JPS62134547A - Apparatus for measuring thermal diffusivity - Google Patents

Abstract

PURPOSE:To make it possible to obtain a measured value of thermal diffusivity without irregularity even with respect to a specimen having large thermal diffusivity even if a thickness and a shape change, by irradiating the specimen which is held so as to cross the irradiation axis of a high energy ray irradiation apparatus at a right angle, with laser beam through an aperture and measuring the temp. of the specimen at the predetermined position of the back surface thereof by a non-contact thermal sensor. CONSTITUTION:The titled apparatus is constituted of a laser irradiation apparatus 11, an aperture 12 arranged in the laser irradiation direction of said apparatus 11 in order, a specimen holding apparatus 14 holding a flat plate shaped specimen so as to cross the irradiation axis of said apparatus 11 at a right angle and a non-contact thermal sensor 15 movable to the direction crossing the irradiation axis at a right angle. When the thermal diffusivity of the flat plate shaped specimen is measured using this thermal diffusivity measuring apparatus, the laser beam irradiating position on the specimen 13 is separated by a predetermined distance from the measuring position of the non-contact thermal sensor 15 and laser beam is allowed to instantaneously irradiate the specimen 13 from the laser irradiation apparatus 11. The heat history curve of the back surface temp. of the specimen is measured by the non-contact thermal sensor 15 to calculate thermal diffusivity according to a predetermined formula.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal diffusivity measuring device used for measuring the thermal diffusivity of an infinite flat plate by a laser flash method.

Technical background of the invention and its problems] The laser flash method has been known as a method for measuring the thermal diffusivity of a flat plate sample of constant thickness.

In this method, the thermal diffusivity of the sample is determined by instantaneously irradiating a flat sample with uniform thickness with radar light and measuring the temperature rise curve on the back side of the sample.

However, such a conventional laser flash method has a problem in that when a sample is relatively thin with constant thickness and shape and has a high thermal diffusivity, the measurement values vary widely.

[Purpose of the Invention] The present invention has been made in order to solve these conventional difficulties.In the thermal diffusivity measurement method using the laser flash method, even if the thickness and shape change, the sample with a large thermal diffusivity can be measured. [Summary of the Invention] That is, the thermal diffusivity measuring device of the present invention is a high-energy ray irradiation device. , a sample holding device that holds the sample so as not to be perpendicular to the irradiation axis of the high-energy beam irradiation device; an aperture disposed on the high-energy beam path between the high-energy beam irradiation device and the sample holding device; and the sample holding device. By including a non-contact heat-sensitive sensor disposed toward the back of the device, and a moving device that moves the high-energy ray irradiation device or the non-contact heat-sensitive sensor in a plane orthogonal to the high-energy ray path, thickness and Even if the shape changes,
Moreover, it is possible to obtain a measured value of thermal diffusivity without variation even for a sample having a large thermal diffusivity.

[Embodiments of the invention] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing the principle of the laser flash method using the present invention.

As shown in the figure, a portion of a fairly large flat sample 1 with a thickness of °C was instantaneously irradiated with a flash light 3 having a uniform energy and a radius of ro using an aperture 2 to heat the sample 1. If the distance from the center of the flash light is 2itr
The temperature rise curve θ on the sample surface on the opposite side of the flash light irradiation, which is separated by the same distance as the flash light irradiation, can be obtained by solving the five two-dimensional heat diffusion equations, ignoring heat loss from the sample to the outside and the influence of the sample external shape. ......(I) .........(n)

Here, Q is energy per unit area, ρ is density, Cp
is the heat capacity, λ is the thickness, α is the thermal diffusivity, and t is the elapsed time after the flash light is irradiated.

Note that if G=1 is set in equation (I), the equation becomes the same as that of the conventional laser flash method. When the sample thickness is thin, the inside becomes 1 in a very short time, and equation (I) becomes .

FIG. 3 shows the relationship of G to 4αt/r'' when r/ro=1.5.2.2.5.

FIG. 1 is a perspective view of a thermal diffusivity measuring device according to an embodiment of the present invention.

As shown in this figure, the thermal diffusivity measurement device of this example includes a laser irradiation device 11, an aperture 12 with an aperture diameter of 3.5 mm arranged in order in the laser irradiation direction, and a flat sample 13. A sample holding device 14 held perpendicular to the irradiation axis, a non-contact thermal sensor 5 movable in a direction perpendicular to the irradiation axis, and a non-contact thermal sensor 15 (not shown) are arranged perpendicular to the optical axis of the laser beam. It consists of a moving device that moves within a plane.

Note that the moving device may be configured to move the optical axis of the laser beam in parallel without moving the non-contact heat sensitive heat sensitive sensor 15.

When measuring the thermal diffusivity of a flat sample using this thermal diffusivity measurement device, the laser beam irradiation position on the sample 13 and the measurement position of the non-contact thermal sensor 15 are separated by a predetermined distance. Instantaneous sample 1 from the laser irradiation device 11
1. Irradiate laser light. Then, the thermal history curve of the surface temperature of the back surface of the sample 11 at a position a predetermined distance away from the irradiation point is measured by the non-contact heat-sensitive sensor 15, and the thermal diffusivity is determined by each of the above-mentioned formulas.

Next, an example in which thermal diffusivity was measured using the thermal diffusivity measuring device of this embodiment will be described.

Using 5US304 with a thickness of 0.5 mm as a sample, the temperature history curve was measured at a position 5 mm away from the center of the aperture. The results are shown in FIG.

Using this sample as a standard sample (thermal diffusivity 0.034c/S), the thermal diffusivity of the 3i wafer was measured and the result was 0.79.
cf/s.

Further, measurements were carried out with the thickness of the test piece varied in the range of 0.5 to 1 mm, but no difference was observed depending on the thickness of the sample.

[Effects of the Invention] As explained above, according to the present invention, it is possible to eliminate variations in measured values even for a relatively thin plate-like sample with constant thickness and shape by the thermal diffusivity measurement method. Therefore, it is possible to obtain useful knowledge for checking the rolling or drawing conditions of the sample, checking for cracks in the sample, setting heat treatment conditions, etc., and can be used for quality control, process control, etc.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing one embodiment of the present invention, and FIG.
The figure is a diagram of the principle of the laser flash method using the present invention.
The figure is a graph showing the change in the relationship between the functions of the two-dimensional heat diffusion equation when the distance between the laser irradiation position and the measurement position is changed. It is a graph showing a temperature history curve of a sample. 11... Laser irradiation device 12-
・・・・・・・・・・・・Aperture 13・・・・・・
・・・・・・Flat sample 14・・・・・・・・・・・・
Sample holding device 15...Non-contact thermal sensor Fig. 1 Fig. 2 Fig. 4 Doctor t/rA Fig. 3 Fig. 4 Procedure Correction 1ll (voluntary) 1, J case f7
)ti show special m[1i? 60-274360 No. 2,
Name of the invention: Thermal diffusivity measurement device 3, Relationship with the person making the amendment/Patent applicant: 72 Horiyo-cho, Saiwai-ku, Yosaki-shi, Kanagawa (307) Toshiba Corporation 4, Agent: Chiyoda, Tokyo 101 Details of the invention at 2-1 Kanda Tamachi, ward, $l! Explanation column 6, contents of correction (1) The formula on page 4, line 5 is corrected as follows. (2) In the second line from the above, ``Short It￥dama inside wa'' is corrected to ``Shortly in () inside wa'''. (3) 317th line from the bottom of No. 6, ``Effect of invention'' is corrected to ``Effect of invention.''that's all

Claims (1)

[Claims] a high-energy beam irradiation device; a sample holding device that holds a sample perpendicular to the irradiation axis of the high-energy beam irradiation device; and an aperture arranged in a high-energy beam passage between the high-energy beam irradiation device and the sample holding device. and a non-contact heat-sensitive sensor disposed toward the back of the sample holding device, and a moving device that moves the high-energy ray irradiation device or the non-contact heat-sensitive sensor in a plane orthogonal to the high-energy ray path. A thermal diffusivity measuring device characterized by the following.