CN212845611U

CN212845611U - High-precision graphite crucible resistivity testing device

Info

Publication number: CN212845611U
Application number: CN202021508483.3U
Authority: CN
Inventors: 蒋文广; 张红岩; 周国顺; 黄长航; 王秀平; 王永方
Original assignee: Shandong Tianyue Advanced Technology Co Ltd
Current assignee: Shandong Tianyue Advanced Technology Co Ltd
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2021-03-30
Anticipated expiration: 2030-07-27

Abstract

The application provides a graphite crucible resistivity test device of high accuracy, the device including the test host computer, and with the resistivity test subassembly that the test host computer electricity is connected, the resistivity test subassembly includes: the test device comprises a base for bearing the graphite crucible and a test rod extending along the height direction, wherein four electric contacts which are respectively electrically connected with a test host and distributed at equal intervals are arranged on the test rod, and contact ends of the electric contacts face the graphite crucible and are positioned on the same straight line; the number of the test rods is at least two, and the test rods are uniformly distributed along the circumferential direction of the graphite crucible. The resistivity testing device for the graphite crucible, provided by the application, can test and obtain the resistivity of a plurality of positions on the outer wall of the graphite crucible under the condition that the graphite crucible to be tested and the testing rod are not moved, improves the testing precision, and is particularly suitable for testing the resistivity of the high-purity graphite crucible.

Description

High-precision graphite crucible resistivity testing device

Technical Field

The application relates to the technical field of resistivity testing equipment, in particular to a high-precision graphite crucible resistivity testing device.

Background

The graphite crucible has good heat conduction and high temperature resistance, is used for a heating source of induction heating under proper resistivity besides being used for a specific container, can obviously reduce power loss, and the resistivity of the graphite crucible directly influences the efficiency of the induction heating and the stability of a heating temperature field, so that the test of the resistivity of the graphite crucible is very important.

Currently, the commonly used method for measuring the resistivity of graphite articles is the four-probe method, which uses a single surface test site for testing, and four probe contact points constitute one test unit during end point testing with probe tips. In addition, a four-probe resistance tester commonly used in the prior art generally arranges a four-probe assembly capable of being lifted above a sample, and pricks four probes on the surface of the sample, so that the four-probe resistance tester is suitable for testing the resistivity of a block-shaped or sheet-shaped sample.

However, high purity graphite crucibles used in the production of silicon carbide crystals are generally cylindrical in shape, have an open cavity therein, and have walls of generally uniform thickness. Therefore, the conventional four-probe method has good test accuracy for the solid graphite piece with the regular shape and uniform overall density distribution, because the solid graphite piece with the regular shape has smaller relative influence on the introduced errors of the area S and the length L in the current applying path or area difference and the resistivity calculation process; however, for graphite crucible products with hollow interiors, the existing four-probe method is adopted to test the outer circle side surface or the two end surfaces of the crucible main body, and the difference of the test results is large, because S and L adopted in calculation are calculated on the basis of solid materials, so that the resistance S, L is an introduced inaccurate factor in the process of participating in formula calculation. The graphite crucible is irregular in shape and has a hollow structure, S and L are difficult to accurately give numerical values, the calculated resistivity accuracy is not ideal, and in addition, the resistance obtained by selecting different positions in the test of the existing method is different.

In the prior art, some technical solutions for testing the resistivity of a cylindrical sample are provided, for example, CN208156083U discloses a resistance testing jig, in which four probes are also provided to measure the resistivity, and the four probes can move in the vertical direction, the circumferential direction, and the radial direction of the circumference, but in this solution, the fixing effect of the resistor to be tested is not good, and shaking is easy to occur, and if the resistivity at multiple positions needs to be tested, the resistor or the probes need to be rotated to be able to be implemented, and moving the resistor or the probes multiple times can also increase the testing error.

Therefore, the prior art has not provided a test device for testing resistivity with high precision for a graphite crucible.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems, the present application provides a high-precision graphite crucible resistivity testing apparatus, comprising:

the resistivity test assembly comprises a test host and a resistivity test assembly electrically connected with the test host, wherein the resistivity test assembly comprises: the testing device comprises a base, a testing machine and a testing system, wherein the base is provided with a sample stage for bearing a graphite crucible and a testing rod extending along the height direction, the testing rod is provided with four electric contacts which are respectively electrically connected with a testing host machine and are distributed at equal intervals, and the contact ends of the electric contacts face the graphite crucible and are positioned on the same straight line; the number of the test rods is at least two, and the test rods are uniformly distributed along the circumferential direction of the graphite crucible.

It can be understood that the "electrical contact" in this application belongs to a contact medium for electrical test, which is used to make the electrical connection between the test host and the resistor to be tested similar to the probe in the four-probe method, and the shape of the electrical contact can also be similar, that is, the electrical contact can be a needle or cone shape extending for a certain length along the horizontal direction, and has a tip contacting with the graphite crucible. Meanwhile, the electrical connection in the present application may be implemented in various manners, such as wire connection, wireless connection, and the like.

In a preferred embodiment, the electrical contact can be made to be a telescopic structure on the test rod by an elastic member such as a spring, and is in a state of being compressed and having a rebound tendency during testing, so that good electrical connection with the graphite crucible is realized, and poor contact is avoided.

In the above apparatus, the graphite crucible to be measured for resistivity is placed on the base in its vertical height direction, i.e., the electrical contacts on the test rod extending in the height direction are fitted to the side wall of the graphite crucible to test the resistivity at the outer surface of the side wall of the graphite crucible. Similar to the prior four-probe method, four electrical contacts on a test bar form a test unit, so that a resistivity data can be obtained after a test by a test bar.

At least two testing rods uniformly distributed along the circumferential direction of the graphite crucible are arranged in the device, so that at least two pieces of resistivity data can be obtained, or the resistivity data can be understood as a plurality of pieces of resistivity data, and when the error among the plurality of pieces of resistivity data is small, the final resistivity data can be obtained by averaging the plurality of pieces of resistivity data. Compared with the mode of obtaining data at a single test position, the mode of testing a plurality of data to obtain an average value can reduce the error influence caused by different shapes of the test position as much as possible, has higher calculation precision, can obtain the resistivity of a plurality of positions on the side wall of the graphite crucible without moving the crucible or a test rod during testing, obviously can fix other variables except the test position during testing, and further improves the accuracy; on the other hand, the test rods uniformly distributed along the circumference can cover the whole material of the graphite crucible as much as possible, so that the maximum range is covered, and the resistivity of the whole graphite crucible is obtained.

In addition, the graphite crucible testing device can judge whether the different positions of the graphite crucible to be tested have material differences (namely whether the material of the pot body is uniform) or whether the contact point on the electric contact element on the testing rod has poor contact or abnormal testing conditions according to the data difference measured among different testing rods, and the testing accuracy is ensured.

Preferably, the number of the test rods is 2-8, and more preferably 4.

Further, the electrical contact includes two voltage probes and two current probes, the two current probes being respectively close to the top end and the bottom end of the graphite crucible in the height direction.

Wherein, because the graphite crucible is vertically arranged on the base, the top end and the bottom end of the graphite crucible can be understood as two circular bottom surfaces, and the two current probes are respectively arranged near the end parts of the graphite crucible, so that the current passing through the whole side wall of the graphite crucible is measured. Meanwhile, the four electric contacts are distributed at equal intervals, the graphite crucible has a certain height, so that the intervals between the four electric contacts are larger, the four probes are arranged according to the mode, the positions of the four probes on different testing rods can be respectively fixed on the same horizontal plane, the error caused by the position difference of contact points does not exist in the testing direction of each testing rod, and further the plurality of testing rods are free of uncontrollable factors except the material difference during error comparison.

Further, the two voltage probes are located between the two current probes; the current probe adopts a graphite electrode.

The arrangement of the two voltage probes and the two current probes on the test rod is equivalent to four probes (namely, one test unit) in a four-probe method. Preferably, the voltage probe is a metal probe, and the current probe is a graphite electrode, more preferably a high-purity graphite electrode, i.e., less than 5ppm of impurities. Because the current electrode is electrified with the crucible to be tested during testing, the graphite electrode with high purity can prevent surface layer metal atoms from permeating at the contact point during electrification to pollute the crucible, and the graphite electrode is exposed in the air at ordinary times, and the air is only adsorbed nitrogen or oxygen, so that the crucible cannot be polluted. More preferably, the contact end of the graphite electrode is tapered.

Furthermore, the testing rod is provided with an electric contact adjusting mechanism, and the electric contact adjusting mechanism is constructed to drive the electric contact to move in the height direction along the testing rod, so that the height position of the electric contact is adjustable.

The electric contact adjusting mechanism can adopt various embodiments, for example, the electric contact can be directly clamped on different positions of the testing rod by using the fixing clamp; or a sliding rail is arranged on the testing rod, a matched sliding block is arranged at the electric contact piece, and the electric contact piece can automatically limit the position after sliding to a specific position; or a screw thread is arranged on the test rod, and a matched screw nut is arranged at the electric contact piece.

Further, the electric contact adjusting mechanism comprises an adjusting screw rod arranged on the testing rod and an adjusting nut arranged on the electric contact, and the adjusting nut is matched with the adjusting screw rod to adjust the height position of the electric contact.

Optionally, the position of the electrical contact or the testing rod in the horizontal direction is also adjustable, for example, a movable screw is arranged at the electrical contact or at the bottom of the testing rod, so that the electrical contact can extend in the horizontal direction, or the testing rod can tilt forward or backward in the horizontal direction, so as to be suitable for a pot body in a truncated cone shape or a cone shape, for example.

Further, at least two test rods are respectively positioned at two ends of the graphite crucible in the diameter direction. Preferably, two test rods are provided at both ends of the graphite crucible in the maximum diameter direction.

Wherein, the test rods are arranged at two ends of the crucible in the diameter direction so as to cover the whole crucible. The circular crucible pot body of practical use is generally not an absolute circle, and has certain ellipticity, and the ellipse can all have certain influence to resistance and electric current, and every pole in a plurality of test bars all is a certain vertical position of measuring the crucible lateral wall, and the test current of different excircle departments can have certain difference, consequently can reduce this difference with the test bar setting at the both ends of maximum diameter, further improves the accuracy. In addition, the graphite electrode of the current probe belongs to an extremely easy-to-wear part at normal temperature, poor contact can be caused after wear occurs in the later stage, electrode contact can be ensured at the maximum diameter, and the accuracy is greatly improved by matching error monitoring. In one embodiment, the test rod is stationary while adjusting the position of the crucible wall for testing by the test rod prior to testing, and the crucible is rotated so that the test rod measures its maximum diameter.

Further, a first sliding portion is arranged on the base, and the bottom of the test rod is in sliding connection with the first sliding portion in a matched mode, so that the test rod is close to or far away from the graphite crucible along the radial direction of the graphite crucible. Preferably, the first sliding portion extends in a radial direction of the graphite crucible on the base.

The testing rod with the arrangement can move in the radial direction of the graphite crucible, on one hand, the testing rod can be far away from the graphite crucible before testing and is close to the graphite crucible during testing, so that the operation is convenient; on the other hand, the test rod can be suitable for graphite crucibles with different outer diameter sizes.

In a preferred embodiment, the bottom of the test rod may be provided with an adjusting slider, and the adjusting slider is slidably connected with the first sliding part. The first sliding part and the adjusting slider can be implemented in various ways, for example, they can be a lead screw and a lead screw nut which are connected in a sliding manner in a matching manner, or a slide rail and a pulley which are matched with each other, and the adjusting slider also has a supporting function on the test rod. It can be understood that the test rod can be fixed at a specific position in various ways after being slid to the position and can not move any more, so that the test rod is ensured not to shake when being tested.

Further, a crucible positioning assembly is arranged on the base and comprises a second sliding portion and a positioning sliding block which is connected with the second sliding portion in a matched mode, and the crucible positioning assembly is used for fixing the position of the graphite crucible in the horizontal direction.

Preferably, the crucible positioning assembly also ensures that the graphite crucible is at a particular location, such as the midpoint of the sample stage.

Preferably, the second sliding part extends along the radial direction of the graphite crucible on the base, so that the positioning slide block can also be close to or away from the graphite crucible, and when the positioning slide block is used for positioning and fixing the graphite crucible, at least part of the positioning slide block is abutted against the outer side wall of the graphite crucible, and the positioning slide block is made of an insulating material.

Preferably, the base is provided with at least two second sliding parts which are uniformly distributed around the circumference of the graphite crucible so as to fix the graphite crucible in multiple directions; more preferably, the plurality of second sliding portions provided on the base may be provided at intervals from the plurality of test bars.

Optionally, a positioning sensor may be further disposed on the base, and configured to control the movement of the positioning slide in a wireless control manner, so as to push the graphite crucible to a specific position for positioning.

Furthermore, the device also comprises a pressure rod positioned above the graphite crucible and a pressure rod fixing frame arranged on the base, wherein the pressure rod is connected with the pressure rod fixing frame through a lifting mechanism.

The pressure rod can be arranged to fix the graphite crucible, the pressure rod can be used for pressing the crucible to fix the graphite crucible before testing, and then the position of the testing rod is adjusted to enable the electric contact part to be in contact with the crucible wall, so that the crucible is effectively deviated when the position of the testing rod is adjusted. Preferably, the lifting mechanism can adopt various modes in the prior art, such as screw lifting and dropping and the like.

In one embodiment, a pressure sensor can be further arranged at the placing position of the graphite crucible for monitoring the pressure condition of the graphite crucible in real time and ensuring that the graphite crucible is fixed under proper pressure. For example, a pressure of 5N is set.

In one embodiment, a sample stage can be further disposed on the base, and the graphite crucible is placed on the sample stage. The sample table protrudes out of the surface of the base and can be connected with the base through the bearing shaft, and at the moment, the positioning sensor and the pressure sensor can be arranged at the bottom of the sample table. The size of the sample platform is matched with the area of the bottom of the graphite crucible, and the optimal area of the sample platform is not larger than the area of the bottom of the graphite crucible, so that the situation that the test rod and the positioning slide block cannot be in contact with the graphite crucible due to the fact that the sample platform is far larger than the graphite crucible is avoided.

Preferably, the movement adjustment of the parts in the resistivity testing assembly, such as the electric contact, the lifting mechanism, the adjusting slide block, the positioning slide block and the like, can be controlled by the testing host. The test host can be made of a controller, an integrated circuit and the like in the prior art, and can be electrically connected with the resistivity test component through a lead.

Preferably, the apparatus further comprises a driving assembly for controlling driving by the testing host machine so as to automatically adjust the movement of the components in the resistivity testing assembly, wherein the driving assembly may employ a driving device commonly known in the art, such as a driving motor, etc., and will not be described in detail herein.

In one embodiment, the method for testing the resistivity of the graphite crucible by using the device comprises the following steps:

(1) fixing the position of the graphite crucible;

(2) measuring the current and the voltage of the outer side wall of the graphite crucible, wherein the test points of the current and the voltage are on the same straight line, and calculating the resistivity rho according to the following formula:

wherein rho is resistivity, U is measured voltage, I is measured current, S is cross-sectional area of the graphite crucible, L is height of the graphite crucible, and the correction coefficient is obtained by calculating the ratio of the resistivity of a standard graphite block to the resistivity of the graphite crucible, wherein the standard graphite block is a solid graphite block with the same specification and material as the graphite crucible;

(3) and at least testing two groups of resistivity data, wherein the testing positions of a plurality of groups of current and voltage are uniformly distributed along the circumferential direction of the graphite crucible, and the average value of the plurality of groups of resistivity data is taken.

According to the test method, the solid standard graphite piece is used as a correction standard, the deviation between the hollow graphite crucible and the solid standard graphite piece is corrected in calculation, and the average value of multiple groups of data is finally obtained, so that the accuracy of the resistivity test of the graphite crucible is improved compared with the existing method. Preferably, the test method can be implemented by using the test device provided by the application.

Further, the step (3) further comprises the step of calculating the accumulated error, and when the accumulated error exceeds an error threshold value, reducing the accumulated error by checking the testing device, adjusting the testing position of the current and the voltage on the outer side wall of the graphite crucible and/or adjusting the distance between the testing points, and retesting.

Further, the accumulated error is obtained by calculating a maximum value and a minimum value of the measured sets of resistivity data.

Further, the step (1) includes a step of fixing the graphite crucible in a horizontal direction and a vertical direction.

Further, the graphite content in the graphite crucible is more than or equal to 99 percent, preferably more than or equal to 99.999 percent.

The following beneficial effects can be brought through the application:

according to the resistivity testing device for the graphite crucible, the resistivity of the outer wall of the graphite crucible at multiple positions is measured, and the correction coefficients are introduced, so that the testing error caused by the irregular shape of the graphite crucible is effectively reduced, and the testing accuracy is improved; and the resistivity measurement of the hollow graphite crucible can be realized without moving the test device and the sample to be tested, the test error is further reduced, the test precision is improved, no metal impurities are introduced in the test process, and the method is particularly suitable for testing the resistivity of the high-purity graphite crucible.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a front view of a resistivity testing apparatus for a graphite crucible;

FIG. 2 is a rear view of the resistivity test assembly;

FIG. 3 is an enlarged view of portion A of FIG. 2;

FIG. 4 is a top view of a resistivity test assembly;

in the figure: 1. a base; 2. a sample stage; 3. a test rod; 4. a first sliding section; 5. adjusting the sliding block; 6. a pressure rod fixing frame; 7. a pressure lever; 8. a lifting mechanism; 9. a positioning sensor; 10. a graphite crucible; 11. a current probe; 12. a voltage probe; 13. a pressure sensor; 14. a test host; 15. testing a first channel; 16. a second test channel; 17. a third test channel; 18. testing a channel IV; 19. a first sliding section drive motor; 20. a current probe adjusting lead screw; 21. a voltage probe adjusting lead screw; 22. adjusting the lead screw driving motor; 23. a voltage probe lead screw nut; 24. a current probe lead screw nut; 25. a second sliding section; 26. positioning the sliding block; 27. electrically connected to the lead wires.

Detailed Description

In order to more clearly explain the overall concept of the present application, the following detailed description is given by way of example in conjunction with the accompanying drawings.

It should be noted that in the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, the present application may be practiced in other ways than those described herein, and thus the scope of the present application is not limited by the specific embodiments disclosed below.

In addition, in the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", and the like, indicate orientations and positional relationships based on those shown in the drawings, are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present application.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; either directly or indirectly through intervening media, either internally or in any other relationship. However, the direct connection means that the two bodies are not connected to each other by the intermediate structure but connected to each other by the connecting structure to form a whole. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The embodiment of the application provides a resistivity testing device of a graphite crucible, the device has strong operability, can effectively reduce testing errors and improve testing precision under the condition that a testing part and a sample to be tested are not moved, does not introduce metal impurities in the testing process, and is particularly suitable for testing the resistivity of the high-purity graphite crucible. As shown in fig. 1-4, the apparatus comprises:

a test host 14 and a resistivity testing component, wherein the resistivity testing component is electrically connected with the test host 14. As shown in fig. 1, the resistivity test assembly includes: a pedestal 1 for bearing the graphite crucible 10, and a test rod 3 extending along the height direction, wherein, the test rod 3 is at least provided with two and is evenly distributed along the circumference of the graphite crucible 10. Each test rod 3 is provided with four electric contacts which are respectively electrically connected with the test host 14 and are distributed at equal intervals, and the contact ends of the four electric contacts face the graphite crucible 10 and are positioned on the same straight line.

In the embodiment shown in fig. 1, a sample stage 2 is further provided on the base 1 for carrying the graphite crucible 10 and positioning the placing position of the graphite crucible 10, and the graphite crucible 10 is placed vertically on the sample stage 2, i.e. with its circular bottom surface facing upward. The sample table 2 protrudes out of the surface of the base 1 and can be connected with the base 1 through a bearing shaft, the size of the sample table 2 is matched with the area of the bottom of the graphite crucible 10, and preferably does not exceed the area of the bottom of the graphite crucible 10, so that the situation that an electric contact piece on the test rod 3 cannot be contacted with the graphite crucible 10 due to the fact that the sample table 2 is far larger than the graphite crucible 10 is avoided.

Wherein, the test rod 3 can set up 2 ~ 8, and preferably, at least two test rods 3 are located graphite crucible 10 diameter direction's both ends respectively, make it can cover the crucible wholly. In the embodiment shown in fig. 1 to 4, 4 test rods 3 are provided and uniformly distributed circumferentially around the graphite crucible 10, and the 4 test rods 3 arranged in this way are respectively located at two ends of the graphite crucible in two diameter directions, and the two diameter directions are perpendicular to each other. On one hand, 4 pieces of resistivity data can be provided for calculation, high accuracy in calculation is guaranteed, and reference can be provided for error judgment among different test rods 3; on the other hand, the test operation can be simplified compared to an excessive number of test bars.

In a preferred embodiment, the electrical contact may be made to be of a telescopic construction by a spring or the like on the test rod 3 and be in a state of being compressed and having a tendency to spring back during testing to achieve a good electrical connection with the graphite crucible 10 to avoid a poor contact condition.

It can be understood that the electrical contact member described in the present application is a contact medium for electrical test, and is used to make the electrical connection between the test host 14 and the resistor to be tested similar to the probe in the four-probe method, and the shape of the electrical contact member can also be similar, that is, the electrical contact member can be a needle or cone shape extending for a certain length along the horizontal direction, and has a tip contacting with the graphite crucible 10, but when the electrical contact member of the present application is used, the electrical contact member contacts with the graphite crucible 10 and forms a good electrical connection, and does not need to be pricked into the crucible wall, thereby avoiding damage to the graphite crucible. Meanwhile, the electrical connection in the present application may be implemented in various manners, such as wire connection, wireless connection, and the like.

As shown in FIG. 1, a graphite crucible 10 for resistivity to be measured is placed on a base 1 in its vertical height direction, i.e., electrical contacts on a test bar 3 extending in the height direction are fitted to the side wall of the graphite crucible 10 to test the resistivity at the outer surface of the side wall of the graphite crucible 10. Similar to the prior four-probe method, four electrical contacts on one test bar 3 constitute one test unit, so that one resistivity data can be obtained after one test bar test. At least two test rods 3 uniformly distributed along the circumferential direction of the graphite crucible 10 are arranged in the device, so that at least two pieces of resistivity data can be obtained, for example, four pieces of resistivity data can be obtained by four test rods 3, and when the error between the four pieces of resistivity data is small, the final resistivity can be obtained by averaging the four pieces of resistivity data. According to the device, on one hand, compared with a mode of obtaining data at a single test position, a mode of testing a plurality of data to obtain an average value can reduce error influence caused by different shapes of the test position as much as possible, the calculation precision is higher, the resistivity of a plurality of positions on the side wall of the graphite crucible can be obtained without moving the crucible or a test rod during testing, obviously, other variables except the test position can be fixed in the testing process, and the accuracy is further improved; on the other hand, the test rods 3 uniformly distributed along the circumference can cover the whole material of the graphite crucible 10 as much as possible, and cover the maximum range, so as to obtain the resistivity of the whole graphite crucible. In addition, the material difference (namely whether the material of the pot body is uniform) of different positions of the graphite crucible 10 to be tested can be judged according to the data difference measured among different testing rods 3, or the condition that whether the contact point on the electric contact piece on the testing rod 3 is in poor contact or abnormal in test is monitored, and the testing accuracy is ensured.

With continued reference to fig. 1, the electrical contacts on each test bar 3 comprise two voltage probes 12 and two current probes 11, wherein the two current probes 11 are respectively located close to the top and bottom ends of the graphite crucible 10 in the height direction. Since the graphite crucible 10 is vertically placed on the susceptor 1, its top and bottom ends can be understood as two circular bottom surfaces thereof, and two current probes 11 are respectively disposed near the ends of the graphite crucible 10 so that they measure the current passing through the entire side wall of the graphite crucible 10.

Preferably, current probe 11 is a graphite electrode, more preferably a high purity graphite electrode, i.e., less than 5ppm impurities. Because the current electrode is electrified with the crucible to be tested during testing, the graphite electrode with high purity can prevent surface layer metal atoms from permeating at the contact point during electrification to pollute the crucible, and the graphite electrode is exposed in the air at ordinary times, and the air is only adsorbed nitrogen or oxygen, so that the crucible cannot be polluted. More preferably, the contact end of the graphite electrode is tapered.

Two voltage probes 12 are located between the two current probes 11, and the two voltage probes 12 are made of metal. The four electric contacts are distributed at equal intervals, the graphite crucible 10 has a certain height, so that the intervals between the four electric contacts are larger, the four probes are arranged according to the mode, the positions of the four probes on different testing rods 3 can be respectively fixed on the same horizontal plane, the error caused by the position difference of contact points does not exist in the testing direction of each testing rod 3, and further uncontrollable factors except the material difference do not exist in the error comparison of the plurality of testing rods 3. And, the arrangement of the two voltage probes 12 and the two current probes 11 on the test bar is equivalent to four probes (i.e., one test unit) constituting the four-probe method.

In other preferred embodiments, two of the test rods 3 may be disposed at both ends of the graphite crucible 10 in the maximum diameter direction. This is because the circular crucible pot body of actual use is generally not absolute circle, has certain ellipticity, and the ellipse can all have certain influence to resistance and electric current, and every pole in a plurality of test bars 3 all is a certain vertical position of measuring the crucible lateral wall, and the test current of different excircle departments can have certain difference, consequently sets up the test bar and can reduce this difference at the both ends of maximum diameter, further improves the accuracy. In addition, the graphite electrode of the current probe belongs to an extremely easy-to-wear part at normal temperature, poor contact can be caused after wear occurs in the later stage, electrode contact can be ensured at the maximum diameter, and the accuracy is greatly improved by matching error monitoring. In one embodiment, the test rod is stationary while adjusting the position of the crucible wall for testing by the test rod prior to testing, and the crucible is rotated so that the test rod measures its maximum diameter.

Wherein, still can be equipped with electrical contact adjustment mechanism on the test bar 3 for drive electrical contact along the test bar 3 in the direction of height removal, so that the high position of electrical contact is adjustable, so set up both can make the device satisfy the demand of different height size crucibles, can inspect the fine setting to electrical contact high position again when great error appears.

As shown in fig. 2 to 3, the electric contact adjusting mechanism includes a current probe adjusting lead screw 20 and a voltage probe adjusting lead screw 23 provided at the test bar 3. As shown in fig. 3, the non-contact ends of the two current probes 11 are provided with current probe screw nuts 24 which are matched with the current probe adjusting screw 20, so that the current probes 11 can slide on the current probe adjusting screw 20 to a specific position, namely, the height position is adjustable, and the current probes are fixed after sliding the specific position. The non-contact ends of the two voltage probes 12 are provided with voltage probe screw nuts 23 which are matched with the voltage probe adjusting screws 21, so that the voltage probes 12 can slide on the voltage probe adjusting screws 21 to a specific position, namely, the height position is adjustable, and the voltage probes are fixed after sliding to the specific position. Preferably, a regulating screw driving motor 22 is provided at the bottom of each of the current probe regulating screw 20 and the voltage probe regulating screw 23 for providing a driving force for the height regulation of the current probe 11 and the voltage probe 12.

Optionally, the position of the electrical contact or the testing rod 3 in the horizontal direction is also adjustable, for example, a movable screw is arranged at the electrical contact or at the bottom of the testing rod 3, so that the electrical contact can extend in the horizontal direction, or the testing rod 3 can tilt forward or backward in the horizontal direction, so as to be suitable for a pot body in a shape of an inverted circular truncated cone or a cone, for example.

With continued reference to fig. 2, each test rod 3 is provided with a first sliding portion 4 provided on the base 1, wherein the first sliding portion 4 extends on the base 1 in the radial direction of the graphite crucible 10. The bottom of the test rod 3 is in sliding fit with the first sliding part 4, so that the test rod 3 is close to or far from the graphite crucible 10 along the radial direction of the graphite crucible 10. Preferably, the bottom of the testing rod 3 may be provided with an adjusting slider 5, and the adjusting slider 5 is slidably connected with the first sliding part 4. The first sliding part 4 and the adjusting slider 5 can adopt various embodiments, in this embodiment, the first sliding part 4 adopts a lead screw, the adjusting slider 5 adopts a lead screw nut, in other embodiments, the first sliding part can also be a slide rail, a pulley and the like which are matched with each other, and the adjusting slider 5 also has a supporting function on the test rod. It will be appreciated that the test rod 3 may be fixed in a number of ways after being slid radially to a particular position and then not moved further to ensure that the test rod 3 does not wobble during the test. The arrangement enables the test rod 3 to move in the radial direction of the graphite crucible 10, on one hand, the test rod can be far away from the graphite crucible 10 before testing and is close to the graphite crucible 10 during testing, so that the operation is convenient; on the other hand, the test rod 3 can be suitable for graphite crucibles 10 with different outer diameter sizes.

As shown in fig. 4, the base 1 is further provided with a crucible positioning assembly, which includes a second sliding portion 25 and a positioning slider 26 cooperatively connected with the second sliding portion 25, for fixing the position of the graphite crucible 10 in the horizontal direction, and also ensuring that the graphite crucible 10 is at a specific position, for example, the graphite crucible 10 is always located at the center of the sample stage 2.

In the embodiment shown in fig. 4, the second sliding portion 25 extends on the base 1 in the radial direction of the graphite crucible 10, so that the positioning slider 26 can also be moved closer to or farther from the graphite crucible 10, and when the positioning slider 26 is used to position and fix the graphite crucible 10, the positioning slider 26 is at least partially in contact with the outer side wall of the graphite crucible 10, and the positioning slider 26 is made of an insulating material. Preferably, the base 1 is provided with at least two second sliding parts 25 which are uniformly distributed around the circumference of the graphite crucible 10, so as to fix the graphite crucible 10 in multiple directions; more preferably, the plurality of second sliding portions 25 provided on the base 1 may be provided at intervals from the plurality of test bars 3.

In one embodiment, a positioning sensor 9 may be further disposed on the base 1 for controlling the movement of the positioning slide by wireless control or the like to push the graphite crucible 10 to a specific position for positioning.

The testing device further comprises a pressure rod 7 and a pressure rod fixing frame 6 arranged on the base 1, as shown in fig. 2 and 4, the pressure rod 7 is connected with the pressure rod fixing frame 6 through a lifting mechanism 8, and the pressure rod 7 is located right above the graphite crucible 10. The pressure rod 7 can fix the graphite crucible 10, the pressure rod 7 can be used for pressing the crucible to fix before testing, and then the position of the testing rod 3 is adjusted to enable the electric contact piece to be in contact with the crucible wall, so that the crucible can be effectively deviated when the position of the testing rod 3 is adjusted. Preferably, the lifting mechanism 8 can adopt various manners in the prior art, such as screw lifting and the like.

In one embodiment, a pressure sensor 13 may be further disposed at the placing position of the graphite crucible for monitoring the pressure condition of the graphite crucible 10 in real time, so as to ensure that the graphite crucible is fixed under the proper pressure. For example, a pressure of 5N is set.

Preferably, the positioning sensor 9 and the pressure sensor 13 may be disposed at the bottom of the sample stage 2.

As shown in fig. 4, 4 electrical contacts on each test rod 3 are electrically connected to the test host 14 to form a test channel, i.e. in this embodiment, there are 4 test channels, i.e. test channel one 15, test channel two 16, test channel three 17 and test channel four 18.

Preferably, the movement adjustment of the components in the resistivity testing assembly, such as the electrical contacts, the lifting mechanism 8, the adjustment slide 5, and the positioning slide 26, can be controlled by the testing host 14. The test host 14 may be made of a controller, an integrated circuit, etc. in the prior art, and the resistivity test component may be electrically connected to the test host 14 through the electrical connection wires 27.

Preferably, the apparatus further comprises a driving assembly for controlling driving by the testing host 14, so as to automatically adjust the movement of the components in the resistivity testing assembly, wherein the driving assembly may employ a driving device commonly known in the art, such as a driving motor, etc., and will not be described in detail herein.

In one embodiment, the method for testing the resistivity of the graphite crucible by using the testing device comprises the following steps, wherein the content of graphite in the graphite crucible is more than or equal to 99.999 percent:

(1) placing a graphite crucible 10 on a sample table 2, and fixing the graphite crucible 10 in the vertical direction and the horizontal direction by using a pressure rod 7 and a positioning slide block 5;

(2) the current probe 11 and the voltage probe 12 on the test rod 3 were brought into contact with the outer side wall of the graphite crucible 10, the current and the voltage on the same straight line were measured, and the resistivity ρ was calculated according to the following formula:

wherein rho is resistivity, U is voltage measured by a voltage probe 12, I is current measured by a current probe 11, S is the cross-sectional area of a cylinder of the graphite crucible (considered as a solid pot body), L is the height of the graphite crucible, and a correction coefficient is obtained by calculating the ratio of the resistivity of a standard graphite block to the resistivity of the graphite crucible, wherein the standard graphite block is a solid graphite block with the same specification and material as the graphite crucible;

(1) sequentially obtaining resistivity data of a first test channel 15, a second test channel 16, a third test channel 17 and a fourth test channel 18, and displaying the resistivity data on a display screen of a test host 14, wherein the test precision is 0.01 mu omega m, and when the difference between the maximum value and the minimum value in the resistivity data measured by the four test channels is not more than 0.5 mu omega m, taking the average value of the four resistivity data as the final resistivity of the graphite crucible; when the resistivity data measured by the four testing channels has obviously abnormal data, so that the difference between the maximum value and the minimum value is larger than 0.5 mu omega m, the method can be adjusted by checking whether the electrical contact on the abnormal testing rod is in poor contact, whether the position difference between the current probe 11 and the voltage probe 12 is overlarge, and the like, and retesting.

In one embodiment, the graphite crucible gauge to be measured is 154 x 185(mm), the inner diameter is 120.05 (mm); the top is threaded, and the machining precision is +/-0.05 mm. The crucible of the specification model uses a standard sample with the specification of

The solid cylinder is used for measuring a correction coefficient, wherein the calculation process of the correction coefficient is as follows: under the premise of not giving coefficients, the average resistivity of a standard sample is measured by using the device, then the crucible is measured to be 10.01, the correction coefficient is 11.28/10.01-1.126, the coefficients are input into a system, and the system can be used for testing crucibles with the same specification and size subsequently, and the resistivity difference under the conditions of different materials, purities or densities can be obtained.

The resistivity was measured using the above test method in the first graphite crucible having the above specification, and the measured data was as follows, in units of μ Ω m:

average resistivity	P1	P2	P3	P4	Pc
						11.54	11.41	11.49	11.51	11.76	0.35

The resistivity of the second graphite crucible having the above specification was measured by the above test method, and the measured data was as follows, in units of μ Ω m:

average resistivity	P1	P2	P3	P4	Pc
						10.98	11.25	11.06	10.96	10.94	0.31

The resistivity of the two crucibles was measured using a laboratory four-probe joint (two red and black clamps) of a common four-probe resistivity meter for comparison with the resistivity of the same four positions in the example, and the results were as follows: the test results of the first graphite crucible are respectively 13.55 mu omega m, 10.68 mu omega m, 12.06 mu omega m and 11.21 mu omega m, and the cumulative error is 2.87 mu omega m; the results of the test on the second graphite crucible were 11.40. mu. OMEGA.m, 9.38. mu. OMEGA.m, 12.41. mu. OMEGA.m, and 10.15. mu. OMEGA.m, respectively, with a cumulative error of 3.03. mu. OMEGA.m.

It can be seen that the cumulative error of the resistivities of the two graphite crucibles measured by the method and the apparatus provided by the present application is 0.35 μ Ω m and 0.31 μ Ω m, respectively, and the cumulative error is about 0.3 μ Ω m after a plurality of experiments. The cumulative error of the resistivities of the two graphite crucibles measured by the conventional instrument and method is 2.87 mu omega m and 3.03 mu omega m respectively, and after a plurality of tests, the cumulative error is about 3 mu omega m, so that the large error can obviously influence the preparation process of the silicon carbide crystal in practical production. Obviously, the method and the device provided by the application have a remarkable effect on improving the resistivity test precision of the graphite crucible.

In other embodiments, there is theoretically a calibration factor, so long as the shape meets the requirement of probe contact and standard samples with the same specification and shape can be manufactured, the test method and the device provided by the application can also be used for measuring the resistivity of graphite crucibles and even other samples with different materials, purities, densities, permeabilities, expansion coefficients, thermal conductivities and other properties.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A high-precision graphite crucible resistivity testing device is characterized by comprising: the resistivity test assembly comprises a test host and a resistivity test assembly electrically connected with the test host, wherein the resistivity test assembly comprises:

the testing device comprises a base, a testing machine and a testing system, wherein the base is provided with a sample stage for bearing a graphite crucible and a testing rod extending along the height direction, the testing rod is provided with four electric contacts which are respectively electrically connected with a testing host machine and are distributed at equal intervals, and the contact ends of the electric contacts face the graphite crucible and are positioned on the same straight line; the number of the test rods is at least two, and the test rods are uniformly distributed along the circumferential direction of the graphite crucible.

2. The high precision graphite crucible resistivity testing device of claim 1 wherein the electrical contact includes two voltage probes and two current probes, the two current probes being respectively close to the top end and the bottom end of the graphite crucible in the height direction.

3. The high precision graphite crucible resistivity testing device of claim 2 wherein the two voltage probes are located between two current probes; the current probe adopts a graphite electrode.

4. The high precision graphite crucible resistivity testing device of claim 1, wherein the testing rod is provided with an electrical contact adjusting mechanism, and the electrical contact adjusting mechanism is configured to drive the electrical contact to move along the testing rod in the height direction.

5. The high-precision graphite crucible resistivity testing device of claim 4, wherein the electric contact adjusting mechanism comprises an adjusting lead screw arranged on the testing rod, and an adjusting nut arranged on the electric contact, and the adjusting nut is matched with the adjusting lead screw to adjust the height position of the electric contact.

6. The apparatus for measuring resistivity of a graphite crucible with high precision as claimed in claim 1, wherein at least two of the measuring rods are respectively located at two ends of the graphite crucible in a diameter direction.

7. The high-precision graphite crucible resistivity testing device as claimed in claim 1, wherein the base is provided with a first sliding part, and the bottom of the testing rod is in sliding connection with the first sliding part in a matching manner, so that the testing rod is close to or far away from the graphite crucible along the radial direction of the graphite crucible.

8. The high-precision graphite crucible resistivity testing device as claimed in claim 7, wherein the first sliding part extends on the base along the radial direction of the graphite crucible, and the bottom of the testing rod is provided with an adjusting slide block matched with the first sliding part.

9. The high-precision graphite crucible resistivity testing device of claim 1, wherein a crucible positioning assembly is arranged on the base, and the crucible positioning assembly comprises a second sliding part and a positioning slide block which is in fit connection with the second sliding part.

10. The high-precision graphite crucible resistivity testing device of claim 1, further comprising a pressure rod positioned above the graphite crucible and a pressure rod fixing frame arranged on the base, wherein the pressure rod is connected with the pressure rod fixing frame through a lifting mechanism.