducing pollutants such as NOx, PM2.5 and the like in air, and the current main technical route is to add a tail gas post-treatment system on the basis of reducing the original emission of an engine and treat the pollutants through gas-solid catalytic reaction.
The core of the tail gas after-treatment system is a catalytic unit which comprises a ceramic carrier, a liner and a metal shell. A ceramic carrier support gasket (hereinafter referred to as "gasket") is generally disposed in the gap between the ceramic carrier and the metal shell, and mainly plays a role in fixing, sealing and heat insulation. The liner is typically an inorganic fiber-based composite material that needs to provide adequate fixation of the ceramic carrier by friction at normal temperatures to engine exhaust temperatures. Along with the popularization and application of the ultra-thin-wall ceramic carrier with lower compressive strength, the requirement of the catalytic unit on the density consistency of the liner surface is higher and higher: locally too high an areal density of the liner can create excessive stress to a small extent, thereby crushing and damaging the expensive ultra-thin wall ceramic carrier. As the emissions of internal combustion engines have decreased and the catalyst loading of exhaust aftertreatment systems has decreased, attention has been paid to needle-punched polycrystalline alumina fiber mats having low or even no organic binder content. The main component of the needled polycrystalline alumina fiber mat is polycrystalline alumina fiber, and sometimes includes functional fillers and binders.
The manufacturing process of the needle-punched polycrystalline alumina fiber pad comprises the following steps: firstly, preparing glue, namely condensing an aluminum source and a silicon source by using a sol-gel method to prepare spinning glue; spinning, namely adopting a spinning method, a blowing method or an electrostatic spinning method and the like, enabling spinning colloid to flow out of a spinning assembly, stretching and drying in an air duct, converting into precursor fiber, and flatly paving to form a precursor fiber aggregate; finally, the precursor fiber aggregate is converted into the polycrystalline alumina fiber pad with good rebound performance at normal temperature to 1400 ℃ by methods of heat treatment, needling and the like, and optional processes of gluing and drying.
The needling process uses barbed needles to reciprocate in a direction perpendicular to the fiber aggregate, so that the fibers are interwoven to form fiber bundles perpendicular to the plane of the web, and the fiber aggregate has good peel strength and large volume weight. If the needling degree is insufficient, the fiber interweaving is insufficient, the peel strength of the liner can be obviously reduced, and the liner cannot be completely inserted into a gap between the ceramic carrier and the metal shell; if the needling is excessive, the fibers are broken or damaged by local stress concentration, which causes not only a decrease in peel strength but also a decrease in aged surface pressure of the gasket, resulting in failure of the gasket to provide a sufficient fixing force to the ceramic carrier. Since needle machines generally have a fixed reciprocating stroke, the magnitude of the degree of needling is directly dependent on the uniformity of the precursor fiber assembly.
The mass per unit area is defined as the areal density, usually in g/m2. CN207904417U discloses an electrostatic spinning device, CN202380142U discloses an inclined slit spinning device, and CN208414659U discloses a blowing spinning device, these spinning devices have simple structures, the spatial distribution of the spinning colloid outlet is fixed and unadjustable, and the surface density distribution uniformity of the precursor fiber cannot be ensured and adjusted.
Therefore, the invention provides a manufacturing device and a manufacturing method of the polycrystalline alumina fiber liner, which can conveniently improve the surface density distribution uniformity of the polycrystalline alumina precursor fiber aggregate, and further improve the surface density distribution uniformity, the peel strength and the aging surface pressure of the polycrystalline alumina fiber liner.
Disclosure of Invention
The invention provides a device and a method for manufacturing polycrystalline alumina fiber liners, which can conveniently improve the surface density distribution uniformity, the peel strength and the aging surface pressure of a polycrystalline alumina fiber liner by improving the surface density distribution uniformity of a polycrystalline alumina precursor fiber assembly.
One aspect of the present invention provides an apparatus for manufacturing a polycrystalline alumina fiber mat, comprising at least: spinning nozzle module, set up in the wind channel of spinning nozzle module below, set up in the collection net of wind channel below, connect a fibre surface density detection module of this collection net, and connect this collection net afterbody one and fill up the module, wherein, contain a plurality of mobilizable spinning nozzles in this spinning nozzle module, spinning colloid is from this spinning nozzle module blowout back, through this wind channel, collect the net and collect, form polycrystalline alumina precursor fiber aggregate, this fibre surface density detection module detects the surface density distribution of polycrystalline alumina precursor fiber aggregate, according to surface density distribution, mobilizable spinning nozzle is removed to corresponding position, this polycrystalline alumina precursor fiber aggregate is needled into polycrystalline alumina fiber liner by the module of making up.
Preferably, the spinning nozzle module further comprises at least a first slide rail and a second slide rail, the spinning nozzle is disposed on the first slide rail and can move along the first slide rail, and the first slide rail is disposed on the second slide rail and can move along the second slide rail.
Preferably, this spinning nozzle includes the shower nozzle outer tube at least, the shower nozzle inner tube, and the casing, the shower nozzle outer tube, shower nozzle inner tube and casing all are cylindrical hollow structure, shower nozzle outer tube and shower nozzle inner tube are fixed in the casing, the shower nozzle inner tube nestification is intraductal in the shower nozzle outer tube, the lower extreme of shower nozzle inner tube is provided with the toper nozzle, the bottom that the gas cover was gathered to the toper is provided with the opening, this opening size is greater than this toper nozzle, the inner wall of shower nozzle outer tube and the outer wall of this shower nozzle inner tube form an annular cavity, when this polycrystalline alumina fiber spinning liquid was spout from the toper nozzle, an air current passed through from the annular cavity, and gather the opening blowout of gas cover from the toper.
Preferably, a rectifier is arranged between the outer wall of the inner tube of the nozzle and the outer tube of the nozzle, the filter is provided with a plurality of through holes, and the air flow passes through the rectifier and is ejected from the opening of the conical air gathering cover.
Preferably, a filter is arranged in the nozzle inner pipe, a plurality of through holes are formed in the filter, and the polycrystalline alumina fiber spinning solution passes through the filter and is sprayed out of the conical nozzle.
Preferably, the nozzle inner tube is provided with an orifice plate near the conical nozzle, the center of the orifice plate is provided with an orifice, and the polycrystalline alumina fiber spinning solution is sprayed out from the orifice of the orifice plate.
Preferably, the fiber areal density detection module at least comprises a film matrix pressure sensor and a calculation unit, the film matrix pressure sensor is covered on the surface of the collection net to record the gravity distribution of the polycrystalline alumina precursor fiber assembly and send the gravity distribution to the calculation unit, and the calculation unit analyzes the gravity distribution of the polycrystalline alumina fibers to obtain the polycrystalline alumina fiber areal density distribution.
Preferably, the pad making module includes at least a heat treatment unit and a needling unit.
Another aspect of the present invention provides a method for manufacturing a polycrystalline alumina fiber mat, the method at least comprising the steps of:
step one, preparing a polycrystalline alumina fiber spinning colloid;
step two, preparing a polycrystalline alumina precursor fiber aggregate: adjusting the surface density of the polycrystalline alumina precursor fiber assembly by using a manufacturing device of the polycrystalline alumina fiber gasket;
step three, cushion making: the polycrystalline alumina precursor fiber assembly is subjected to heat treatment, needling and other processes by using a manufacturing device of the polycrystalline alumina fiber gasket to manufacture the polycrystalline alumina fiber gasket. (optionally, the third step also comprises the procedures of gluing and drying)
Preferably, the second step further comprises: detecting the surface density distribution of the polycrystalline alumina precursor fiber aggregate, and moving a spinning nozzle to a corresponding position according to the surface density distribution.
Drawings
The invention may be better understood by describing one embodiment thereof in conjunction with the following drawings, in which:
fig. 1 is a block diagram of an apparatus for manufacturing a polycrystalline alumina fiber mat according to the present invention.
Fig. 2 is a structural view of a spinning nozzle block of the apparatus for manufacturing a polycrystalline alumina fiber mat according to the present invention.
Fig. 3 is a structural diagram of a single spinning nozzle of a spinning nozzle module according to the present invention.
Fig. 4 is an exploded view of a single spinneret of a spinneret module according to the present invention.
Fig. 5 is a cross-sectional view of a single spinneret of a spinneret module according to the present invention.
Detailed Description
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description and in the claims does not indicate any order, quantity, or importance, but rather is used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the material or item listed before "comprises" or "comprising" covers the material or item listed after "comprising" or "comprises" and its equivalents, and does not exclude other materials or items.
The invention discloses a manufacturing device and a manufacturing method of a polycrystalline alumina fiber liner. The main components of the polycrystalline alumina fiber are alumina and silica, the content of alumina is generally 65-98 wt.%, the content of silica is generally 2-35 wt.%, and the polycrystalline alumina fiber with the content of alumina being about 72% and the content of silica being about 28% is also generally called polycrystalline mullite fiber. The manufacturing device of the polycrystalline alumina fiber liner has the functions that spinning colloid of polycrystalline alumina passes through an air channel in a blowing mode to form precursor fiber, and a precursor fiber aggregate is formed on a collecting net. The polycrystalline alumina precursor fiber assembly is further processed to form a polycrystalline alumina fiber mat.
Fig. 1 is a schematic diagram of a manufacturing apparatus for a polycrystalline alumina fiber mat provided by the present invention, which includes a spinning nozzle module 1, an air duct 2, a collecting net 3, a fiber areal density detection module 4, and a mat manufacturing module 5. And 1 or more spray heads are arranged below the spinning spray head module 1, and the outlets of the spray heads are aligned with the air duct 2 below. The specific number and distribution of the nozzles can be determined according to the product characteristic requirements and process parameters of the required polycrystalline precursor fiber assembly. In this embodiment, the air duct 2 is a cylindrical tube, or other shapes in other embodiments, one or more air inlets and suction air inlets are disposed on the side surface or the top of the air duct 2, and multiple sets of temperature and humidity sensors and air speed sensors are disposed in the air duct. The collection net 3 is arranged under the air duct 2, the collection net 3 can be made of stainless steel, polyurethane, polytetrafluoroethylene and the like, the mesh number is generally 60-325 meshes, and the collection net is driven by a motor and a driving roller in a conveying belt manner and can move at a specified speed. The tail part of the collecting net 3 is connected with a cushion making module 5, and the cushion making module 5 makes the precursor fiber aggregate collected by the collecting net 3 into a cushion.
After the polycrystalline alumina spinning colloid is sprayed out from the spray head, the polycrystalline alumina spinning colloid is stretched in the air duct 2 under the action of gravity and the wind force of the air duct, and the sprayed silk is converted into a precursor fiber aggregate after being dried by the air duct. Precursor fibers uniformly fall on the driven collecting net 3 to form a polycrystalline alumina precursor fiber aggregate. The collecting net 3 is provided with a fiber surface density detection module 4, the fiber surface density detection module 4 collects the gravity distribution of the polycrystalline alumina precursor fiber aggregate in real time, and calculates the surface density distribution of the polycrystalline alumina precursor fiber aggregate. Preferably, in some embodiments, the variation coefficient of the areal density can be obtained according to the ratio of the standard deviation to the average value of the areal density of a plurality of sampling points. The smaller the coefficient of variation of the areal density, the more uniform the areal density distribution. Further, the fiber areal density detection module 4 may employ a thin film pressure sensor array, millimeter wave basis weight scanning, X-ray basis weight scanning, and the like. In this embodiment, a thin film pressure sensor array is employed. The film pressure sensor array is attached to the surface of the collecting net 3 and moves along with the collecting net, the gravity distribution of the polycrystalline alumina precursor fiber aggregate is weighed in real time and is known and processed by the computing unit, wherein the computing unit can be a unit which can perform digital operation in various computers, embedded equipment and the like in the prior art.
Through years of research, the inventor finds that the surface density of the polycrystalline alumina precursor fiber aggregate depends on the initial spatial distribution of the spinning colloid and the movement process of the spinning colloid in the air duct, the former is limited by the spatial distribution of a spinning nozzle of a spinning module, and the latter is limited by the flow velocity of the spinning colloid and the structure, the air speed, the temperature and the humidity of the air duct. Particularly, the temperature and the humidity in the air duct are greatly coupled with the initial space distribution and the flow velocity of the spinning colloid and controlled in the process of gas-solid two-phase flow in a turbulent flow state. Various technical schemes in the prior art avoid the control of the factors, and seek to improve the surface density distribution uniformity of the precursor fiber assembly through the subsequent lapping process, and belong to post-treatment. According to the polycrystalline alumina fiber liner preparation device provided by the invention, the spatial position of the spinning nozzle is subjected to feedback correction control according to the collected surface density distribution information of the precursor fiber aggregate, the influence of natural fluctuation of temperature and humidity in the air duct is counteracted as much as possible through a dynamic control process, and the position of the nozzle is repeatedly optimized until the variation coefficient of the surface density distribution of the precursor fiber aggregate is lower than a certain threshold value. By adjusting the distribution of the spray heads of the spinning colloid, the surface density distribution uniformity of the fiber aggregate formed by the spinning equipment can be obviously improved.
In some embodiments, the calculation unit may present the calculated surface density distribution of the polycrystalline alumina precursor fiber assembly on a screen in a graphic form, and an operator observes the surface density distribution of the polycrystalline alumina precursor fiber assembly on the screen, and if the non-uniformity and other conditions requiring manual intervention and adjustment are found, moves the position of one or some of the nozzles, and repeats the above process until the surface density distribution uniformity of the polycrystalline alumina precursor fiber assembly reaches the standard.
Furthermore, the computing unit may further include some algorithms, such as marking the places with uneven surface density, and prompting the uneven places through various alarm forms, such as sound and light alarm, etc. Preferably, the calculation unit of the fiber areal density detection module 4 can also output instructions to control the robotic arm. And a position sensor is arranged between the sliders to feed back the position of the nozzle slider in real time, after the mechanical arm finishes the action execution, the actual position of the nozzle slider is fed back by the distance sensors on the slide rail and the sliders and is checked with a target value, if the target position passes the check, the surface density distribution detection is executed again after a certain time interval, and if the target position does not pass the check, the robot alarms to notify manual intervention. Wherein the robotic arm may be a commercially available multi-axis robot, or other automated control device. According to the self-adaptive fiber surface density detection module feedback control system and the manufacturing method, the position of the spinneret can be actively adjusted in the whole polycrystalline alumina fiber spinning process so as to match with the change of environmental factors, greatly offset the influence of the environment in an air duct, improve the surface density uniformity of the polycrystalline alumina precursor fiber aggregate, and lay a foundation for improving various performances of the polycrystalline alumina fiber liner manufactured subsequently.
Referring to fig. 2, the spinneret module 1 comprises slide rails 101 and 102 in two directions X-Y, wherein the X direction is perpendicular to the moving direction of the collecting screen 3 and the Y direction is perpendicular to the X direction. And a plurality of parallel slide rails are arranged in the Y direction to serve as a base, and a plurality of slide rails in the X direction are arranged on the slide rails of the base. The housings of the plurality of spinning nozzles 40 are fixedly mounted on nozzle slides 104, the nozzle slides 104 can move along X-direction slide rails, which can move on Y-direction slide rails, and each nozzle slide is provided with a damper, so that the spatial position of the nozzle can be freely adjusted and fixed at a set position. Preferably, a plurality of independent motors are arranged in the X-Y directions, and the motors can receive commands sent by the computing unit to control the position of the sliding block in the X-Y space.
Fig. 3 is a schematic view showing an embodiment of a single spinning nozzle 40, and fig. 4 is an exploded view of the spinning nozzle 40. As shown in fig. 4, the spinning nozzle 40 includes a nozzle outer tube 402, a nozzle inner tube 401, and a housing 403. The outer showerhead pipe 402, the inner showerhead pipe 401, and the housing 403 are each formed in a cylindrical hollow structure and are nested with one another, and the outer showerhead pipe 402, the inner showerhead pipe 401, and the housing 403 are formed of stainless steel, preferably SUS304 or stainless steel having higher corrosion resistance. A showerhead outer tube 402 and a showerhead inner tube 401 are fixed within the housing 403.
Referring to fig. 5, a thread structure is provided on an upper section of an inner wall of the housing 403, and a corresponding thread structure is provided on an upper section of an outer wall of the nozzle inner tube 401, so that the nozzle inner tube 401 can be fixed in the housing 103 by rotation. A thread structure is arranged on the lower section of the inner wall of the shell 403, a corresponding thread structure is also arranged on the upper section of the outer wall of the nozzle outer pipe 402, and the nozzle outer pipe 402 can be rotatably fixed in the shell 103. It should be noted that the thread structure is only one embodiment, and any structure of metal parts which is easy to disassemble and can be fixed at the same time is within the protection scope of the present invention. Due to the design of quick replacement, a certain spray head can be conveniently and quickly replaced after being blocked.
With continued reference to fig. 3 and 4, the showerhead inner tube 401 nests within the showerhead outer tube 402, with the inner wall of the showerhead outer tube 402 and the outer wall of the showerhead inner tube 401 forming an annular cavity 404. The lower end of the nozzle inner pipe 401 is provided with a conical nozzle 407, the lower end of the nozzle outer pipe 402 is provided with a conical gas gathering cover 409, and the bottom of the conical gas gathering cover 409 is provided with an opening, and the size of the opening is larger than that of the conical nozzle. The upper end of the inner wall of the shell 403 can be provided with a guide pipe for inputting polycrystalline alumina fiber spinning colloid, and the guide pipe is butted with the upper end of the nozzle inner pipe 401. The polycrystalline alumina fiber spinning colloid is prepared by a sol-gel method and is prepared by condensation according to a certain proportion of an aluminum source and a silicon source. Referring to fig. 5, the polycrystalline alumina fiber spinning dope is fed from the upper end of the housing 403, passes through the inner cavity of the nozzle inner tube 404, and reaches the conical nozzle 407 of the nozzle inner tube 404. Near the outlet of the conical nozzle 407, a centrally perforated orifice plate is mounted, the aperture of the central hole being 0.05-0.5mm, preferably 0.1-0.3mm, and the ratio of the thickness of the orifice plate to the aperture of the central hole being 5-50, preferably 10-30. The orifice plate is mounted in the lower half section, the inner diameter of the upper half section is 3-8mm, the taper of the lower half section is 2:1 to 1:1, and the optimization is carried out
The orifice plate is used for controlling the flow of spinning colloid sprayed by the spray head, and the material of the orifice plate can be selected from various acid-resistant materials with higher hardness, such as stainless steel, ceramics and the like, and preferably alumina and zirconia. Preferably, a filter 410 is disposed in the inner cavity of the nozzle head inner tube 404 at a position close to the conical nozzle, and the filter 410 is provided with a plurality of through holes, preferablyThe filter is a through hole with the size larger than 200 meshes, not only can filter impurities to prevent blockage, but also can make the internal pressure of the spinning colloid passing through the filter uniform by utilizing the damping effect of pressure drop, and further improve the uniformity of the spinning colloid.
Referring to fig. 5, in this embodiment, the surface of the housing 103 has a vent hole 405, the vent hole 405 communicates with the annular cavity 404, and compressed air flows into the annular cavity 404 through the vent hole 405, and the compressed air flows downward from the annular cavity 404 and is ejected from the opening of the conical air collecting cover 409. Preferably, referring to fig. 4, an annular rectifier 410 is disposed between the outer wall of the inner nozzle tube 101 and the outer nozzle tube 102, the annular rectifier 410 is attached to the inner nozzle tube 101 and the outer nozzle tube 102, a plurality of through holes, preferably through holes larger than 200 meshes, are disposed on the annular rectifier 410, and after compressed air passes through the annular rectifier 410, the air flows are rectified and then parallel to each other, thereby further improving uniformity of the compressed air.
With continued reference to fig. 1, the present invention also provides a method for manufacturing a polycrystalline alumina fiber mat using the above mat manufacturing apparatus, comprising at least the steps of:
step 1: preparing sol-gel, mixing an aluminum source and a silicon source according to a set molar ratio, adding a spinning auxiliary agent and a colloid stabilizer, and concentrating to obtain the sol-gel, wherein the aluminum-silicon weight ratio is (65-98): (35-2) spinning colloid with the viscosity of 0.1-10 Pa.s, namely the spinning colloid; or mixing an aluminum source and a silicon source according to a set molar ratio, and concentrating to obtain the aluminum-silicon composite material with the weight ratio of (65-98): (35-2), adding a spinning auxiliary agent and a colloid stabilizer, and adjusting to obtain a spinning colloid with the viscosity of 0.1-10 Pa.s, namely the spinning colloid; the aluminum source in the sol in the step 1 is a reaction product of an acidic substance, aluminum powder and water under the condition of heating reflux, or a commercially available aluminum salt is used, the acidic substance can be aluminum chloride, hydrochloric acid, aluminum sulfate, sulfuric acid, aluminum nitrate, nitric acid, formic acid, acetic acid, lactic acid and the like and a mixture thereof, the aluminum salt is basic aluminum chloride, aluminum lactate and the like, the silicon source in the sol is TEOS, silica sol, preferably SiO is used215-50% of silica sol, and spinning auxiliary agent is water-soluble polymer with fiber forming capabilityCompounds such as polyvinyl alcohol, polyethylene oxide, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, sucrose or starch, soluble derivatives of cellulose such as acetate-modified starch, hydroxyethyl starch, methyl cellulose or ethyl cellulose, and the like; the concentration of the spinning aid is 0.1-15 wt.%. The colloid stabilizer is water-soluble organic acid, and the concentration of the water-soluble organic acid such as lactic acid, acetic acid, citric acid and the like is 0.1-15 wt.%;
step 2: use the spinning module of above-mentioned polycrystalline alumina fiber liner manufacturing installation to spin polycrystalline alumina fiber spinning colloid, the spinning colloid made in step 1 passes through the high-pressure pump and inputs shower nozzle inner tube 401, and spout through shower nozzle toper nozzle 407, and simultaneously, compressed air gathers gas cover 409 bottom opening blowout from the toper after annular cavity 404, form high-speed annular air current and stretch and stereotype spun spinning colloid, hot air drying in the wind channel is passed through to the back, form polycrystalline alumina precursor fibre, be collected on fibre collection net 3, form polycrystalline alumina precursor fibre aggregate. The collecting net 3 is provided with a fiber surface density detection module which collects the gravity distribution of the polycrystalline alumina precursor fiber aggregate and calculates the surface density distribution of the polycrystalline alumina precursor fiber aggregate. And adjusting the positions of the spinning nozzles according to the surface density distribution of the polycrystalline alumina precursor fiber aggregate until the surface density distribution of the polycrystalline alumina precursor fiber aggregate is uniform. In some embodiments of the present invention, the adjusting means may be manual adjustment, or may be controlled by the aforementioned mechanical arm or stepping motor, and the specific implementation manner thereof may be any manner in the prior art, which is not limited herein.
The tail part of the collecting net 3 continuously outputs the polycrystalline alumina precursor fiber aggregate with uniformly distributed surface density, and a cushion making module 5 is connected with the tail part of the collecting net 3. The pad making module 5 at least comprises a heat treatment unit, the heat treatment unit can adopt a roller kiln, the temperature in the kiln can reach 1350 ℃, and a precursor fiber aggregate is calcined, so that precursor fibers are pyrolyzed and oxidized to form polycrystalline alumina fibers. The precursor fiber aggregate was goodThe surface density distribution uniformity of the liner can ensure that the precursor fibers are heated uniformly in space and have the same reaction history and conversion rate, thereby enhancing the uniformity of the aging performance of the liner in the spatial dimension, avoiding the influence of local 'dead spots' on the overall aging performance of the liner and further improving the overall aging performance of the liner. The cushion making module 5 also comprises a needling unit which drives the needle beam, the needle plate and the felting needles to do up-and-down reciprocating motion through a crank-connecting rod mechanism by main transmission. The fibre assembly is fed to the needling unit at the end of the collecting web 3 and is fed to the needling zone of the needling unit. When the needle plate moves downward, the needles penetrate the fiber aggregate. The barb structure at the end of the needles causes the fibers to move upwardly with the needles as the needle plate moves upwardly. The feeding speed is matched with the output speed, and the feeding speed can be intermittently stepped or continuously moved. After the fiber assembly passes through the needling zone, the density is increased, the thickness is reduced, interweaving is formed, and the tensile strength is generated. Wherein the needling speed is 0.5-10 cm/s, preferably 2-5 cm/s. The greater the number of needle pricks per unit area, the greater the density of the liner and the higher the peel strength, generally 1 to 50 needles/cm2Preferably 3 to 20 needles/cm2。
Preferably, the mat-making module can further comprise a gluing unit and a drying unit, wherein the gluing unit can glue the polycrystalline alumina fiber mat partially or wholly and then form a surface organic coating or a whole organic coating after being dried by the drying unit, and the organic coating can further improve the peel strength of the polycrystalline alumina fiber mat and prevent the mat from being scratched when the mat is inserted into the gap between the ceramic carrier and the metal shell. The coating unit can adopt common processes of spray coating, roll coating and the like, and the types of coated organic matters comprise but are not limited to commercially available polyurethane emulsion, acrylic emulsion, styrene-acrylic emulsion, polyoxyethylene emulsion and the like. The drying unit includes, but is not limited to, hot air drying, microwave drying, cylinder drying, and the like.
By using the method in the step 1, 940g of crystalline aluminum chloride (with the content of 97%) is dissolved in 3200g of water, 500.5g of metal aluminum powder (with the particle size of 70-100 meshes and the aluminum content of more than 99%) is added, the mixture is stirred and reacted at 80 ℃ until the solution is completely clear, a small amount of water volatilizes in the reaction process, and a very small amount of unreacted metal aluminum powder is filtered out, so that a colorless and transparent basic aluminum chloride aqueous solution with the aluminum oxide content of 27.8 wt.% and the aluminum/chlorine molar ratio of 1.97 is obtained. To this aqueous aluminum chlorohydrate solution were added in the order of 35g of citric acid (citric acid monohydrate content 99%), 2202g of alkaline silica sol (average particle diameter 7 nm, silica content 20%), 1285g of aqueous polyvinyl alcohol solution (type 2088, concentration 5 wt.%). After mixing uniformly, the mixture was distilled under heating at normal pressure to obtain a polycrystalline alumina colloid having a viscosity of 1.6 pas (measured at 25 ℃ C.) and good spinnability.
By using the method of step 2, the polycrystalline alumina spinning colloid was pumped in from the upper end of the shell at a rate of 1.5L/hr. The taper of the nozzle is
The central aperture of orifice plate is 0.2mm, and orifice plate thickness is 25mm, has fixed a 275 mesh filters in the position that is close to the nozzle in the shower nozzle inner tube, and the colloid is from the blowout of conical nozzle again behind the filter, and such design can make the shower nozzle inner tube flow direction colloid of nozzle more even. Meanwhile, 0.4MPa of annular airflow is sprayed out of the annular cavity, the polycrystalline alumina spinning colloid sprayed out under the action of the airflow is stretched, and then the polycrystalline alumina spinning colloid passes through an air duct with 45 ℃ hot air drying and is uniformly stacked on a collecting net which moves at a constant speed. The fiber surface density detection module detects the surface density distribution of the polycrystalline alumina precursor fiber aggregate on the collection net, and the position of the spinning nozzle is manually and repeatedly adjusted according to the surface density distribution until the variation coefficient of the surface density of the polycrystalline alumina precursor fiber aggregate is less than 1.5 percent.
By using the method in the step 2, the polycrystalline alumina precursor fiber aggregate with the surface density variation coefficient less than 1.5 percent is conveyed to the pad making module from the tail part of the collecting net, the temperature of a roller kiln of the pad making module is set to 1350 ℃, after heating for 25 minutes, the polycrystalline alumina fiber is subjected to up-and-down reciprocating needling motion by a needle machine, and finally, the continuous polycrystalline alumina fiber pad is formed. The thickness of the polycrystalline alumina fiber liner is 12mm, and the width of the polycrystalline alumina fiber liner is 1200 mm. According to different use scenes, a cutting machine can be used for cutting the polycrystalline alumina fiber liner into corresponding sizes.
To verify the performance of the polycrystalline alumina fiber pad, the inventors purchased a commercially available needled polycrystalline alumina fiber pad (model a); fixing spinning nozzles in X, Y direction, and uniformly distributing to obtain 1200mm wide polycrystalline alumina fiber pad (type B); and the same spinning colloid and the same device are used, but the spinning nozzles are optimally distributed according to the method of the invention to prepare a 1200mm wide polycrystalline alumina fiber liner (type C). The three are respectively measured and compared with the surface density distribution uniformity, the peel strength and the aging surface pressure. The measurement method of each index is as follows:
method for measuring the uniformity of density distribution of pad surface. The mat was cut without space into square blocks of 100mm by 100 mm. The sampling quantity in the length direction is consistent with that in the width direction. In the scheme, sampling is performed on each model of pad in sequence, the number of sampling columns in the width direction is 12 columns, and the number of sampling rows in the length direction is 12 rows, that is, 144 sample blocks are collected in each model. Weighing the blocks one by one using an analytical balance with an accuracy of at least 0.001g, dividing the mass of each block by 0.01m2The area of the sample block is obtained. And (4) calculating the ratio of the standard deviation and the average value of the surface density of all the sample blocks, namely the coefficient of variation of the surface density of the gasket. The smaller the coefficient of variation of the areal density of the liner, the more uniform the areal density distribution.
Method for measuring liner peel strength. The polycrystalline alumina fiber mat sheet was cut into 200mm by 50mm strips with 25 samples per model. Stripping the sample strip by 50mm from the half thickness along the direction vertical to the thickness, respectively clamping the stripped parts at two sides by using a clamp, carrying out separation movement on the clamp at a relative speed of 10mm/min, measuring the pulling force required by moving the clamp in the whole stripping process, and defining the ratio of the stable value of the pulling force to 50mm as the stripping strength of the liner.
Method for measuring the aging surface pressure of the gasket. Holding the pad in two parallel plates loaded with heating device, heating to 900 deg.C, and dynamically adjusting the gap between the two platesThe density of the pad is 400kg/m3And 333kg/m3The density of the gasket in each circulation process is recorded to be 333kg/m by using a high-precision pressure sensor3The pressure is divided by the area of the gasket, and the pressure provided by the gasket is obtained through conversion. The pressure provided by the gasket at the 2500 th cycle was taken as the aging surface pressure of the gasket. The number of test specimens was 25 specimens per model.
As shown in table 1, the coefficient of variation of the area density of the model a is 3.47%, which is not much different from the coefficient of variation of the area density of the model B by 3.35%, while the coefficient of variation of the area density of the model C is only 1.55%, which indicates that the uniformity of the area density distribution of the model C is better than that of the model a and the model B. In addition, compared with the model A and the model B, the peeling strength and the aging surface pressure of the model C are improved. The fundamental reason why the performance of the polycrystalline alumina pad prepared by the method provided by the invention is obviously superior to that of the blowing polycrystalline alumina fiber pad in the prior art is that the uniformity of the areal density distribution of the precursor fiber aggregate is effectively controlled in the fiber manufacturing stage.
TABLE 1
In summary, the apparatus for preparing a polycrystalline alumina fiber mat and the method for manufacturing polycrystalline alumina fibers according to the present invention can improve the uniformity of the areal density distribution, the peel strength, and the aged areal pressure of the polycrystalline alumina fiber mat by improving the uniformity of the areal density distribution of the polycrystalline alumina precursor fiber aggregate.
While the invention has been described in conjunction with specific embodiments thereof, it will be understood by those skilled in the art that many modifications and variations may be made to the invention. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit and scope of the invention.
Claims (10)
1. An apparatus for manufacturing a pad of polycrystalline alumina fibers, comprising at least: a spinning shower nozzle module, set up in an wind channel of spinning shower nozzle module below, set up in a collection net of wind channel below, connect collect a fibre areal density detection module of net, and connect collect a system pad module of web foot portion, wherein, contain a plurality of mobilizable spinning shower nozzles in the spinning shower nozzle module, the spinning colloid is followed spinning shower nozzle module blowout back, warp the wind channel, quilt collect the net and collect, form a polycrystalline alumina precursor fiber aggregate, fibre areal density detection module detects polycrystalline alumina precursor fiber aggregate's areal density distribution, according to areal density distributes, mobilizable spinning shower nozzle removes to corresponding position, polycrystalline alumina precursor fiber aggregate is by system pad module makes polycrystalline alumina fiber liner.
2. The apparatus of claim 1, wherein the pad module comprises at least a needling unit.
3. The apparatus of claim 1, wherein the spin head module further comprises at least a first slide rail and a second slide rail, the spin head is disposed on the first slide rail and can move along the first slide rail, and the first slide rail is disposed on the second slide rail and can move along the second slide rail.
4. The apparatus for manufacturing the polycrystalline alumina fiber mat according to claim 1, wherein the spinning nozzle comprises at least an outer nozzle tube, an inner nozzle tube, and a housing, the outer nozzle tube, the inner nozzle tube, and the housing are all cylindrical hollow structures, the outer nozzle tube and the inner nozzle tube are fixed in the housing, the inner nozzle tube is nested in the outer nozzle tube, the lower end of the inner nozzle tube is provided with a conical nozzle, the lower end of the outer nozzle tube is provided with a conical gas gathering cover, the bottom of the conical gas gathering cover is provided with an opening, the opening is larger than the conical nozzle, the inner wall of the outer nozzle tube and the outer wall of the inner nozzle tube form an annular cavity, when the polycrystalline alumina fiber spinning solution is sprayed from the conical nozzle, an air flow passes through the annular cavity, and is sprayed out from the opening of the conical gas gathering cover.
5. The apparatus of claim 3, wherein a rectifier is disposed between the outer wall of the inner tube and the outer tube, and the filter has a plurality of through holes, and the air flows through the rectifier and is ejected from the opening of the conical air-gathering hood.
6. The apparatus as claimed in claim 4, wherein a filter is provided on an inner wall of the nozzle inner tube, the filter having a plurality of through holes, and the polycrystalline alumina fiber dope is discharged from the conical nozzle through the filter.
7. The apparatus as claimed in claim 5, wherein the nozzle inner tube is provided with an orifice plate near the conical nozzle, the baffle plate is provided with a flow hole at its center, and the polycrystalline alumina fiber spinning solution is sprayed from the flow hole of the orifice plate.
8. The apparatus of claim 1, wherein the fiber areal density detection module comprises at least one film matrix pressure sensor and a computing unit, the film matrix pressure sensor is covered on the surface of the collecting web to record the weight distribution of the assembly of polycrystalline alumina precursor fibers and send the weight distribution to the computing unit, and the computing unit analyzes the weight distribution of the polycrystalline alumina fibers to obtain the polycrystalline alumina fiber areal density distribution.
9. A method of manufacturing a pad of polycrystalline alumina fibres, characterised in that the method of manufacture comprises at least the steps of:
step one, preparing a polycrystalline alumina fiber spinning colloid;
a second step of preparing a polycrystalline alumina precursor fiber aggregate, and adjusting the areal density of the polycrystalline alumina precursor fiber aggregate using the apparatus for producing a polycrystalline alumina fiber mat according to claim 1;
step three, cushion making: the polycrystalline alumina precursor fiber aggregate is needle-punched into a polycrystalline alumina fiber mat using the manufacturing apparatus for a polycrystalline alumina fiber mat according to claim 1.
10. The method of making a polycrystalline alumina fiber mat according to claim 9, wherein step two further comprises: and detecting the surface density distribution of the polycrystalline alumina precursor fiber aggregate, and moving a spinning nozzle to a corresponding position according to the surface density distribution.
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