412 results about "Negative thermal expansion" patented technology

PCT No. PCT/JP96/03000 Sec. 371 Date Jun. 16, 1997 Sec. 102(e) Date Jun. 16, 1997 PCT Filed Oct. 16, 1996 PCT Pub. No. WO97/14983 PCT Pub. Date Apr. 24, 1997A diffraction grating portion (12) is formed in an optical fiber (10), having a diameter of 125 mu m and serving to transmit light, along its optical axis. The optical fiber is concentrically surrounded by a lower coating portion (14) having an outer diameter of 300 mu m and consisting of a silicone resin. The lower coating portion is concentrically surrounded by a coating portion (16) having an outer diameter of 900 mu m and consisting of a liquid crystal polymer, e.g., polyester amide. The coating portion is further surrounded by an outermost coating portion (18) having an outer diameter of 1 mm and consisting of a UV curing resin colored for identification. Both the optical fiber (10) and the lower coating portion (14) have positive thermal expansion coefficients. In contrast to this, the coating portion (16) consisting of the liquid crystal polymer has a negative thermal expansion coefficient.

Negative thermal expansion materials, methods of preparation and uses therefor are disclosed. The materials are useful for negative thermal expansion substrates, such as those used for optical fiber gratings.

Disclosed are composites having very low coefficients of thermal expansion and methods of preparing the composites. Also disclosed are composites having negative coefficients of thermal expansion. Applications of the composites to a wide variety of uses, such as electronic and optoelectronic devices are also disclosed.

The present invention relates to a filler featuring a negative coefficient of thermal expansion and a bi-modal size distribution of filler particles. In an embodiment, the filler has micron and nanometer size filler particles. The present invention also relates to a composite having a polymer and a filler with nanometer size filler particles. Additionally, the present invention discloses a method of forming an electronic package with a composite having a polymer and a filler with nanometer size filler particles.

Disclosed are a nano-rare earth zirconate ceramic powder material for high-temperature thermal barrier coatings, and the preparation method, relating to a nano-rare earth zirconate ceramic powder material for high-temperature thermal barrier coatings, and the preparation method. The invention solves the problems that the existing ceramic materials for high-temperature thermal barrier coatings are of phase change failure, serious sintering, and too high thermal conductivity and mismatch with the matrix thermal expansion. The chemical formula of the nano-rare earth zirconate ceramic powder material for high-temperature thermal barrier coatings is Ln2Zr2O7, wherein, Ln is the combination of one or more rare earth elements among Gd, Sm, Nd or Yb. The preparation method is that rare earth oxide or soluble salt and zirconium salt containing rare earth oxides are used to respectively prepare the solution containing Ln3 + and the solution containing Zr4 +; the two solutions are mixed and added with surfactant under the ongoing mixing conditions; the mixed solution is dropped into precipitator to get sediment; after repeated washing, the sediment is dried, grinded and calcined. The invention can effectively protect high temperature alloy.

A honeycombed porous ceramic having a high thermal conductivity and an ultralow expansion coefficient relates to the technical field of the silicate industry. The ceramic having a low even negative thermal expansion coefficient and a high thermal conductivity is obtained through treating a rare earth mixture, potassium phosphotungstate, zirconium oxide and amorphous quartz particles as a sintering aid, and expansion coefficient and thermal conductivity adjustment agents, and the ceramic has a high-orientation sheet iolite structure and has a good catalyst coating performance and good mechanical strengths; and ethylene oxide having different molecular weights are adopted as a ceramic molding binder, rapeseed oil or peanut oil is treated as a primary molding lubrication agent, a paste goes through a high-pressure extruder orientation extruding channel, a crystal orientation carding die and a honeycombed porous die to obtain a green body having high-orientation arranged crystals, and a special sintering curve is adopted to obtain the ceramic. The above whole ceramic preparation process flow and the above formula are economic, stable and environmentally-friendly.

A large-relative-aperture long-focal length non-cooled infrared athermalization optical system is arranged in front of the focal plane in the light spreading direction, and is composed of a main reflector, a secondary reflector, a first positive crescent lens, a second positive crescent lens, a reflection/diffraction mixed lens, a movable lens and a second negative crescent lens which are coaxially arranged in parallel. The system adopts a cassette system to increase the optical path by multiple reflections of light, thereby realizing the long coking of the optical system, wherein F<#> is 1; the focal length is 500mm; the center block is smaller or equal to 0.3; and the optical total length and focal length ratio is smaller than or equal to 0.64. Through the secondary imaging, the impact of stray light on the image quality of the system can be effectively inhibited. With the utilization of characteristics of negative dispersion and negative thermal expansion coefficient of the diffractive element and the reasonable distribution of the focal power of the reflection/diffraction mixed lens, the defocusing amount caused by the infrared optical system due to the temperature change is reduced, and combined with the mechanical active athermalization, the image plane defocusing compensation of the system in the temperature range of from -40 DEG C to +60 DEG C is achieved.

The invention discloses a TiNi alloy-based composite material with a near-zero thermal expansion characteristic and a preparation method thereof. The method comprises the following steps of: uniformly mixing pure Ti powder and pure Ni powder according to an atomic ratio of titanium and nickel of (54-58 percent):(42-46 percent), preparing a porous TiNi alloy with negative thermal expansion and uniformly distributed pores by combining a holing technology and a unit metal powder step sintering method, and introducing a magnesium alloy with conventional positive thermal expansion into the pores of the porous TiNi alloy by using a light metal pressureless infiltration method to obtain the TiNi alloy-based composite material with the near-zero thermal expansion characteristic. The TiNi alloy-based composite material prepared by the method still has a shape memory effect and a hyperelastic behavior, is lighter than a compact TiNi alloy, has higher strength than the common porous TiNi alloy, and has the near-zero thermal expansion characteristic under certain conditions. The invention is used for preparing near-zero thermal expansion materials and controlling the thermal expansivity of the materials.

A semiconductor device comprises an N-type insulated-gate field-effect transistor including a first insulating layer that is provided along side walls of a gate electrode, has a negative thermal expansion coefficient, and applies a tensile stress to a channel region of the N-type insulated-gate field-effect transistor. The device also comprises a P-type insulated-gate field-effect transistor including a second insulating layer that is provided along side walls of a gate electrode, has a positive thermal expansion coefficient, and applies a compression stress to a channel region of the P-type insulated-gate field-effect transistor.

The invention discloses a high-performance thermoelectric device and an ultrafast fabrication method thereof. In the high-performance thermoelectric device, a segmented structure is employed to perform optimal matching of a thermoelectric material and a temperature difference environment, a blocking layer and a buffer stress layer are employed to reduce interface element migration and longitudinalcontact thermal expansion stress and improve bonding strength, a phonon scattering layer and a negative thermal expansion buffer layer are embedded to fix a thermoelectric leg so as to improve internal thermal resistance and horizontal thermal matching performance of the high-performance thermoelectric device, internal package and external package are employed to prevent the thermoelectric material from being oxidized and sublimed and improve external collision-resistant capability, the technical bottlenecks of low energy conversion efficiency, small specific power, poor thermal stability, poor collision performance, complicated fabrication process and the like of a traditional thermoelectric device are effectively broken through, meanwhile, the thermal stability and the mechanical structural performance of the high-performance thermoelectric device are improved to a great extent, long-term and excellent electrical output performance is guaranteed, and the working environment is expanded.

The invention discloses a sintering and synthesizing method of negative thermal expansion material Zr2P2MO12, belonging to the field of inorganic nonmetallic materials. The negative thermal expansion material has a molecular formula as follows: Zr2P2MO12, wherein M is W or Mo. The method is characterized by comprising the following steps: taking materials based on that a mole ratio of ZrO2 to WO3 to P2O5 or ZrO2 to MoO3 toP2O5 of 2:(1-1.2): (1-1.2), grinding and evenly mixing, and directly sintering the mixed raw materials or sintering the mixed raw materials after tabletting. The invention uses the high temperature rapid sintering and synthesizing method to prepare the negative thermal expansion material Zr2P2MO12 and takes P2O5 as the raw material, thereby avoiding discharge of redundant ammonia and reducing pollution; and the negative thermal expansion material can be sintered for one time at the same time. The invention has the advantages that the reaction process is simple, the sintering speed is rapid, and the sintering time is short; and the raw materials can fully react at high temperature, and the produced product has high purity.

The invention discloses a liquid crystal display device, which comprises an array substrate and a color film substrate opposite to each other, wherein frame sealing glue is coated on the array substrate or the color film substrate, a display area is arranged within a frame sealing glue area, and an area between the peripheral edge of the display area and the inner side of the frame sealing glue is provided with a negative thermal expansion material. The liquid crystal display device disclosed by the invention solves the problems that low-temperature air bubbles are generated within the display area of a liquid crystal panel at a low temperature, and high-temperature vertical flows are generated at a high temperature.

A slider having a magnetic read/write head and including, a base coat, a reader element having a transducer, a writer element, the writer element including at least one conductive coil, the coil being electrically insulated by a composition which has a negative coefficient of thermal expansion, and an overcoat.

The invention proposes a copper-based material with low thermal expansion and high thermal conductivity having good machinability and adaptability to nickel plating and also proposes a method for producing the same. The copper-based material is prepared through the steps of: adding 5 to 60% of iron-based alloy power having a certain value in thermal expansion coefficient into a matrix powder of pure copper phase powder and/or a precipitation hardening copper alloy powder; mixing the powders together; compacting the obtained powder mixture into a green compact and sintering it at temperatures of 400 to 600° C.

The invention discloses a thermal switch based on negative thermal expansion. The thermal switch comprises a negative thermal expansion element and a conductive element. The negative thermal expansion element is made of a negative thermal expansion material. The negative thermal expansion element is connected with the conductive element. When the temperature of the negative thermal expansion element is above a predetermined threshold, the conductive element and a thermal load are disconnected. When the temperature of the negative thermal expansion element is below the predetermined threshold, the conductive element and the thermal load are connected. According to the invention, the thermal switch based on negative thermal expansion is simple in structure and only has two parts; the running stroke of the thermal switch is large; a large gap caused by a large stroke can reduce an angle coefficient between two end faces of the gap; radiation heat transfer can be reduced; and disconnected thermal resistance is increased.

A method of synthesizing negative-thermal-expansion ceramics of synthesizing Zr(1-x)XxW2O8 in which X represents a substituent element for zirconium Zr, and 0<=x <<1, having a negative thermal expansion coefficient, the method comprising mixing two mols of tungsten trioxide WO3 and one mol of the sum of zirconium oxide ZrO2 and a substituent element X in accordance with substitution amount x at a stoichiometrical ratio, further mixing the thus obtained starting material in a powdery form having a particle size distribution including two groups of particles comprising smaller diameter particles with a particle size of 0.1 to 1 mum and larger diameter particles with a particle size of 5 to 50 mum, and then sintering the staring powder being placed in a desired molding die whereby negative-thermal-expansion ceramics having an increased density equal with or higher than that of press molding products and of a larger size than that of the press molding products without press-molding the starting powder can be synthesized.

A negative coefficient of thermal expansion particle includes a first bilayer having a first bilayer inner layer and a first bilayer outer layer, and a second bilayer having a second bilayer inner layer and a second bilayer outer layer. The first and second bilayers are joined together along perimeters of the first and second bilayer outer layers and first and second bilayer inner layers, respectively. The first bilayer inner layer and the second bilayer inner layer are made of a first material and the first bilayer outer layer and the second bilayer outer layer are made of a second material. The first material has a greater coefficient of thermal expansion than that of the second material.