173 results about "Thermal expansion" patented technology

The invention relates to the field of textile detection, and discloses a fabric flame retardance analysis method based on infrared thermal imaging sensing data, which comprises the following steps: performing non-contact temperature measurement on a fabric sample in a controlled heat shock disturbance field, acquiring an infrared imaging signal sequence, and performing energy projection rearrangement on the infrared imaging signal sequence; based on the discontinuous change of the energy flow density in the primary thermal behavior field, establishing a boundary disturbance model of a local overheating region, and comparing the morphological difference between a thermal expansion path and a radiation energy attenuation region; mapping the heat potential difference of each region in the critical response diagram into an energy constraint state inside the material, and deducing time bias distribution of energy conduction; introducing a spectrum equalization function under time offset distribution, and executing asymmetric compensation on local abnormal points of the infrared response data; and based on the decomposition threshold dynamic trajectory, calculating a flame-retardant response equilibrium rate and an energy flow retention rate, and forming a flame-retardant performance evaluation index. The method has the advantage of improving the accuracy of flame retardant detection.

The invention provides a preparation method and application of ceramic slurry for high-temperature bonding of aluminum nitride ceramics, and relates to the technical field of high-temperature ceramic materials.The preparation method comprises the following steps that firstly, an organic carrier is prepared, a polymer binder, an organic solvent, a plasticizer and a dispersing agent are weighed according to the weight ratio and stirred at the temperature of 60-70 DEG C till complete dissolution and clarification are achieved for use; 2, an inorganic functional phase is prepared, aluminum nitride powder, yttrium oxide powder and alkaline earth metal oxide powder are weighed according to the weight proportion and placed in a ball milling tank to be evenly mixed, the obtained ceramic slurry serves as a bonding layer, the tolerable temperature can reach 1000 DEG C or above and is far higher than that of metal brazing filler metal, and the ceramic slurry is suitable for severe environments such as aerospace and high-temperature sensors. The main components of the bonding layer are consistent with the base material, and the thermal expansion coefficient is highly matched, so that the thermal stress can be greatly relieved, and the failure of the device caused by thermal fatigue in the temperature cycle is avoided.

The invention provides a doped yttrium hydride neutron moderation material and a preparation method and application thereof, and belongs to the technical field of radiation shielding materials. At least one of samarium, europium and gadolinium is doped in yttrium hydride in the form of hydride, and the mass ratio of metal yttrium to metal gadolinium to metal europium to metal samarium is controlled, so that the neutron moderation effect of the neutron moderation material can be improved. According to the invention, at least one of gadolinium hydride, europium hydride and samarium hydride is mixed with yttrium hydride under the protective atmosphere, so that the mass content of each element in the doped yttrium hydride neutron moderation material can be accurately controlled. According to the invention, the mixture is sintered and molded, and the sintering parameters of sintering and molding are controlled, so that the components of the mixture are sintered in a compact state, cracks generated by thermal expansion and cold contraction can be reduced, and the doped yttrium hydride keeps high density and has fewer cracks and defects.

The invention discloses a high-temperature-resistant epoxy resin-based mold prepreg as well as a preparation method and application thereof, and belongs to the technical field of resin-based composite materials. The preparation method comprises the following steps: mixing and stirring the epoxy resin A and the heat-conducting filler, and grinding to obtain a premix I; mixing and stirring a curing agent and epoxy resin B to obtain a premix II; mixing and stirring the premix I and the premix II to obtain a mixture; and coating release paper with the mixture, covering the release paper with fiber cloth, and carrying out hot-pressing impregnation to obtain the high-temperature-resistant epoxy resin-based mold prepreg. The invention also discloses the high-temperature-resistant epoxy resin-based mold prepreg prepared by the method and application of the high-temperature-resistant epoxy resin-based mold prepreg in preparation of a composite material mold. The prepreg prepared by the method has excellent high temperature resistance, low thermal expansion coefficient and high heat conductivity coefficient, and the service life of a composite material mold can be greatly prolonged.

The invention relates to the technical field of thermal barrier coatings, in particular to a gadolinium oxide and aluminum oxide co-doped modified YSZ: Dy thermal barrier sensing coating material as well as a preparation method and application thereof. The invention provides a thermal barrier sensing coating material. The chemical composition of the thermal barrier sensing coating material is Y Gd Al < c > Zr < d > DeyOf, wherein a is equal to 0.01 to 0.04, b is equal to 0.15 to 0.35, c is equal to 0.40 to 0.60, d is equal to 0.35 to 0.70, e is equal to 0.01 to 0.02, and f is equal to 1.50 to 1.70. The temperature measurement upper limit of the thermal barrier sensing coating material is 1200 DEG C, and the average thermal expansion coefficient is increased by 18% at the room temperature of 1200 DEG C, so that the thermal shock resistance of the thermal barrier sensing coating is effectively improved, and the service life of the thermal barrier sensing coating is prolonged.

Provided is a glass which can replace a Li2O-Al2O3-SiO2-based crystallized glass and which has a low coefficient of linear thermal expansion and excellent light transmittance. A glass characterized by containing, in mass%, 45 to 80% of SiO2, 10 to 30% of Al2O3, 0 to 12% of B2O3, and 0 to 5% of Li2O.

A method of integrating a first substrate having a first surface with a first insulating material and a first contact structure with a second substrate having a second surface with a second insulating material and a second contact structure. The first insulating material is directly bonded to the second insulating material. A portion of the first substrate is removed to leave a remaining portion. A third substrate having a coefficient of thermal expansion (CTE) substantially the same as a CTE of the first substrate is bonded to the remaining portion. The bonded substrates are heated to facilitate electrical contact between the first and second contact structures. The third substrate is removed after heating to provide a bonded structure with reliable electrical contacts.

The invention relates to the technical field of functional material preparation, in particular to a high-low-temperature-resistant high-performance packaging composite material for a vehicle energy storage system and a forming process of the high-low-temperature-resistant high-performance packaging composite material. 30-50 parts of a heat-conducting filler; 5-10 parts of a high and low temperature resistant modifier; 3-8 parts of a toughening agent; 0.5-2 parts of a catalyst; 1-3 parts of an auxiliary agent; a three-dimensional heat conduction network is formed in the composite material, the heat conduction coefficient is larger than or equal to 3.5 W / (mK), the low-temperature tensile strength at-40 DEG C is larger than or equal to 15 MPa, the high-temperature tensile strength at 150 DEG C is larger than or equal to 12 MPa, the volume resistivity is larger than or equal to 1 * 10 < 14 > omegacm, and the thermal expansion coefficient is smaller than or The material is excellent in thermal conductivity, balanced in high and low temperature resistance and mechanical property, good in aging resistance and barrier property, optimized in forming process and high in performance consistency, and provides reliable guarantee for safe and stable operation of a vehicle energy storage system.

This invention belongs to the field of glass technology and relates to a high-temperature resistant structural glass material, its preparation method, and its applications. The glass is composed of the following components by mass percentage: 60%-70% silicon dioxide, 5.5%-11% boric acid, 0.1%-5% aluminum hydroxide, 0%-3% potassium nitrate, 5.5%-13% potassium carbonate, 0%-12% sodium carbonate, 0.1%-4% calcium carbonate, 0%-2% calcium fluoride, 0%-1% lithium carbonate, 0%-2% basic magnesium carbonate, 0.1%-1% titanium dioxide, 0%-2% zirconium dioxide, and 0%-1% cerium dioxide; the total mass percentage of potassium nitrate, potassium carbonate, sodium carbonate, and lithium carbonate does not exceed 22%. This structural glass possesses a high softening temperature, a suitable coefficient of thermal expansion, high-temperature resistance, thermal shock resistance, and processing performance, making it suitable as a structural material for optoelectronic devices.

Provided is a glass substrate that reduces errors in the correction of thermal deformation.　This glass substrate has a rectangular main surface (MS1). When the main surface is divided into nine equal parts in a direction perpendicular to a first side (S1) and divided into nine equal parts in a direction perpendicular to a second side (S2), thereby dividing the main surface into a group of 81 rectangular regions (A11-A99), the rectangular regions, in the group of 81 rectangular regions, the centers of which are located on a diagonal line of the main surface passing through a first vertex (P1) that is an intersection point of the first side and the second side, satisfy expression (1A), where TZ11、TZ22、TZ33、TZ44、TZ55、TZ66、TZ77、TZ88、and TZ99 are zero crossover temperatures in ˚C, at which the thermal expansion coefficient of the glass substrate becomes 0 ppb / K, starting from the closest to the first vertex. (1A): (TZ11+TZ99)-(TZ22+TZ88)＜0.00

A glass includes silica, alumina, boria, and yttria. The glass may have high fracture toughness, often greater than 1 MPa·m1 / 2, as well as high Vickers hardness, on the order of 800 kgf / mm2 or greater. Furthermore, Applicants find that, due to surprisingly large high-temperature coefficient of thermal expansion (e.g., over 35 ppm / °C at about 875°C) and high elastic modulus (e.g., >120 GPa) the glass may be particularly suitable for thermal tempering, which may strengthen a corresponding article comprising the glass.

The utility model discloses a zipper machine for conveying high-temperature materials, and relates to the technical field of material conveying equipment, the zipper machine comprises a conveying groove body and a driving unit, a transmission shaft is rotatably arranged in the conveying groove body, the driving unit is used for driving the transmission shaft to rotate, and extension shafts are coaxially and fixedly arranged at the two ends of the transmission shaft; the two sides of the conveying groove body communicate with supporting sleeves, the extending shafts on the corresponding sides are sleeved with the supporting sleeves, the ends, away from the conveying groove body, of the supporting sleeves communicate with sealing covers, the distance between the sealing covers and the conveying groove body is not smaller than 300 mm, and oil seals are arranged in the sealing covers and used for sealing gaps between the extending shafts and the supporting sleeves. The extension shaft is sleeved with a bearing, and the outer ring of the bearing is fixedly connected with the sealing cover. The influence of heat transferred by high-temperature materials on the bearing and the oil seal can be effectively reduced, the problem that lubricating oil needs to be frequently filled due to high-temperature evaporation is solved, and meanwhile structural thermal deformation and damage caused by thermal expansion are prevented.

The invention provides a method for solving crazing defects of a composite material product, which comprises the following steps: a) controlling the temperature of liquid resin to be within a preset range in the process of applying the liquid resin to the inside and the surface of a solid material component of the composite material product; b) in the pre-curing process of the composite material, controlling the actual heating rate of the liquid composite material to be within a preset range; and c) in the post-curing / heat treatment process of the composite material, controlling the actual temperature of the composite material to be within a preset range. By controlling the infiltration, permeation and adsorption process of the liquid-state base material, the liquid-state base material reaches the optimized infiltration and adsorption state on the molecular level on each interface of different materials and different combined structures; and meanwhile, local stress concentration caused by the difference of thermal expansion and cold contraction multi-mode response of the material is controlled to be lower than a critical value for inducing craze formation, so that the craze whitening phenomenon of a composite material product is solved.

Closure arrangement (10) for covering and closing openings in buildings, roofs, walls, in particular for weather protection, for pergolas, for canopies, for doors, gates and the like, comprising at least one profile arrangement (5, 5'), wherein the profile arrangement (5, 5') has at least one hollow chamber (50, 51) and at least one connecting element (3) and / or at least one connecting device (4), wherein the profile arrangement (5, 5') has at least one structural layer (6), wherein the at least one structural layer (6) has at least a portion of a polymeric material, wherein the profile arrangement (5, 5') has at least one reinforcing insert (7), preferably fully embedded in the structural layer (6), characterized in that the profile arrangement (5, 5') has a bending stiffness about the x-axis of approximately 17 to 29 × 10 9 N / mm 2 , preferably about 18 to 22 × 10 9 N / mm 2according to DIN EN ISO 178-2019-08, the profile arrangement (5,5') has a linear coefficient of thermal expansion α of approximately 12 to 64 × 10 -6 / K, preferably 16 to 30 × according to DIN EN ISO 11359-2:2021-11, having the material of the at least one structural layer (6) comprising microhollow spheres consisting of a plastic shell filled with a gas.

The invention discloses a high-performance low-expansion heat-resistant purple sand tea set with a far infrared radiation function, and belongs to the technical field of ceramic tea sets, the tea set adopts an inner-outer double-layer composite structure, the inner layer is a low-expansion enhancement layer, and raw materials comprise 58-73% of purple sand raw ore, 2-3% of rare earth, 10-20% of surface hydroxylation cordierite micro powder, 5-15% of mullite particles and 2-5% of a sintering aid; the outer layer is a far infrared radiation functional layer and comprises the following raw materials: 30-40% of far infrared radiation powder, 30-40% of purple sand fine powder and 10-15% of a high-temperature binder; a quartz sand transition layer is arranged between the inner and outer layers. According to the high-performance low-expansion heat-resistant purple sand tea set with the far infrared radiation function, through the inner layer hydroxylation cordierite micro powder modification technology, the interface bonding strength of cordierite and a purple sand matrix is improved, and the framework supporting effect of mullite particles is matched, so that the thermal expansion coefficient of the inner layer is reduced, and the thermal shock resistance is improved; the problem of temperature difference cracking is solved.

The application discloses a preparation method of aluminum silicon carbide material based on plasma deposition, which comprises the following steps: 1) particle grading; 2) preliminary coating; 3) thermal spray coating; 4) plasma deposition; and 5) hot isostatic pressing of the rough blank, and finally aluminum silicon carbide is obtained. The application discloses a preparation method of aluminum silicon carbide material based on plasma deposition, and aluminum silicon carbide material with high silicon carbide volume fraction, low porosity, high thermal conductivity and adjustable thermal expansion coefficient is obtained.

The invention discloses a silicon-carbon material and a preparation method and application thereof. The silicon-carbon material comprises a carbon material core and a coating layer which at least covers part of the surface of the carbon material core, the coating layer comprises silicon dioxide, and the carbon material core comprises sp2 hybrid carbon; a C-O-Si covalent bond is arranged between the carbon material core and the coating layer. Therefore, the silicon-carbon material disclosed by the invention has the advantages of high carbonization rate, low dielectric constant, high mechanical strength, low thermal expansion coefficient and the like, and shows excellent comprehensive performance.

The utility model relates to a Teflon lining anti-corrosion pipe fitting, and belongs to the technical field of pipeline corrosion prevention, the Teflon lining anti-corrosion pipe fitting comprises a drainage pipe, the left side and the right side of the drainage pipe are each provided with a connecting flange for prolonging the service life of the drainage pipe and improving the connecting stability of the drainage pipe, and four locking grooves are formed in the drainage pipe. According to the Teflon lining anti-corrosion pipe fitting, the stainless steel layer can provide good supporting performance for the whole pipeline, the Teflon layer fixed to the inner side can remarkably improve the corrosion resistance of the pipeline, good high-temperature resistance is achieved, and finally, the connecting effect is guaranteed through the connecting flange, and meanwhile the service life of the pipeline is prolonged. The thermal expansion and cold contraction effect of the drainage pipe can be matched in a slight telescopic mode, the overall high-temperature-resistant effect of the pipe fitting is further improved, the upper limit of the applicable temperature interval is greatly improved, the requirement for alternate conveying of cold and hot materials on the same pipeline can be met, the industrial production flexibility is widened, and the production cost is reduced. And moreover, the daily maintenance frequency and cost are reduced, and the increase of economic benefits is indirectly promoted.

This utility model discloses a multicolor telescope body cladding, including a cladding tube. Support tubes are connected to both sides of the cladding tube. Sealing slots are provided on both sides of the cladding tube, outside the support tubes. Sealing components, including sealing caps, are installed on both sides of the cladding tube. This utility model utilizes the high resilience and wear resistance of the styrene-butadiene rubber (SBR) inner tube, which is less prone to deformation and cracking, thus improving fatigue resistance. The use of a polyethylene (PE) tube optimizes structural strength and weather resistance, reduces the impact of thermal expansion and contraction by dispersing stress, adapts to temperature differences from -40℃ to 60℃, and prevents aging and embrittlement. The use of a maleic anhydride-modified TPE tube achieves a balance between lightweight and impact resistance, and also has low-temperature resistance, preventing aging and embrittlement. The use of a nitrile rubber (NBR) outer tube enhances oil resistance, chemical resistance, and low-temperature toughness, effectively resisting sweat, oil stains, or extreme environmental corrosion, improving overall durability and sealing.

This invention relates to a method for preparing a silicon nitride wear-resistant coating on the surface of a graphite part. The method involves coating the graphite part with polynitrosilane, followed by drying and subsequent decoking and high-temperature ceramization treatments. The process is precisely designed as a multi-stage heating decoking and high-temperature ceramization process. By strictly controlling the heating rate and holding time, the method avoids coating shrinkage and cracking caused by rapid heating, as well as resource waste and increased internal stress caused by excessively slow heating. Simultaneously, the decoking temperature is optimized to prevent excessive decomposition and escape of polynitrosilane or residual small molecules. This effectively solves the coating cracking problem caused by the difference in thermal expansion coefficients between graphite and silicon nitride, thereby obtaining a dense, uniform, and crack-free silicon nitride coating.

The application relates to the technical field of building detection, and discloses a building outer wall crack detection device which comprises a detection mechanism, a dynamic bearing mechanism and an auxiliary support assembly. The detection mechanism comprises a shell and an auxiliary support assembly arranged at the top of the shell. The dynamic bearing mechanism comprises a mounting plate, an adaptive assembly arranged on one side of the mounting plate and a damping gasket fixedly arranged on the other side of the mounting plate. The adaptive buffer structure of the dynamic bearing mechanism is adopted to automatically compensate the deformation of metal materials, so that the detection reference is long-term stable. The sealing and drying mechanism is provided with multiple protective barriers and a humidity sensing alarm system. The sealing and drying mechanism not only blocks the invasion of external pollutants, but also triggers an early warning when the sealing material is initially aged. The adjustable rigid structure of the auxiliary support assembly is matched with the flexible connection design, so that the support strength is guaranteed and the thermal expansion and cold contraction of the material can be adapted. The active protection system is formed, the material performance attenuation in the initial stage can be identified and warned, and the influence of the accumulation of hidden damage on the detection precision is avoided.

The invention discloses a mica ceramic heating plate and an assembling method thereof, and belongs to the technical field of electric heating equipment, the heating plate comprises a plate body assembly, the plate body assembly comprises an upper plate cover and a lower plate seat, one end of the lower plate seat is provided with a mounting groove matched with the upper plate cover, and the other end of the lower plate seat is provided with a cavity communicated with the mounting groove; a heating assembly is arranged in the mounting groove and located between the upper disc cover and the lower disc base, the heating assembly comprises a base plate matched with the mounting groove and mica sheets arranged on the surfaces of the two sides of the base plate, and the mica sheets on the two sides of the base plate are flexibly attached to the lower disc base and the upper disc cover respectively. According to the heating disc of the scheme, thermal resistance caused by air gaps in the heating disc can be eliminated, and heat is efficiently conducted to the heating disc; meanwhile, stress generated by thermal expansion and cold contraction of an internal structure can be effectively absorbed, damage such as cracking of the disc body is prevented, and the service life of the disc body is effectively prolonged. According to the scheme, the assembly method is simple, and heat loss caused by air gaps in the heating disc can be effectively eliminated.

To provide a polyimide having all of solvent solubility, high transparency, high glass transition temperature and low linear thermal expansion coefficients.SOLUTION: A polyimide contains, in the main chain, a constitutional unit derived from a diamine represented by general formula (1): (R1 and R2 each denote a C1-12 alkyl group or a C1-12 aromatic group, R3 and R4 each denote a C1-12 alkyl group, a C1-12 aromatic group or a halogen atom, n1 and n2 each denote an integer of 0-3), and a constitutional unit derived from a tetracarboxylic acid dianhydride.SELECTED DRAWING: None

The utility model relates to the technical field of heat treatment, in particular to a high-temperature-resistant container which comprises a bearing part and a limiting part, the limiting part is provided with an absorption groove used for absorbing deformation caused by thermal expansion and cold contraction of the limiting part, and the absorption groove prevents the limiting part from being heated or cooled to deform; the absorbing groove for absorbing deformation is formed in the limiting part, it is guaranteed that deformation of the container is controllable under the high-temperature working condition, the situation that the limiting part extrudes internal materials due to too large deformation, the product quality is affected, and meanwhile the service life of the container is shortened is avoided, and the problems that in the prior art, the service life is short due to the fact that a material frame is prone to deformation under the high-temperature working condition are solved. And middle materials are easy to extrude.

The temperature control assembly comprises an installation shell, a piston and a temperature sensing bulb, the installation shell is provided with a containing cavity and an opening communicated with the containing cavity, the temperature sensing bulb is arranged in the containing cavity, and the piston penetrates through the opening so that a part of the piston can stretch into the containing cavity and abut against the temperature sensing bulb. The temperature sensing material in the temperature sensing bulb is the nanometer temperature sensing material, the nanometer temperature sensing material is high in temperature sensitivity and can rapidly respond to temperature changes to expand or contract in a specified temperature interval, the nanometer temperature sensing material is heated evenly, the expansion coefficient is large, and the sensitivity of the temperature sensing bulb can be improved. In the specified temperature interval, the expansion or contraction amplitude of the temperature sensing bulb along with the temperature change is obvious, and the corresponding action can be quickly and effectively executed according to the temperature change. The nano temperature sensing material is stable in performance, can still keep stable performance after undergoing a physical change process of thermal expansion and cold contraction for a long time, and is long in service life.

The application relates to the field of textile detection and discloses a fabric flame resistance analysis method based on infrared thermal imaging sensing data, which comprises the following steps: non-contact temperature measurement on a fabric sample in a controlled thermal excitation field, acquisition of an infrared imaging signal sequence, energy projection rearrangement on the infrared imaging signal sequence; based on the discontinuous change of the energy flow density in a primary thermal behavior field, a boundary disturbance model of a local overheating area is established, the morphological difference between a thermal expansion path and a radiation energy decay area is compared, the thermal potential difference of each area in a critical response graph is mapped into the energy constraint state inside the material, the time bias distribution of energy conduction is deduced, a spectral equalization function is introduced under the time bias distribution, asymmetric compensation is performed on the local abnormal points of the infrared response data, based on a decomposition threshold dynamic track, the flame resistance response equalization rate and the energy flow retention rate are calculated, and a flame resistance performance evaluation index is formed. The application has the advantage of improving the accuracy of flame resistance detection.

The application relates to the technical field of building materials, and discloses a wall heat preservation structure which comprises a heat preservation plate main body and a plurality of pedestals embedded in the wall, and a heat preservation unit which comprises cavity one, cavity two and cavity three which are sequentially arranged in the heat preservation plate main body from left to right and are used for buffering thermal expansion and cold contraction caused by temperature change, a first air hole for air circulation is arranged between the cavity one and the cavity two, a second air hole for air circulation is arranged between the cavity two and the cavity three, the cavity two is further provided with a through hole connected with the outside, and the pedestal is provided with a connecting unit used for connecting the heat preservation plate main body. The three-layer cavity can inhibit heat transfer, the first air hole, the second air hole and the through hole are cooperatively used to realize synchronous pressure balance of the three-layer cavity, and the problem that traditional single-cavity heat preservation is not comprehensive and the structure is easy to be damaged is solved.

The invention discloses a benzocyclobutene resin with low dielectric loss and low thermal expansion coefficient, which is prepared by the following steps: adding a benzocyclobutene functional monomer, a vinyl compound, 1, 3-diolefin and an organic solvent into a reaction kettle, uniformly stirring at low temperature, adding an initiator, reacting for a period of time, adding a small amount of methanol for quenching reaction, and cooling to room temperature to obtain the benzocyclobutene resin with low dielectric loss and low thermal expansion coefficient. After the reaction liquid is recovered to the room temperature, pouring the reaction liquid into methanol to precipitate and filter, drying a filter cake, adding methylbenzene to dissolve, washing with ultrapure water, drying and concentrating to obtain the benzocyclobutene resin, which has the advantages of adjustable molecular weight, adjustable glass transition temperature and the like, and omits the tedious step of prepolymerization of the resin in the past; the benzocyclobutene resin has excellent thermal stability, mechanical property and dielectric property after being cured at high temperature, and can be used as a high-temperature-resistant dielectric material, a high-performance composite material, an electronic packaging material and an aeronautical material to be applied to the field of interlayer packaging of 5G / 6G high-frequency PCBs and chips.

The invention provides a hard alloy material for an optical mold, a preparation method of the hard alloy material and a near-net forming preparation method of the optical mold. The hard alloy material for the optical mold is formed by mixing 90-93 wt.% of tungsten carbide powder, 90-93 wt.% of vanadium carbide powder and 100 wt.% of silicon nitride powder and then carrying out SPS (spark plasma sintering) on the mixture, and the content of the tungsten carbide powder, the vanadium carbide powder and the silicon nitride powder is 100 wt.% of the total weight of the material. The content of the vanadium carbide is 0.95 wt.% to 1.05 wt.%; and the balance being silicon nitride. The hard alloy material has certain hardness and strength, the thermal expansion coefficient can be matched with the mold core material, the eccentricity of the aspheric lens and the lens assembly yield are effectively improved, the problems that materials are wasted and the machining period is prolonged due to a cake material prepared through a traditional spark plasma sintering technology are solved, and the yield of the optical mold is effectively improved.

The furnace door comprises an outer wrapping layer and a heat preservation inner layer, the outer wrapping layer is provided with a heat preservation groove, the heat preservation inner layer is arranged in the heat preservation groove, and a part of the heat preservation inner layer extends out of the heat preservation groove so that the heat preservation inner layer can be inserted into a furnace opening of the box-type heating furnace. The heat preservation inner layer comprises an aluminum silicate ceramic fiber plate, aluminum silicate heat preservation cotton and a heat insulation aluminum plate, the aluminum silicate ceramic fiber plate has elasticity and good heat stability, the situation that the aluminum silicate ceramic fiber plate deforms due to temperature changes, thermal expansion and cold contraction or other reasons, and consequently the nearby structure is extruded and damaged is avoided, and meanwhile the requirement for manufacturing and assembling installation tolerance is lower; the aluminum silicate heat preservation cotton wrapping the periphery of the aluminum silicate ceramic fiber plate can be better attached to the furnace mouth, the gap between the heat preservation inner layer and the furnace mouth is reduced, and the heat insulation aluminum plate can block heat transmitted from the furnace mouth to the external space. Therefore, the closed furnace door and the furnace body can form a closed heat preservation space together, heat loss of the furnace door is effectively reduced, and the heat preservation performance of the furnace door is improved.