JP4621385B2 - Diffusion test equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a diffusion test apparatus for measuring a diffusion coefficient of a sample under zero gravity or on the ground.
[0002]
[Prior art]
A diffusion test is planned to measure the diffusion coefficient of a sample under zero gravity at a space experiment facility in orbit around the earth. Conventionally, a test means called a long capillary method has been applied to the diffusion test. In this long capillary method, two kinds of rod-shaped samples are sealed in a cylindrical cartridge with their end surfaces in contact with each other, heated in a weightless state to once melt the whole, and then a predetermined diffusion time. The sample is cooled and solidified later, and after the test is completed (after cooling), the sample is shredded on the ground, each composition is analyzed, and the diffusion coefficient of the sample is measured from the difference.
[0003]
However, in such a long capillary method, the end faces (interfaces) of the two types of samples are always in contact during temperature rise, diffusion, and cooling, so that diffusion is performed in addition to a predetermined diffusion time in which the temperature is kept constant. However, there was a problem that the precise diffusion coefficient could not be measured.
[0004]
In order to solve this problem, a test means called a shear cell method has been proposed and has already been implemented in part. In this shear cell method, as schematically shown in FIG. 4, ring-shaped members 4 (referred to as shear cells) in which the samples 1 and 2 are inserted into the through holes are arranged in close contact with each other in the axial direction, and drive rings are provided from both ends. It is sandwiched between the members 5 and stored in a cartridge (not shown). Each shear cell 4 is provided with a protruding portion 4a protruding in the axial direction and a fan-shaped recessed portion 4b (stopper) into which the protruding portion is fitted with a predetermined play in the circumferential direction. In this figure, the shear cell 4 and the drive ring member 5 are shown separated in the axial direction for clarity of the drawing.
[0005]
In FIG. 4, by rotating the drive ring member 5 within the cartridge, the protrusion 5a of the drive ring member 5 and the stopper 4b of the shear cell 4 are engaged, and the adjacent first shear cell 4 rotates, and then the first When the protrusion of the shear cell 4 rotates to the stopper 4b of the second shear cell 4, it engages and the second shear cell 4 turns, and when the second shear cell rotates to the stopper, the third shear cell starts to rotate, When the third shear cell rotates to the stopper of the fourth shear cell, the fourth shear cell starts to rotate, so that it can be rotated sequentially from the end shear cell.
[0006]
Therefore, by this shear cell method, as schematically shown in FIG. 5, (A) the temperature of the two types of rod-shaped samples 1 and 2 is increased separately, and (B) the shear cell is fixed at a predetermined constant temperature. The end surfaces of the samples 1 and 2 are brought into contact with each other sequentially and held for a predetermined diffusion time in this state. (C) Next, the shear cells are sequentially rotated to chop the samples 1 and 2 into each shear cell. The sample is cooled and solidified later, and each composition is analyzed after the test is completed (after cooling), and the diffusion coefficient of the sample can be measured from the difference. Therefore, by using this means, the end surfaces (interfaces) of the samples 1 and 2 are in contact with each other only while they are kept at a constant temperature in order to promote diffusion, so that a more precise diffusion coefficient than the long capillary method. Can be measured.
[0007]
[Problems to be solved by the invention]
As described above, in order to obtain a diffusion coefficient with high accuracy, a shear cell method has been developed in order to reduce the influence of diffusion during temperature rise and fall of a sample. Further, in order to eliminate the influence of convection of the molten sample as much as possible, it is effective to reduce the sample diameter, and means for casting the sample into the capillary at the start of the diffusion experiment has been reported (for example, “Application of the shear cell technology to diffusion measurements measurements of semiconducting compounds "Journal of Crystal Growth 186, 1998, 511-519).
[0008]
FIG. 6 is a schematic diagram of the diffusion test apparatus disclosed in this report. As shown in this figure, in this diffusion test apparatus, a disc-shaped shear cell 4 is provided with a through hole 6 (capillary), which is stacked and accommodated in a cartridge (not shown), and two cylindrical members 7a. , 7b. One cylindrical member 7 a is provided with a hot water pool for samples 1 and 2, and a pressurized gas is supplied to the top of the samples 1 and 2 to cast a molten sample into the capillary 6.
[0009]
However, the conventional means described above involves casting the gas in the capillaries 6 by applying pressure to the melted samples 1 and 2 with the following problems.
(1) The pressure cannot be reliably cast when the applied pressure is low and the sample diameter is about 1 mm or less.
(2) Even if a high-purity gas is used, the sample is contaminated by impurities in the gas.
(3) Since a gas pressure is applied to the surface of the molten sample, a free surface exists, and there is a concern that the Marangoni convection generated there adversely affects the diffusion experiment.
(4) In a microgravity environment, gas may enter the capillary and cannot be used.
[0010]
The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to ensure casting even if the sample diameter is about 1 mm or less, there is little risk of contamination of the sample by impurities in the gas, there is no influence of Marangoni convection by the free surface, zero gravity or microgravity An object of the present invention is to provide a diffusion test apparatus that does not cause a gas to enter the capillary even under an environment.
[0011]
[Means for Solving the Problems]
According to the present invention, a plurality of disk-shaped shear cells (12) having capillaries (12a) stacked so as to be rotatable about an axis Z and extending in the axial direction, and gripping the plurality of shear cells in the axial direction. And a pair of end disks (14) having a puddle (14a) communicating with the capillary, a pair of casting rods (16) fitted to the puddle, and a pressure for pressing the casting rod toward the capillary A pressure device (18) ,
The pressure device (18) is positioned between a pair of end disks (17a, 17b) fixed to both ends of the cartridge (11) and the end disks and the end disks (14) and moves in the axial direction. A possible pair of push members (18a) and a pair of biasing members (18b) for biasing the push members outward, whereby at least one of the pair of push members is axially A diffusion test apparatus is provided, which is moved inwardly and moves a pair of casting rods (16) toward a capillary by a pair of push members (18a) .
[0012]
According to the configuration of the present invention, the pressure rod (18) presses the casting rod (16) toward the capillary (12a) to heat and melt the samples 1 and 2 placed in the puddle (14a). The molten samples 1 and 2 can be directly cast into the capillary by a mechanical pressure mechanism. This makes it possible to obtain the diffusion coefficient with higher accuracy by using a sample having a smaller diameter than before without using a gas.
In addition, since it becomes possible to cast a small-diameter sample into the capillary even in a zero-gravity or microgravity environment, diffusion experiments can be performed in the most ideal form possible to prevent convection in the capillary. Become.
[0014]
Further, the push member can be urged outward by the urging member (18b) to hold the casting rod (16) in contact with the molten samples 1 and 2 in the capillary (12a) without being pressurized. In addition, after heating and melting the samples 1 and 2 placed in the puddle (14a), at least one of the push members is moved inward in the axial direction, whereby a pair of push members (18a) The molten samples 1 and 2 can be directly cast into the capillary by moving the casting rod (16) toward the capillary (12a).
[0015]
In addition, a center shaft (13) extending through the axial center Z through the center hole of each shear cell is provided, and both ends of the center shaft are supported by the pair of end disks (14).
With this configuration, the plurality of disc-shaped shear cells (12) can be supported by the center shaft (13) so as to be rotatable about the axis Z.
[0016]
Furthermore, a rotary drive device (20) for rotating each shear cell about the axis Z is provided, and the rotary drive device (20) is a rotary disc positioned between the push member (18a) and the end disc (17a). (20a), an actuator rod (20b) having one end fixed to the outer periphery of the rotating disk and extending in the axial direction along the inner surface of the cartridge (11), and one end fixed to the center of the rotating disk and penetrating the end disk And a pair of casting rods (16) via a pair of push members (18a) due to the axially inward movement of the rotation shaft (20c). Is moved toward the capillary, and each shear cell is rotated about the axis Z by the rotational movement of the rotating shaft (20c).
[0017]
By this rotational drive device (20), the pair of casting rods (16) is moved toward the capillary (12a) via the pair of push members (18a) by the axially inward movement of the rotation shaft (20c). The molten samples 1 and 2 can be directly cast into the capillary. Further, each shear cell can be rotated about the axis Z by the rotational movement of the rotation shaft (20c).
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.
[0019]
FIG. 1 is an overall configuration diagram of a diffusion test apparatus according to the present invention. As shown in this figure, the diffusion test apparatus 10 of the present invention includes a plurality of disc-shaped shear cells 12, a center shaft 13, a pair of end disks 14, a pair of casting rods 16, and a pressure device 18.
In this example, 16 shear cells 12 are stacked around a center shaft 13 that penetrates the center hole so as to be rotatable about an axis Z. Both ends of the center shaft 13 are supported by a pair of end disks 14.
Each shear cell 12 is provided with at least one thin through hole 12a (capillary) for casting samples 1 and 2. The diameter of the capillary 12a is preferably as thin as possible to improve the measurement accuracy of the diffusion test, and is preferably 1 mm or less, more preferably about 0.5 mm.
[0020]
The pair of end disks 14 grips the plurality of shear cells 12 in the axial direction. Further, the end disk 14 is provided with a puddle 14a at a position communicating with the capillary 12a. The puddle 14a is a cylindrical cavity sufficiently larger than the diameter of the capillary 12a, and the lower end communicates with the capillary 12a of the shear cell 12 through a through hole 15 having substantially the same diameter as the capillary 12a. Further, the opposite side of the cylindrical water puddle 14 a is opened in the cartridge 11. It should be noted that the samples 1 and 2 are charged as solids into the puddles 14a of the end disks 14, respectively.
[0021]
The pair of casting rods 16 has a cylindrical portion that fits into the cylindrical water puddle 14a. This cylindrical portion has a slight gap between the cylindrical surface of the puddle 14a and can move smoothly in the axial direction. The casting rod 16 is made of a material that does not react with the samples 1 and 2, for example, BN. The cast bar 16 is inserted into the puddle 14a so that there is no gap between the puddle 14a and the samples 1 and 2 after the samples 1 and 2 are inserted into the puddle 14a.
[0022]
The pressure device 18 includes a pair of end disks 17a and 17b fixed to both ends of the cartridge 11, and a pair of push members which are positioned between the end disks 17a and 17b and the end disk 14 and are movable in the axial direction. 18a and a pair of urging members 18b for urging the push member 18a outward. In this example, the rotating disk 20a is located between one (upper side in the figure) push member 18a and the end disk 17a.
With this configuration, at least one of the pair of push members 18a (in this example, the upper push member 18a via the rotary disk 20a) is moved inward in the axial direction, and the distance between the pair of push members 18a is reached. As a result, the pair of casting rods 16 are moved toward the capillary 12a, so that the molten samples 1 and 2 can be pressurized.
[0023]
In FIG. 1, the diffusion test apparatus 10 of the present invention further includes a rotation drive device 20 that rotates each shear cell 12 about an axis Z. The rotary drive device 20 includes a rotary disk 20a positioned between the push member 18a and the end disk 17a, and an actuator rod 20b extending in the axial direction along the inner surface of the cartridge 11 with one end fixed to the outer periphery of the rotary disk 20a. And a rotating shaft 20c that has one end fixed at the center of the rotating disk 20a and protrudes outward (upward in the figure) through one (upper in the figure) end disk 17a.
[0024]
2 is a cross-sectional view taken along line AA in FIG. As shown in this figure, each shear cell 12 has a fan-shaped notch on the outer periphery thereof. That is, in this example, the notch extends in the circumferential direction from its end surface 12b to 12c, and the actuator rod 20b extends in the axial direction in the notch. The actuator rod 20b can freely turn around the rotation axis Z within an angle θ ₁ from the end faces 12b to 12c. In this case, the shear cell 12 does not rotate. Further, when the actuator rod 20b is turned in the range of the angle θ ₂ or θ ₃ , the end face 12b or 12c is moved by the actuator rod 20b, and the shear cell 12 can be rotated in that range.
[0025]
In the initial assembly state, as shown in FIG. 1, the capillaries 12a of the upper half shear cell 12 and the capillaries 12a of the lower half are positioned on a straight line. In this state, the two kinds of rod-shaped samples 1 and 2 are heated and melted in the puddle 14a, respectively, and then a pair of castings are performed via the pair of push members 18a by the axial movement of the rotating shaft 20c. By moving the rod 16 toward the capillary and pressurizing the molten samples 1 and 2, different samples 1 and 2 can be cast into the upper and lower capillaries 12a, respectively.
[0026]
Further, the range of the angle θ ₁ of each shear cell 12 is set differently. Therefore, after casting the samples 1 and 2, the shear cell 12 is moved in the direction of the angle θ ₂ by turning the actuator rod 20b, the upper and lower capillaries 12a are made to coincide, and the samples 1 and 2 are brought into contact with each other at their end faces. Hold for a predetermined diffusion time.
Finally, to pivot the actuator rod 20b in the opposite direction, it is moved at an angle theta ₃ direction and was successively rotating shear cell, shredding samples 1 and 2 to each shear cell due to the difference in the position of the end face 12c.
After completion of the test (after cooling), each composition is analyzed, and the diffusion coefficient of the sample is measured from the difference.
[0027]
FIG. 3 is an enlarged view of a portion B in FIG.
As described above, in the diffusion test apparatus 10 of the present invention, the inside of the cartridge 11 including the capillary 12a is evacuated to a high vacuum, and then the whole is heated to melt the samples 1 and 2 in the puddle 14a. . Thereafter, the casting rod 16 is pushed to pressurize the molten samples 1 and 2 and cast into the capillary 12a.
Further, by setting the gap between the casting rod 16 and the shear cell 12 to an appropriate size as shown in FIG. 3, after the samples 1 and 2 fill the capillary 12a, the internal pressure further increases to some extent. It can leak out from the gap between the casting rod 16 and the puddle 14a. Thereby, the samples 1 and 2 can be reliably cast only by controlling the displacement of the casting rod 16.
[0028]
In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.
[0029]
【The invention's effect】
As described above, according to the configuration of the present invention, the casting rod 16 is pressurized toward the capillary 12a by the pressurizing device 18, and the samples 1 and 2 placed in the puddle 14a are heated and melted. The molten samples 1 and 2 can be directly cast into the capillary by the pressurizing mechanism. This makes it possible to obtain the diffusion coefficient with higher accuracy by using a sample having a smaller diameter than before without using a gas.
[0030]
In addition, since it becomes possible to cast a small-diameter sample into the capillary 12a even in a gravity-free or microgravity environment, it is possible to conduct a diffusion experiment in the most ideal form possible for preventing convection in the capillary. It becomes.
[0031]
Therefore, a diffusion test apparatus according to the present invention can be cast into a capillary of a sample having a smaller diameter (sample diameter: about 0.5 mm) than before without using a gas, and a more systematic diffusion experiment is performed. Is possible.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a diffusion test apparatus according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is an enlarged view of a portion B in FIG.
FIG. 4 is a schematic configuration diagram of a diffusion test apparatus using a conventional shear cell method.
FIG. 5 is a schematic view of a sample obtained by a conventional shear cell method.
FIG. 6 is a schematic view of another conventional diffusion test apparatus.
[Explanation of symbols]
1, 2 sample, 4 shear cell, 4a protrusion, 4b recess (stopper),
5 drive ring member, 5a protrusion, 6 through hole (capillary),
7a, 7b cylindrical member,
10 diffusion test equipment, 11 cartridges,
12 shear cell, 12a capillary, 12b, 12c end face,
14 End disk, 14a Hot water pool,
16 casting rod, 17 end disk,
18 pressure device, 18a push member, 18b biasing member,
20 rotation drive device, 20a rotation disk,
20b Actuator rod, 20c Rotating shaft

Claims (3)

A plurality of disc-shaped shear cells (12) having capillaries (12a) stacked so as to be rotatable about an axis Z and penetrating in the axial direction, and hot water for gripping the plurality of shear cells in the axial direction and communicating with the capillaries A pair of end disks (14) having a pool (14a), a pair of casting rods (16) fitted in the pool, and a pressurizing device (18) for pressurizing the casting rods toward the capillaries; equipped with a,
The pressure device (18) is positioned between a pair of end disks (17a, 17b) fixed to both ends of the cartridge (11) and the end disks and the end disks (14) and moves in the axial direction. A possible pair of push members (18a) and a pair of biasing members (18b) for biasing the push members outward, whereby at least one of the pair of push members is axially A diffusion test apparatus characterized by moving inwardly and moving a pair of casting rods (16) toward a capillary by a pair of push members (18a) . A center shaft (13) extending through an axis Z through the center hole of each shear cell is provided, and both ends of the center shaft are supported by the pair of end disks (14). Item 2. The diffusion test apparatus according to Item 1 . A rotary drive device (20) that rotates each shear cell about an axis Z is provided. The rotary drive device (20) is a rotary disc (20a) positioned between the push member (18a) and the end disc (17a). ), An actuator rod (20b) having one end fixed to the outer peripheral portion of the rotating disk and extending in the axial direction along the inner surface of the cartridge (11), and one end fixed to the center of the rotating disk and penetrating the end disk. It consists of a rotating shaft (20c) projecting outward, and by this movement of the rotating shaft (20c) in the axial direction, a pair of casting rods (16) is connected to the capillary via a pair of push members (18a). according to any one of claims 1 to 2 is moved, and rotates each shear cell by the rotation movement of the rotation shaft (20c) around the axis Z, characterized in that toward the Diffusion test equipment.

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