158 results about "Interfacial shear" patented technology

The invention relates to a waterborne polyurethane sizing agent, a preparation method thereof and a carbon fiber, and belongs to the technical field of carbon fiber preparation. The preparation method of the waterborne polyurethane sizing agent comprises the following steps: S10, dispersing and mixing amino modified polydimethylsiloxane and graphene oxide in an organic solvent, carrying out grafting reaction, and carrying out vacuum drying to obtain amino modified polydimethylsiloxane grafted graphene oxide; s20, mixing polyether glycol, diisocyanate and a hydrophilic chain extender, and carrying out a first reaction to obtain a first reaction solution; mixing the first reaction liquid, a small molecule chain extender and amino modified polydimethylsiloxane grafted graphene oxide for second reaction to obtain a polymerization system; and carrying out a neutralization reaction on the polymerization system and a neutralizer, and dispersing in water to obtain the waterborne polyurethane sizing agent. The waterborne polyurethane sizing agent can effectively increase the surface roughness of carbon fibers and improve the interfacial shear strength between the carbon fibers and a resin matrix.

The invention relates to a glass fiber reinforced polyurethane composite material and a preparation process thereof, and belongs to the technical field of polymer composite materials. The formula of the glass fiber reinforced polyurethane composite material comprises the following components in parts by weight: 60-80 parts of thermoplastic polyurethane, 15-25 parts of modified glass fiber, 2-5 parts of an interface modifier, 1-2 parts of an antioxidant and 1-3 parts of a lubricant. A covalently bonded silane coupling agent-nano silicon dioxide composite transition layer is formed by mixing chopped glass fibers and continuous glass fibers to construct a synergistic enhancement system and combining argon-oxygen plasma activation and nano silicon dioxide sol coating processes, so that the interfacial shear strength is remarkably improved, the stress concentration is effectively relieved, and the service life is prolonged. The tensile strength and the impact strength of the material are obviously improved.

An experimental apparatus for planar interfacial shear of a hydrate-bearing sediment includes a planar interfacial shear box, a torsional and axial loading device, a nitrogen gas source, a methane gas source, a pressure-volume controller, a water bath device, a back pressure valve, a gas-water separator, a gas flowmeter, and a data acquisition system. The planar interfacial shear box includes an upper pressing plate, an upper adapter, an upper thermal insulation plate, a ram adapter, a lower ram, an upper base, a lower base, a lower thermal insulation plate, a lower adapter, and a lower pressing plate that are coaxially connected in sequence from top to bottom. The experimental apparatus offers a simple specimen preparation method, enabling in-situ formation of a hydrate-bearing sediment in the shear box. The experimental apparatus ensures uniform stress distribution during shearing, and can acquire the interfacial shear mechanical characteristic between the hydrate-bearing sediment and a structure.

The invention relates to the technical field of metal material fracture resistance testing, in particular to a prediction method for interface fracture toughness of a polar region ship composite steel plate, which comprises the following steps: S1, preparing a composite steel plate; s2, carrying out a three-point bending fracture test; s3, performing an interfacial shear strength test; s4, data analysis and model construction: performing fitting analysis on the obtained fracture toughness data of the large-size sample and the obtained shear strength data of the small-size sample, determining undetermined parameters, and constructing a mathematical model between the interface fracture toughness and the interface shear strength of the composite steel plate; and S5, verifying the accuracy of the model. According to the method, the mathematical model is established by analyzing the correlation between the shear strength measured by the small-size interface shear sample and the fracture toughness measured by the large-size fracture sample, and the model has the advantages of simplicity in construction, rapidness in use and the like, so that rapid prediction and evaluation of the fracture toughness of the composite steel plate are realized, the test process is greatly simplified, and the test efficiency is improved. And the research and production efficiency is improved.

The invention relates to the technical field of conductive materials, in particular to a conductive material based on TPU composite carbon nanotubes and a preparation method and application of the conductive material. Comprising the following raw materials in parts by mass: 70-78 parts of homogeneous TPU; 5 to 8 parts of multi-walled carbon nanotubes; 1 to 3 parts of aminated MXene; 2 to 5 parts of chopped carbon fiber; 0.5 to 2 parts of doped polyaniline; 0.3 to 1 part of zirconium phosphate nanosheets; 1 to 1.5 parts of ionic liquid [VBIM] Br; 1 to 2 parts of hydrophobic nano SiO2; 0.5 to 1 part of a silane coupling agent; 0.3 to 0.5 part of an antioxidant; and 0.5 to 1 part of zinc stearate. According to the preparation method, multi-element fillers such as the multi-walled carbon nanotubes, the aminated MXene, the short carbon fibers and the doped polyaniline are compounded, so that the broadband electromagnetic shielding effectiveness is improved, and the interfacial shear strength is improved.

The invention discloses a high-thermal-conductivity graphene fiber composite material based on conjugate interface adaptation and a preparation method thereof, and relates to the technical field of fiber composite materials. According to the method, a conjugated interface conformation adaptive design of an interface phase is realized by utilizing a functionalized phenylsilane coupling agent through active sites of topological wrinkles on the surface of a graphene fiber, and a molecular conjugated interface layer with an efficient heat conduction path and a strong mechanical interlocking effect is formed. According to the graphene fiber / epoxy resin composite material treated by the method, the interfacial shear strength can reach 90 MPa, the in-plane heat conductivity coefficient reaches up to 550 W / mK, and the performance retention rate exceeds 98% after 100 times of thermal shock cycles. By regulating and controlling the adaptability of the fiber surface wrinkle structure and the interface molecule conformation, the problem that a traditional carbon fiber modification method is insufficient in applicability on graphene fibers is solved, the thermal and mechanical property synergistic effect of the graphene fiber composite material is remarkably improved, and the graphene fiber composite material is suitable for a stable advanced thermal management system in an extreme thermal environment.

The invention relates to Ni3Al-based alloy powder for laser cladding of a copper alloy surface, a cladding layer and a preparation method of the Ni3Al-based alloy powder, belongs to the technical field of laser processing materials, and is used for solving at least one of the problems of poor abradability, low hardness, low interfacial shear strength and the like of an existing copper alloy cladding layer. The Ni3Al-based alloy powder comprises the following chemical components in percentage by mass: 6.6%-7.1% of Al, 3.0%-3.5% of C, 34.5%-37.5% of Cr, 0.041%-0.06% of B, less than or equal to 200ppm of O, less than or equal to 30ppm of N, less than or equal to 5ppm of H and the balance of Ni. By adopting the Cr7C3 reinforced Ni3Al-based alloy powder provided by the invention, a cladding layer which is compact in organization structure, high in bonding strength with a matrix and excellent in wear resistance can be directly prepared on the copper surface. Specifically, the average hardness of a cladding layer on the surface of the copper alloy is larger than or equal to 490 HV, the shear strength of an interface is larger than or equal to 350 MPa, and under the dry friction condition (point friction and opposite grinding materials are Si3N4), the room-temperature wear rate is smaller than or equal to 1.85 * 10 <-5 > mm < 3 > / (N.m), and the wear rate at the temperature of 300 DEG C is smaller than or equal to 2.00 * 10 <-5 > mm < 3 > / (N.m).

The invention belongs to the technical field of polyurethane adhesives, and particularly relates to a two-component polyurethane structural adhesive as well as a preparation method and application thereof. The bi-component polyurethane structural adhesive comprises a component A and a component B which are independently stored, the component A comprises polyester polyol, polyether polyol, castor oil polyol and optional first filler, first molecular sieve, first plasticizer and first aid; the component B comprises an isocyanate compound, an isocyanate double-terminated polyurethane prepolymer and optional second filler, a second molecular sieve, a second plasticizer and a second aid; the first filler and the second filler are independently selected from filler modified by a silane coupling agent. The key of the invention lies in that polyester polyol, polyether polyol and castor oil polyol with long carbon chain structures are introduced as polyol raw materials, and a specific filler modified by a silane coupling agent is introduced, so that the obtained bi-component polyurethane structural adhesive has excellent interfacial shear strength and T peel strength at the same time.

The invention relates to the technical field of polyaryletherketone composite materials, in particular to a modified carbon fiber reinforced polyaryletherketone composite material and a preparation method thereof.The preparation method comprises the following steps that S1, polybenzimidazole is attached to the surface of phosphorus-containing group functionalized carbon fiber; s2, in a protective atmosphere, preheating polyaryletherketone in a mold pressing mold, then uniformly laying the phosphorus-containing group functionalized carbon fibers treated in the step S1 on a preheated polyaryletherketone material, and carrying out stepped mold pressing forming, so as to obtain the modified carbon fiber reinforced polyaryletherketone composite material. The interface shear strength of the carbon fiber reinforced polyaryletherketone composite material is greatly improved through the action of surface modification of the phosphoric acid on the carbon fiber and interface transition of the polybenzimidazole.

Typical commercial surface treatments for continuous carbon fibers are often unavailable for discontinuous fibers. As such, there is little variety of chopped fiber surfaces leading to non-ideal coating solutions which result in poor interfacial compatibility between fibers and a composite matrix. A method of applying a highly effective coating using a high throughput technique for chopped carbon fibers. The method provides the ability to tune both the coating thickness and chemical functionality using processing parameters. The coatings are evaluated using X-ray photoelectron spectroscopy (XPS) for uniformity and composition. Using this technique, thermoplastic composites are highlighted showing an increase in interfacial shear strength (IFSS) of 25 MPa. This process shows promise for increasing the throughput of surface treatment of chopped fiber on the industrial scale.

The invention discloses a composite material based on multiple synergistic modification and a gradient nanostructure and a preparation method of the composite material, and relates to the technical field of high-performance composite materials. The problems of weak interface bonding and insufficient load transmission efficiency of the composite material in the prior art are solved, the cohesiveness of the fiber surface and the matrix is greatly enhanced, the problem of high-temperature long-time curing of PAN / CNT grafting is avoided through microwave curing of the nano structure, rapid low-temperature curing is realized, the process period is shortened, and the production cost is reduced. The interface shear strength, the tensile strength and the bending strength of the composite material are obviously improved.

The invention provides an anti-aging resin core rod for a composite insulator and a preparation method of the anti-aging resin core rod, the anti-aging resin core rod comprises modified glass fibers and an epoxy resin sizing material, and the modified glass fibers are obtained by modifying glass fibers through imidazolium-phosphate; the epoxy resin sizing material comprises the following raw materials in parts by mass: 100 parts of epoxy resin, 70-90 parts of an anhydride curing agent and 0.1-1 part of a curing accelerator. An imidazolium-phosphate interface layer is introduced to the surface of the glass fiber and is matched with an anhydride cured epoxy resin system, so that the bonding performance of a fiber / resin interface can be remarkably improved, the shear bearing capacity of the interface is improved, and the attenuation of the interface strength in a humid and hot environment is effectively inhibited; and the core rod material can still keep higher interface bonding stability and mechanical bearing performance under a long-term hydrothermal condition.

The invention is applicable to the technical field of phase-change materials, and provides a semi-solid phase-change composite material for heat conduction of aerospace electronic devices and a preparation method thereof.The composite material is prepared from modified paraffin, modified polyethylene glycol, modified pyroxene powder, modified graphene and heat-conducting fiber. Through nanometer confinement and carbon quantum dot grafting, by adding modified polyethylene glycol, a dynamic cross-linked network is formed, high latent heat and zero leakage are achieved, by adding modified pyroxene powder, the surface hydroxyl density is increased, the interface shear strength is improved, the coating provides an additional heat conduction path, and the heat conduction coefficient of single particles is improved; the heat conductivity coefficient and saturation magnetization are improved, the magnetic field induced orientation arrangement efficiency is improved, graphene / fiber three-dimensional ordered distribution is achieved through magnetic field-shearing cooperation, the heat conductivity of the material is remarkably improved, the phase change energy storage capacity of the phase material is combined with the high heat conductivity of the solid-phase filler, and efficient heat dissipation is achieved.

The invention discloses a pile-soil interface shearing algorithm considering related characteristics of a soil body state. The pile-soil interface shearing algorithm is suitable for calculating pile side friction resistance after a pile foundation is driven in offshore engineering. The method mainly comprises the following steps: (1) transferring stress and strain tensors obtained by calculation of a constitutive model considering that rigidity and strength parameters of a soil body change along with the state of the soil body to a soil and structure interface shear model; (2) assuming that a soil and structure contact interface is in a simple shearing state, and iteratively solving the normal strain of the interface; and (3) calculating the normal stress and the interface tangential stress through the calculated normal strain, and considering the influence of the strength change of the pile-side soil body on the interface shear strength. According to the method, the soil constitutive model related to the state is introduced on the basis of traditional coulomb friction, constitutive responses of the soil in different confining pressure and shear strain states can be reflected, pile-soil interface mechanical behaviors are calculated, and the influence of soil characteristics on the interface behaviors is reflected more reasonably.

The invention discloses a method for adjusting mechanical properties of a carbon fiber composite material based on a strain rate effect, which comprises the following steps: acquiring static mechanical parameters of carbon fibers, strain rate sensitive parameters of a matrix material and dynamic shear characteristic parameters of a fiber-matrix interface, and constructing a fiber-matrix-interface ternary parameter set; based on the ternary parameter set, calculating the dynamic ultimate strength of the matrix by adopting a Cowper-Symonds model introduced with an interface shear correction term, and generating a corrected matrix dynamic performance parameter set covering a preset strain rate range; according to the corrected dynamic performance parameter set of the matrix, the performance of the composite material is calculated through a three-phase collaborative mixing rule, and a dynamic performance parameter set of the composite material is output; and comparing the dynamic performance parameter set of the composite material with multi-strain-rate experimental data, and constructing a strain rate-interface coupling performance model. According to the embodiment of the invention, the prediction precision of the dynamic mechanical property of the composite material can be improved.

The invention discloses a functional osteochondral repair material which comprises a cartilage layer, a transition layer and a bone layer which are sequentially connected, the cartilage layer takes hyaluronic acid, I-type collagen and chitosan as base materials, the transition layer takes hydroxyapatite and a polylactic acid-glycolic acid copolymer as base materials, and the bone layer takes hyaluronic acid, I-type collagen and chitosan as base materials. The bone layer takes beta-tricalcium phosphate, hydroxyapatite and a polylactic acid-glycolic acid copolymer as base materials, the invention relates to the technical field of medical biological materials, by designing the organic-inorganic composite transition layer, the gradient connection cartilage layer and the bone layer, and the interfacial shear strength is greater than or equal to 0.5 MPa, the problem of interlayer stripping of a traditional layered material is effectively solved, and the medical material has the advantages of high mechanical strength, high mechanical strength and high mechanical strength. According to the selective laser sintering 3D printing material, the shearing stress and the compression stress during joint movement can be borne, mature medical material production equipment such as freeze drying, compression molding and sintering is adopted in the preparation process, large-scale batch production can be achieved, meanwhile, personalized preparation of selective laser sintering 3D printing is supported, and the requirements of different clinical scenes are met.

The application discloses an automatic testing system for single-fiber interfacial shear strength, which comprises a single fiber with a resin drop, a clamp assembly for vertically fixing the single fiber and stretching the resin drop, and a testing system for detecting the single-fiber interfacial shear strength; the clamp assembly comprises a fixing frame for fixing two ends of the single fiber and movable along the direction of a single-fiber fixing shaft, and a pair of cutters located on both sides of the connection between the fiber and the resin drop; the testing system comprises a resin drop length acquisition module, a shearing force acquisition module, a motion control module and a calculation module. The application further provides an automatic testing method. The system provided by the application can effectively improve the detection accuracy and efficiency of the single-fiber interfacial shear strength.

The invention relates to a carbon fiber surface treatment method, which improves the interfacial compatibility of carbon fibers and a matrix material, improves the interfacial shear strength by 70-90%, and is simple and convenient to operate, easy to control and suitable for large-scale industrial production.

The present invention provides a hot-rolled steel sheet for building structures, comprising a base layer, a corrosion-resistant layer, and an interfacial transition layer located between the base layer and the corrosion-resistant layer. The hot-rolled steel sheet of the present invention has a yield strength of ≥350 MPa, a tensile strength of ≥490 MPa, a yield-to-tensile ratio of 0.71 to 0.80, an impact energy of ≥190 J at -40°C, a corrosion resistance rate of ≤0.006 mm / year from sea spray, an interfacial transition layer thickness of ≤10 μm, and an interfacial shear strength of ≥252 MPa, and can be used to manufacture structural components suitable for sea spray environments. The present invention also provides a method for manufacturing the hot-rolled steel sheet.

This invention discloses a high-performance wood-plastic composite frame structure for building doors and windows, belonging to the field of building materials technology. The frame structure includes a wood-plastic outer wall and an internal cavity. A continuous support mesh structure composed of an array of topological units is integrally formed within the cavity. The topological units are configured with a tensile geometry exhibiting a negative Poisson's ratio effect, including multiple load-bearing members and connecting nodes. When the wood-plastic outer wall experiences axial expansion tensile strain due to heat, the topological units compensate for this displacement through node rotation and member bending, thereby significantly reducing interfacial shear stress and suppressing the arching deformation of the frame. When external fasteners are subjected to axial pull-out force, the topological units undergo centripetal contraction deformation, enhancing the frictional gripping force on the fasteners. This invention resolves thermal stress through microscopic geometric reconstruction, effectively addressing the shortcomings of poor thermal stability and insufficient nail-holding power in wood-plastic profiles.

The invention relates to a composite material pressure vessel forming method which comprises the following steps: rigidly connecting a front joint and a rear joint to two ends of a positioning shaft to form a support frame body; the supporting frame body is vertically fixed, the 3D printer is driven to extrude fiber reinforced thermoplastic composite wires in the circumferential direction of the positioning shaft, and a printing layer is formed between the front connector and the rear connector; the supporting frame body with the printing layer is horizontally installed on a horizontal rotating support, a positioning shaft is driven to rotate, prepreg fibers are wound around the outer surface of the printing layer, and a fiber winding layer is formed; and after the front / rear skirt is mounted, curing to form an integral structure, and finally removing the horizontal rotating bracket and the positioning shaft. The printing layer is constructed through the 3D printing technology, then the prepreg fibers are wound on the outer surface of the printing layer, and the design precision, the forming efficiency and the bursting pressure of the container are guaranteed; and finally, the prepreg fibers are cured on the printing layer, the interfacial shear strength between the prepreg fibers and the printing layer is guaranteed, and demolding is not needed.

The present invention belongs to the technical field of metal composite plate preparation and relates to a high-bonding-strength bimetallic layered composite material and its preparation process, comprising the following steps: material preparation: cutting titanium alloy and cemented carbide as raw materials, cutting iron foil and vanadium foil as intermediate layer materials, and surface treating the raw materials and intermediate layer materials respectively; stacking the surface-treated raw materials and intermediate layer materials in the order of cemented carbide / iron foil / vanadium foil / titanium alloy to form a composite blank to be composited; placing the composite blank in a hot pressing furnace for hot pressing and diffusion composite bonding. After the hot pressing and diffusion composite bonding is completed, the blank is cooled to room temperature in the furnace and removed to prepare the bimetallic layered composite material. The use of the Fe / V composite intermediate layer material in the present invention can reduce interfacial residual stress and effectively avoid the formation of malignant brittle interlayer compounds. The resulting titanium alloy / hard alloy composite plate has high interfacial bonding strength, with an interfacial shear strength of at least 120 MPa.

The invention relates to a method for testing interfacial shear strength of fiber and resin, and belongs to the technical field of carbon fiber detection. The method comprises the following steps: preparing a micro-droplet debonding sample, fixing the micro-droplet debonding sample, vertically placing fibers into a fiber rail, ensuring verticality, fixing the fibers by using an adhesive tape, connecting a clamp with a bracket, testing the size of the micro-droplet, placing the micro-droplet debonding sample on an objective table, opening a three-dimensional optical contourgraph, finding interference fringes on the surface of the sample, and constructing the three-dimensional shape of the surface of the sample. Data analysis and processing are carried out through a software algorithm to obtain accurate values of the fiber embedding length and the fiber diameter, an interfacial shear strength test is carried out, a DCAT25 fiber microdroplet debonding measuring instrument is turned on, scraper accessories are placed on a base, fibers are located between scrapers, the distance between the two scrapers is adjusted to be closest, and the fiber microdroplet debonding measuring instrument is obtained. The fiber can move but the microdroplet cannot pass through a scraper gap, testing is started after the fiber embedding length and the fiber diameter are input into software, the full-direct-acting measurement process is completed, and the interfacial shear strength tau is determined according to a formula.

The present invention relates to an aqueous sizing modified organic fiber and a preparation method thereof. The aqueous sizing modified organic fiber comprises a fiber body and a sizing layer autonomously adhered to the surface of the fiber body. The fiber body comprises aramid fiber, poly(p-phenylene benzobisoxazole) (PBO) fiber, polyester fiber and polyamide fiber. The thickness of the sizing layer is 3.0 - 5.33 nm, and the interfacial shear strength between the aqueous sizing modified aromatic organic fiber and epoxy resin is 54.4 - 65.22 MPa. Preparation method: Immerse the fiber body in a sizing agent, take it out, wash with water and dry it to form a sizing layer on the surface of the fiber body, thereby obtaining the aqueous sizing modified organic fiber. In the present invention, by controlling the pH value of the sizing agent, the thickness of the sizing layer on the fiber surface is controlled to be 3.0 - 5.33 nm, so that the sized modified organic fiber and epoxy resin have excellent interfacial bonding properties.

This invention discloses a layered titanium / aluminum composite plate and its preparation method, belonging to the field of metal composite material manufacturing technology. During the rolling process, SiCp powder is sprayed into the titanium / aluminum composite plate, wherein SiCp particles with a size of 20 μm or less account for more than 95% of the powder. This invention uses pure titanium as the cladding layer and aluminum alloy as the substrate to prepare a Ti / Al layered composite plate, combining the characteristics of these two metals. It possesses both the lightweight and low cost of aluminum and the high strength and rigidity of titanium. Through reasonable process design, the SiCp powder is rolled together, significantly enhancing the bonding strength of the composite plate. The titanium / aluminum composite plate exhibits an interfacial shear strength ≥130 MPa, a tensile strength ≥280 MPa, and a bending resistance ≥10 times. Furthermore, it avoids the environmental pollution problems associated with electroplating and physicochemical coating methods. This is a titanium / aluminum metal layered composite material preparation and processing technology with excellent development potential, reducing production costs and saving social resources.

The invention relates to the technical field of fireproof heat-insulating materials, and particularly discloses a fireproof heat-insulating strip for steel doors and windows and a preparation process of the fireproof heat-insulating strip. The fireproof heat insulation strip is composed of a modified basalt fiber braided fabric and a resin material wrapping the surface of the modified basalt fiber braided fabric, and the resin material is formed by attaching a resin glue solution to the surface of the modified basalt fiber braided fabric and curing the resin glue solution. The resin glue solution is mainly prepared from the following raw materials; liquid phenolic epoxy resin, a curing agent and an organic silicon surfactant; the modified basalt fiber braided fabric is obtained by treating the basalt fiber braided fabric with sodium hydroxide, 3-(4-urea amino) propyl triethoxy silane and 3-(trimethoxysilyl) propyl 3-oxobutyrate. The fireproof heat insulation strip has the characteristics of high tensile strength, good bending strength and high interfacial shear strength, prolongs the service life, has good fireproof performance and heat insulation performance, meets the market requirements, and has commercial application prospects and economic values.

The invention provides a foundation-covering interface shear instability prediction system, and relates to the technical field of ocean foundation-covering interfaces, an ocean rock mass slope prediction region is divided into a plurality of sub-regions through a region division module, a three-dimensional model is obtained, and the generated surface height and foundation height are analyzed, so that a fluctuation contribution index is calculated; a roughness interference analysis module combines a roughness index to evaluate the interference degree between a slip slope and a rock mass slope, and a water level influence module analyzes the influence of a water level on shear strength, generates a water level strength change index, and analyzes the water level change index. And the comprehensive analysis module performs correlation analysis on the various items, generates an anti-shearing instability coefficient, reflects the anti-shearing capability of the sub-region when the external load, the water level and the roughness are considered, and outputs the strength grade of the anti-shearing capability of the sub-region through comparison with a threshold value, so that a basis is provided for risk assessment and prevention and treatment.

The invention discloses a cushion block composite layer for a semiconductor, a preparation method and a cushion block, the cushion block composite layer sequentially comprises a composite coating and a surface microstructure from a substrate close to beryllium copper to a position far away from the substrate, and the composite coating sequentially comprises a chromium transition layer, an alpha-diamond-like carbon layer and a self-lubricating layer doped with tungsten disulfide from a position close to the substrate to a position far away from the substrate. Hard metal carbide reinforced phase crystal grains are uniformly distributed in the alpha-diamond-like carbon layer; the surface micro-texture comprises a plurality of pits, and each pit is filled with a nano-particle solid lubricant; through the structure, the cushion block is compatible with the high process temperature, an additional cooling device is not needed, and the interface shear stress of the composite layer is reduced, so that the copper powder falling amount is greatly reduced, the hardness, the wear-resisting life, the wear-resisting particle penetrability and the high recognition accuracy of the cushion block are greatly improved, and the low friction coefficient of the surface is maintained; and the roughness is still kept at a lower level after the lead frame is carried for multiple times.

The invention discloses a method for predicting the crack width of a ceramic matrix composite matrix. The method comprises the following steps: fitting a relational expression between the crack width and stress through a quadratic polynomial; calculating crack widths under different temperature environments according to a thermal expansion theory, and constructing a relational expression between the crack widths and the environment temperature; analyzing the change of the interfacial shear stress of the ceramic-based composite material through microscopic and tensile curves, and constructing a relational expression between the interfacial shear stress of the ceramic-based composite material and the ambient temperature, the initial shear stress, the oxidation rate and the oxidation action time; constructing a relation model of the matrix width, the stress, the temperature and the oxidation time of the ceramic matrix composite material; and solving the crack width of the ceramic-based composite material by utilizing a Newton iteration method based on a relation model of the matrix width of the ceramic-based composite material and the stress, the temperature and the oxidation time according to the initial value condition. The method can accurately predict the crack width of the ceramic matrix composite matrix under different stress, temperature and oxidation effects.

The invention discloses a modified PBO fiber reinforced epoxy resin composite material as well as a preparation method and application thereof. The composite material comprises matrix resin and modified PBO fibers, wherein the matrix resin is prepared from the following components in parts by mass: 100 parts of epoxy resin, 75 to 85 parts of methylhexahydrophthalic anhydride and 0.3 to 0.8 part of 2, 4, 6-tri (dimethylaminomethyl) phenol; the modified PBO fibers account for 1-4% of the modified PBO fiber reinforced epoxy resin composite material by mass. The preparation method effectively solves the problems of strong surface inertia and poor interface adhesion with epoxy resin of the PBO fiber, obviously improves the interface shear strength, mechanical properties, thermal stability and thermal conductivity of the composite material through synergistic physical etching and chemical bonding, keeps high breakdown strength, and has the advantages of mild and controllable process, small fiber damage and low cost. The method is suitable for manufacturing the extra-high voltage insulation core rod.