Method and device for measuring heat conductivity coefficient and thermal diffusion coefficient of film material under strains

Abstract

The invention discloses a method and device for measuring a heat conductivity coefficient and a thermal diffusion coefficient of a film material under strains. A sample is tensioned through a tensioning mechanism; the sample, the tensioning mechanism and a driving mechanism are placed in a vacuum cavity; the sample is heated by laser; a whole-process temperature distribution diagram of the samplefrom heating to a steady state under a fixed strain is obtained through an infrared camera; the film is regarded as two-dimensional heat transfer; an experimental picture is processed to obtain the temperature of each pixel point on the film surface; the film is divided into a plurality of micro elements according to the size of the pixel points; steady-state and transient-state heat balance equations are established; the heat conductivity coefficient and the heat diffusion coefficient of the film at different temperatures are solved; the sample is driven to generate different strains by a driving mechanism; and the condition that the heat conductivity coefficient and the heat diffusion coefficient of the sample change along with the temperature under different strains is solved. The method is convenient to operate and high in measurement accuracy, and can obtain the condition that the heat conductivity coefficient and the thermal diffusion coefficient of the sample change along with the temperature under different strains.

Description

technical field [0001] The invention belongs to the technical field of heat transfer, and in particular relates to a method and a device for measuring the thermal conductivity and thermal diffusivity of thin film materials under strain. Background technique [0002] Thin films are not only the most effective materials for miniaturizing devices and systems, but in the field of sensors, thin films are also used as one of the components to measure different physical quantities. The working temperature of the film is generally changed, and in the process of use, due to the transfer, vibration and heat generation, it will also be subjected to different degrees of stress to produce small strains. The reliability of the device or system needs to be verified after the thermal properties of the film are changed. Therefore, it is important to correctly determine the relationship between the thermal conductivity and thermal diffusivity of the film under strain and temperature to determ...

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Problems solved by technology

The existing problem is that the theoretical value of the thermal conductivity of the material needs to be known in advance, which has limitations; the second is that on this basis, the value of the thermal conductivity needs to be modified many times to match the test temperature distribution map, and the workload is large and the error is also large. very big

However, the heat equation established in this method is one-dimensional heat transfer. In fact, thin films, as a common two-dimensional material, cannot be ignored even under the premise that the heating light field has an aspect ratio greater than 2. The heat transfer in the width direction, so the error of the thermal conductivity obtained by this method through the one-dimensional heat conduction equation is relatively large

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