Composite hard mat and method of making same

Abstract

The application discloses a composite hard felt and a preparation method thereof. The preparation method comprises the following steps: preparing a carbon-carbon composite material shell and an uncarbonized resin-based hard felt respectively, bonding the carbon-carbon composite material shell and the uncarbonized resin-based hard felt by brushing a resin, coating a protective coating slurry outside the carbon-carbon composite material shell layer, curing all the resins at high temperature, bonding the carbon-carbon composite material shell and the hard felt into an integrated whole, and simultaneously curing the protective coating slurry, so that a protective coating layer mainly made of silicon carbide is formed on the carbon-carbon composite material shell layer, and then the carbon-carbon composite material shell is graphitized to obtain a composite hard felt product blank, and finally, the composite hard felt product blank is machined into a final product. The composite hard felt prepared by the application has high structural strength, high compression resistance and bending resistance, good oxidation resistance and friction resistance, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, in particular to a composite hard felt and a preparation method thereof. BACKGROUND

[0002] The existing hard felt on the market is divided into two types, namely, whole hard felt and laminated hard felt. The whole hard felt is generally made by cutting and laying carbon fiber filaments to form a net tire, then needle punching to form, then impregnating resin, heat curing, and then carbonizing and graphitizing to form. The laminated hard felt is made by coating resin between the layers of soft felt (carbon felt or graphite felt), bonding layer by layer, then impregnating resin, heat curing, and then carbonizing and graphitizing to form.

[0003] If these two types of cured felts are directly used as the inner wall of the furnace or installed on the furnace door, they generally need to be attached with graphite paper or carbon cloth, or first attached with carbon cloth and then attached with graphite paper. The purpose of attaching carbon cloth is mainly: (1) to increase the strength of the hard felt; (2) to improve the flatness of the hard felt; (3) to protect the hard felt from damage caused by knocking and friction. The purpose of attaching graphite paper is mainly: (1) to increase the smoothness of the hard felt; (2) to seal the hard felt to prevent volatile substances from polluting the furnace; (3) to play the role of infrared reflection to reduce heat loss and increase heat preservation performance.

[0004] However, the existing scheme has the following problems: (1) the strength of carbon cloth and graphite paper is poor, especially graphite paper, which is basically not resistant to scratching and is easily scratched during furnace installation or when materials are put in and out; (2) carbon cloth and graphite paper are not resistant to oxidation, especially at the furnace door position, which is easily oxidized; (3) during the production of hard felt, the carbon fiber cloth or graphite paper may be unevenly glued, and continuous thermal expansion and contraction during use can cause delamination and peeling of the carbon fiber cloth or graphite paper. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a composite hard felt and a preparation method thereof, which prolongs the service life of the hard felt and has a higher cost performance.

[0006] In a first aspect, the present application provides a composite hard felt, which is realized by the following technical scheme.

[0007] The composite hard felt comprises a hard felt layer, a carbon-carbon composite material shell layer formed on one side or both sides of the hard felt layer, and a protective coating layer formed on the carbon-carbon composite material shell layer located on the outer side of the composite hard felt.

[0008] In a second aspect, the present application provides a preparation method of a composite hard felt, which is realized by the following technical scheme.

[0009] The preparation method of the composite hard felt comprises the following steps:

[0010] S1. Preparing non-carbonized resin-based hard felt;

[0011] S2. Preparing carbon-carbon composite material shell;

[0012] S3. Bonding the carbon-carbon composite material shell with the non-carbonized resin-based hard felt by brushing the resin, and then coating a protective coating slurry on the carbon-carbon composite material shell layer;

[0013] S4. High-temperature curing of all resins, and then carbonization and graphitization to produce a composite hard felt finished product blank, which is machined into a shape.

[0014] Further, in step S1, the preparation method of the non-carbonized resin-based hard felt is as follows: cutting carbon fiber filaments, making carbon fiber web tires by needling, layer-by-layer laying up the carbon fiber web tire, then impregnating resin and heating and curing the resin to prepare a non-carbonized and graphitized whole needled cured hard felt.

[0015] Further, the layer density of the layer-by-layer laid-up carbon fiber web tire is 5-15 layers / cm; the whole needling density is 10-20 needles / cm 2 ; the density of the non-carbonized and graphitized whole needled cured hard felt is 0.12-0.2 g / cm 3 .

[0016] Further, in step S1, the preparation method of the non-carbonized resin-based hard felt is as follows: selecting a graphitized PAN-based or viscose-based graphite felt, layer-by-layer bonding the soft felt by resin, then impregnating resin and heating and curing the resin to prepare a non-carbonized and graphitized laminated cured hard felt.

[0017] Further, the thickness of the graphitized PAN-based or viscose-based graphite felt is 2-10 mm; the density of the non-carbonized and graphitized laminated cured hard felt is 0.2-0.3 g / cm 3 .

[0018] Further, in step S2, the preparation method of the carbon-carbon composite material shell is as follows:

[0019] a. Laying carbon fiber filaments by drawing to make carbon fiber cloth;

[0020] b. Cutting carbon fiber filaments, making carbon fiber web tires by needling;

[0021] c. Alternately laying up carbon fiber cloth and carbon fiber web tires, and whole needling to obtain a preform; wherein the mass fraction of carbon fiber cloth is 20%-80%, and the rest is carbon fiber web tire; the needling density is 20-50 needles / cm 2 , the layer density is 10-20 layers / cm, and the density of the preform is 0.4-0.5 g / cm 3 ;

[0022] d. impregnate the preform with resin, then hot-press and cure to obtain a carbon-carbon composite shell (interlayer density 8-20 layers / cm), the thickness of the carbon-carbon composite shell being 3-10 mm.

[0023] Further, in step S2, the carbon-carbon composite shell is prepared as follows:

[0024] a. carbon fiber filaments are laid out by drawing to form a carbon fiber cloth;

[0025] b. the carbon fiber cloth is adhered and laid by brushing resin layer by layer, the interlayer density being 10-20 layers / cm;

[0026] c. impregnate with resin again, then hot-press and cure to obtain a carbon-carbon composite shell (interlayer density 8-20 layers / cm), the thickness of the carbon-carbon composite shell being 3-10 mm.

[0027] Further, in step S3, the protective coating slurry comprises the following components by mass percentage:

[0028]

[0029] Further, the powder comprises silicon carbide powder and carbon conductive powder, the mass ratio of the silicon carbide powder and the carbon conductive powder being (1-4):1; the carbon conductive powder is selected from one or a mixture of several of graphite powder, carbon nanotube powder, graphene powder, carbon black powder, and carbon fiber powder.

[0030] Further, the film-forming agent is selected from an alcohol substance.

[0031] Further, the dispersing agent is selected from a polyquaternary ammonium salt surfactant or a non-ionic high molecular surfactant.

[0032] Further, the defoaming agent is selected from an alcohol or modified silicone defoaming agent.

[0033] Further, the thickening agent is selected from a non-ionic high molecular polymer.

[0034] Further, the leveling agent is a polyether-modified silicone high molecular polymer.

[0035] Further, in step S4, the curing temperature is 100-300°C, and the curing time is 20-60 min.

[0036] Further, in step S4, the carbonization temperature is 800-1600℃, the carbonization temperature rising rate is 3-15℃ / min, the holding time at the highest temperature is 30-200min, and the natural cooling is performed when the power is cut off during the temperature decreasing; the graphitization temperature is 1700-2800℃, the graphitization temperature rising rate is 3-15℃ / min, the holding time at the highest temperature is 30-200min, and the natural cooling is performed when the power is cut off during the temperature decreasing.

[0037] The present application has the following beneficial effects.

[0038] 1. The composite hard felt surface layer of the present application is composed of high-strength carbon-carbon composite material, so the structure strength of the hard felt is high, and the hard felt has high compression resistance and bending resistance (bending resistance≥3Mpa; compression resistance≥5Mpa), and is resistant to friction and will not be scratched when loading or unloading materials.

[0039] 2. The carbon-carbon composite material of the composite hard felt surface layer of the present application has high oxidation resistance, and has higher oxidation resistance after being coated with a protective coating.

[0040] 3. The carbon-carbon composite material of the composite hard felt surface layer of the present application is integrally covered on the outside, and will not delaminate during use.

[0041] 4. The protective coating of the composite hard felt surface layer of the present application is polished by surface grinding, and has a surface as smooth as graphite paper, which can reflect infrared rays, reduce heat loss, and increase heat preservation performance.

[0042] 5. The carbon-carbon composite material of the composite hard felt surface layer of the present application has a relatively dense density, and the more dense protective coating seals the hard felt and prevents volatile substances from polluting the furnace. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a schematic diagram of the layered structure of the composite hard felt of the present application (single-sided carbon-carbon composite material shell);

[0044] Figure 2 is a schematic diagram of the layered structure of the composite hard felt of the present application (double-sided carbon-carbon composite material shell).

[0045] Among them, 1. protective coating; 2. carbon-carbon composite material shell layer; 3. hard felt layer. DETAILED DESCRIPTION

[0046] The present patent application is further described below in conjunction with examples.

[0047] In the following examples, the experimental methods used are conventional methods unless otherwise specified; the materials, reagents, etc. used in the following preparation examples and examples can be obtained from commercial channels unless otherwise specified.

[0048] The present application combines carbon / carbon composite material with hard felt to make a new type of cured felt of the two. The main process scheme is:

[0049] The preform is prepared by needling carbon fiber web (plain carbon fiber cloth made of Zhongfu Shenying 49s-12K carbon fiber yarn and carbon fiber web, with one layer of carbon cloth and one layer of web alternately laid, preform needling density 20-50 needles / cm 2 , interlayer density 10-20 layers / cm, preform density 0.4-0.5 g / cm 3 ) or completely using carbon fiber cloth layer-by-layer bonding and laying (Zhongfu Shenying 49s-12K plain carbon fiber cloth with interlayer density 10-20 layers / cm, layer-by-layer bonding and laying by brushing resin (phenolic, furan and epoxy resin), then impregnating resin (such as phenolic, furan and epoxy resin), and then hot pressing and curing to prepare a carbon / carbon composite material shell layer with a thickness of 3-10 mm. The carbon / carbon composite material shell layer is brushed with resin and combined with hard felt (web layers laid layer by layer using Zhongfu Shenying 49s-12K, with interlayer density 5-15 layers / cm, then needled at 10-20 needles / cm 2 , then impregnated with resin, and the resin is heated and cured to prepare a whole needled cured hard felt with a density of 0.12-0.2 g / cm 3 that has not been carbonized and graphitized; or using a 10mm thick, 1800-2200℃ graphitized PAN-based or viscose-based graphite felt, layer-by-layer bonding the soft felt with resin, then impregnating the resin, and heating and curing the resin to prepare a graphite felt with a density of 0.2-0.3 g / cm 3The carbon carbon composite material shell layer is adhered to the uncured and graphitized laminated cured hard felt by adhesion, and a protective coating slurry (coating slurry with a powder solid content of 10-50%, the powder being mainly silicon carbide powder, and further adding one or more of a mixture of high-purity graphite powder, carbon nanotube powder, graphene powder, carbon black powder, and carbon fiber powder, with fineness in the range of 50-10,000 mesh) is coated on the outer layer of the carbon carbon composite material shell layer. First, the powder is uniformly dispersed in a solvent that is compatible with the selected resin (if a sand mill is selected, the grinding speed is 500-5,000 r / min, and the time is 2-10 h) by using a stirrer, a horizontal sand mill, a basket sand mill, or other mechanical dispersion equipment. A dispersing agent is added during the dispersion process, and the amount of the dispersing agent is 0.1-5% of the total amount of the dispersion. Then, the prepared dispersion is added to the selected resin, and a defoaming agent, a thickening agent, a leveling agent, and a film-forming agent are further added. The resin accounts for 5%-50% of the total mass of the slurry. The film-forming agent accounts for 5‰-2% of the mass of the resin, and the film-forming agent is an alcohol substance. The dispersing agent is a polyquaternary ammonium salt surfactant or a non-ionic high-molecular surfactant, and the amount of the dispersing agent is 5%-30% of the powder. The defoaming agent is an alcohol or a modified silicone defoaming agent, and the amount of the defoaming agent is 2‰-5% of the total mass of the slurry. The thickening agent is a non-ionic high-molecular polymer, and the amount of the thickening agent is 5‰-5% of the total mass of the slurry. The leveling agent is a polyether-modified silicone high-molecular polymer, and the amount of the leveling agent is 2‰-5% of the total mass of the slurry. The viscosity of the coating slurry is 100 cps-5,000 cps. The dispersion and the resin are fully and uniformly mixed by using a stirring device, and the protective coating slurry is prepared by repeatedly extruding the mixture through a three-roll mill. Then, the resin is cured at a high temperature of 100-300°C, so that the carbon carbon composite material shell layer and the hard felt are adhered to form an integrated whole, and a protective coating layer is formed on the carbon carbon composite material shell layer. Then, the carbon carbon composite material shell layer and the hard felt are carbonized and graphitized (carbonization temperature: 800-1,600°C; graphitization temperature: 1,700-2,800°C) to prepare a composite hard felt. Finally, the composite hard felt is machined and ground to form a finished product.

[0050] Embodiment

[0051] A method for preparing a composite hard felt, comprising the following steps:

[0052] 1. Preparing a shell layer blank: a carbon fiber web tire preform (a plain carbon fiber cloth and a carbon fiber web tire are prepared by using Zhongfushengying 49s-12K carbon fiber yarn, and the preform is prepared by alternately stacking one layer of carbon cloth and one layer of web tire, with the mass ratio of carbon cloth to web tire being 4:1, the needle punching density of the preform being 30 needles / cm 2 , the interlayer density being 15 layers / cm, and the preform density being 0.5 g / cm 3 ) is impregnated with a phenol formaldehyde resin, and is laminated and cured by heating (the interlayer density is 30 layers / cm) to prepare a carbon carbon composite material shell blank;

[0053] 2. Preparation of hard felt layer: carbon fiber web tire layer is made by using Zhongfugongying 49s-12K carbon fiber yarn, the density between layers is 10 layers / cm, then 10 needles / cm 2 Needle punching is performed, then phenolic resin is impregnated, the resin is cured by heating, and a hard felt blank with a density of 1.2-1.8 g / cm 3 Non-carbonized and graphitized resin-based integral needle-punched hard felt blank;

[0054] 3. Preparation of coating slurry: the solid content of the powder in the coating slurry is 50%, the powder is mainly silicon carbide powder, the mass fraction of silicon carbide in the powder is 70%, 10% by mass of carbon nanotube powder and 20% by mass of 300-mesh carbon fiber powder are further added. The powder is first dispersed in deionized water (solid content of powder 10-20%) by a horizontal sand mill at 1000 r / min for 6 h to prepare a dispersion liquid. A dispersing agent is added in an amount of 5‰ of the mass of the dispersion liquid during the dispersion process. Then, the prepared dispersion liquid is added to the water-based phenolic resin, the mass fraction of the resin in the total slurry is 20%, and a defoaming agent, a thickening agent, a leveling agent and a film-forming agent are further added. The film-forming agent is 1% of the total slurry by mass of propylene glycol. The dispersing agent is polyvinylpyrrolidone. The defoaming agent is n-butanol, and the amount is 3% of the total mass of the slurry. The thickening agent is polyethylene oxide, and the amount is 1% of the total mass of the slurry. The leveling agent is polyether modified silicone, and the amount is 3% of the total mass. The viscosity of the coating slurry is 3000 cps. After sufficient stirring by a stirring device, the dispersion liquid and the resin are fully and uniformly dissolved with each other, and then the coating slurry is prepared by repeatedly passing through a three-roll mill three times to form a protective coating slurry;

[0055] 4. Interlayer adhesion: the carbon-carbon composite shell blank is adhered to the non-carbonized resin-based hard felt by brushing the resin;

[0056] 5. Coating: the protective coating slurry is coated on the outer layer of the carbon-carbon composite shell layer by the brushing process, and a curing agent is added in an amount of 10% by mass of the resin to make the coating quickly surface dry;

[0057] 6. Curing and bonding resin: all the resins are cured at a high temperature of 200℃ to bond the carbon-carbon composite shell layer and the hard felt into an integral whole, and at the same time, the protective coating slurry is also cured to form a protective coating layer on the carbon-carbon composite shell layer;

[0058] 7. Carbonization and graphitization: the composite hard felt finished product blank is prepared by carbonization and graphitization (carbonization temperature is 1200℃, carbonization furnace heating rate is 5-10℃ / min, holding time at the highest temperature is 100 min, and natural cooling is performed when power is cut off during cooling; graphitization temperature is 2200℃, graphitization furnace heating rate is 5-10℃ / min, holding time at the highest temperature is 200 min, and natural cooling is performed when power is cut off during cooling);

[0059] 8. Forming: machining forming as needed.

[0060] Performance testing

[0061] 1. Bending strength test: test the bending strength ≥ 5Mpa according to the method specified in GB / T 40398.2-2021. The existing process generally has a bending strength ≥ 0.5Mpa, and the bending strength is increased by more than 1000%;

[0062] 2. Compressive strength test: test the compressive strength ≥ 10Mpa according to the method specified in GB / T 34559-2017. The existing process generally has a bending strength ≥ 2Mpa, and the bending strength is increased by more than 500%;

[0063] 3. High temperature resistance test: process 200mm*100mm*30mm size, put into high temperature furnace, 20℃ / min to the highest temperature 2800℃, holding time 200min, when cooling down, power off and naturally cool to room temperature, take out, the material does not crack and deformation, and the interlayer does not separate;

[0064] 4. Oxidation resistance test: process 200mm*100mm*30mm size, put into muffle furnace, in air environment, heat to 450℃, and maintain 450℃, 2h, the surface of the material coating side does not have obvious oxidation, and the coating does not have obvious peeling.

[0065] The embodiments of the specific embodiment are the preferred embodiments of the present application, and are not limited to the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method of making a composite hard mat, characterized by: The composite hard felt comprises a hard felt layer, a carbon-carbon composite material shell layer formed on one side or both sides of the hard felt layer, and a protective coating layer formed on the carbon-carbon composite material shell layer on the outer side of the composite hard felt. The composite hard felt preparation method comprises the following steps: S1. preparing an uncarbonized resin-based hard felt; S2. preparing a carbon-carbon composite material shell; S3. bonding the carbon-carbon composite material shell and the uncabonized resin-based hard felt by brushing resin, and then coating a protective coating slurry on the carbon-carbon composite material shell layer; S4. curing all the resins at high temperature, and then carbonizing and graphitizing to obtain a composite hard felt finished product blank, which is machined into a shape; In step S2, the carbon-carbon composite material shell is prepared by the following method: a. carbon fiber filaments are laid out by drawing to form a carbon fiber cloth; b. the carbon fiber filaments are cut and needled to form a carbon fiber web; c. Alternately lay up carbon fiber cloth and carbon fiber web, and integrally needle punch to obtain a preform; wherein the mass percentage of the carbon fiber cloth is 20-80%, and the rest is the carbon fiber web; the needle punching density is 20-50 needles / cm 2 , the interlayer density is 10-20 layers / cm, and the preform density is 0.4-0.5 g / cm 3 ; d. the preform is impregnated with resin, and then hot-pressed and cured to obtain the carbon-carbon composite material shell; or the carbon-carbon composite material shell is prepared by the following method: a. carbon fiber filaments are laid out by drawing to form a carbon fiber cloth; b. the carbon fiber cloth is bonded and laid layer by layer by brushing resin, and the layer density is 10-20 layers / cm; c. the resin is then impregnated, and then hot-pressed and cured to obtain the carbon-carbon composite material shell; In step S3, the protective coating slurry comprises the following components by mass percentage: Powder 10%-50%; Dispersing agent 2‰-1%; Resin 5%-20%; Defoaming agent 2‰-5%; Thickening agent 5‰-5%; Leveling agent 2‰-5%; Film-forming agent 5‰-1%; Solvent 13%-83.4%; The powder comprises silicon carbide powder and carbon conductive powder, and the mass ratio of the silicon carbide powder to the carbon conductive powder is (1-4):1; the carbon conductive powder is selected from one or a mixture of several of graphite powder, carbon nanotube powder, graphene powder, carbon black powder, and carbon fiber powder.

2. The method of claim 1, wherein: In step S1, the uncabonized resin-based hard felt is prepared by the following method: carbon fiber filaments are cut and needled to form a carbon fiber web, the carbon fiber web is laid layer by layer and needled as a whole, and then the resin is impregnated and cured by heating to obtain an uncabonized and graphitized whole-needled cured hard felt.

3. The method of claim 2, wherein: The interlayer density of the carbon fiber web tire layer layer lay-up is 5-15 layers / cm; the overall needling density is 10-20 needles / cm 2 ; the density of the un-carbonized and graphitized overall needling solidified hard felt is 0.12-0.2 g / cm 3 .

4. The method of claim 1, wherein: In step S1, the uncabonized resin-based hard felt is prepared by the following method: a graphitized PAN-based or viscose-based graphite felt is selected, the soft felt layers are bonded by resin, and then the resin is impregnated and cured by heating to obtain an uncabonized and graphitized laminated cured hard felt.

5. The method of claim 4, wherein: The thickness of the graphitized PAN-based or viscose-based graphite felt is 2-10 mm; the density of the uncarbonized and graphitized laminated cured hard felt is 0.2-0.3 g / cm 3 .

Images