31results about How to "Avoid the introduction of impurities" patented technology

The invention discloses a method for preparing copper-tungsten alloy doped graphene. The method comprises the following steps: uniformly and quantitatively depositing a layer of copper on the surfaceof tungsten powder, and modifying the surface state of copper-plated tungsten powder and graphene respectively with PVA and PVP; sufficiently stirring in a liquid medium to sufficiently mix the copper-plated tungsten powder and graphene, and performing cold-press molding and hog-press sintering to obtain the graphene doped copper-tungsten alloy. The method can be used for improving the wetting performance of the sintering process, and the chemical, electrical, thermal and other performance of the alloy prepared by the method are greatly improved in comparison with those of alloy prepared by atraditional method, the vacuum ablation performance is promoted when the alloy is applied to an electrical contact, the service life of the contact is prolonged, and the ablation can be more uniform.

The invention discloses a method-static shearing method for detecting the kiln coating suspension performance of a fireproof brick for a cement kiln, and a principle, equipment, a sample, steps and result calculation thereof. The static shearing method is low in experimental expense, strong in operability and quantizable, especially the shearing position is proper, the data is stable and good in repeatability in the shearing range, the influence caused by errors is greatly reduced, the practical kiln coating suspension performance of the fireproof brick for the cement kiln can be really reflected, the conventional fireproof material detection equipment is made full use of, and the conventional performance detection method for the fireproof brick is further improved.

The invention is applicable to the technical field of semiconductor and provides a method for preparing single-layer graphene on the surface of ultranano diamond. The method comprises preprocessing anultranano diamond film to eliminate surface impurities and surface stress; forming a metal layer on the nucleation surface of the preprocessed ultranano diamond film, wherein the metal layer is composed of a nickel layer and a copper layer on the upper surface of the nickel layer or is a copper-nickel alloy layer; performing high-temperature annealing treatment on the ultranano diamond film withthe grown metal layer to self-organize the single-layer graphene. The method for preparing the single-layer graphene on the surface of the ultranano diamond saves a second transfer process by directlygrowing the single-layer graphene on the ultranano diamond film, thereby effectively avoiding introduced impurities and lattice imperfection during second transfer processes; meanwhile, the grown single-layer graphene is small in lattice mismatch and surface change.

The invention discloses a production method of durene. The method includes: gasification and mixing of xylene and an alkylating agent, alkylation reaction, refining, freezing crystallization filtration and squeezing. The production method of durene provided by the invention has the advantages of: high catalyst activity and long service life, high product selectivity, high production safety, few alkylation by-product, stable finished product quality, low consumption of raw and auxiliary materials, and long service life of equipment, and is suitable for large-scale industrial production.

The invention discloses a dual deterioration method of a hypereutectic Al-Si alloy. An intermediate alloy of fine grain hypereutectic Al-Si alloy is added to achieve dual deterioration of primary crystal Si and eutectic Si, the intermediate alloy has the same components as a matrix alloy, impurities and elements are prevented from being introduced into the reaction, the process is simple and the operation is convenient; the size of the primary crystal Si in the hypereutectic Al-Si alloy is thinned from 44 microns to 14 microns after deterioration, the eutectic Si is deteriorated from a faller gill shaped into a highly branched fiber shape.

The invention relates to the technical field of medicinal preparations, and specifically discloses a compound electrolyte injection and a preparation method thereof. The preparation method includes: successively adding L-malic acid, magnesium chloride, sodium chloride, potassium chloride, calcium chloride, sodium acetate and sodium hydroxide with a prescription dosage in order into 70-80% of the total preparation volume of water for injection, performing stirring and dissolving, performing heating to a boil, maintaining for 10-20 min; and replenishing the water for injection to the total preparation volume, performing filtering by using multistage polyethersulfone filter with successively reduced pore diameters, performing filling, and then performing sterilization to obtain the compound electrolyte injection. Through the one-step preparation method, the compound electrolyte injection (II) having significantly reduced impurity types and content can be obtained; the storage stability of the injection can be significantly enhanced; in a stability investigation test, the increasing of impurity content is not obvious; in addition, production technologies are greatly simplified, production efficiency is enhanced, and costs of production are reduced; and therefore, commercial production can be realized. The compound electrolyte injection and the preparation method thereof have wide application prospects.

The invention discloses a plastic screen cloth for chemical engineering powder screening, and relates to the technical field of chemical equipment. The plastic screen cloth is prepared from, by weight, 20-25 parts of hard PVC regeneration particles, 10-15 parts of saturated polyester resin, 5-10 parts of C5 petroleum resin, 5-10 parts of lignocellulose, 3-6 parts of organic filler, 3-6 parts of bamboo powder, 2-4 parts of gum dammar, 2-4 parts of superfine polytetrafluoroethylene powder, 2-4 parts of ceramic micro powder, 1-2 parts of polymethyl methacrylate, 1-2 parts of molecular sieve raw powder, 0.5-1 part of nanometer zinc oxide, 0.5-1 part of lanonol and 0.05-0.1 part of lanthanum oxide. The screen cloth has the excellent corrosion resistance, wear resistance and vibration resistance and is applicable to screening of powder capable of achieving easy moisture absorption or corrosivity; the service life is long, and the replacement cost of the screen cloth is effectively lowered.

The invention relates to the field of lithium batteries, and discloses a graphene modified-carbon coated lithium iron phosphate material and a preparation method thereof, and a solid lithium ion battery, the preparation method comprises the following steps: dissolving a phosphate radical raw material, an iron salt and a lithium source in an alcoholic solution, then adding a template agent, a carbon source and an antioxidant, then adding graphene oxide, and carrying out ultrasonic dispersion, so as to obtain the graphene modified-carbon coated lithium iron phosphate material. Pouring into a reaction kettle, and carrying out hydrothermal synthesis to obtain a solid-phase material; and placing the solid-phase material in a vacuum oven for drying, and then placing the dried solid-phase material in a muffle furnace for high-temperature calcination to obtain the graphene modified-carbon coated lithium iron phosphate material. When the G/LFP/C material is applied to a solid-state battery, the transportation of electrons and lithium ions can be facilitated, and the interface impedance is reduced, so that the solid-state battery prepared from the G/LFP/C material can have excellent rate capability, electrochemical lithium storage performance and cycle performance.

The invention belongs to the field of hard alloy and material metallurgy, and particularly discloses a method for preparing cobalt-coated tungsten carbide powder by freezing. According to the method,metal cobalt salt and tungsten carbide powder are used as raw materials, and the preparation of the uniform cobalt-coated tungsten carbide powder is realized through the steps of dissolution, freezingcrystallization, three-step heat treatment and the like. The method comprises the following steps that the cobalt salt is dissolved in a hot liquid to obtain a cobalt-containing precursor solution, the tungsten carbide powder is added as a nucleating agent and gradually cooled in the stirring process, the cobalt salt is separated out and adhered and wraps outside the tungsten carbide powder to obtain uniformly-wrapped tungsten carbide, and the cobalt salt composite powder is dried, decomposed and reduced to obtain the uniformly-mixed cobalt-coated tungsten carbide powder at three different temperatures. The method realizes uniform tungsten carbide. The preparation method of the cobalt-coated powder has the advantages that the process flow is simple, the Co content of different brands canbe obtained, the granularity is easy to control, and the problem that a cobalt pool and the like in the current hard alloy production process are not uniform is effectively solved.

A high-purity semi-insulating silicon carbide crystal growing apparatus and a method therefor are provided, the apparatus comprising a growth crucible, a bottom part of the growth crucible having inserted a gas pipe, a top part of the growth crucible being provided with a growth crucible cover, a feedstock crucible having a bowl-shaped structure being disposed in the growth crucible, an upper part of the feedstock crucible being provided with a baffle, a bottom part of the feedstock crucible being provided with a ring-shaped supporting feedstock crucible bottom foot, the diameter of the feedstock crucible bottom foot being ⅛ the diameter of the feedstock crucible, and the feedstock crucible bottom foot having disposed thereon 8-36 evenly distributed gas holes.

The invention discloses a preparation method of niobium-soluble lithium titanate solid-solution medium ceramic powder. The microwave medium ceramic powder adopts LiNO3, Ti(C4H9O)4 and Nb2O5 as raw materials. The method comprises the steps of weighing the LiNo3 and Ti(C4H9O)4 according to a molar ratio of (2+x): (1-4x) (wherein x is more than 0 and less than 0.2), adding the well-prepared citric acid solution, adding ethylene glycol, adjusting the pH value by utilizing ammonia water, uniformly stirring the obtained solution, standing the solution in a sealing manner so as to obtain gel, drying and grinding the gel, adding the Nb2O5 into the dry gel powder according to the molar ratio of Li: Nb: Ti of (2+x): 3x: (1-4x) (wherein x is more than 0 and less than 0.2), carrying out ball milling and mixing by adopting the absolute ethyl alcohol as the medium, and drying and calcining the obtained powder so as to obtain the ceramic powder. The method is simple in synthesis process, stable in process under the normal temperature and good in repeatability and has a wide application prospect.

The invention relates to a cycloalkane catalyst prepared from lignin through in-situ phosphorization and a preparation method and application of the cycloalkane catalyst, Cu-Mg-Al hydrotalcite serves as a precursor of the catalyst, a Cu/CuMgAlOx intermediate is obtained through calcination and reduction, and then the catalyst is prepared through in-situ phosphorization. The preparation method specifically comprises the following steps: respectively dropwise adding a mixed solution containing Cu < 2 + >, Mg < 2 + > and Al < 3 + > and a NaOH solution into a Na2CO3 solution, controlling the temperature and pH of the mixed solution, and precipitating; after dropwise adding is finished, aging, filtering, washing and drying the mixed solution in a stirring state to obtain a precursor; grinding the precursor into powder, and calcining to obtain a metal oxide; metal oxide is reduced and activated to obtain an intermediate, and mixed powder of red phosphorus and the intermediate is subjected to in-situ phosphorization in an inert atmosphere to obtain the catalyst. The catalyst has high catalytic activity on deep deoxidation of cycloalcohol intermediates in the lignin conversion process, and the yield and selectivity of cycloalkanes in the product are improved.

The invention provides a method for preparing TiAl alloy bars, relating to a method for preparing alloy bars. The invention solves the problem of difficult hot extrusion in preparation of the TiAl alloy bars by the existing casting metallurgical method and the problems of easy introduction of impurities and low compactness of the TiAl alloy bars prepared by the powder metallurgical method. The method of the invention is as follows: 1) preparing Ti powder into porous Ti by cold compressing and sintering; 2) forming a hot-pressing piece by the porous Ti and alusil alloy; 3) preparing Ti-Al bimetal complexes by using a vacuum pressure infiltration method; 4) extruding to obtain Ti-Al bimetal composite bars; and 5) performing heat treatment to obtain the TiAl alloy bars. In the invention, theextrusion operation of the bars is carried out at lower temperature, the bar has the advantages that the extrusion is easy, no ball milling process is needed, the impurities are less, the tissues of the bars are uniform and fine, the compactness is 97-99%, and the tensile strength is 730-780 MPa, thereby be capable of being used in the fields of aviation, spaceflight and automobile.