390 results about "Thermal diffusivity" patented technology

An electrosurgical instrument is provided. The electrosurgical instrument includes an active electrode in close proximity to a return electrode. The active electrode has a first thermal diffusivity. The second electrode has a second thermal diffusivity greater than the first thermal diffusivity. The volume, shape, and thermal diffusivity of the second electrode facilitate the transport of heat.

A radiant heating for heating the building material in a laser sintering device and a laser sintering device having such a radiant heating are described. The radiant heating has a sheet-like heat radiating element (113, 213, 313), which is characterized in that it is made of a material, that has a low thermal inertia with a thermal diffusivity of preferably more than 1.5·10⁻⁴ m²/s and preferably has a thickness of 2 mm or less.

The present invention provides a method for measuring thermophysical properties that includes: rapid resistive self-heating of a specimen by using a heating current; emitting a light to the specimen heated by the rapid resistive self-heating of the specimen; measuring a temperature change of the specimen induced by emitting the light to the specimen; and deriving a thermal diffusivity of the specimen from the temperature change induced by emitting the light to the specimen.

The invention provides a device for measuring a thermal diffusivity. The device comprises an excitation light source, an optical control device, a vacuum heating furnace, a temperature controlling device, a temperature measuring device and a data acquiring and processing device, wherein the excitation light source generates excitation light beams; the optical control device is provided with an optical component group, a light beam mass spectrometer and an energy meter and regulates the energy of the excitation light beams through a replaceable optical element in the optical component group; a heating element for heating a sample is arranged in the vacuum heating furnace; the temperature controlling device is used for controlling the heating temperature of the vacuum heating furnace; the temperature measuring device amplifies a temperature rise signal of the sample measured by a detector through a pre-amplifier and transmits the amplified signal to the data acquiring and processing device; the data acquiring and processing device comprises a data acquiring system and a data processing system; the data acquiring system transmits all acquired data signals to the data processing system; and the data processing system analyzes and repeatedly and theoretically corrects the data signals. The device for measuring the thermal diffusivity designed by the invention has the advantages of reducing the measuring repeatability of the thermal diffusivity of a material to be less than 1 percent, lowering uncertainty of measurement, improving the level of thermal diffusivity measurement and laying foundations for the establishment of a standard thermal diffusivity device in China, the preparation of a standard thermal diffusivity substance and the establishment of a standard thermal diffusivity database.

The invention discloses folding preventing less-layer graphene powder, components of composite material thereof and application, and belongs to the technical field of graphene preparation. The folding preventing less-layer graphene powder can be applied to conductive plastics, conductive coating paint and printing ink, and can also be applied to mechanical enhancement of conductive adhesive and various and various resins. In addition, the graphene powder can also be applied to the preparation of electrodes of lithium batteries and supercapacitors, composite material requiring high thermal diffusivity, and any other material requiring good electric conductivity, thermal conductivity and mechanical enhancement. The graphene powder has the characteristics that special dispersant is utilized to prepare graphene solution, and secondary folding of graphene piece layers is effectively prevented during the drying process, so that thinner less-layer graphene powder is obtained, and excellent electric conductivity, mechanical property and thermal conductivity can be obtained in polymer or other base material through lower additive amount.

An object of the present invention is to provide a graphite film, and a graphite composite film both having an excellent thermal diffusivity which can sufficiently manage heat dissipation of electronic instruments, precision instruments and the like, along with an excellent flex resistance which can withstand application to bent portions.

Means for Resolution of the present invention is a graphite film exhibiting the number of reciprocal foldings being 10,000 times or more as measured using a rectangular strip test piece having a width of 15 mm until the test piece breaks in a MIT folding endurance test under conditions of: a curvature radius R of the bending clamp being 2 mm; a left-and-right bending angle being 135°; a bending rate being 90 times/min; and a load being 0.98 N.

Wherein, using electric excitation and electric parameter measurement to analyze material parameters and extract on-line; applying dc, ac and transient voltage or current to the MEMS device to force target generating opposite action and changing electric parameters (I, R, U and C); measuring parameters, and obtaining the required parameters (R, E, F, etc) according to software.

An object of the present invention is to industrially easily mold a molded article which is excellent in thermal conductivity, electric insulation property, low density, and an injection moldability and has a thermal conduction anisotropy. The present invention relates to a highly thermally conductive resin molded article having a thermal diffusion anisotropy, the highly thermally conductive resin molded article comprising a resin composition, the resin composition containing at least resin (A) and plate-like hexagonal boron nitride powder (B) in a (A)/(B) volume ratio falling within a range of 90/10 to 30/70, the resin (A) including a thermoplastic polyester resin and/or a thermoplastic polyamide resin, the highly thermally conductive resin molded article having a thickness of not more than 1.3 mm in a part of or all over a three-dimensional shape of the highly thermally conductive resin molded article, a thermal diffusivity measured in a plane direction of the highly thermally conductive resin molded article, being (i) two or more times higher than a thermal diffusivity measured in a thickness direction of the highly thermally conductive resin molded article and (ii) not less than 0.5 mm²/sec.

A method and a system for generating a high spatial resolution multi-dimensional image representing the chemical composition of a sample. Highly localized IR light is used to cause the heating and thermal expansion of the sample. Modulating this IR light will cause this effect to take place at various depths of the material. The method and system of the present invention are used to generate a chemical profile of the sample using a combination of: (i) measurements of the thermal expansion and temperature change caused by absorbing IR radiation together; and (ii) measurements of the thermal expansion properties and thermal properties (such as thermal diffusivity and conductivity) of sites on the surface of the sample and the material surrounding it.

A lamp cap of an LED module street lamp with high thermal diffusivity and adjustable lighting angle belongs to the technical field of semi-conductor illumination. The lamp cap comprises a lamp cap upper cover, a lamp cap lower cover, a supporting framework, a lamp cap trim cover, a junction box, a plurality of LED light source drive, a power supply and at least one LED light source module; the LED light source module is connected and fixed with the supporting framework by an end cover, the lamp cap trim cover is fixed at the head of the supporting framework, and the upper cover and the lower cover of the lamp cap are appositioned face to face and are fixedly connected at the tail of the supporting framework. By adopting LED light source and scientific and reasonable design, the invention has the advantages of high light efficiency, stability, energy saving, and environmental protection, etc. By making use of the design of modularization combination, the LED light source module can satisfy the requirements of diverse heights and lighting angles by adding or reducing LED light source modules according to application condition, thus one lamp has various usages. The invention has wide application range, low cost and convenient assembly. The lighting angle of the LED light source module can be adjusted to realize optimal light distribution requirements of different roads.

A system and method for determining lateral thermal diffusivity of a material sample using a heat pulse; a sample oriented within an orthogonal coordinate system; an infrared camera; and a computer that has a digital frame grabber, and data acquisition and processing software. The mathematical model used within the data processing software is capable of determining the lateral thermal diffusivity of a sample of finite boundaries. The system and method may also be used as a nondestructive method for detecting and locating cracks within the material sample.

The invention relates to a graphene enhanced aluminium-based silicon carbide composite and a preparation method thereof. The composite comprises the following substances by volume percent: 40% to 70% of silicon carbide and 0.5% to 5% of graphene, and the balance being aluminium alloy. The composite is prepared through the powder metallurgy method and is obtained through the steps of blending, powder mixing, bagging, vacuum degassing and hot iso-hydrostatic forming treatment. The composite has the advantages of high thermal conductivity, high strength, high plasticity, light weight, good thermal diffusivity, isotropy, and the like, and becomes a second-generation electronic packaging material with wide application.

Provided is a long and large-area graphite film having improved thermal diffusivity and flex resistance, and accompanied by ameliorated ruffling. According to a method for producing a graphite film, in which graphitization of a heat-treated film consisting of a carbonized polymer film is carried out in a state being wrapped around an internal core, the method being characterized in that a heat treatment is executed by controlling distance(s) between the internal core and the film, and/or between the layers of the film, a graphite film accompanied by significantly ameliorated ruffling can be obtained.

The invention relates to a method and a device for testing the thermal physical property of a solid material with an independent probe by using a harmonic method. The device comprises the independent probe, a pressure adjusting part, a torque measuring part and a harmonic measuring unit, wherein the independent probe is positioned between two identical samples to be tested to form a sandwich structure and is arranged parallel to a sample fixing table; the pressure adjusting part is positioned and pressed on the upper end face of the first sample to be tested; the sandwich structure is arranged on the sample fixing table; the torque measuring part is sleeved on one end of the pressure adjusting part; the harmonic measuring unit is electrically connected with the independent probe; and a torsion value and contact thermal resistance between the independent probe and the two samples to be tested are fitted and calculated according to a harmonic measurement principle. In the test, the sandwich structure is arranged on a lug boss of the sample fixing table, the pressure adjusting part is adjusted until the torsion value is displayed to be the optimal torsion value, and then the thermal conductivity coefficient and the thermal diffusivity of the sample to be tested are tested by the harmonic method. Differences among thermal conductivity values of the samples to be tested under the condition of a plurality of torsion values smaller than the optimal torsion value are measured and calculated for obtaining the contact thermal resistances between the samples to be tested and the independent probe under the condition of the plurality of torsion values.

In a spark ignition engine, a thermal insulation thin layer is formed over a wall surface, facing an inside of a combustion chamber, of a base material forming the combustion chamber, and for a thermal conductivity λ [W/(m·K)], a thermal diffusivity κ [mm²/s], and a thickness L [μm] of the thermal insulation thin layer, L≧16.7×λ and L≦207.4×(κ)^0.5 are satisfied. With such a configuration, a heat loss Q_total escaping from gas in a cylinder to the wall of the combustion chamber over all strokes can be reduced, and the thermal efficiency can be improved without inducing degradation of knocking due to an increase in an amount of heating Q_intake of the gas in the cylinder during an intake stroke.

A mold assembly including moveable mold parts, one of which includes a plurality of hollow cavities. Each hollow cavity forms an outer wall of an elongated, generally annular portion of a molded part and the other mold part includes a corresponding plurality of core elements, which form an inner wall of the same portion of the molded part. Each core is disposed within a corresponding cavity to define a generally annular mold chamber portion for receiving molten material to be molded to form the shape of the portion of the molded part. Each core element includes a cooling apparatus and each cavity includes an outside cavity-cooling device. Each core element includes a first portion made of high strength material and a tip portion made of material having a greater heat diffusivity and heat transfer coefficient than said first portion.

The invention relates to the area of thermophysical studies of media and is intended for the determination of thermal properties of solid media by placing a measuring device on the surface of the medium. A heater, which is made in the form of a flexible membrane capable of taking the shape of the solid body surface under the action of the hold-down pressure and which additionally serves as a temperature sensor, is pressed to the solid body surface by using a hold-down element in such a way as to ensure that the heater shape fits the shape and irregularities of the solid body surface. The heater temperature is registered throughout the heater surface during and after the heating. The thermal conductivity and thermal diffusivity of the solid body are determined by processing the heater temperature measurement data both in the time range from the start of the solid body heating to the start of the thermal convention of the ambient medium and after the termination of the solid body heating process.

The invention relates to a composite material and a preparation method of the composite material, in particular to an ultrahigh heat-conduction diamond/aluminum composite material and a preparation method of the ultrahigh heat-conduction diamond/aluminum composite material. In order to solve the technical problems that a diamond/aluminum composite material prepared with the existing method is low in heat conductivity and poor in interface combination strength, the ultrahigh heat-conduction diamond/aluminum composite material is composed of a reinforcement body and matrix alloy. The preparation method includes the steps that monocrystal diamond particles are contained in a cavity of a graphite die for preheating, and melted aluminum or aluminum alloy is poured to the interior of the graphite die; pressure impregnation is carried out, cooling is carried out, die releasing is carried out, and then the ultrahigh heat-conduction diamond/aluminum composite material is obtained. The diamond/aluminum composite material is good in interface combination and has the advantages of being light, high in thermal conductivity, devisable in coefficient of thermal expansion and the like. According to the ultrahigh heat-conduction diamond/aluminum composite material prepared with the method, the size fraction of the reinforcement body can range from 55% to 70%, the heat conductivity can reach 670 W/(m K), and the thermal diffusivity can reach 3.0 cm<2>/s. The ultrahigh heat-conduction diamond/aluminum composite material and the preparation method belong to the field of composite material preparation.

Devices and methods useful for sensing epidermal tissue are disclosed. Thermal data from the devices allows for determination of thermal transport properties, such as thermal conductivity, thermal diffusivity and heat capacity per unit volume. From these data, tissue parameters, such as hydration state, stratum corneum thickness, epidermis thickness and vasculature structure may be determined. These parameters may be used, for example, to evaluate the efficacy of dermatological compounds.

Disclosed are a photoelectronic device including a first electrode including a first metal; an active layer disposed between the first electrode and a second electrode; and a diffusion barrier layer disposed between the first electrode and the active layer; the diffusion barrier layer including a second metal, wherein the second metal has a thermal diffusivity that is lower than a thermal diffusivity of the first metal, and wherein the first electrode and the diffusion barrier layer are configured to transmit light, and an image sensor including the photoelectronic device.

An object of the invention is to make it possible to correctly and easily measure a thermal diffusivity within a three-layer substance containing an non-metal substance. A non-metal film 1 whose thermophsical properties are unknown is disposed between a first metal film 2 and a second metal film 3, thereby forming a sample having a three-layer structure. The metal films 2 and 3 have predetermined known thermophsical properties, belong to the same sort of substance and have the same thickness. The three-layer substance is disposed on a transparent substrate 4 and is heated from below the second metal film 3, using a picosecond light pulse coming from below and passing through the transparent substrate 4. The light pulse used in the irradiation is converted into a heat in the second metal film 3 during only one picosecond, with such heat diffusing through interface/non-metal film layer/interface and thus arriving at the first metal film 2. By measuring a temperature change on the surface of the first metal film 2, it is possible to perform correct measurement by using the thermoreflectance method formerly suggested in a patent application by the inventors of the present invention.

The invention provides a method and an apparatus for measuring thermal diffusivity of materials through transient fluorescence. The method includes the steps of: (1) irradiating the surface of a sample by means of modulating pulse laser as a heating light source for the sample and an excitation light source for a fluorescence signal; (2) collecting the fed-back fluorescence signal when the sample is excited, and comparing the signal intensity with a fluorescence intensity-temperature curve of the sample, thus obtaining temperature information of the sample; (3) changing the pulse width of the pulse laser for several times to obtain transient temperature increase of the sample in different transient heating periods; and (4) according to an analytic solution expression of temperature field of a heat conduction model of the to-be-tested sample, substituting several groups of test data and performing fitting to obtain the thermal diffusivity of the material. On the basis of the method, a measurement apparatus platform is correspondingly designed. The method is not liable to cause sample damage, has low measurement error and is high in efficiency during the measurement of the thermal diffusivity of materials.

The invention provides an experimental device for testing a heat conductivity coefficient of a building material based on quasi steady state and unsteady state methods, relates to the field of a testing technology of thermophysical parameters of a building material, and solves the problems that an existing thermophysical parameter experimental device can not simultaneously load the measurement processes by using three methods including a quasi steady state method, a normal power method and a heat pulse method, and one-time testing time is long and a measurement maximum relative error is large. An anode and a cathode of a low-potential potentiometer are correspondingly connected with a switch control interface of an oil immersed key conversion switch; thermoelectromotive force signals output by thermocouples are respectively connected into a thermoelectromotive force signal output end of the oil immersed key conversion switch; cold ends of the thermocouples are respectively inserted into an ice bottle containing an ice-water mixture; measuring ends of the thermocouples are respectively contacted with a testing piece to be tested; a heating resistor is used for heating the testing piece to be tested. The theoretical error analysis and the actual measurement prove that the measurement maximum relative errors are as follows: the heat conductivity coefficient is less than or equal to 5.1%, the thermal diffusivity is less than or equal to 9.2% and the specific heat value is less than or equal to 7.7%; the requirement on precision by engineering is met.

A thermoplastic resin composition comprises (A) about 30 to about 50% by weight of a thermoplastic resin, and (B) about 50 to about 70% by weight of a spherical magnesium oxide, wherein the thermal diffusivity of the thermoplastic resin composition in the horizontal or vertical direction is about 0.065 to about 0.20 cm²/sec and the ratio of thermal diffusivity of the horizontal direction : vertical direction is about 1:0.5 to about 1:1. A thermoplastic resin composition according to a second embodiment comprises (A) about 30 to about 50% by weight of a thermoplastic resin, and (B) about 50 to about 70% by weight of a spherical magnesium oxide, wherein the spherical magnesium oxide is treated on its surface with a silane compound.