A vacuum heating and degassing device for geological samples applied to K / Ar dating test system

Abstract

The application provides a geological sample vacuum heating and degassing device applied to a K / Ar dating method test system, which comprises a sample heating fixing seat, a top plate, a bottom plate and one side plate, and the longitudinal section of the sample heating fixing seat is in the shape of a Chinese character "kou" with an open end; the top plate is provided with a first temperature measuring contact screw hole penetrating through the top plate, and the side plate is provided with a plurality of first heating sheet fixing screw holes penetrating through the side plate; the top plate and the bottom plate are respectively extended downwards and upwards away from the side plate to form an upper limiting plate and a lower limiting plate; the first temperature measuring contact is provided with an external thread and is screwed from top to bottom with the first temperature measuring contact screw hole, and is used for measuring the temperature of the top of the geological sample; the ceramic heating sheet; a plurality of threaded top screws are screwed with the first heating sheet fixing screw holes of the side plate; and a high-temperature control system is used for receiving the temperature signal of the temperature measuring contact and controlling the heating temperature of the ceramic heating sheet. The application has the advantages of small volume, high heating efficiency, good stability and convenient installation and adjustment.

Description

Technical Field

[0001] This application belongs to the field of heating and degassing technology for original rock geological samples in a vacuum, specifically relating to a vacuum heating and degassing device for geological samples used in K / Ar dating testing systems. Background Technology

[0002] Because rocks are rich in potassium (K), the Ar isotopes that decay from K are less likely to diffuse and are more easily preserved within the rock. Therefore, K / Ar dating is widely used in geological dating, especially in deep space exploration missions such as those to the Moon and Mars, where it may be the only feasible in-situ dating method. The K / Ar method typically employs X-ray fluorescence analysis for determination. 40 The K content was measured using a quadrupole mass spectrometer or a magnetic analysis mass spectrometer. 40 Ar content, then use 40 K / 40 Determining the age of an analytical sample by comparing the Ar content ratio requires correlation with the sample's mass, thus introducing numerous measurement error factors. With the continuous improvement of the energy resolution and sensitivity of X-ray energy dispersive spectroscopy (SDD), X-ray fluorescence analysis (XRF) can simultaneously measure K / Ar elemental content, enabling direct dating of geological samples without mass correlation. This method can achieve dating accuracy exceeding 10% for samples older than 1 billion years, significantly simplifying the dating process and reducing the complexity of the dating instrument, making it particularly suitable for deep space exploration. However, geological samples readily adsorb atmospheric Ar, which severely interferes with Ar isotope content measurements during K / Ar dating. Therefore, geological samples need to have adsorbed atmospheric Ar removed under vacuum. Conventional sample processing involves pulverizing the geological sample into fine particles and then placing it in a specially designed quartz or metal furnace, baking it at 300 degrees Celsius for at least two hours in a vacuum chamber. Due to factors such as obstruction, fluorescence interference, and difficulty in adjusting the geometric layout of the measuring device, this degassing method is not suitable for dating methods based on simultaneous K / Ar content measurements. Summary of the Invention

[0003] The purpose of this application is to overcome the shortcomings of existing technologies that are not applicable to dating methods based on simultaneous measurement of K / Ar content.

[0004] To achieve the above objectives, this application proposes a vacuum heating and degassing device for geological samples used in a K / Ar dating system, comprising:

[0005] The sample heating fixture consists of a top plate, a bottom plate, and a side plate, forming a "U"-shaped structure with an open section at one end. The top plate has a through-hole threaded hole for a first temperature measuring contact. The side plate has multiple through-hole threaded holes for fixing first heating elements. The top plate and the bottom plate extend downward and upward from the side away from the side plate, respectively, to form an upper limit plate and a lower limit plate.

[0006] The first temperature measuring contact has an external thread, which is threadedly connected from top to bottom to the threaded hole of the first temperature measuring contact, and is used to measure the temperature of the top of the geological sample.

[0007] Ceramic heating element;

[0008] Multiple threaded set screws are threadedly connected to the first heating element fixing threaded hole of the side plate;

[0009] A high-temperature control system is used to receive the temperature signal from the temperature measuring contact and control the heating temperature of the ceramic heating element.

[0010] As an improvement to the above-mentioned device, it also includes:

[0011] Multiple support columns are fixed below the base plate to support the sample heating fixture.

[0012] As an improvement to the above-mentioned device, the length and width of the support column are 0.5-1mm, and the height is 3-10mm.

[0013] As an improvement to the above-mentioned device, the side plate has a through-hole for a second temperature measuring contact thread;

[0014] The device also includes a second temperature measuring contact with an external thread, which is threaded from the outside in to the threaded hole of the second temperature measuring contact, for measuring the temperature of the side of the geological sample.

[0015] As an improvement to the above-mentioned device, the top plate also has a plurality of through-holes for fixing the second heating element with threaded holes, which are used to fix the geological sample by using set screws through the through-holes for fixing the second heating element.

[0016] As an improvement to the above-mentioned device, the upper part of the base plate includes a downwardly recessed heat insulation groove near the side plate.

[0017] As an improvement to the above-mentioned device, the thickness of the heat insulation groove is 0.2-0.5 mm.

[0018] As an improvement to the above-mentioned device, the length of the outer contour cross-section of the sample heating fixture is 20-25mm, the width is 10-15mm, and the height of the sample heating fixture is 25-35mm.

[0019] Compared with existing technologies, the advantages of this application are:

[0020] To address the needs of K / Ar dating systems, this invention proposes a vacuum-based geological sample heating and degassing device. This device features a compact size to match miniaturized X-ray sources and SDD equipment, while simultaneously enabling high-temperature, high-efficiency 300°C heating of intact geological samples to remove adsorbed Ar, ensuring sample stability while maximizing the exposure of the irradiated surface. Furthermore, it allows for easy adjustment of relative geometric configurations to optimize experimental conditions. This invention is particularly suitable for geological sample heating and degassing in K / Ar dating systems that do not require mass correlation, offering advantages such as small size, high heating efficiency, good stability, and convenient installation and adjustment. Attached Figure Description

[0021] Figure 1 The diagram shows the structure of a K / Ar statutory annual testing system that does not require quality correlation.

[0022] Figure 2 The diagram shows the structure of a geological sample heating, degassing, and fixing device.

[0023] Figure 3 The diagram shows the structure of the geological sample heating fixture. Detailed Implementation

[0024] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0025] In order to solve such Figure 1 This invention addresses the challenges of high-temperature treatment and fixation of geological samples in a mass-independent K / Ar dating system. It proposes a vacuum heating and degassing device for geological samples used in K / Ar dating systems. This miniaturized device enables high-temperature isothermal heating of geological samples and incorporates multiple insulation features, resulting in more efficient sample heating while minimizing heat conduction to other equipment through the vacuum chamber mounting plane. The device maximizes the exposure of the sample's irradiated surface while employing a highly stable fixation method. This improves the geometric stability of the experimental setup during sample testing and facilitates easy adjustment of the relative positions of the experimental components.

[0026] like Figure 2 As shown, the vacuum heating and degassing device for geological samples may include: a ceramic heating element 1, a temperature measuring contact 2, a high-temperature control system, and a sample heating fixture 5.

[0027] The ceramic heating element 1 can be a square or rectangular sheet structure with a heating area of ​​5×5mm to 20×20mm, a thickness of 1mm to 3mm, a resistance of 2Ω to 30Ω, and a heating power of 5-60W. It can be powered by DC. The ceramic heating element 1 can directly contact the back of the geological sample 3, and close contact with the sample 3 can be achieved through the pressure of 2-4 threaded set screws 4. To efficiently transfer heat from the ceramic heating element 1 to the geological sample 3, and to reduce heat transfer from the ceramic heating element 1 to the sample heating holder 5, the threaded set screws 4 can minimize the contact area between the set screws and the ceramic heating element 1 while still meeting the fixing force. In other embodiments, the ceramic heating element 1 can also be a sheet structure of other shapes, such as circular, elliptical, or other arbitrary shapes.

[0028] Temperature sensing contact 2 can be a type K thermocouple with a threaded structure, whose high-temperature end is above 300 degrees Celsius and whose low-temperature end covers room temperature. The structure of temperature sensing contact 2 can be made of stainless steel, and the power supply line can withstand temperatures above 300 degrees Celsius.

[0029] The high-temperature control system receives a temperature signal from the temperature sensing contact 2 and compares it with the set temperature value to generate an error temperature signal. The ceramic heating element 1 can be connected in series with an external power supply and a relay in the high-temperature control system. The error temperature signal controls the opening and closing of the relay, thereby controlling the opening and closing of the heating circuit and achieving constant temperature control of the set temperature. The high-temperature control system can have a high-temperature setting function and an output power of not less than 60W to power the ceramic heating element.

[0030] The sample heating holder 5 can rapidly heat the geological sample 3 to the set temperature. Based on the temperature requirements for removing adsorbed gases from the geological sample, it typically needs to be heated to 300 degrees Celsius and continuously heated for more than 2 hours. In addition to its heating function, the sample heating holder 5 must also ensure that heat is not conducted to the vacuum chamber base plate in contact with the holder; otherwise, it would damage the SDD detector mounted on the base plate, which is very close to the sample. Furthermore, the geometric configuration of the geological sample 3, X-ray excitation source, and SDD detector needs to be optimized during the experiment. This requires that the relative positions and geometric configurations of the sample heating holder 5, geological sample 3, X-ray excitation source, and SDD detector remain unchanged during the heating and degassing process and throughout the experiment. Moreover, the sample heating holder 5 should be convenient, quick, and have a fast heating rate and high heating efficiency when fixing or changing the geological sample 3, without causing sample tipping or displacement. Furthermore, the ceramic heating element and temperature measuring contact 2 should maintain good contact even when heated to 300 degrees Celsius. Based on these requirements, the detailed design of the geological sample heating holder 5 is as follows:

[0031] The sample heating fixture 5 can be made of titanium alloy, which has the characteristics of high strength, high density, high melting point and low thermal conductivity.

[0032] like Figure 3 As shown, the main body of the sample heating fixture 5 can adopt a "U"-shaped envelope structure, but on the side facing the excitation source and SDD detector, one side of the "U" shape can be almost completely cut open. This ensures both the angle adjustment of the X-ray excitation source and that all X-rays emitted by the X-ray excitation source irradiate the geological sample 3, avoiding fluorescence interference from the excited titanium alloy. At the lower end of the main structure, four support columns 6 can be used to support the "U"-shaped main structure.

[0033] The main structure of the fixing base can match the size of the geological sample 3. Typically, the length of the outer contour of the structure can be 20-25mm, the width can be 10-15mm, and the height can be 25-35mm. The preferred length is 25mm, the preferred width is 15mm, and the preferred height is 30mm. This not only has a certain adaptability to the volume of the geological sample 3, but also meets the requirements of the excitation irradiation surface size, and facilitates movement and rotation during the geometric layout optimization process.

[0034] The function of the support column 6 is to support the main structure of the fixing base and minimize heat conduction from the sample heating fixing base 5 while meeting stability requirements. The support column 6 can also be made of titanium alloy and can be integrally processed with the main structure of the sample heating fixing base 5. The length and width of the support column 6 can be 0.5-1mm, preferably 1mm, and the height can be 3-10mm. The cross-sectional area of ​​the support column 6 in this application is smaller than that of conventional devices. This design reduces heat conduction from the base to the external contact plane through the support column and also reduces heat loss, improving the efficiency of the high-temperature heating device. If the insulation effect of the support column 6 is poor, heat from the main structure of the fixing base will be transferred to the mounting plate in the vacuum cavity through the support column 6, which will rapidly diffuse to the nearby SDD detector and X-ray source, affecting their normal operation. The structural design of this support column 6 has been experimentally verified. When the temperature of the geological sample 3 reaches 300 degrees Celsius and is maintained for more than 2 hours, the temperature of the base plate in contact with the support column 6 is only 28 degrees Celsius. In other embodiments, the number of support columns 6 can be greater than 2.

[0035] The temperature measuring contact 2 can be a commercially available, mature product. It integrates a thermocouple and has a stainless steel shell with an M6 thread. The contact is secured by screwing it into a matching first temperature measuring contact threaded hole 7 and / or second temperature measuring contact threaded hole 8. The first temperature measuring contact threaded hole 7 is located at the top of the mounting base, while the second temperature measuring contact threaded hole 8 can be located at the back of the mounting base. When installing the temperature measuring contact 2 in the second temperature measuring contact threaded hole 8, the contact 2 must be offset from the ceramic heating element 1, and it needs to be in direct contact with the geological sample 3. Compared to adhesive mounting, threaded mounting allows for operation at high temperatures and a secure contact with the sample surface, resulting in more accurate temperature measurement. By measuring temperatures at both the top and back, the temperature at different locations on the sample can be compared, providing better monitoring of the uniformity of sample heating. It also provides an alternative temperature measurement option for confined vacuum volumes.

[0036] Five threaded holes 9 for fixing the first heating element can be designed on the side plate 15 of the main structure of the fixing base. Five positions are reserved to meet the fixing needs of ceramic heating elements 1 of different areas. Typically, 2-3 threaded holes are sufficient to achieve a firm contact between the ceramic heating element 1 and the geological sample 3. All five threaded holes 9 can be designed as M1.6 threads. This is to meet the fixing strength requirements while minimizing heat transfer from the ceramic heating element 1 to the main structure of the fixing base, thereby reducing heat loss. The threaded set screw 4 can be a stainless steel screw or a titanium alloy screw. In other embodiments, the number of threaded holes 9 for fixing the first heating element can be less than or more than five, depending on the need to clamp the geological sample 3. In other embodiments, the diameter of the threaded holes 9 for fixing the first heating element can be 1.2-3 mm.

[0037] In addition to a pre-drilled M6 first temperature measuring contact threaded hole 7 for fixing the temperature measuring contact, the top of the main structure of the sample heating fixture 5 can also have two small second heating element fixing threaded holes 10. The diameter of the second heating element fixing threaded holes 10 can be M1.6 or 1.2-3mm. Their main function is to fix the geological sample 3 downwards via screws. If the geological sample 3 is too small to be confined within the "mouth" structure, the force from the back threaded set screw 4 and the lower baffle can easily generate a torque, causing the sample to flip. The second heating element fixing threaded holes 10 in the top structure allow the heating device to accommodate samples of more sizes. In other embodiments, the number of second heating element fixing threaded holes 10 can be one or more than two, depending on the need to clamp the geological sample 3.

[0038] To increase the stability of the main structure of the mounting base and the robustness of the entire heating and degassing device under high-temperature conditions, a sample fixing and limiting plate can be added to the sample irradiation surface side of the main structure of the mounting base. This can include an upper limiting plate 11 and a lower limiting plate 12. The length of the limiting plate can be the same as the length of the main structure, the height can be between 0.5-1 mm, and the thickness can be between 0.2-1 mm. This design ensures maximum exposure of the irradiation surface of the geological sample 3 while preventing the geological sample 3 from falling out of the sample heating mounting base 5 during fixing or testing. Furthermore, a heat insulation groove 13 can be added to the lower end of the mounting base where the geological sample 3 contacts. The heat insulation groove 13 can be located in the transition zone between the sample placement area 14 and the side plate 15, and its thickness can be only 0.2-0.5 mm, a reduction of 1.5 mm compared to the 2 mm thickness of the sample placement area 14. The heat insulation groove 13 ensures that the centroid of the main structure is closer to the center of the structure, thereby increasing the stability of the degassing device. In addition, it also helps to ensure that more heat from the ceramic heating plate 1 is used to heat the geological sample 3. The smaller cross-sectional area results in less heat being conducted to the side plate 15 of the main structure, making the heat more concentrated in the sample heating area and the heating efficiency higher.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application, and should all be covered within the scope of the claims of this application.

Claims

1. A vacuum heating and degassing device for geological samples used in a K / Ar dating system, characterized in that, include: The sample heating fixture consists of a top plate, a bottom plate, and a side plate, forming a "U"-shaped structure with an open end in its longitudinal section. The open end faces the excitation source and the SDD detector, and one side of the "U" shape is almost entirely cut off. The top plate has a through-hole threaded hole for a first temperature measuring contact. The side plate has multiple through-hole threaded holes for fixing first heating elements. The top plate and the bottom plate extend downward and upward from the side away from the side plate, respectively, to form an upper limit plate and a lower limit plate. The first temperature measuring contact has an external thread, which is threadedly connected from top to bottom to the threaded hole of the first temperature measuring contact, and is used to measure the temperature of the top of the geological sample. Ceramic heating element; Multiple threaded set screws are threadedly connected to the first heating element fixing threaded hole of the side plate; and A high-temperature control system is used to receive the temperature signal from the temperature measuring contact and control the heating temperature of the ceramic heating element.

2. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 1, characterized in that, Also includes: Multiple support columns are fixed below the base plate to support the sample heating fixture.

3. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 2, characterized in that, The length and width of the support column are 0.5-1mm, and the height is 3-10mm.

4. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 1, characterized in that, The side plate has a through-hole for a second temperature measuring contact thread; The device also includes a second temperature measuring contact with an external thread, which is threaded from the outside in to the threaded hole of the second temperature measuring contact, for measuring the temperature of the side of the geological sample.

5. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 1, characterized in that, The top plate also has multiple through-holes for fixing the second heating element, which are used to fix the geological sample by using a set screw through the through-holes for fixing the second heating element.

6. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 1, characterized in that, The upper part of the base plate includes a downwardly recessed heat insulation groove near the side plate.

7. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 6, characterized in that, The thickness of the heat insulation groove is 0.2-0.5 mm.

8. The vacuum heating and degassing device for geological samples applied to the K / Ar dating system according to claim 1, characterized in that, The length of the outer contour cross-section of the sample heating fixture is 20-25mm, and the width is 10-15mm; the height of the sample heating fixture is 25-35mm.

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