1928 results about "Graphite crucible" patented technology

The invention discloses a preparation method for a fiber reinforced carbon-silicon carbide-zirconium carbide-based (C/C-SiC-ZrC) composite material. The preparation method comprises the following steps of: (a) evenly dispersing ZrC nanopowder in absolute ethyl alcohol; (b) mixing phenolic resin and ZrC dispersion liquid to form slurry; (c) immersing a two-dimensional carbon fiber sheet into the slurry for dipping and drying, then carrying out continuous superposition paving on the two-dimensional carbon fiber sheet, and carrying out curing and post-curing treatment to prepare a fiber-reinforced sintered body; (d) cracking the fiber-reinforced sintered body to obtain a porous C/C prefabricate; (e) placing silicon powder into a graphite crucible, burying the porous C/C prefabricate into the silicon powder, heating to 1,500-1,650 DEG C, and preserving heat for preset time so as to carry out liquid silicon permeation. The method can be used for improving the high-temperature oxidizing property and ablation property of the carbon fiber reinforced ceramic (C/C-SiC) composite material.

The invention relates to a method for preparing a Cu2Se thermoelectric material. The method for preparing the Cu2Se thermoelectric material by the low-temperature solid-phase reaction is characterized by comprising the following step: 1) weighing Cu powder and Se powder according to the molar ratio of 2:1 and mixing the Cu powder and the Se powder uniformly to obtain mixed powder, wherein the Cu powder and the Se powder serve as raw materials; 2) pressing the mixed powder into a block body by using tablet press, placing the block body into a graphite crucible, vacuumizing, sealing into a quartz glass tube, placing into a muffle furnace, performing solid-phase reaction at the temperature of between 650 and 750 DEG C for 12 to 24 hours, and grinding the obtained product into powder; and 3) performing spark plasma sintering on the powder obtained in the step 2) to obtain a compact block body, namely the Cu2Se thermoelectric material. By the method, the raw materials have low cost; the reaction temperature is low; energy is saved; and the materials are fed according to the stoichiometric ratio of the Cu2Se, so the product composition can be controlled precisely; and the repeatability is high.

The invention discloses an aluminum-silicon based aluminum section. The aluminum section is composed of, by weight, 5.0-14.0% of silicon, 0.2-0.7% of magnesium, less than 0.03% of boron, less than 0.06% of strontium, 0.1-6.55% of strengthening elements, less than 0.25% impurity elements, and the balance aluminum. The aluminum-silicon based aluminium section has the advantages of high strength, high hardness, good wear resistance, etc. the invention also discloses a preparation technology for the aluminum-silicon based aluminum section, which comprises a first step of adding aluminum-silicon alloy to a graphite crucible and heating the alloy to form melt; a second step of adding the magnesium, the silicon and the strengthening elements; a third step of adding hexachloroethane for refinement; a forth step of adding the strontium for deterioration, casting to a cast iron die to form an ingot casting; and a fifth step of hot extruding, hot rolling for deformation, solid solution treating and aging treating in sequence after annealing the ingot casting, thereby obtaining the aluminum-silicon based aluminum section. The preparation technology is simple.

The invention discloses an electric locomotive pantograph copper-impregnated carbon contact strip producing method. The method comprises the steps that 1, pitch coke powder, graphite powder, siliconized graphite powder and high temperature pitch are mixed according to the proportion to be ground into powder; the mixed powder is prepressed into a stage stock column, and then the stage stock column is solidified and squeezed to be molded and roasted, so that a composite carbon contact strip is obtained; 2, the composite carbon contact strip is cleaned and dried, then is cooled and placed into a graphite crucible, and is placed in an electric furnace at temperature of 1300-1400 DEG C to be preheated; copper liquid is poured into the crucible to soak the composite carbon contact strip, then the crucible is placed in an oil press cover, nitrogen is led in, heat preservation is kept for 3-5 min under the specific intensity of pressure, and finally cooling is carried after pressure releasing. According to the electric locomotive pantograph copper-impregnated carbon contact strip producing method, the electroconductibility of the copper-impregnated carbon contact strip is improved, the electrical resistivity is lowered, the mechanical strength of the carbon contact strip and copper impregnated angle can be increased, then the carbon contact strip abrasive resistance and self-lubrication are improved, the copper-impregnated carbon contact strip is more resistant to abrasion, main line damage and block dropping are avoided, the shock resistance is high, and the service life of the copper-impregnated carbon contact strip is prolonged.

A bulk silicon carbide single crystal of good crystalline quality which includes a minimized number of structural defects and is free from micropipe defects can be produced by crystal growth in a melt of an alloy comprising Si, C, and M (wherein M is either Mn or Ti) and having an atomic ratio between Si and M in which the value of x, when express as Si_1-xM_x, is 0.1≦×≦0.7 in the case where M is Mn or 0.1≦×≦0.25 in the case where M is Ti at a temperature of the melt which is below 2000° C. The C component is preferably supplied into the melt by dissolution of a graphite crucible which contains the melt such that the melt is free from undissolved C. One method of crystal growth is performed by cooling the melt after a seed substrate is immersed in the melt.

The invention relates to a graphite crucible for growing large-size silicon carbide single crystal by a physical vapor deposition method. The graphite crucible comprises a crucible barrel for holding a silicon carbide raw material, and an upper cover, wherein mutually screwed threads are arranged on the inner wall of the crucible barrel and the outer wall of the upper cover, and the upper cover is in threaded connection with the crucible barrel; a positioning block for placing of a porous graphite plate is arranged on the inner wall of the crucible barrel; and the porous graphite plate is placed on the positioning block, and the outside diameter of the porous graphite plate is in correspondence with the inside diameter of the crucible barrel. According to the invention, the influence of carbonization of the silicon carbide raw material on the crystal growth is effectively avoided, and the crystal growth stability and success rate are improved.

The invention discloses a graphite matrix flawless TaC coating and a manufacturing method thereof. A tie coat is deposited on a graphite matrix. A TaC main coating is deposited on the outer layer of the tie coat. The tie coat is composed of a SiC-TaC codeposition coating or compounded by two transition layers of the SiC-TaC codeposition coating and a SiC-TaC laminated coating. When the tie coat is compounded by two transition layers of the SiC-TaC codeposition coating and the SiC-TaC laminated coating, the SiC-TaC codeposition coating serves as a first transition layer, and the SiC-TaC laminated coating serves as a second transition layer; and then the deposition of the tie coat is ended; or the SiC-TaC codeposition coating and the SiC-TaC laminated coating are alternatively deposited many times. Good TaC coating which has small heat stress, no macroscopic cracking, corrosion-resistance, and good thermal stability is deposited out of the surface of the graphite material. The method is suitable for preparing graphite substrate, graphite crucible, graphite windpipe, graphite guide shell coating in the crystal and semiconductor production, protecting and cleaning coating such as antisepsis, anti-pollution, anti-infiltration, anti-oxidation of graphite parts in other various hot environments.

The invention provides a preparation method of a high temperature oxidation-resistant coating on the surface of a carbon/carbon composite material. The preparation method comprises placing Si powder, C powder, and Al2O3 into an agate ball milling tank, adding distilled water, mixing and ball milling, taking out the mixed solution, and drying to form inner layer embedded powder; placing the treated C/C composite material into the powder in a graphite crucible; placing into a vertical type vacuum furnace with graphite being the heating body for preparing an undercoat; mixing the Si powder, Mo powder, W powder and C powder with absolute ethanol and silica sol to obtain slurry; and uniformly brush coating surface of the SiC inner layer of the C/C composite material I with the slurry, drying, and placing into an alumina crucible for preparing a top coating. The antioxidant protective time of the C/C composite material is increased from 100 hours in prior art to 200-252 hours in 1500 DEG C air using high temperature oxidation resistance of MoSi2 and WSi2 via combination of the undercoat and the top coating.

The invention belongs to the technical field of ceramic materials and discloses a ceramic with multi-element high entropy as well as a preparation method and application of the ceramic. The ceramic isprepared by the following steps: taking an oxide of Me1, an oxide of Me2, an oxide of Me3, an oxide of Me4, an oxide of Me5 and amorphous boron powder as raw materials, performing ball milling, mixing and pressing into a green body; adding the green body into a graphite crucible, and performing vacuum heat treatment to obtain (Me1xMe2yMe3zMe4nMe5m)B2 solid solution powder; raising the temperatureof the solid solution powder to 1000-1400 DEG C by adopting spark plasma sintering, filling a protective atmosphere, and raising to a temperature of 1800-2200 DEG C for calcining, thereby obtaining the product. The prepared multi-element high-entropy ceramic has the relative density of more than 95%, the hardness of 25-35GPa, the breaking tenacity of 2-8MPa*m1/2 and the grain size of 0.1-1.1 microns, and after the heat treatment of 1000-1500 DEG C, the weight change rate is 0.3-1%.

The invention relates to a preparation method of a low-stress and high-purity semi-insulating SiC single crystal. The method includes the steps that synthesis of high-purity SiC powder is carried out, crystal growth is carried out with a physical vapor transport method, the concentration of shallow energy level impurities is reduced in the synthesis and crystal growth processes, a heat insulation material is subjected to high-temperature pretreatment, and boron impurities are prevented from being blended in; a silicon powder raw material and a carbon powder raw material are put into a graphite crucible with a coating for SiC synthesis; the obtained high-purity SiC powder is pretreated, seed crystals are fed, vacuumizing is carried out, high-purity argon or mixed gas of argon and hydrogen is introduced in to carry out crystal growth, then the temperature is rapidly lowered to enlarge point defects, and then the temperature is slowly lowered to the room temperature to eliminate stress. SiC crystal growth is carried out in an equilibrium state, so that the obtained crystal is small in stress, low in microtubule density and good in quality, and the resistivity on the area of the whole crystal is 108 ohm.cm or above. The method is small in preparation investment, high in safety and free of pollution.

The invention relates to an Al-Si-Cu-Zn-Sn-Ni aluminum-based brazing filler metal and a preparation method thereof. The components of the aluminum-based brazing filler metal are 7 to 13 percent by weight of Si, 5 to 11 percent by weight of Cu, 4 to 11 percent by weight of Zn, 1 to 6 percent by weight of Sn, 1 to 3 percent by weight of Ni, 0.02 to 0.3 percent by weight of Ce, 0.01 to 0.1 percent by weight of Sr, 0.01 to 0.2 percent by weight of Zr and the balance of Al. The process flow for preparing the aluminum-based brazing filler metal is that: pure aluminum is added into a graphite crucible and covered by flux for aluminum under the condition of 800 DEG C to 900 DEG C, and slag is removed after melting; the aluminum-based intermediate alloy of high-melting point elements and flux for aluminum are added at the same time, and melting, stirring and slag removal are carried out; the aluminum-based intermediate alloy of low-melting point elements is added under the protection of nitrogen, and melting and stirring are carried out; the mixture of argon and hexachloroethane is added to carry out refining, and standing and slag removal are carried out; the intermediate alloy of trace elements is added, and melting and stirring are carried out; secondary refining and slag removal are carried out; and under the protection of nitrogen, casting formation is carried out. The Al-Si-Cu-Zn-Sn-Ni aluminum-based brazing filler metal has the advantages of low melting point, high strength, high toughness, high corrosion-resistant property and good wetting property and spreadability.

The invention discloses a preparation method of continuous high-performance intermediate-phase asphalt-based carbon fiber. The preparation method includes: winding spun carbon fiber precursor into a microporous graphite crucible through a garnett, disposing the graphite crucible in a pre-oxidation furnace, and feeding air to pre-oxidize the carbon fiber precursor in the pre-oxidation furnace; after pre-oxidation is finished, feeding inert gas, and performing low-temperature carbonization and high-temperature carbonization on pre-oxidized carbon fiber; cooling the pre-oxidation furnace to normal temperature, taking out the graphite crucible, and disposing the same in an intermittent high-temperature graphitizing furnace for graphitizing to obtain continuous high-strength high-modulus high-heat-conductivity asphalt-based carbon fiber. The preparation method is simple and high in controllability and yield, and the defect that a domestic continuous graphitizing furnace cannot be heated to higher than 2800 DEG C is overcome; tensile strength of the high-performance intermediate-phase asphalt-based carbon fiber is 2.2-3.5GPa, modulus of elasticity is 650-750GPa, and heat conductivity is 900-1050 W/m*K.

A seed crystal for silicon carbide single crystal growth (13) which is attached to the lid of a graphite crucible charged with a raw material silicon carbide powder. The seed crystal includes a seed crystal (4) formed of silicon carbide having one surface defined as a growth surface (4a) for growing a silicon carbide single crystal by a sublimation method, and a carbon film (12) formed on the surface (4b) opposite to the growth surface of the seed crystal (4). Further, the film density of the carbon film (12) is 1.2 g/cm³ to 3.3 g/cm³.

The invention provides a method for removing phosphorus and boron from metallurgical-grade silicon, which relates to the purification of metallurgical-grade industrial silicon. The provided method for removing the phosphorus and the boron from the metallurgical-grade silicon has the advantages of less investment, lower production cost, less environmental pollution and the like. The method comprises the following steps of: putting a bulk silicon material into a smelting furnace; smelting the bulk silicon material, and covering the bulk silicon material with a slag former to obtain a silicon block mixture; vacuumizing the smelting furnace until the pressure is between 800 and 1,200 Pa, and charging argon until the pressure is between 8,000 to 12,000 Pa; heating the silicon block mixture to be melted, introducing water vapor, pouring a melted mixture on a loading graphite crucible below a smelting crucible, and taking out the silicon material after being cooled; crushing and milling the silicon material after slag forming to obtain silicon powder; soaking the powdered silicon in hydrochloric acid; soaking the silicon powder after being soaked in the hydrochloric acid in dilute aqua regia; and soaking the silicon powder after being soaked in the dilute aqua regia in hydrofluoric acid to obtain the metallurgical-grade silicon without the phosphorus and the boron.

The invention relates to the field of structural ceramic manufacturing, in particular to a preparation method of zirconium diboride ceramic with in-situ-introduced boron as an additive. The preparation method comprises the following steps: firstly, performing ball milling and mixing zirconium dioxide and elemental boron in a mol ratio of (1: 3.5)-(1: 4.5), and drying to obtain ZrO2/ B mixed powder; secondly, putting the ZrO2/ B mixed powder into a graphite crucible, and performing high-heat treatment at the air pressure of below 200Pa to obtain ZrB2/ B powder; and finally, sieving the obtained ZrB2/ B powder, performing isostatic pressing, putting the ZrB2/ B powder into the graphite crucible, performing pressureless sintering in an argon atmosphere, controlling the sintering temperature at 1800 -2100 DEG C, the heat-preserving time at 1-3 hours and the heating rate at 10-50 DEG C/ min, and preserving heat for 0.5 hours at 1500-1700 DEG C to obtain the compact zirconium diboride ceramic. By the preparation method, a ball milling medium is not introduced, the impurity content is reduced, excellent performance of the zirconium diboride ceramic can be maintained easily, and the sintering compactness of the zirconium diboride ceramic is realized at a relatively low temperature (2000 DEG C).

Articles for use with highly reactive alloys that include a graphite crucible having an interior, and at least a first protective layer applied to the interior of the graphite crucible in which the graphite crucible having the first protective layer is used for melting highly reactive alloys.