RU72329U1 - HIGH TEMPERATURE CAMERA FOR X-RAY DIFFRACTOMETER - Google Patents

Abstract

A high-temperature chamber to an X-ray diffractometer, comprising a cooled case with a beryllium window for the passage of X-rays and two nozzles for connecting gas pipelines, hermetically connected to a water-cooled base, which is installed using a landing plate on a goniometer, a temperature circuit including a high-temperature furnace mounted on a water-cooled base equipped with a replaceable heater and heat shields, of which two distant windows for X-ray passage x rays are covered with a beryllium foil, a thermocouple, the ends of which are led out to the temperature controller, and a sample holder mounted in an adjustable bearing of the water-cooled base with the possibility of rotational-vibrational motion using an electric drive, characterized in that it is equipped with a system for maintaining the partial pressure of oxygen, including an electrochemical oxygen pump stabilized zirconia, oxygen sensor stabilized zirconia, control controller, gas pipeline supply and removal of a gas atmosphere and a circulation pump to ensure a constant gas flow, which together with a cooled case sealed on a water-cooled base and two pipes for connecting gas pipelines form a closed loop of the gas atmosphere, and the control controller provides control and regulation of the partial pressure of oxygen in the gas atmosphere .

Description

The utility model relates to scientific instrumentation and can be used to create equipment for studying the structure of materials at high temperatures and in a controlled atmosphere.

High-temperature diffractometry makes it possible to study the phase transformations and deformations of materials when the temperature changes in different media, to study the symmetry and structure of phases existing only at elevated temperatures, and to approximately simulate natural processes.

The possibilities of staging such experiments increased significantly with the development of high-temperature X-ray diffraction — a method for directly observing the phase state of a material with temperature.

Known temperature X-ray chamber - an attachment to an X-ray diffractometer (Temperature attachments to an X-ray diffractometer, operating on the principle of blowing a sample, E.E. Reader; I.V. Isakov; V.N. Dudarev. Equipment and methods of x-ray analysis. Collection. L. "Mechanical Engineering", 1974, issue 14. p.127-131), designed to study samples of materials in the temperature range from - 170 ° C to + 200 ° C.

Famous camera consists of:

- A thick-walled case made of asbestos cement having a beryllium window for transmitting X-rays, an annular collector for

connecting a gas pipeline to create atmospheric conditions and an opening in the upper part for venting gas that creates atmospheric conditions;

- platforms with a landing plate for mounting the camera on an x-ray goniometer;

- a temperature circuit including a tubular furnace mounted in the gas supply pipe, with the possibility of manually changing the power using an autotransformer, and a controlled nitrogen vapor supply system consisting of a Dewar vessel and an adjustable evaporator;

- a sample holder having a channel for supplying gas to the sample and fixed to the base of the chamber, which oscillates under the influence of a cam mounted on an electric drive shaft.

Camera Operation:

The camera is mounted on an x-ray goniometer using the platform landing plate.

The temperature and atmospheric conditions of the sample of the studied material are ensured by its gas blowing - nitrogen vapors, the temperature of which is regulated by heating the tube furnace and the rate of nitrogen evaporation in a controlled nitrogen vapor supply system. Gas escapes from the chamber through the upper opening in the housing.

To prevent heating of the goniometric device, the camera is cooled externally by a fan.

The disadvantages of this camera is that:

- the study is limited to the temperature range to which it is possible to heat the gas in a gas stream that creates atmospheric conditions. This does not allow the study of phase transformations of materials and the study of structures existing at temperatures above 200 ° C;

- only nitrogen vapors can be used as gas;

- the partial pressure of oxygen in the chamber is not controlled.

Known high-temperature chamber - an attachment to an X-ray diffractometer (High-temperature chamber - an attachment to an X-ray diffractometer for studying reactions of the "solid-gas" type, V.E. Rudnichenko. Equipment and methods of X-ray analysis. Collection. L. "Engineering", 1969, no. 4. p.32-37), designed to study the changes in time of the phase composition of a solid during reactions at a given temperature and flow rate of the reaction gas.

Famous camera consists of:

- a cooled case having a beryllium window for transmitting X-rays, mounted on a water-cooled base on a rubber gasket;

- the base, which is fixed on the goniometer with the ability to oscillate around the axis of the goniometer;

- a gas circuit, including a reaction vessel in the form of a quartz tube, having sector cut-outs for x-rays, a flat section for sealing the connection with the sample holder, two nozzles for the gas flow (one for supplying gas, one for exhausting gas) and a nozzle for supplying inert gas . A tube-shaped supply pipe passes from above inside the upper half of the reaction vessel, then spirals outward of the quartz tube, wrapping the reaction vessel around the temperature zone heater, and again enters the reaction vessel in the form of a nozzle directed at the sample. The outlet pipe is located at the top of the reaction vessel — the “hole in the lid”. It is possible to output gaseous products without loss to any gas analyzer;

- a temperature circuit including a heater in the form of a ceramic pipe with sector cut-outs for x-rays covered by a beryllium foil, with grooves on the inner surface,

with a nichrome spiral laid around the glass-shaped nickel reflective screens with sector cut-outs for x-rays and openings for the reaction vessel and a thermocouple mounted in the sample holder;

- the sample holder in the form of a quartz tube cut in half with a quartz ring welded to it, while the cut plane is polished for precise - strictly fixed installation of the interchangeable holder in the base. The sample holder is replaceable.

The functioning of the camera. The sample is placed in a removable holder, which is installed in

base of the camera. The camera is mounted.

The chamber is filled with an inert gas through the gas circuit. The necessary power is supplied to the temperature circuit, the heating of the sample is controlled by the readings from the thermocouple.

After reaching the set temperature and holding the sample, the chamber is cleaned of inert gas. Exit to the atmosphere opens, exposure is given, and the chamber is filled with the necessary reaction gas.

X-ray diffraction measurements are made.

The exhaust gas stream is directed to an external gas analyzer and an inert gas is supplied to the chamber. The reaction gas products, the residual reaction gas, together with the inert gas, are sent for analysis.

The disadvantages of this camera are:

- the eclecticism of the results associated with a change in the course of the experiment of the total absorption coefficient of the sample, which is justified in industry-oriented studies that do not require the accuracy and reproducibility that are necessary for scientific research;

- indirect control of the composition of the gas atmosphere;

- limited temperature range of studies by the melting temperature of quartz, as the material from which the reaction block is made.

Known high-temperature X-ray camera type UVD-2000 (Technical description and operating instructions. NPO "Burevestnik", Leningrad, 1979), designed for x-ray studies on diffractometers like DRON-3, DRON-UM-1, on flat samples using the " on reflection ”in the temperature range from room temperature to 2000 ° C in vacuum no worse than 2 × 10 ^-5 mm Hg and up to 1200 ° C in air and in an inert gas atmosphere in the range of angles provided by the diffractometer (prototype).

Famous camera - prototype consists of:

- a cooled case - 5, with a beryllium window - 6 for passing x-rays, mounted on a water-cooled base - 3 on a gasket - 2 and fixed by bolts - 4, and a pipe for connecting a vacuum pipe or gas pipeline-10, to create atmospheric conditions for the study;

- a water-cooled base-3 with a landing plate for mounting the camera on an x-ray goniometer;

- a temperature circuit, including a high-temperature furnace -11, equipped with a replaceable heater - 12 with heat shields - 13, of which two distant windows for the passage of x-rays are closed with beryllium foil - 7, and a thermocouple - 9, the ends of which are led to a high-precision temperature controller - 23;

- sample holder - 1, which is fixed in an adjustable bearing and can perform rotational-vibrational movements around its axis by means of a lever using an electric drive - 14.

The material from which the heater - 12 and heat shields - 13 are made is determined by the planned atmosphere of the experiment.

The functioning of the camera.

The camera is mounted on an x-ray goniometer using a landing plate of a water-cooled base - 3.

The temperature of the sample of the studied material - 8 is provided by heating a high-temperature furnace - 11, controlled by a thermocouple - 9 and supported by a high-precision temperature controller - 23.

Atmospheric conditions inside the chamber are set by external systems.

Process description.

Step 1. A sample - 8 is prepared from the studied powder and its research program is determined.

Step 2. A high-temperature furnace - 11 is equipped with an interchangeable heater - 12 and heat shields 13 in accordance with the objectives of the study.

Step 3. A sample of the studied material - 8 is placed in the chamber during its assembly on the sample holder - 1, which is fixed in an adjustable bearing.

Step 4. The cooled case - 5, is installed on the water-cooled base - 3 on the gasket - 2, is fixed with bolts - 4, and an external system is connected to the nozzle - 10, which creates the necessary pressure or pressure.

Step 5. The high-temperature furnace - 11 is heated with temperature control of the sample of the material under study - 8 with a thermocouple - 9 and a high-precision temperature controller. The warm-up schedule is set by the research plan.

Step 6. Upon reaching the desired temperature and the necessary exposure, the required X-ray diffraction measurements are made.

Step 7. A planned series of temperature effects is made on the sample of the studied material - 8, followed by X-ray diffraction measurements.

Step 8. The high-temperature furnace - 11 is cooled, the atmosphere in the unit for creating the conditions of the investigation is brought to the state of "ambient air", the chamber is disassembled and a sample of the studied material is extracted - 8.

The disadvantage of this chamber is that it is designed to study the structure either in air or in a vacuum or inert gas atmosphere with the need to replace the heater. At the same time, the composition of the gas atmosphere and its change during the experiment cannot be controlled without additional analysis.

The use of a fore-vacuum oil pump can lead to contamination of the system with carbon-containing organic additives.

Changing the heater leads to a change in the experimental conditions.

The technical result of the proposed utility model is the possibility of studying the structure of a substance at atmospheric pressure in the atmosphere with a variable partial pressure of oxygen at high temperatures, with high accuracy in maintaining experimental conditions.

The specified technical result is achieved by the fact that the high-temperature chamber to the X-ray diffractometer, containing a cooled case with a beryllium window for the passage of X-rays and two pipes for connecting gas pipelines, is hermetically connected to the cooled base, which is installed on the goniometer using a landing plate, temperature circuit,

including a high-temperature furnace mounted on a water-cooled base, equipped with a replaceable heater and heat shields, of which at the two far windows for the passage of X-rays are closed by a beryllium foil, a thermocouple, the ends of which are brought out to the temperature regulator, and a sample holder mounted in an adjustable bearing of the water-cooled base with the possibility of rotational-oscillatory motion using an electric drive, according to the invention, is equipped with a system for maintaining partial pressure oxygen, including an electrochemical oxygen pump made of stabilized zirconia and an oxygen sensor made of stabilized zirconia, installed in a tube furnace, a control controller, gas supply and exhaust pipelines and a circulation pump to ensure a constant gas flow, which together with a cooled case, hermetically installed on a water-cooled base, and two pipes for connecting gas pipelines form a closed loop of the gas atmosphere. The control controller provides control and regulation of the partial pressure of oxygen in the gas atmosphere.

The electrochemical oxygen pump and the electrochemical oxygen sensor are structurally combined on one ceramic product, consisting of two parts of stabilized zirconia, which are electrically isolated from each other in order to eliminate unwanted polarization of the sensor. The electrodes of the pump and the sensor deposited on the inner surface of the ceramic product are in contact with the gas atmosphere inside the insulated circuit, the electrodes deposited on the outer surface are in contact with air. The gas system is organized in such a way that with the help of a circulation pump and gas inlets the gas mixture is fed to the electrochemical oxygen pump, then it is supplied to the electrochemical oxygen

the sensor, taken close to the latter, enters the circulation pump, then it is fed to the test sample.

The proposed camera for x-ray diffraction studies of the structure and phase composition of the material at high temperatures on flat samples by the "reflection" method in the temperature range from room temperature to 1300 ° C in an air atmosphere with a controlled oxygen partial pressure in the range from 1 to 1 · 10 ^-18 atm.

The figure shows a diagram of a chamber for X-ray diffraction studies of the structure and phase composition of the material at high temperatures in the atmosphere with a controlled partial pressure of oxygen.

The proposed camera consists of:

- a closed loop of a gas atmosphere containing a cooled case - 5 with a beryllium window - 6 for the passage of x-rays, nozzles - 10 and 15, and a system for maintaining the partial pressure of oxygen, including a tube furnace - 20, an electrochemical oxygen pump made of stabilized zirconia - 22, an oxygen sensor made of stabilized zirconium dioxide - 21, a control controller - 18, as well as gas pipelines - 16, 17 and a circulation pump - 19;

- the temperature circuit, including a high-temperature furnace - 11, with a heater - 12 and heat shields - 13, of which at two distant windows for the passage of x-rays are closed with beryllium foil - 7, thermocouple - 9 and temperature regulator 23;

- water-cooled base - 3 with a landing plate for mounting the camera on an x-ray goniometer.

The cooled case - 5 of the gas atmosphere of the study is installed on a water-cooled base - 3 on the gasket - 2 and is fixed with bolts - 4.

The sample of the studied material - 8 is placed on the sample holder - 1, which is fixed in an adjustable bearing and can rotate-oscillate around its axis by means of a lever with the help of an electric drive - 14.

The functioning of the camera.

A camera with a sample of the studied material - 8 is mounted on an x-ray goniometer using a landing plate of a water-cooled base - 3.

The temperature regime of the sample of the studied material - 8 is provided by the temperature circuit. The sample of the studied material - 8 is heated using a high-temperature furnace - 11, the temperature is controlled by a thermocouple - 9 and supported by a high-precision temperature controller - 23. The sample of the studied material - 8 is cooled by natural heat removal to the environment.

Atmospheric conditions inside the chamber are created and maintained by the circuit of the gas atmosphere. The partial pressure of oxygen in the gas circuit is changed by means of an electrochemical oxygen pump made of stabilized zirconium dioxide - 22, controlled by an oxygen sensor made of stabilized zirconium dioxide - 21, and automatically maintained by the control controller - 18.

The identical value of the partial pressure in the zone of the sample of the studied material - 8 and the oxygen sensor made of stabilized zirconia - 21 is ensured by the active circulation of the gas atmosphere inside the closed circuit using the circulation pump - 19.

The performance of the electrochemical oxygen pump made of stabilized zirconium dioxide - 22 and the oxygen sensor made of stabilized zirconium dioxide - 21 is ensured

maintaining a temperature of about 800 ° C in a tube furnace - 20 using the control controller - 18. Description of the process.

Step 1. A sample of the studied material - 8 is prepared from the studied powder and a program for its study is formulated.

Step 2. A sample of the studied material - 8 is placed in the chamber - during its assembly on the sample holder - 1, which is fixed in an adjustable bearing.

Step 3. Assembling an isolated circuit of the gas atmosphere of the study: on a water-cooled base - 3 on a gasket - 2 with bolts - 4, a cooled case - 5 with nozzles - 10 and 15 is installed, to which a circulation pump - 19 is connected using gas pipelines - 16 and 17 and an electrochemical oxygen pump of stabilized zirconia - 22 with an oxygen sensor of stabilized zirconia - 21.

Step 4. The assembled chamber with the sample of the studied material - 8 is installed on the x-ray goniometer using the landing plate of the water-cooled base - 3. The necessary adjustment is made in accordance with the requirements of the radiographic installation.

Step 5. The output to the mode of the electrochemical oxygen pump from stabilized zirconium dioxide - 22 and the oxygen sensor from stabilized zirconium dioxide - 21. The oxygen partial pressure maintenance system is turned on: control controller - 18 and the tube furnace - 20. The electrochemical oxygen pump from stabilized dioxide is heated zirconium - 22 and an oxygen sensor made of stabilized zirconium dioxide -21, while the temperature

in a tubular furnace - 20 is controlled according to the testimony of the control controller - 18.

Step 6. Setting the required value of the partial pressure of oxygen in a closed loop of the gas atmosphere. Upon the fact that the temperature in the tube furnace - 20 reaches 800 ° C, which is determined by the necessary pumping speed, the control controller - 18 sets the necessary value of the partial oxygen pressure. The achieved value of the partial pressure of oxygen in a closed loop of the gas atmosphere is controlled by the test controller 18.

Step 7. Heating and stabilization of the sample temperature. A sample of the studied material - 8 is heated to a temperature, the value of which is determined by the research program and controlled by a thermocouple - 9 according to the readings of a high-precision temperature controller - 23.

Step 8. Establish equilibrium between the sample and the gas atmosphere. Upon reaching the required temperature of the sample and the required partial pressure of oxygen in the closed loop of the gas atmosphere, to establish equilibrium between the sample and the gas atmosphere, the sample and all camera systems are held until the voltage and current are stabilized on an electrochemical oxygen pump made of stabilized zirconium dioxide - 22, which are controlled by testimony of the control controller - 18.

Step 9. Upon the stabilization of the sample temperature - 8 and the partial pressure of oxygen in the gas atmosphere and the necessary exposure to establish equilibrium between the sample and the gas atmosphere, X-ray diffraction measurements are performed.

Further, “steps 7-9” are repeated several times in accordance with the research program.

Step 10. The end of the formulated research program. High-temperature furnaces - 11 and 20 are cooled, thereby the system for maintaining the partial pressure of oxygen is stopped, the camera is removed from the goniometer and disassembled, a sample of the studied material is extracted - 8.

Claims (1)

A high-temperature chamber to an X-ray diffractometer, comprising a cooled case with a beryllium window for the passage of X-rays and two nozzles for connecting gas pipelines, hermetically connected to a water-cooled base, which is installed using a landing plate on a goniometer, a temperature circuit including a high-temperature furnace mounted on a water-cooled base equipped with a replaceable heater and heat shields, of which two distant windows for X-ray passage x rays are covered with a beryllium foil, a thermocouple, the ends of which are led out to the temperature controller, and a sample holder mounted in an adjustable bearing of the water-cooled base with the possibility of rotational-vibrational motion using an electric drive, characterized in that it is equipped with a partial oxygen pressure maintenance system, including an electrochemical oxygen pump stabilized zirconia, oxygen sensor stabilized zirconia, control controller, gas pipeline supply and removal of a gas atmosphere and a circulation pump to ensure a constant gas flow, which together with a cooled case sealed on a water-cooled base and two pipes for connecting gas pipelines form a closed loop of the gas atmosphere, and the control controller provides control and regulation of the partial pressure of oxygen in the gas atmosphere .