CN116553838B - Method and device for coating metal on fiber surface, and metallized fiber - Google Patents

Abstract

The present disclosure provides a method, apparatus, and metallized fiber for coating a fiber surface with metal. The method comprises: applying a slurry containing graphite powder, a coupling agent, and a resin to the fiber surface; curing the slurry to form a coating on the fiber surface; electrostatically spraying metal powder onto the coating surface; and allowing the metal powder to melt onto the coating surface. The present disclosure can produce a continuous, dense metal coating and ensure good adhesion strength.

Description

Method and device for coating metal on fiber surface and metallized fiber

Technical Field

The disclosure relates to the technical field of coating, in particular to a method and a device for coating metal on the surface of a fiber and a metallized fiber.

Background

In order to improve the mechanical properties of the fibers (e.g., improve the brittleness, abrasion resistance, and damage resistance of glass fibers) and/or to provide the fibers with good optoelectronic functions, the surfaces of the fibers are typically coated with a metal to obtain metallized fibers having more excellent properties or new properties.

The prior art generally uses methods such as vacuum evaporation, chemical Vapor Deposition (CVD), magnetron sputtering, and plasma deposition to apply a metal coating to the surface of the fiber. However, these methods have difficulty in achieving complete coverage of the fiber surface with the metal coating, and are not capable of forming a continuous dense metal coating.

US4390589 discloses a method for hot dip coating glass fibers with molten metal, which enables the on-line application of aluminum coatings to glass fibers of any drawn length. However, holes are easy to appear in the metal coating of the aluminized glass fiber prepared by the method, the strength and fatigue resistance of the product are reduced due to the existence of the cavity of the holes, the adhesion force of the metal coating is not strong, and the metal coating is easy to peel off after friction or washing, so that the application of the aluminized glass fiber is affected.

Disclosure of Invention

The technical problem to be solved by the present disclosure is that a continuous and compact metal coating cannot be formed when the surface of the fiber is coated with metal in the prior art, and the adhesion of the metal coating is not strong.

In order to solve the technical problems, the embodiment of the disclosure provides a method for coating metal on a fiber surface, which comprises the steps of coating a slurry on the fiber surface, wherein the slurry comprises graphite powder, a coupling agent and resin, solidifying the slurry and forming a coating on the fiber surface, spraying the metal powder on the coating surface in an electrostatic manner, and cladding the metal powder on the coating surface.

In some embodiments, the graphite powder has a particle size of 0.5-3 μm, and/or the coupling agent is a siloxane coupling agent and/or an epoxy silane coupling agent, and/or the resin has a molecular weight of less than 5000.

In some embodiments, the weight ratio of graphite powder, coupling agent, and resin in the slurry is (50-80): (5-10): (10-25) on a dry basis.

In some embodiments, the slurry is applied by passing the fibers through the slurry and the fibers pass through the slurry at a velocity no greater than 10m/min, and/or the method further comprises acid treating the fibers prior to applying the slurry.

In some embodiments, the surface density of the graphite powder on the surface of the fiber is from 0.1X10 ^-5g/cm² to 1X 10 ^-5g/cm², and/or the surface resistivity of the fiber with the coating formed is no higher than 10 ⁵ Ω -cm.

In some embodiments, the resin comprises an ultraviolet initiator such that curing the slurry comprises subjecting the slurry coated fibers to infrared radiation and ultraviolet radiation, and exposing the slurry coated fibers to an inert gas environment while subjected to ultraviolet radiation.

In some embodiments, electrostatically spraying the metal powder onto the surface of the coating includes positively charging the fibers forming the coating and passing through a powder spray chamber and spraying negatively charged metal powder onto the coating during the passing, and/or cladding the metal powder onto the surface of the coating, including thermally melting the metal powder and forming a molten film on the surface of the coating, and annealing the fibers forming the molten film.

The embodiment of the disclosure also provides a device for coating metal on the surface of the fiber, which comprises a slurry tank, a curing mechanism, an electrostatic spraying mechanism and a cladding mechanism, wherein the slurry tank is used for containing slurry containing graphite powder, a coupling agent and resin, the curing mechanism is used for curing the slurry, the electrostatic spraying mechanism comprises a powder spraying chamber, a positive charge applying part and a spray gun, the spray gun is used for applying negative charge to the metal powder and spraying the metal powder, the cladding mechanism comprises a heating furnace, the heating furnace can heat the metal powder to a molten state, and a plurality of winding rollers are used for driving the fiber to move and sequentially pass through the slurry tank, the curing mechanism, the powder spraying chamber and the heating furnace.

In some embodiments, the curing mechanism includes a curing chamber and an emitting portion that emits infrared and ultraviolet light into the curing chamber, and/or the cladding mechanism further includes an annealing oven through which the plurality of rolls further drive the fibers.

The embodiment of the disclosure also provides a metallized fiber, which comprises a fiber body, a coating layer arranged on the surface of the fiber body, wherein the coating layer is a solidified product of slurry, the slurry comprises graphite powder, a coupling agent and an adhesive, and a metal cladding layer arranged on the surface of the coating layer is obtained by cladding metal powder which is sprayed to the surface of the coating layer by static electricity.

Through the technical scheme, the method for coating the metal on the fiber surface can obtain a continuous compact metal coating and can ensure that the metal coating has good adhesive strength.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.

FIG. 1 is a flow chart illustrating a method of coating a fiber surface with metal in accordance with an exemplary embodiment of the present disclosure;

FIG. 2 is a schematic partial structure of an apparatus for coating a fiber surface with metal according to an exemplary embodiment of the present disclosure;

FIG. 3 is another partial schematic view of an apparatus for coating a fiber surface with metal according to an exemplary embodiment of the present disclosure;

FIG. 4 is a cross-sectional view of a metallized fiber shown in an example embodiment of the disclosure;

Fig. 5 is a scanning electron microscope image of a cross section of a metallized fiber prepared in example 1 of the present disclosure.

Reference numerals illustrate:

10. Slurry tank, 20, solidifying mechanism, 22, solidifying chamber, 30, electrostatic spraying mechanism, 31, powder tank, 32, powder spraying chamber, 33, gas cylinder, 34, positive charge applying part, 36, spray gun, 40, cladding mechanism, 42, heating furnace, 44, annealing furnace, 50, roller, 100, metallized fiber, 101, fiber body, 103, coating, 105 and metal cladding layer.

Detailed Description

Embodiments of the present disclosure are described in further detail below with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the disclosure and not to limit the scope of the disclosure, which may be embodied in many different forms and not limited to the specific embodiments disclosed herein, but rather to include all technical solutions falling within the scope of the claims.

The present disclosure provides these embodiments in order to make the present disclosure thorough and complete, and fully convey the scope of the disclosure to those skilled in the art. It should be noted that the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments should be construed as exemplary only and not limiting unless otherwise specifically stated.

It should be noted that, in the description of the present disclosure, unless otherwise indicated, the meaning of "a plurality" is greater than or equal to two, and the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate orientations or positional relationships are merely for convenience in describing the present disclosure and simplifying the description, and do not indicate or imply that the devices or elements being referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present disclosure. When the absolute position of the object to be described is changed, the relative positional relationship may be changed accordingly.

Furthermore, the use of the terms first, second, and the like in this disclosure do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The "vertical" is not strictly vertical but is within the allowable error range. "parallel" is not strictly parallel but is within the tolerance of the error. The word "comprising" or "comprises" and the like means that elements preceding the word encompass the elements recited after the word, and not exclude the possibility of also encompassing other elements.

It should also be noted that, in the description of the present disclosure, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, or may be directly connected, or indirectly connected via an intermediary. The specific meaning of the terms in the present disclosure may be understood as appropriate by those of ordinary skill in the art. When a particular device is described as being located between a first device and a second device, there may or may not be an intervening device between the particular device and either the first device or the second device.

All terms used in the present disclosure have the same meaning as understood by one of ordinary skill in the art to which the present disclosure pertains, unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods, and apparatus should be considered part of the specification.

Fig. 1 is a flowchart illustrating a method of coating metal on a fiber surface according to an exemplary embodiment of the present disclosure, and as shown in fig. 1, the method of coating metal on a fiber surface includes the steps of:

coating sizing agent on the surface of the fiber, wherein the sizing agent comprises graphite powder, a coupling agent and resin;

allowing the slurry to cure and form a coating on the surface of the fiber;

Electrostatic spraying of metal powder on the surface of the coating;

so that the metal powder is coated on the surface of the coating.

In the embodiment of the disclosure, the slurry containing the graphite powder is coated on the surface of the fiber, and because the graphite powder has certain conductivity, charges can move on a special lamellar molecular structure of the graphite powder, and more static charges are accumulated by utilizing the action of drift dragging, the formed coating has conductivity or semi-conductivity, the electrostatic attraction of the fiber can be enhanced, the electrostatic attraction is favorable for uniformly and firmly spraying the metal powder on the surface of the coating through electrostatic spraying, the metal powder sprayed on the surface of the coating is melted in the cladding process and then spread on the surface of the coating to form a molten film, and the molten film is condensed to form the metal coating.

The multiple steps employed in the present disclosure all facilitate the formation of a continuous dense metal coating and ensure good adhesion strength of the metal coating. Specifically, for continuous compactness, the slurry can be uniformly and continuously coated on the surface of the fiber, and graphite powder in the slurry can be uniformly dispersed in the slurry and then uniformly distributed in a coating formed after the slurry is solidified, so that the coating has uniform electrostatic attraction capability, metal powder is uniformly and continuously sprayed on the surface of the coating in the electrostatic spraying process, and the metal powder sprayed on the surface of the coating can be uniformly spread in the cladding process to finally form a uniform and continuous metal coating. For the adhesion strength, the graphite powder can be firmly combined on the fiber through the reaction of the coupling agent, and meanwhile, the electrostatic spraying can realize good combination strength between the metal powder and the graphite powder, so that the adhesion strength between the metal coating and the fiber is finally enhanced.

Referring to fig. 1, a fiber having a certain length (e.g., several tens to hundreds of meters, or even several meters to thousands of meters) may be moved and sequentially subjected to a slurry coating process, a curing process, an electrostatic spraying process, and a cladding process using a plurality of winding rollers 50. The non-metal coated fibers may be paid out from the unwind roll, converted to metal coated fibers after the above process and collected into a take-up roll. Therefore, the method can realize on-line continuous metal coating, and is beneficial to realizing batch production of the metallized fiber.

The methods of vacuum evaporation, chemical Vapor Deposition (CVD), magnetron sputtering, plasma deposition and the like adopted in the prior art also have the problems that the fiber is easily damaged, so that the high-strength metallized glass fiber is difficult to obtain, and the problems that equipment is expensive, the processing temperature is high, the process is complex, additional materials are required in the post-treatment process, and the reactive gas with high danger is required. Compared with the methods, the electrostatic spraying mode adopted by the method has the advantages of mild development environment, easiness in powder recovery, controllable coating thickness and the like, damage to fibers can be reduced or avoided, and the processes of slurry coating, curing, electrostatic spraying, cladding and the like are simpler, are convenient to operate, and do not need to use gas with high dangerousness. For the molten metal hot dip coating process of U.S. patent No. 4390589, holes at the glass fiber to metal interface are inherent drawbacks of the process because the hydrodynamic instability of the melt flow of the glass fiber near the molten aluminum inlet meniscus causes oscillations in the form of standing waves of the melt meniscus. Compared with the U.S. patent 4390589, the present disclosure can avoid the problem of holes caused by hot dip plating of molten metal.

In some embodiments, the fibers may be non-metallic fibers, such as glass fibers, carbon fibers, quartz fibers, silicon carbide (SiC) fibers, basalt fibers, etc., such that the non-metallic fibers may be provided with metallic properties, improving the mechanical properties of the non-metallic fibers, and providing optoelectronic properties by the methods of the present disclosure. The glass fibers are not particularly limited in the present disclosure, and may be E-glass fibers, C-glass fibers, E-CR glass fibers, advantex glass fibers, S-glass fibers, R-glass fibers, T-glass fibers, and the like. In some embodiments, HYBON _2032E-glass fibers from PPG industry may be used, which have a diameter of 12-20 μm, a linear thermal expansion coefficient of 4.8X10 ^-6 cm/cm.K, a specific heat of 0.19 cal/g.K, a thermal conductivity of 0.86 kcal/m.K, and a softening temperature of 860 ℃. In some embodiments, the fibers may be metal fibers, and one metal surface may be plated with another metal by the methods of the present disclosure, with a difference between the properties of the two metals, such that a composite material having a combination of properties may be obtained. In embodiments of the present disclosure, the metal may be any suitable pure metal or alloy, including, but not limited to, aluminum, copper, zinc, bismuth, tin, lead, indium, and the like.

In some embodiments, the graphite powder is a nano-scale ultra-fine graphite powder, the particle size of the ultra-fine graphite powder may be 0.5-3 μm, for example 0.5-1 μm, the compacted density of the ultra-fine graphite powder is about 1.6-1.9 g/cm ³, the specific surface area is about 1.0-10 m ²/g, and the particle shape of the ultra-fine graphite powder is approximately spherical. The superfine graphite powder can be ensured to be more densely and firmly distributed on the surface of the fiber by adopting the superfine graphite powder, so that the continuous compactness and the adhesive strength of the final metal coating are further improved. The nano-sized ultrafine graphite powder according to the embodiments of the present disclosure is not particularly limited, and a commercially available nano-sized ultrafine graphite powder reagent, such as Sigma-aldrich_282863 ultrafine graphite powder, may be used.

In embodiments of the present disclosure, the coupling agent may be any coupling agent capable of firmly binding the graphite powder to the fiber through a chemical reaction. In some embodiments, when the fibers are fibers (e.g., glass fibers) having uncondensed free silanol functional groups on the surface, the coupling agent may be a siloxane coupling agent and/or an epoxy silane coupling agent. The surface of the glass fiber is provided with a plurality of uncondensed free silanol functional groups, the surface of the graphite powder is also provided with a plurality of hydroxyl groups with chemical reactivity, and the graphite powder and the glass fiber can be firmly combined together in a chemical bond mode through the chemical reaction of the siloxane coupling agent and/or the epoxy silane coupling agent. Coupling agents useful in embodiments of the present disclosure include, but are not limited to, at least one of gamma-methacryloxypropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, gamma-epoxypropyl (methyl) diethoxysilane, gamma-methacryloxypropyl trimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, and gamma-chloropropyltrimethoxysilane.

In some embodiments, the method further comprises acid treating the fibers prior to applying the slurry. By acid treatment of the fibers (e.g., glass fibers), the number of uncondensed free silanol functional groups on the surface of the fibers can be increased to obtain a stronger bonding ability with the graphite powder.

In the embodiment of the disclosure, the resin plays a role of a carrier, so that the graphite powder can be distributed in the resin, and the resin also plays a certain role of adhesion, so that the graphite powder can be adhered to the surface of the fiber. In some embodiments, the resin is a low molecular weight resin having a molecular weight of less than 5000. By adopting the low molecular weight resin, the resin can be ensured to have better fluidity, namely the viscosity of the resin is controlled within a certain range, the aggregation and agglomeration of graphite powder in the slurry are prevented, and the resin can be ensured to be solidified or carbonized at a lower temperature (not higher than 300 ℃).

In embodiments of the present disclosure, suitable low molecular weight resins may be oligomeric epoxy resins, oligomeric polyacrylates, oligomeric polyvinylpyrrolidone, oligomeric polyamides, hydroxyethyl acrylate, oligomeric hydroxyethyl methacrylate, oligomeric isooctyl acrylate, oligomeric N-vinyl pyrrolidone, oligomeric epoxy acrylates, oligomeric amino acrylates, and the like. In some embodiments, an oligomeric epoxy resin having an epoxy value of 1 to 1.5 may be employed, which may have a number average molecular weight of 500 to 1000, such as 550 to 750, and a room temperature viscosity of 500 to 1300 mpa-s, such as 800 to 1000 mpa-s. The oligomeric epoxy resin having the above characteristics may be, for example, an Olympic DER6224 low molecular weight epoxy resin. In some embodiments, the low molecular weight epoxy resin may include an epoxy curing agent such as triethanolamine or other additives.

In some embodiments, the weight ratio of graphite powder, coupling agent, and resin in the slurry is (50-80): (5-10): (10-25) on a dry basis. By such proportions, it is ensured that the graphite powder occupies a large specific gravity to provide sufficient conductivity and to be firmly bonded to the fibers, while ensuring that the amount of coupling agent can be used to promote the chemical reaction of the graphite powder and the fibers and that the resin can provide a good carrier function in a sufficient amount. In general, such proportions can ensure a sufficient amount of graphite powder, improve coating uniformity, and increase the adhesive strength between the slurry and the fibers. In some embodiments, the slurry may further comprise a quantity of a solvent, which is not particularly limited by the present disclosure, and may be tetrahydrofuran or ethanol, for example. In the slurry containing the solvent, the content of graphite powder can be 50-80 wt%, the content of the coupling agent can be 5-10 wt%, the content of the resin can be 10-25 wt%, and the content of the solvent can be 5-15 wt% on a dry basis.

Referring to fig. 2, in some embodiments, the slurry is applied by passing the fibers through the slurry, which may facilitate continuous application of the slurry, and the speed at which the fibers pass through the slurry is no greater than 10m/min, which may be, for example, 2 to 5m/min, which may ensure uniformity of slurry application and the amount of graphite powder applied. The three rollers 50 can be utilized to drive the fiber to travel along the V-shaped path, the three rollers 50 are also arranged in a V shape, the three rollers comprise a first roller, a second roller and a third roller which are sequentially arranged along the fiber running direction, the second roller is positioned at the lowest position and is arranged in the slurry, the first roller and the third roller are positioned at the high position and can be arranged above the slurry, the fiber is led into the slurry through the first roller, sizing finishing is carried out at the second roller, and the fiber is led out of the slurry through the third roller, so that slurry coating is completed and the uniform stability of the coating process is ensured. The slurry coating may be performed in an air atmosphere and the temperature environment at which the slurry is applied may be 20 ℃ to 70 ℃, for example 50 ℃ to 60 ℃, ensuring that the slurry is used in a suitable temperature environment.

In the embodiment of the disclosure, the surface density of the graphite powder on the surface of the fiber is about 0.1×10 ^-5g/cm² to 1×10 ^-5g/cm², for example, 0.5×10 ^-5g/cm² to 0.8×10 ^-5g/cm², so that the surface resistivity of the fiber after the slurry is solidified is not higher than 10 ⁵ Ω -cm, and the fiber has better electrostatic attraction capability. The surface density of the graphite powder on the surface of the fiber can be adjusted by adjusting the proportion of the slurry, the particle size of the graphite powder, the running speed of the fiber and the like.

In some embodiments, the resin comprises an Ultraviolet (UV) photoinitiator, such as 2, 2-dimethoxy-1, 2-diphenylethan-1-one, etc., which can initiate in situ polymerization of the fiber sizing and enhance the connection of the graphite powder to the fibers by ultraviolet radiation. The resin may also contain an epoxy curing agent such as triethanolamine, the mass of the epoxy curing agent and photoinitiator being no more than one percent of the total mass of the low molecular weight resin. In embodiments where the resin comprises an ultraviolet initiator, the step of curing the slurry may include subjecting the slurry-coated fibers to infrared radiation and ultraviolet radiation, and exposing the slurry-coated fibers to an inert gas environment while the ultraviolet radiation is being applied. The slurry can be quickly solidified through infrared radiation, the method is suitable for continuously producing metallized fibers in an industrial scale, chemical links between graphite powder and the fibers can be triggered through ultraviolet radiation, the adhesion between the graphite powder and the fibers is further enhanced, and the adhesive strength of a final metal coating is improved. The fibers coated with the slurry are exposed to an inert gas atmosphere during the ultraviolet irradiation, so that oxidation damage to the graphite powder can be prevented. In some embodiments, the infrared radiation temperature is 150 ℃ to 300 ℃, such as 150 ℃ to 200 ℃, the infrared radiation distance is 5cm to 30cm, such as 10cm to 15cm, the infrared radiation power is 30kw to 36kw, and the infrared radiation curing time is no more than 3 minutes. The ultraviolet light wavelength may be 200nm to 300nm and the ultraviolet radiation power may be 5kw to 10kw. The inert gas environment can be a nitrogen environment, nitrogen flow can be introduced into the curing chamber, and the flow rate of the nitrogen can be 1-5 m/s. After the fiber has been coated with the slurry and cured, it becomes fiber 1 and is sent to the next process via a take-up roll 50, as shown in fig. 2.

After the steps of applying the sizing agent and curing the sizing agent, the surface of the fiber is in a conductive or semi-conductive state. The surface resistivity of the fibers may be measured using, for example, a Keithley model 6517A electrometer. In the embodiment of the disclosure, the surface resistivity of the fiber after the slurry is solidified is not higher than 10 ⁵ Ω -cm, for example, is controlled in the range of 10 ⁴ to 7×10 ⁴ Ω -cm, and the values are typical values which can achieve the better electrostatic coating effect of the metal powder through a large amount of experiments and verification of the disclosure, and the surface of the fiber can be sufficiently semi-conductive so as to maintain a stable electrostatic field, and attract the electronegative metal powder to be quickly and efficiently deposited and adsorbed on the surface of the fiber.

In some embodiments, electrostatically spraying the metal powder onto the surface of the coating includes positively charging the fibers forming the coating and passing through a powder spray chamber and spraying negatively charged metal powder onto the coating during the passing. In this way, the metal powder can be attracted to the fibers under the drive of electric and aerodynamic forces and adhere tightly to the fiber surfaces to form a metal powder coating layer of a certain thickness. Referring to fig. 3, the fiber 1 (fiber with a slurry cured coating formed thereon) is changed to the fiber 2 (fiber with a metal powder coating formed thereon) after electrostatic spraying. In some embodiments, the fiber 1 may be passed through the powder coating chamber 32 at a velocity of no more than 1m/min, which is advantageous to ensure uniform continuity of the metal powder coating layer.

Referring to fig. 3, positive charges may be applied to the fiber 1 by a positive charge application part 34 (e.g., a positive voltage output power source), and the fiber 1 may be connected to the positive charge application part 34 through a metal brush to obtain a positive voltage electrostatic field with controllable voltage. The positive voltage output power supply may be, for example, a dual-channel low-voltage power supply (TPS 7a 39) with an output current of 150mA, an output voltage ranging from 1V to 35V, low noise, and high PSRR (power supply rejection ratio). The positive voltage may be set to 1V to 35V, for example, 10V to 20V. The metal powder may be negatively charged and sprayed using a spray gun 36 (e.g., an electric spray gun), for example, the metal powder may be moved to the tip of the spray gun 36 under the impetus of a nitrogen gas stream at a pressure of 0.5MPa to 0.7MPa and electrostatically charged at a high voltage of-20 kV to-90 kV (e.g., -30kV to-60 kV) in a low current field (corona charging), so that the metal powder is charged quickly. Due to the electric repulsive force between the charged metal powder particles, the metal powder is dispersed after leaving the spray gun 36 and is directed to the fiber 1 under the aerodynamic force of the electrostatic field and nitrogen flow, and is tightly adhered to the surface of the fiber 1, forming a metal powder coating layer of a certain thickness. The number of spray guns 36 may be two and distributed on opposite sides of the fiber 1, spraying powder from both sides, so as to rapidly and uniformly perform electrostatic spraying. The distance between the nozzle and the fibre 1 may be 10cm to 50cm, for example 20cm to 30cm, ensuring a good spray result. In performing electrostatic spraying, the spray system (e.g., the closed system outlined by the dashed line in fig. 3) is filled with an inert gas (e.g., nitrogen) to avoid oxidation of the metal, at a pressure of about 1 atm, at a temperature of 30 ℃ to 60 ℃ and a relative humidity of less than 30%.

In some embodiments, the metal powder is a nano-aluminum powder, the nano-aluminum powder has a particle shape of approximately spherical, an average particle diameter of 50nm to 900nm (e.g., 100nm to 200 nm), a purity of 99.99%, a specific surface area of 10 to 30m ²/g, and no surface coverage. The aluminum powder used in the present disclosure may be a commercially available nano aluminum powder reagent such as NG04EO0202 nano aluminum powder manufactured by Nanografi company.

In some embodiments, causing the metal powder to melt onto the surface of the coating includes causing the metal powder to melt under heat and form a molten film on the surface of the coating, and annealing the fibers with the molten film formed. Referring to fig. 3, the fibers 2 (fibers with a metal powder coating layer formed thereon) leave the powder spray chamber 32 and enter a heating furnace 42 (e.g., a tube-type resistance furnace) for cladding, and the heating temperature of the heating furnace 42 reaches the melting point of the metal powder (e.g., 660 ℃ as aluminum), so that the metal powder on the fiber surface is heated and melted and spreads out on the fiber surface to form a continuous molten film and firmly adheres to the fiber surface. The temperature control accuracy of the heating furnace 42 is not more than 1 ℃, and the time for which the fiber passes inside the heating furnace 42 may be 3min to 9min. The metal powder may be heated and melted in an inert gas (e.g., nitrogen) atmosphere to prevent oxidation of the metal, and the flow rate of nitrogen gas introduced into the heating furnace 42 may be 1 to 3m/s. The fiber with the formed molten film further enters an annealing furnace 44 for annealing, and the temperature is gradually changed from 600 ℃ to 100 ℃, so that the molten film is solidified to finally obtain the fiber with the metal coating, and the mechanical strength of the fiber can be improved through annealing.

Fig. 2 and 3 are different partial structural views of an apparatus for coating metal on a fiber surface shown in an exemplary embodiment of the present disclosure, referring to fig. 2 and 3, the apparatus for coating metal on a fiber surface includes a slurry tank 10 for holding a slurry containing graphite powder, a coupling agent, and a resin, a curing mechanism 20 for curing the slurry, an electrostatic spraying mechanism 30, the electrostatic spraying mechanism 30 including a powder spraying chamber 32, a positive charge applying part 34, a spray gun 36 for applying negative charge to the metal powder and spraying the same, a cladding mechanism 40 including a heating furnace 42 capable of heating the metal powder to a molten state, and a plurality of winding rollers 50 for driving the fiber to move and sequentially pass through the slurry tank 10, the curing mechanism 20, the powder spraying chamber 32, and the heating furnace 42.

In some embodiments, referring to fig. 2, three rolls 50 are arranged in a V-shape and disposed in the slurry tank 10, and the three rolls 50 include a middle roll disposed at a low position and two side rolls disposed at both sides of the middle roll and at a high position. In some embodiments, curing mechanism 20 includes a curing chamber 22 and an emitting portion that emits infrared and ultraviolet rays into curing chamber 22. In some embodiments, referring to fig. 3, the electrostatic spraying mechanism 30 further includes a powder tank 31 for storing metal powder and a gas cylinder 33 for storing gas (e.g., compressed nitrogen) connected to the spray gun 36 for providing the metal powder and gas flow to the spray gun 36. The number of spray guns 36 may be two and oppositely disposed. The electrostatic spraying mechanism 30 may also include a hopper, an electrostatic power supply, a controller, an overspray powder collection portion, a powder recovery portion, and the like. The various components included in the electrostatic spray mechanism 30 may be connected by hoses and cables, as well as all necessary regulators and fittings. In some embodiments, the cladding mechanism 40 further includes an annealing furnace 44, and the plurality of rolls 50 further drive the fibers through the annealing furnace 44.

Fig. 4 is a cross-sectional view of a metallized fiber 100 according to an exemplary embodiment of the present disclosure, and as shown in fig. 4, the metallized fiber 100 includes a fiber body 101, a coating layer 103 provided on a surface of the fiber body 101, the coating layer 103 being a solidified product of a slurry containing graphite powder, a coupling agent, and an adhesive, and a metal cladding layer 105 provided on a surface of the coating layer 103, the metal cladding layer 105 being obtained by cladding a metal powder electrostatically sprayed to the surface of the coating layer 103.

In summary, through the technical scheme of the disclosure, the metallized fiber can be prepared, the mechanical strength of the fiber is greatly improved, the application range of the fiber is expanded, the design of a complex inert gas protection system can be avoided, the use of gas with high danger is avoided, the cost of production equipment is reduced, the safety of production is increased, the metallized fiber can be produced in a mass mode in an economical and cheap way, the prepared metallized fiber can obtain a uniform, continuous and compact metal coating with better electrical property, the prepared metallized fiber can avoid the generation of metal-fiber interface holes, and the metal coating has strong adhesive force.

The following is a description of specific examples and comparative examples.

Example 1

The method of coating aluminum on the surface of glass fiber was performed according to the following procedure, wherein the glass fiber was HYBON —2032 glass fiber having a diameter of 20 μm and a softening temperature of 860 ℃.

Step one, coating the glass fiber with the sizing agent in an air atmosphere. The slurry comprises the components of nano-scale ultrafine graphite powder, a coupling agent, low-molecular-weight epoxy resin, a solvent and the like. The average particle size of the nano-grade ultrafine graphite particles is about 0.6 mu m, the compaction density is about 1.6g/cm ³, and the specific surface area is about 6m ²/g. The coupling agent is gamma-methacryloxypropyl trimethoxy silane and gamma-epoxypropyl trimethoxy silane, and the mass ratio of the gamma-methacryloxypropyl trimethoxy silane to the gamma-epoxypropyl trimethoxy silane is 1:1. The low molecular weight epoxy resin was DER6224 low molecular weight epoxy resin, the number average molecular weight was about 700, and the room temperature viscosity was 800 mPas. The low molecular weight epoxy resin contains triethanolamine and UV photoinitiator 2, 2-dimethoxy-1, 2-diphenylethane-1-ketone, wherein the mass of the triethanolamine and the UV photoinitiator is 0.5% of the total mass of the low molecular weight epoxy resin. The solvent is tetrahydrofuran. Mixing nanoscale ultrafine graphite powder, a coupling agent, low-molecular-weight epoxy resin and tetrahydrofuran according to a mass ratio of 14:1:3:1 to prepare slurry. The glass fibers were slurry coated in an air atmosphere at a temperature of 50 ℃ and the glass fibers were passed through a slurry tank at a speed of about 3m/min.

And secondly, the glass fiber coated with the slurry enters a curing box for performing far infrared radiation rapid curing treatment, and simultaneously, in order to strengthen the bonding between the superfine graphite powder and the glass fiber, a UV lamp is added in the curing box for irradiation, and chemical linkage between the graphite powder and the glass fiber is triggered by high-energy UV light. The far infrared radiation temperature is 200 ℃, the infrared radiation distance is 10cm, and the infrared radiation curing time is about 3min. The UV lamp wavelength is 200nm to 300nm, and the power is 10kw. And introducing nitrogen flow into the curing box to prevent oxidation from damaging graphite powder, wherein the flow rate of the nitrogen is about 2m/s.

And thirdly, carrying out electrostatic coating on the nano aluminum powder on the glass fiber after the coating slurry and the curing treatment. The nano aluminum powder particles are approximately spherical, the average particle diameter of the particles is 110nm, the purity is 99.99%, the specific surface area is 20m ²/g, and the surfaces are not covered. The glass fiber is connected with a positive voltage output power supply through a metal brush to obtain a positive voltage electrostatic field with controllable voltage, and the positive voltage is 10V. The spray system was filled with nitrogen at a pressure of about 1 atm at a temperature of 30 ℃ and a relative humidity of less than 30%. The nano aluminum powder moves to the tip of the electric spray gun under the pushing of nitrogen flow with the pressure of 0.5MPa, and is charged electrostatically at the high voltage of-60 kV in a low current field (corona charging). The distance between the mouth of the electric spray gun and the glass fiber is about 25cm, and the negatively charged aluminum powder is guided to the glass fiber under the pneumatic force of the electrostatic field and the nitrogen flow. The axial moving speed of the glass fiber in the powder spraying chamber is about 1m/min. When the glass fiber is immersed in the nanometer aluminum powder cloud, the charged aluminum powder is attracted to the glass fiber under the driving of electric power and aerodynamic force and is tightly adhered to the surface of the glass fiber, so that an aluminum powder coating layer with a certain thickness is formed.

And fourthly, the glass fiber coated with the aluminum powder is pulled out of the spraying chamber to enter the tubular high-temperature resistance furnace and enters the annealing furnace after leaving the tubular high-temperature resistance furnace. The temperature is 660 ℃ in the tubular high-temperature resistance furnace, the temperature control precision is less than or equal to +/-1 ℃, and the nitrogen flow is protected (the flow speed is 1 m/s). The glass fiber passes through the resistance furnace for about 5min, and the nano aluminum powder is melted to form a continuous film and firmly adhered to the surface of the glass fiber. The glass fiber coated with aluminum is gradually transited from 600 ℃ to 100 ℃ in an annealing furnace, and the aluminum coated with aluminum is solidified to finally obtain the aluminum coated glass fiber.

After the aluminized glass fiber is obtained, detecting the conductivity of the aluminized glass fiber by adopting a PCE-COM20 conductivity tester, and taking an average value of all measured values. The aluminum coating thickness on the surface of the aluminized glass fiber was measured using a Mitutoyo DIGITAL PALMER coating thickness meter, and the average was taken from nine measurements equally spaced on the fiber. And testing the adhesive force of the metal coating by adopting a NanoTest Vantage micro-nano indentation scratch instrument. And (3) observing the section morphology of the aluminized glass fiber by adopting a JSM 6510 Scanning Electron Microscope (SEM).

Example 2

Example 2 differs from example 1 mainly in that example 2 was prepared by mixing nanoscale ultrafine graphite powder, a coupling agent, a low molecular weight epoxy resin, and tetrahydrofuran in a mass ratio of 8:1:3:1 to prepare a slurry.

Comparative example 1

Comparative example 1 differs from example 1 mainly in that the slurry of comparative example 1 does not contain a coupling agent, the low molecular weight epoxy resin of comparative example 1 does not contain a UV photoinitiator 2, 2-dimethoxy-1, 2-diphenylethan-1-one, the mass of the curing agent triethanolamine is 1% of the total mass of the low molecular weight epoxy resin, and UV lamp irradiation is not performed in step two.

Comparative example 2

Comparative example 2 differs from example 1 mainly in that the low molecular weight epoxy resin of comparative example 2 does not contain the UV photoinitiator 2, 2-dimethoxy-1, 2-diphenylethan-1-one, the mass of the curing agent triethanolamine being 1% of the total mass of the low molecular weight epoxy resin.

In example 1, the glass fiber was subjected to a coating slurry and a curing treatment, and the surface thereof was in a semiconductive state. The surface density of the ultra-fine graphite powder on the surface of the glass fiber is about 0.5X10 ^-5g/cm². The surface resistivity of the glass fiber was measured using a Keithley 6517A type electrometer, and the surface resistance of the glass fiber after the curing treatment of the coating paste obtained by the measurement was about 6×10 ⁴ Ω·cm.

FIG. 5 is a scanning electron microscope image of a cross section of an aluminized glass fiber prepared in example 1, as shown in FIG. 5, the aluminized glass fiber comprising an innermost glass fiber body and an outermost aluminum coating, there being an interfacial coating formed between the glass fiber and the aluminum coating after the slurry has been cured.

The test results of the parameters related to the aluminized glass fibers of example 1, example 2, comparative example 1 and comparative example 2 are shown in table 1.

TABLE 1 comparison of aluminum metallized fiber properties

As shown in table 1, both example 1 and example 2 achieved better densification and adhesion strength of the aluminum coating, wherein example 2 reduced the amount of graphite powder, resulting in example 2 having poorer densification, conductivity and adhesion strength than example 1. The slurry of comparative example 1 contained no coupling agent, the resin contained no UV photoinitiator and no UV lamp irradiation, compared to example 1, resulted in poor coating thickness, coating compactness, electrical conductivity and adhesion strength of comparative example 1. The absence of UV photoinitiator in the resin of comparative example 2 compared to example 1 resulted in less excellent coating compactness, conductivity and adhesion strength of comparative document 2 than example 1.

Thus, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concepts of the present disclosure, some details known in the art are not described. How to implement the solutions disclosed herein will be fully apparent to those skilled in the art from the above description.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that the foregoing embodiments may be modified and equivalents substituted for elements thereof without departing from the scope and spirit of the disclosure. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict.

Claims (7)

1. A method for coating a metal on a fiber surface, comprising: Coating a slurry on the surface of the fiber, wherein the slurry comprises graphite powder, a coupling agent and a resin; Allowing the slurry to solidify and form a coating on the fiber surface; electrostatically spraying metal powder onto the coating surface; The metal powder is melted onto the surface of the coating; On a dry basis, in the slurry, the weight ratio of the graphite powder, the coupling agent, and the resin is (50-80):(5-10):(10-25). 2. The method according to claim 1, wherein the graphite powder has a particle size of 0.5 to 3 μm; and/or the coupling agent is a siloxane coupling agent and/or an epoxy silane coupling agent; and/or the molecular weight of the resin is less than 5000. 3. The method according to claim 1, wherein the slurry is applied by passing the fiber through the slurry, and the speed at which the fiber passes through the slurry is not greater than 10 m/min; and/or Before applying the slurry, the method further comprises: treating the fiber with acid. 4. The method according to claim 1, wherein the surface density of the graphite powder on the fiber surface is 0.1× ^10-5 g/ ^cm2 to 1× ^10-5 g/ ^cm2 ; and/or the surface resistivity of the fiber formed with the coating is not higher than ¹⁰⁵ Ω·cm. 5. The method according to claim 1 is characterized in that the resin contains an ultraviolet light initiator, and the curing of the slurry comprises: subjecting the fiber coated with the slurry to infrared radiation and ultraviolet radiation, and placing the fiber coated with the slurry in an inert gas environment during the ultraviolet radiation. 6. The method according to claim 1, wherein electrostatically spraying metal powder onto the coating surface comprises: The fiber formed with the coating is made to be positively charged and pass through a powder spraying chamber, and the negatively charged metal powder is sprayed onto the coating during the passing process; and/or The step of cladding the metal powder onto the coating surface comprises: The metal powder is heated to melt and form a molten film on the surface of the coating layer, and the fiber formed with the molten film is annealed. 7. A metallized fiber (100), characterized by comprising: Fiber body (101); a coating (103) provided on the surface of the fiber body (101), wherein the coating (103) is a solidified product of a slurry, wherein the slurry comprises graphite powder, a coupling agent, and a resin; a metal cladding layer (105) provided on the surface of the coating (103), the metal cladding layer (105) being obtained by cladding metal powder electrostatically sprayed onto the surface of the coating (103); On a dry basis, in the slurry, the weight ratio of the graphite powder, the coupling agent, and the resin is (50-80):(5-10):(10-25).