38 results about "Anisotropic growth" patented technology

This invention relates to polycrystal texture ceramic material preparation method, it includes preparation technique principle and corresponding technique method. Diffusion route of ion and polar particle in high temperature field can be affected by electrostatic field, the characteristic is used to induct crystal nucleus growth process and reinforce anisotropy growth to form texture polycrystal material. Different strength orientation electric field is applied, and the strength is related to material system different component, core forming and crystal growth speed, anisotropy radius-thickness ratio expected, and electric breakdown strength of environment and materials. The anisotropy growth of polusrystal texture made is appreciable, polyspinal deformity is uniform, breaking tenacity and fracture toughness of material on wishful direction can be improved. Directed dielectric property can be great improved, and material piezoelectric constant and electromechanical conpling factor can be improved, dielectric loss can be reduced.

The invention discloses a high density ceramic matrix composite material, a preparation method and application thereof. A zirconium diboride-zirconium disilicide-tungsten carbide ceramic matrix composite material is prepared from zirconium diboride powder, zirconium disilicide and tungsten carbide with purity of greater than 98% by a two-step hot pressing sintering process. Specifically, the mass fraction of zirconium diboride powder is 75-90%, and the adding of high content zirconium diboride into the ceramic matrix composite material is in favor of improving the physical and chemical performance of the composite material. The mass fraction of zirconium disilicide is 10-15%, and the adding of the zirconium disilicide with the mass fraction into the ceramic matrix composite material can significantly lower the sintering temperature of the material. The mass fraction of tungsten carbide is 0-10%, the added tungsten carbide can promote the anisotropic growth of crystal grains in the material. The grain size of the three original powder is 1-5 microns, and the grain size in the range is conducive to uniform mixing of each phase. The material provided by the invention can be used as a surface heat insulation layer of hypersonic flight vehicles, and has the characteristics of high density and high mechanical properties.

This invention relates to a method for manufacturing polar glass ceramic. The method comprises: (1) mixing raw material micropowder with 0-15 wt.% of melting agent and 0-15 wt.% of seed crystal powder, and putting into a crucible; (2) placing the crucible in a high-temperature electric furnace, melting, taking out, molding and cooling to form ordinary glass; (3) cutting into a certain shape, polishing, putting into the high-temperature zone of an ordinary high-temperature electric furnace or a temperature-gradient electric furnace, placing electrodes on both sides of the glass or the crucible, and crystallizing at a medium temperature; (4) simultaneously applying a DC electric field to assist orientation crystallization; (5) cooling and shaping to obtain the final product. The method is reliable, and easy to control. The polar ceramic glass has high crystallization volume fraction, high orientation degree, and stable quality.

The invention discloses a textured boride base ultra-high temperature ceramic material and its preparation method. The ceramic material is a boride-silicide base composite material and is prepared from raw materials of group IVB metal, boron, silicon and transition metal. In addition, the microstructure of the composite material contains boride crystal grains of anisotropic grain growth and directional arrangement. The ceramic material is prepared by the following steps of: firstly performing reactive hot-pressing sintering to prepare densified boride base ceramic with the anisotropy crystal grain microstructure, and carrying out microstructure modulation on the ceramic which has undergone reactive hot-pressing sintering by a hot forging method to realize directional arrangement of the crystal grains of anisotropic grain growth. Therefore, the textured boride base ultra-high temperature ceramic material with the anisotropic grain growth crystal grain microstructure is obtained. According to the invention, relative density of the obtained ceramic material is greater than 98%; Lotgering orientation factor f (001) can reach up to 0.91; and its oxidation resistance, thermal conductivity and other properties all show obvious anisotropy.

The invention provides a method for improving lithium battery negative electrode rate performance through a magnetic effect. A one-dimensional negative electrode material is adopted for loading ferrofluid and ferrite materials to form an oriented structure under a magnetic field, and by vertical combination with a copper current collector, a negative electrode in a three-dimensional dense array structure is formed. The problem of lithium ion intercalation difficulty caused by excessively high internal resistance resulted from anisotropic growth of the negative electrode of a traditional lithium battery negative electrode material in a lithium ion de-intercalation process is solved; by combination of the ferrite materials, the ferrofluid and the negative electrode through van der Waals force, the negative electrode material is vertically combined on the surface of the copper current collector in an oriented manner under the action of the magnetic field to form the three-dimensional dense array, active points of the material can be exposed more completely, a lithium ion transmission passage is formed, de-intercalation and migration performances of lithium ions in the negative electrode material are effectively improved, the battery rate performance is improved, and improving electrical performances of the negative electrode material through control of the negative electrode structure instead of components is realized.

The invention belongs to the field of nano-material preparation, and particularly discloses a method for preparing hexagonal copper sulfide nano-sheets. The method includes steps of mixing copper saltand long-chain alkylamine with each other, heating and vacuumizing the copper salt and the long-chain alkylamine to dissolve the copper salt and the long-chain alkylamine and carrying out complexation on copper ions and amino to form reaction liquid A; heating and dissolving powdered sulfur and long-chain alkylamine to form reaction liquid B; adding the reaction liquid B into the reaction liquidA to form mixed solution; carrying out reaction, then adding absolute ethyl alcohol into the mixed solution to dissolve copper sulfide nano-sheets out from solution, and centrifugally washing and drying dissolved substances by the aid of absolute ethyl alcohol to obtain the copper sulfide nano-sheets with hexagonal structures. The method has the advantages that the long-chain alkylamine is used asa structure-directing agent and a solvent, accordingly, growth of copper sulfide nano-crystals can be effectively controlled in reaction procedures, excellent directing effects can be realized for anisotropic growth of the hexagonal copper sulfide nano-sheets, and excellent protective media further can be provided to the morphological regularity of the hexagonal copper sulfide nano-sheets.

In the method of embodiments of the invention, the metal seeded carbon allotropes are reacted in solution forming zero valent metallic nanowires at the seeded sites. A polymeric passivating reagent, which selects for anisotropic growth is also used in the reaction to facilitate nanowire formation. The resulting structure resembles a porcupine, where carbon allotropes have metallic wires of nanometer dimensions that emanate from the seed sites on the carbon allotrope. These sites are populated by nanowires having approximately the same diameter as the starting nanoparticle diameter.

The invention relates to a preparation method for glass ceramics. The preparation steps are as follows: firstly, selecting a raw material micro powder for forming glass ceramics, then adding an agent of fusion with weight percentage of 0-15%, and then adding a network modifier or crystal seed powder with weight percentage of 0-15%, performing even mixing, putting the mixture into a crucible, then performing melting at high temperature in a high-temperature electric furnace, taking out an obtained product and then pouring the obtained product into a mould and performing moulding and cooling, so as to obtain ordinary glass; secondly, cutting the glass into desired shapes and polishing the surface, then putting the polished glass in a high temperature work area of a common high-temperature electric furnace or ladder gradient-temperature electric furnace, placing electrodes onto parallel upper and lower surfaces of the glass or the crucible, applying a direct current electric field to assist directional crystallization treatment during crystallization of glass at medium temperature, wherein the electrostatic potential of the electric field is used as an auxiliary method to control grain nucleation and anisotropic growth; and thirdly, after the crystallization process is finished, performing cooling to form polar glass ceramics with the characteristics of a high devitrification volume fraction and high grain orientation. The method has the advantages of novel principle, reliable process, easy control as well as stable and reliable quality.

The invention discloses a method for preparing a monoclinic phase vanadium dioxide nanowire. The method comprises the following steps: mixing a vanadium source, stearic acid and water, carrying out a hydrothermal reaction on the obtained mixed solution, sequentially centrifuging, washing and drying the obtained product after the hydrothermal reaction is completed, thereby obtaining the monoclinic phase vanadium dioxide nanowire. By utilizing the dual effects of inducing anisotropic growth of crystals through a reducing agent and a surfactant in the stearic acid, the monoclinic phase vanadium dioxide nanowire with thermal induced phase transition property can be prepared in a one-step process, the preparation process is simple, complicated equipment is not needed, the production cost is low, the reaction conditions are easy to control, and large-scale industrial production is easily realized; and moreover, the monoclinic phase vanadium dioxide nanowire is uniform in distribution and high in crystallinity and can be applied to the fields of smart windows, photoelectric switches, camouflage and stealth, infrared detection devices and the like.

The invention discloses a preparation method of controllable arrayed nanowires and a preparation method of an FET (field effect transistor) comprising the controllable arrayed nanowires. According to the preparation method of the controllable arrayed nanowires and the preparation method of the FET comprising the controllable arrayed nanowires, materials with anisotropic growth rates of growing materials in different crystal orientations in epitaxial growth are selected as substrates, so that growth of the nanowires is realized; configurations and diameters of the patterned substrates are designed, so that cycles, the number, lengths and diameters of the arrayed nanowires can be controlled accurately, and different FET requirements can be met; growth conditions of group-VI-rich or group-V-rich atoms realize the surface inhibition effect, isotropic migrations of the metal atoms on surfaces are reduced, and growth of the nanowires is facilitated; the FET comprising the controllable arrayed nanowires can be prepared with a traditional semiconductor device preparation technology, the technology is simple, the controllability is high, the cost is low, and mass production can be realized.

The invention discloses a rare earth complex nanobelt and a preparation method thereof. The method comprises enabling rare earth nitrate to react with phthalic acid, performing deprotonation of carboxyl of phthalic acid by adjusting the pH value of a solution, achieving coordinate bond between rare earth ions and phthalic acid, generating massive crystal nucleuses, enabling crystal nucleuses to achieve anisotropic growth in a polar solvent environment, and obtaining the rare earth complex nanobelt with the chemical formula to be RE4(1,2-BDC)6(H<2>O)2-nH<2>O or RE4(1,2-BDC)6(H<2>O)2-nH<2>O: xLn3+. Due to the fact that the pH value is 5.5-6.5, complete deprotonation of carboxyl of phthalic acid under the pH value is achieved, rare earth hydroxide is not formed, the solution is in a hypersaturated state, massive crystal nucleuses are generated rapidly, anisotropic growth is achieved so that a belt-shaped structure is formed, and block-shaped crystal caused by slow growth is avoided. Experimental results show that the width of the rare earth complex nanobelt is 100-150nm, the thickness of the rare earth complex nanobelt is 10-20nm, and the length of the rare earth complex nanobelt is over hundreds of microns.

The invention provides a preparation method of a PdRh alloy electrocatalyst for a fuel cell, and the method comprises the following steps: weighing P123, dissolving the P123 in deionized water, addinga complexing agent PEI, performing stirring, and adding a formaldehyde solution to obtain a mixed solution A; dissolving potassium chloropalladate and rhodium chloride powder in deionized water to obtain an orange-yellow solution B; dropwise adding the orange-yellow solution B into the mixed solution A, and obtaining a precursor solution after the solution is completely changed into a grey blackturbid solution; transferring the precursor liquid into a polytetrafluoroethylene high-pressure reaction kettle at room temperature, and putting the polytetrafluoroethylene high-pressure reaction kettle into a drying oven for reaction; after the reaction is finished, performing the natural cooling to the room temperature, and performing centrifugal washing to obtain the fuel cell PdRh alloy electrocatalyst. According to the method, the PEI is used as a complexing agent and complexed with precursor ions, so the reaction rate is decreased, and the anisotropic growth of the PdRh alloy has a moreopen structure. The prepared alloy catalyst has good methanol oxidation performances, and has a wide development prospect in direct methanol fuel cells.

A method for synthesizing nanostructures includes introducing a solution of seed crystals into an initial growth solution to form a nanostructure synthesis mixture. The initial growth solution includes a precursor material and a reducing agent in a surfactant solution. Growth of nanostructures in the nanostructure synthesis mixture is monitored during a period of anisotropic growth of the nanostructures to determine a shift from stage II growth of the nanostructures to stage III growth of the nanostructures. The shift from stage II growth to stage III growth is identified, and after identifying the shift, a second growth solution is added to the nanostructure synthesis mixture coincident in time with the shift. The second growth solution includes the precursor material and the reducing agent in the surfactant solution.

The invention discloses a universal two-dimensional rare earth MOFs material, a solvent-free chemical stripping method and application thereof. According to the invention, different quaternary ammonium salts are used as a morphology regulator and an intercalation stripping agent, and under a solvent-free state, a mechanical grinding method and heating treatment in a reaction kettle are carried outin sequence so as to achieve effective regulation and control of the rare earth MOFs material from a 3D block shape to a 2D two-dimensional sheet shape are realized; in the process, the quaternary ammonium salt is attached to the surface of the rare earth MOFs material, anisotropic growth of the rare earth MOFs material is caused, and then the ultrathin MOF nanosheet is formed; and the synthesismethod of the rare earth MOFs material provided by the invention is simple and convenient, high in yield and relatively mild in condition, meets the requirements of the 2D rare earth MOFs material onmaterial performance in fluorescence and sensing application, and further has a large-scale production prospect.

The invention discloses a preparation method and application of a red phosphorus/gold nanoflower composite material. The preparation method is characterized by comprising the following steps: (1) preparing nano red phosphorus by adopting a hydrothermal method; (2) preparing red phosphorus/gold nanoparticles by adopting an in-situ deposition method; and (3) preparing the red phosphorus/gold nano-flower composite material by adopting an anisotropic growth strategy: sequentially adding 1ml of the red phosphorus/gold nano-particle aqueous solution prepared in the step (2), 5ml of a 4-mercaptobenzoic acid solution and 12.5 ml of an ascorbic acid solution into 2.5 ml of a chloroauric acid solution, slightly shaking, enabling the mixture to react for 30 minutes, then washing with deionized water and ethanol for several times, and removing the modified 4-mercaptobenzoic acid molecules by photocatalysis to obtain the red phosphorus/gold nanoflower composite material. The red phosphorus/gold nanoflower composite material can be used for preparing a sandwich immune structure for detecting tumor markers, and has the advantage that the detection sensitivity of the tumor markers is improved.

The invention discloses a method and device for simulating metal surface hydrogenation spot corrosion morphology evolution, and the method comprises the steps: building a hydrogenation spot corrosion phase field model coupled with anisotropic elastic energy through employing an anisotropic elastic constant, and constructing an equivalent elastic constant through employing an interpolation function method to represent the non-uniformity of a system; the method is suitable for anisotropic metal materials, can simulate the morphology difference caused by elastic anisotropic growth of the metal materials, and better shows the growth morphology characteristics of hydrogenation point corrosion; in the pitting corrosion phase field model, a finite element method is adopted to solve a mechanical equilibrium equation of a non-periodic boundary condition, and the problem of non-periodic physical parameter periodicity caused by Fourier transform solving of a periodic elastic field can be avoided.