42 results about "Critical transition temperature" patented technology

Synthesis of warm sensitive aquagel from ultraviolet light radiation polymerization is carried out by adding reacting raw materials into deionized water to prepare preformed solution, laying aside under ultraviolet light radiation, exposing, polymerizing directly to prepare cross-linking polymer, putting the polymer into sorbitic extractor, extracting from boiled deionized water for 24hrs, taking it out, and drying in vacuum drier to obtain warm sensitive aquagel. Its low critical temperature varies between 30-40 Deg C. with raw material formula. It can be used for various aquagels, medicine control-releasing system, memory element switch, artificial muscle and chemical industrial separation. It achieves low cost, simple process, high efficiency and normal-temperature operation.

The invention relates to a structure of a high molecular composite membrane, in particular to a self-cleaning high molecular reverse osmosis membrane. The self-cleaning reverse osmosis membrane is characterized in that a porous support membrane is compounded with a polyamide ultrathin desalting layer through interfacial polycondensation of aromatic polyamine and polyatomic acyl chloride, and the compounded desalting layer is compounded with a temperature-sensitive functional high molecular material with low critical transition temperature through solution coating technology. The self-cleaning reverse osmosis membrane has the advantage that the desalting rate and water flux of the reverse osmosis membrane are not lower than those of the prior anti-pollution reverse osmosis membrane technology, and also has the advantages of universality, simplicity, high efficiency and the like; and a preparation method thereof is comparatively simple. The reverse osmosis membrane of the invention has wide application.

The invention relates to the technical field of special steel forge pieces, in particular to high-performance hot work die steel and a production process thereof. The high-performance hot work die steel is prepared from, by weight, 0.36-0.39% of C, 0.10-0.50% of Si, 0.20-0.60% of Mn, 4.7-5.3% of Cr, 2.4-2.6% of Mo, 0.50-0.70% of V, 0.40-0.70% of Ni, 0.002% or less of S, 0.015% or less of P and thebalance Fe. The preparation process comprises the steps of electric arc furnace melting, external refining, pouring, electroslag remelting in protective atmosphere, smithing, high-temperature diffusion and spheroidizing annealing. In the high-performance hot work die steel and the production process thereof, the proportion of the raw materials of the hot work die steel is optimized, an optimizedChemical composition scheme for the hot work die steel is provided, the heat intensity, hardness and toughness of the steel can be improved, the critical transition temperature during heating and cooling of the steel can be increased, and the strength and toughness are improved. By adding the Ni element, the quenching degree of the die steel is increased, the plasticity and toughness of the steelcan be improved at the same strength, and the service life of a die can be greatly prolonged.

The invention relates to the preparation and application method of a temperature sensitive micelle with magnetocaloric effect, belonging to the field of drug carrier in biological medicine, which adopts the technical proposal that: a quantity of temperature sensitive polymer is dissolved into an organic solvent; then the organic solvent together with drugs and Mn-Zn ferrite nanometer particles undergoes dialysis process in a great amount of deionized water to get a temperature sensitive micelle with magnetocaloric effect; and finally after certain biological treatment, the micelle is injected into human body; which is characterized in that an outside magnetic field locates the drug carrier near the tumor site; at the same time an alternating magnetic field raises the temperature of the micelle to reach the lowest critical temperature, so that the drug is released at the shrinking of the micelle. The method has an advantage that a new type of bio-control sustained release carrier is provided for the field of biological medicine.

The invention relates to a heat treatment method for a U71MnH steel rail flash welding joint, and belongs to the technical field of steel rail welding. The problem that harmful structures such as martensites are generated to influence the joint hardness due to the fact that the local cooling speed is higher than the critical transition temperature when an existing steel rail welding joint is cooled in the heat treatment process is solved. The heat treatment method for the U71MnH steel rail flash welding joint comprises the steps that a U71MnH steel rail welding joint welding seam area which iscooled to 300 DEG C or below after being welded is heated to 870-930 DEG C, then heating is stopped, air spraying cooling is adopted and stopped after the steel rail joint tread temperature is lowered to 420-470 DEG C, and natural cooling is conducted till the room temperature is achieved. By adopting the method, it is guaranteed that the joint structure is normal while the hardness of the U71MnHsteel rail flash welding joint is effectively controlled.

The invention provides an Nb-doped YBCO (Yttrium Barium Copper Oxide) super-conducting film and a preparation method. The super-conducting film is prepared by mixing a nano-particle BYNO (Ba2YNbO6) with a double perovskite structure into a YBCO film, wherein an Nb material is 1 to 10% of total quantity of a material of a metal cation. The preparation method comprises the following steps of: preparing a YBCO precursor solution; preparing an Nb precursor solution; preparing an Nb-doped YBCO precursor solution; coating same on a gel film; roasting at a low temperature; and sintering at a high temperature. The preparation method provided by the invention is simple and easy to carry out; a mixture ratio of doped materials can be randomly controlled; and furthermore, raw materials are cheap and easy to obtain, vacuum equipment is not needed, and low cost is ensured; a prepared film has higher critical transition temperature, critical current density and an excellent biaxial texture.

The essence of the invention is the use of supercooled superconductors for generation of high-frequency electric oscillations. The superconductor is supercooled, i.e. in the normal phase at a temperature lower than the critical transition temperature for superconductivity, under an applied electric energy source. In such non equilibrium conditions the superconductor can have negative differential conductivity which can be used as an active medium in generators of electric ( current and voltage) oscillations. Such generators can be used in the superconducing electronics. Oscillation can be modulated by the change of bias voltage, electrostatic doping by a gate electrode, or by light. When small amplitude oscillations are stabilized near to the critical temperature the generator can be used as a bolometer. The supercooled superconductors can be used also as transistors and frequency mixers. The negative differential conductivity of superconductor is created by the excess conductivity of fluctuation Cooper pairs. This behavior is predicted by the solution of the Boltzmann kinetic equation of the metastable in the normal phase Cooper pairs. Boltzmann equation for fluctuation Cooper pairs is derived as a state-of-the-art application of the microscopic theory of superconductivity.

The invention relates to the technical field of high-entropy alloys and discloses a six-element high-entropy alloy with a first-order magnetic phase transition and a preparation method thereof. The six-element high-entropy alloy with the first-order magnetic phase transition has a general formula structure of MgaMnbFecCodNieGdf and is obtained by electrochemical reduction deposition, wherein an electrolyte in the electrochemical reduction deposition comprises the following components: dimethyl sulfoxide, tetraethylammonium hexafluorophosphate, vitamin C, GdCl3, FeCl2, CoCl2, NiCl2, MnCl2 and MgCl2. The prepared alloy is an amorphous alloy, the magnetic transition of the prepared alloy is the magnetic transition caused by strong electron correlation without being restrained by the crystal form transformation of a material, and therefore, the high-entropy alloy has the advantages of large temperature range of magnetic phase transition, controllable critical transition temperature and reversibility.

The invention relates to a V-doped YBCO (Yttrium Barium Copper Oxide) superconducting thin film and a preparation method thereof, and belongs to the technical field of preparation of YBCO coating superconducting thin films. The preparation method of a double perovskite structure nanoparticle BYVO-doped YBCO superconducting thin film comprises the following steps: 1) first, preparing a precursor liquor, and mixing yttrium acetate, barium acetate and copper acetate at a molar ratio of 1:2:3 to prepare a YBCO precursor liquor; 2) uniformly stirring and then vanadium acetylacetonate, wherein the molar concentration of three metal total ions to prepare the V-doped YBCO precursor liquor; 3) coating a gel thin film; 4) sintering at low temperature; and 5) sintering at high temperature to form the nano BYVO containing YBCO superconducting thin film. The method provided by the invention is simple and accessible, and the proportion of adulterants can be arbitrarily controlled. The thin film prepared has the advantages of higher critical transformation temperature and critical current density and a good biaxial texture.

A SrZrO3 doped YBCO film and a preparation method thereof belong to the technology field of the preparation of the superconducting material with high-temperature coat. The original PLD method has the defect that the equipment is complicated, the cost is high and the proportion of the dopant is not easy to control. The film provided by the invention consists of 1 to 15 molar percent of SrZrO and 85 to 99molar percent of YBCO. The invention prepares YBCO precursor solution by the deposition method of trifluoroacetic acid and metal-organic compound; the YBCO precursor solution and the propionatesolution comprising strontium acetate and zirconium acetylacetone are mixed to obtain the SrZrO3 doped YBCO precursor solution; then the SrZrO3 doped YBCO precursor solution is spin-coated or dip-coated on the base, and the base is sintered under the wet oxygen atmosphere and below 400 DEG C; finally the base is high-temperature sintered under the wet ArO2 mixing atmosphere and between 750 to 850DEG C to obtain the SrZrO3 doped YBCO film. The film of the invention has the advantages of higher critical current density, higher critical conversion temperature and biaxial texture in the magneticfiled, simple equipment and low cost.

The invention relates to a post weld heat treatment (PWHT) method for flash welding joints of U71MnH rails, and belongs to the technical field of rail welding. The invention provides the PWHT method for the flash welding joints of the U71MnH rails in order to solve the problem that when existing rail welding joints are cooled during heat treatment, the hardness of the joints is affected by martensite and other harmful structures which are formed because local cooling rate is higher than critical transition temperature. The PWHT method comprises the steps of heating U71MnH rail welding joint welding seam areas, which are cooled to be below 300 DEG C after welding, to 919-940 DEG C and then stopping heating, performing air jet cooling, stopping air jet cooling after the temperature of treadsurfaces of the joints of the rails drops to 410-435 DEG C, and performing natural cooling to room temperature. While effectively controlling the hardness of the welding joints of the U71MnH rails, the PWHT method ensures the normality of the structures of the joints.

The invention discloses a contact type cooling system adopting a shape memory alloy. The contact type cooling system comprises a cooling device for providing cold, a cooled object, the shape memory alloy and a vacuum Dewar bottle. The cooling device for providing cold, the cooled object and the shape memory alloy are all arranged in the vacuum Dewar bottle, the cooled object and the cooling devicefor providing are in contact and out of contact through prolonging and shortening of the shape memory alloy at about the critical temperature, the cooled object is maintained at the critical conversion temperature, and heat leakage is reduced. Compared with a traditional cooling system, by means of the contact type cooling system, a temperature gauge and a control logic are avoided, frequent start and stop of the device for providing cold are avoided, system operation is more stable, and the overall performance of the cooling system is improved.

The invention relates to a post-welding heat treatment method of U71MnH rail welded joints, and belongs to the technical field of rail welding. The post-welding heat treatment method of the U71MnH rail welded joints aims at solving the problem that the hardness of the joints is affected by harmful tissues such as martensite generated due to the local cooling speed being higher than the critical transition temperature when existing rail welded joints are cooled in the heat treatment process. The post-welding heat treatment method of the U71MnH rail welded joints comprises the following steps ofheating welding seam areas of the U71MnH rail welded joints cooled to below 300 DEG C after being welded to 865-925 DEG C, stopping heating, adopting air spraying for cooling, stopping air spraying for cooling after the temperature of the tread surfaces of the rail joints drops to 458-475 DEG C, and naturally cooling to room temperature. According to the post-welding heat treatment method of theU71MnH rail welded joints, the hardness of the U71MnH rail welded joints is effectively controlled, and meanwhile, normal tissues of the joints is ensured.

The invention discloses a preparation method of a YBCO coating superconducting thin film. According to the preparation method, a YxSm(l-x)BCO superconducting thin film is prepared on a lanthanum perchlorate LAO substrate modified by a palladium nanometer dot, wherein x is greater than or equal to 0 and is less than or equal to 1. The preparation method comprises the following steps: (1) preparing the Pd palladium nanometer dot; (2) preparing a YBCO precursor solution; (3) preparing a SmBCO precursor solution; (4) preparing a YxSm(l-x)BCO precursor solution, wherein x is greater than or equal to 0 and is less than or equal to 1; and (5) sintering YxSm(l-x)BCO, wherein x is greater than or equal to 0 and is less than or equal to 1. The preparation method disclosed by the invention is simple and practicable and has the advantages that the distribution density of the palladium nanometer dot can be controlled at arbitrary, the raw materials are low in cost and easily available, vacuum equipment is not needed during preparation, and the cost is low; and the prepared thin film has relatively high critical transition temperature and good biaxial texture and field performance.

The invention relates to an MgB2-based superconductor with increased critical transition temperature through electroluminescent excitation and a preparation method thereof. The critical transition temperature of the MgB2-based superconductor is changed through ectopic doping of Y2O3:Eu<3+> luminous bodies. Two doping agents of different luminous intensity, namely, Y2O3:Eu<3+>I and Y2O3:Eu<3+>II nano-rods, are prepared through a hydrothermal method, and an MgB2-based superconductor doped with Y2O3:Eu<3+> luminous bodies is prepared through an ectopic doping method. The mass fraction of the Y2O3:Eu<3+> luminous bodies is 1% and 2%. As the luminous intensities of the doping agents increase, the Tc value of the MgB2-based superconductor increases constantly. In the absence of an external magnetic field, when the Y2O3:Eu<3+>II luminous body of high luminous intensity is used as the doping agent and the doping concentration is 2%, Tc of the MgB2-based superconductor is 35.9K, which is higher than Tc (35.8K) of pure MgB2.

The invention discloses an Nb-doped YxYb1-xBCO superconductive film and a preparation method thereof, and belongs to the technical field of YBCO superconductive film modification. The method which allows Nb to be doped in a YxYb1-xBCO film comprises the following steps: 1, preparing a YBCO precursor solution; 2, preparing a Yb precursor solution; 3, preparing a YxYb1-xBCO precursor solution; 4, preparing an Nb precursor solution; 5, preparing an Nb-doped YxYb1-xBCO precursor solution; 6, coating a gel film; 7, sintering at a low temperature; and 8, sintering at a high temperature. The method has the advantages of simplicity, easy implementation, discretionary control of the proportion of a dopant, cheap and easily available raw materials, no need of vacuum equipment, and low cost, and the prepared film has a high phase purity, a high critical transition temperature and a good surface.

The invention discloses a preparation method of a nanocarbon conductive fiber yttrium-barium-copper superconducting material, which is made from, by weight, 4.2-5.1 parts of graphene-coated yttrium powder, 4.8-5.2 parts of barium oxide, 5.1-5.3 parts of copper oxide, 1.7-1.8 parts of benzoic acid, 2.1-2.2 parts of methyl methacrylate, 1.3-1.5 parts of sodium carboxymethylcellulose, 3.2-3.5 parts of sodium stearate, 2.2-2.5 parts of potassium carbonate, 1.3-1.5 parts of quicklime, and 1.7-1.9 parts of polyethylene glycol. The preparation method is simple. Yttrium powder is added to a nanocarbonconductive fiber material solution, so that nanocarbon conductive fibers coat yttrium powder. The obtained product isn't agglomerated after thermal treatment. The nanocarbon conductive fibers uniformly closely combine with yttrium powder, so that the conductivity of yttrium powder is improved. The obtained product is high in critical transition temperature, good in superconducting performance, high in critical current density, good in current carrying performance, less in energy dissipation, low in production cost, and high in practical value.

The invention discloses a method for preparing a nanocarbon conductive fiber yttrium-niobium-aluminum superconducting material. The method is characterized in that yttrium powder is added into a nanocarbon conductive fiber material solution to coat nanocarbon conductive fibers with yttrium powder, clustering is prevented after heat treatment, close and uniform combination with yttrium powder can be realized, the conductivity is improved, and the obtained product is high in critical transition temperature and favorable in superconducting property. According to the method, by use of the gas absorption characteristic of niobium powder, firstly, through the physical and chemical functions between hydrogen and niobium powder, a niobium powder and trace niobium hydrogen compound containing hydrogen is generated, the purpose of refining niobium powder is achieved, activation energy in the reaction is greatly reduced, and the synthetic difficulty is reduced. The prepared nanocarbon conductive fiber yttrium-niobium-aluminum superconducting material is simple in process, regular in shape and appearance, compact in surface, excellent in connection performance and high in superconducting critical temperature.

The invention relates to the field of temperature-responsive materials, and concretely relates to a temperature-responsive ionic gel with an upper critical transition temperature (UCST), and a preparation method and application thereof. An ionic liquid is mixed with a polymer substrate to obtain the mixture ionic gel with the upper critical transition temperature. The method has the characteristics of simple operation, environmental protection, low cost and the like, and the obtained ionic gel has the characteristics of high environmental stability and adjustable response temperature, and hasa wide application prospect in the fields of temperature sensors, intelligent glass, temperature corresponding materials and the like.

Synthesis of warm sensitive aquagel from ultraviolet light radiation polymerization is carried out by adding reacting raw materials into deionized water to prepare preformed solution, laying aside under ultraviolet light radiation, exposing, polymerizing directly to prepare cross-linking polymer, putting the polymer into sorbitic extractor, extracting from boiled deionized water for 24hrs, taking it out, and drying in vacuum drier to obtain warm sensitive aquagel. Its low critical temperature varies between 30-40 Deg C. with raw material formula. It can be used for various aquagels, medicine control-releasing system, memory element switch, artificial muscle and chemical industrial separation. It achieves low cost, simple process, high efficiency and normal-temperature operation.

The invention belongs to a method for pre-sintering a copper-containing active magnesium diboride superconducting block. The method comprises the following steps: adding 1-5 wt% of copper powder to a precursor powder MgB2 powder, fully mixing the copper powder and the precursor powder in an agate mortar, and processing the obtained mixture under a pressure of 2-8 MPa to prepare a small cylindrical sheet; placing the small cylindrical sheet in a thermogravimetric-differential thermal analyzer, heating the small cylindrical sheet in a flowing highly-pure argon atmosphere to 800-1000 DEG C, keeping the temperature for 0-20 min, and sintering the small cylindrical sheet; and cooling the sintered small cylindrical sheet to 600-700 DEG C, keeping the temperature for 0-3 h, and cooling the cooled small cylindrical sheet to room temperature according to a speed of 10-40 DEG C / min. The above prepared MgB2 superconducting material with a high current carrier is obtained through introducing a copper adding technology to a pre-sintering technology, has a stable structure and a high critical conversion temperature, and is better than all MgB2 superconducting blocks prepared through the pre-sintering technology in the current carrying ability; and the preparation method ahs the advantages of simplicity, high controllability, no pollution, wide sources of raw materials, low preparation cost, and wide engineering application and promotion prospect.

The invention discloses a microcapsule for controllably releasing medicines in tumor cells to treat breast cancers. The microcapsule comprises a temperature-sensitive hydrogel, a medicine and a magnetic material, wherein the surface of the temperature-sensitive hydrogel is loaded with phosphatidylcholine. The microcapsule is characterized in that by applying a magnetic field near the tumor tissues, when the medicine flows to the area near the tumor tissues along with fluid, the microcapsule containing the magnetic material is retained near the cells of the tumor tissues under the function of the additional fixed magnetic field; according to the characteristic of cancer cells directly absorbing choline under the endocytosis function, the temperature-sensitive hydrogel microcapsule with surface loaded with the phosphatidylcholine is directly absorbed into the tumor cells; by applying an alternating current magnetic field, the magnetic material produces heat under the function of the additional alternating current magnetic field to heat the microcapsule; when the critical transition temperature of the temperature-sensitive hydrogel is reached, the hydrogel generates phase change within very short time, so as to release the medicine out of the microcapsule, greatly improve the action efficiency of the medicine, and reduce the toxic or side effect of the medicine.

The invention discloses a preparation method of an yttrium-niobium-copper superconducting material. According to the preparation method, niobium powder is added to a nano-carbon conductive fiber material solution, so that coating of the niobium powder with a nano-carbon conductive fiber is achieved, agglomeration is avoided after thermal treatment, the niobium powder can be tightly and uniformly combined, the yttrium-niobium-copper superconducting material has improved conductivity, the obtained product is high in critical transition temperature and good in superconducting property, and the prepared product is simple in process, regular in shape and form, dense in surface, good in connectivity and high in superconducting critical temperature.

The invention relates to a post-welding heat treatment method of U71MnH rail welded joints, and belongs to the technical field of rail welding. The post-welding heat treatment method of the U71MnH rail welded joints aims at solving the problem that the hardness of the joints is affected by harmful tissues such as martensite generated due to the local cooling speed being higher than the critical transition temperature when existing rail welded joints are cooled in the heat treatment process. The post-welding heat treatment method of the U71MnH rail welded joints comprises the following steps ofheating welding seam areas of the U71MnH rail welded joints cooled to below 300 DEG C after being welded to 865-925 DEG C, stopping heating, adopting air spraying for cooling, stopping air spraying for cooling after the temperature of the tread surfaces of the rail joints drops to 458-475 DEG C, and naturally cooling to room temperature. According to the post-welding heat treatment method of theU71MnH rail welded joints, the hardness of the U71MnH rail welded joints is effectively controlled, and meanwhile, normal tissues of the joints is ensured.

The invention relates to a low-temperature sintering method of a Mg<11>B2 isotope superconductor. The method comprises the following steps: sufficiently mixing Mg powder and amorphous <11>B powder in a ratio of (0.9-1.2):2 in an agate mortar, and making the mixture into cylindrical pieces under a pressure of 2-10MPa; putting the cylindrical pieces into a thermogravimetric and differential thermal analyzer; in an atmosphere of flowing high-purity argon, heating to 450-800 DEG C at a rate of 10-40 DEG C / min, and preserving heat for 5-15 hours; cooling to room temperature along with furnace at a cooling speed of 10-40 DEG C / min to synthesize the Mg<11>B2 isotope superconductor. In the invention, a Mg<11>B2 superconductor material with high carrying current and 'low activity' is obtained through a low-temperature and solid-phase sintering method. The crystal structure is a hexagonal structure; and the Mg<11>B2 isotope superconductor has the advantages of relatively high critical transition temperature, stable chemical properties, simple components, no pollution, wide source of raw materials, relatively low preparation cost and use cost and wide application prospect.

The invention relates to a heat treatment method for a U71MnH steel rail flash welding joint, and belongs to the technical field of steel rail welding. The problem that harmful structures such as martensites are generated to influence the joint hardness due to the fact that the local cooling speed is higher than the critical transition temperature when an existing steel rail welding joint is cooled in the heat treatment process is solved. The heat treatment method for the U71MnH steel rail flash welding joint comprises the steps that a U71MnH steel rail welding joint welding seam area which iscooled to 300 DEG C or below after being welded is heated to 870-930 DEG C, then heating is stopped, air spraying cooling is adopted and stopped after the steel rail joint tread temperature is lowered to 420-470 DEG C, and natural cooling is conducted till the room temperature is achieved. By adopting the method, it is guaranteed that the joint structure is normal while the hardness of the U71MnHsteel rail flash welding joint is effectively controlled.

The invention relates to a solid nano porous membrane with temperature sensitive response characteristics and a preparation method thereof. Methacrylic acid benzyl ester with temperature sensitive response characteristics or polymer of derivative of the methacrylic acid benzyl ester is grafted on the solid nano porous membrane serving as a substrate to form the solid nano porous membrane with temperature sensitive response characteristics in a lithium ion battery using ionic liquid as electrolyte. When temperature exceeds lowest critical transformation temperature (120-150 DEG C), in the ionic liquid, of the polymer, the polymer collapses in nano pores of the solid nano porous membrane and on the solid nano porous membrane to block the nano pores, namely the polymer intelligently closes the nano pores to change conductivity of the solid nano porous membrane. In the mean time, the solid nano porous membrane substrate serving as support material is good in stability at high temperature and free of fusing.

The invention relates to the technical field of high-entropy alloys and discloses a six-element high-entropy alloy with a first-order magnetic phase transition and a preparation method thereof. The six-element high-entropy alloy with the first-order magnetic phase transition has a general formula structure of MgaMnbFecCodNieGdf and is obtained by electrochemical reduction deposition, wherein an electrolyte in the electrochemical reduction deposition comprises the following components: dimethyl sulfoxide, tetraethylammonium hexafluorophosphate, vitamin C, GdCl3, FeCl2, CoCl2, NiCl2, MnCl2 and MgCl2. The prepared alloy is an amorphous alloy, the magnetic transition of the prepared alloy is the magnetic transition caused by strong electron correlation without being restrained by the crystal form transformation of a material, and therefore, the high-entropy alloy has the advantages of large temperature range of magnetic phase transition, controllable critical transition temperature and reversibility.

A method for preparing a BSCCO-2223 oxide superconducting article includes annealing an oxide superconductor article comprised of BSCCO-2223 oxide superconductor at a temperature selected from the range of about 500.degree. C..ltoreq.T.ltoreq.787.degree. C. and an annealing atmosphere having an oxygen pressure selected from within the region having a lower bound defied by the equation, P.sub.O2(lower).gtoreq.3.5.times.10.sup.10e- xp(-32,000 / T+273) and an upper bound defined by the equation, P.sub.O2(upper).ltoreq.1.1.times.10.sup.12exp(-32,000 / T+273). The article is annealed for a time sufficient to provide at least a 10% increase in critical current density as compared to the critical current density of the pre-anneal oxide superconductor article. An oxide superconductor having the formula Bi.sub.2-yPb.sub.ySr.sub.2Ca.sub.2Cu.sub.3O.sub.10+x, where 0.ltoreq.x.ltoreq.1.5 and where 0.ltoreq.y.ltoreq.0.6 is obtained, the oxide superconductor characterized by a critical transition temperature of greater than 111.0 K, as determined by four point probe method.

The invention relates to a heat treatment method for a U71MnH steel rail welding joint, and belongs to the technical field of steel rail welding. The problem that harmful structures such as martensites are generated to influence the joint hardness due to the fact that the local cooling speed is higher than the critical transition temperature when an existing steel rail welding joint is cooled in the heat treatment process is solved. The heat treatment method for the U71MnH steel rail welding joint comprises the steps that a U71MnH steel rail welding joint welding seam area which is cooled to 300 DEG C or below after being welded is heated to 915-935 DEG C, then heating is stopped, air spraying cooling is adopted and stopped after the steel rail joint tread temperature is lowered to 405-432DEG C, and natural cooling is conducted till the room temperature is achieved. By adopting the method, it is guaranteed that the joint structure is normal while the hardness of the U71MnH steel railflash welding joint is effectively controlled.