A method for measuring melting point and phase transition temperature of oxide ceramics based on laser heat source heating

Abstract

The application discloses a kind of determination methods of oxide ceramic melting point and phase transition temperature based on laser heat source heating, oxide ceramic raw material column is placed on the object table of high-temperature phase transition determination device, then the light spot of laser radio frequency device emission and the light spot of infrared temperature measuring instrument emission, aim at oxide ceramic raw material column, start laser radio frequency device to oxide ceramic raw material column heating, until oxide ceramic raw material column melts into spherical shape, close laser radio frequency device, then using infrared temperature measuring instrument to oxide ceramic raw material column continues temperature measurement, obtains the melting point and phase transition temperature of oxide ceramic.The method can detect the melting point and phase transition temperature of oxide ceramic in the range of 350-3500 DEG C, realize the quick, simple detection of melting point and phase transition temperature of superhigh temperature oxide ceramic.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a method for determining the melting point and phase transition temperature of oxide ceramics based on laser heating. Background Technology

[0002] Oxide ceramic materials have great application prospects in the automotive, medical, aerospace, and battery industries. Due to their high wear resistance, low dielectric properties, and excellent chemical stability, they have significant application value in structural devices and also show broad application potential in functional devices, such as commonly used piezoelectric ceramics, transparent ceramics, fuel cells, and aerospace thermal protection coatings. Therefore, the development and design of oxide ceramic materials is becoming increasingly important for the development of new applications in the nuclear and aerospace industries. The design and processing of these materials require detailed thermodynamic experimental data on their composition, but data on phase transitions such as melting points are often lacking, hindering the assessment of material stability and further material composition design.

[0003] The melting point and phase transition temperature of oxide ceramic materials are crucial components of material development and composition design. Most of these materials have melting points exceeding 2000℃, making their measurement challenging. Firstly, commonly used differential thermal analyzers (DTAs) have limited temperature measurement capabilities, struggling to reach temperatures above 1500℃. Furthermore, thermocouples used for ultra-high temperature measurements suffer from high cost, time consumption, and a lack of reliable calibration standards. Secondly, reactions between the material and the crucible are unavoidable at high temperatures, and no inert crucible can contain liquid oxide ceramic materials above 2000℃, making it difficult to meet the current design and development needs of high-melting-point oxide ceramic materials. Therefore, developing methods for determining the high-temperature melting point and phase transition temperature of oxide ceramic materials is an important research task. Summary of the Invention

[0004] To address the problems and shortcomings of existing methods, the present invention aims to provide a method for determining the melting point and phase transition temperature of oxide ceramics based on laser heating. This invention uses a carbon dioxide laser radio frequency device as the heating element and an infrared high-speed thermometer as the temperature measuring element, enabling the detection of the melting point and phase transition temperature of oxide ceramics within the range of 350-3500℃, thus achieving rapid and convenient detection of the melting point and phase transition temperature of ultra-high temperature oxide ceramics.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention discloses a method for determining the melting point and phase transition temperature of oxide ceramics based on laser heating. The method involves placing an oxide ceramic raw material column on the stage of a high-temperature phase transition measuring device. Then, the light spots emitted by a laser radio frequency device and an infrared thermometer are aligned with the oxide ceramic raw material column. The laser radio frequency device is activated to heat the oxide ceramic raw material column until it melts into a spherical shape. The laser radio frequency device is then turned off, and the infrared thermometer is used to continuously measure the temperature of the oxide ceramic raw material column to obtain the melting point and phase transition temperature of the oxide ceramic. The ceramic in the oxide ceramic raw material column is a composite ceramic.

[0007] Since the melting points of single oxides have been determined and reported, this invention is used to determine the melting point and phase transition temperature of composite ceramics with unknown melting points.

[0008] In a preferred embodiment, the melting point of the composite ceramic is 350-3500℃. The method of this invention is applicable to determining the melting point of composite ceramics within the range of 350-3500℃, offering a wide measurement range. In particular, it can accurately measure the melting point of high-melting-point composite ceramics.

[0009] In a preferred embodiment, the oxide ceramic raw material column is in block form, with a diameter of 2-5 mm, preferably 3 mm, and a mass of 0.04-0.05 g.

[0010] The inventors discovered that setting the oxide ceramic raw material column to the above range, in synergy with other parameters, resulted in the highest accuracy of the final melting point determination.

[0011] In a preferred embodiment, the oxide ceramic raw material column is obtained by pressing and sintering oxide ceramic powder; or by directly pressing oxide ceramic powder.

[0012] In a preferred embodiment, the laser radio frequency device has a power of 20-400W when heated, a laser wavelength of 10.6μm, an emission frequency of 5-50kHz, and a duty cycle of 5%-50%.

[0013] In actual operation, power affects the output energy of the laser radio frequency device. The power setting should take into account the melting point of the sample within the entire system composition range to ensure that the sample can be melted. Therefore, for samples with high melting points, the melting points of samples within its composition range will generally be high. In this case, it is necessary to increase the power to ensure complete melting.

[0014] In addition, the inventors discovered that turning off the laser radio frequency device after the oxide ceramic raw material column has melted into a spherical shape can prevent the oxide ceramic raw material column from shaking or even rotating, thus affecting the accuracy of the measurement results.

[0015] In a preferred embodiment, when starting the infrared thermometer, the emissivity of the infrared thermometer is first set. The emissivity is set by multiplying the emissivity of each end oxide in the composite ceramic by its mole fraction in the composite ceramic and summing the results.

[0016] For example, for binary composite oxide ceramic A m B n (m and n are mole fractions), where the emissivity of terminal oxide A is x1 and the emissivity of terminal oxide B is x2, then A m B n The emissivity is m·x1+n·x2, and for ternary and higher elements, the same method is used for determination.

[0017] The inventors discovered that by setting the emissivity of the infrared thermometer in the above manner, the emissivity of the infrared thermometer can correspond to the emissivity of the substance, thereby obtaining an accurate temperature. However, if the emissivity is not set properly, it will affect the accuracy of the measurement results.

[0018] In a further preferred embodiment, the emissivity of the terminal oxide is obtained as follows: First, an emissivity is preset on the infrared thermometer. After the terminal oxide ceramic raw material column is melted into a spherical shape as described above, the infrared thermometer is used to continuously measure the temperature of the terminal oxide ceramic raw material column to obtain the measured melting point. Then, based on the difference between the measured melting point and the actual melting point of the terminal oxide ceramic, and the rule that the higher the emissivity, the lower the measured temperature, the emissivity is reset. Another portion of the terminal oxide ceramic raw material column is taken for measurement. The above operation is repeated until the measured melting point is the same as the known melting point of the terminal oxide. Then, the set emissivity is taken as the emissivity of the terminal oxide.

[0019] In a preferred embodiment, the infrared thermometer has an output current of 0-20mA, a response time of 10μs, a measurement frequency of 10μs, and an emissivity of 0-1.

[0020] To ensure the accuracy of the results, all parameters except emissivity were kept consistent during the acquisition of the emissivity of the terminal oxide and the testing of the melting point of the oxide ceramic.

[0021] In the preferred embodiment, an infrared thermometer is activated to continuously measure the temperature of the oxide ceramic raw material column to obtain a temperature curve, from which the melting point and phase transition temperature are obtained.

[0022] When a sample is heated and melted, the supercooled liquid (melt) begins to solidify. The solidification rate is usually very fast. The latent heat of solidification released during the nucleation and transformation to the solid phase is released from the solid-liquid interface into the supercooled liquid at a rate much faster than that released from the droplet surface into the surrounding environment. This causes the droplet temperature to rise, resulting in the "re-glow" phenomenon. This is reflected in the cooling curve as a "curve bulge", a "brief plateau", and an "inflection point of the slope change", thus obtaining the melting point and phase transition temperature.

[0023] In a preferred embodiment, the high-temperature phase transition measuring device includes a stage, a laser radio frequency unit, a reflector group, a light-emitting nozzle, a fiber optic lens, an infrared thermometer, and a computer system. The laser radio frequency unit serves as a laser source for heating the oxide ceramic raw material column. The reflector group ensures that the laser source, after reflection, can vertically irradiate the surface of the oxide ceramic raw material column. The light-emitting nozzle is located directly above the oxide ceramic raw material column and is used to adjust the focusing range of the laser. The infrared thermometer emits LED indicator white light through the fiber optic lens for measuring the temperature of the oxide ceramic raw material column. The computer system is used to collect and process temperature data.

[0024] In a further preferred embodiment, an air inlet is provided above the light-emitting lens nozzle, through which a protective gas is introduced to prevent volatile samples from contaminating the light path.

[0025] In a further preferred embodiment, the high-temperature phase transition measuring device also includes a cooling circulation system for cooling the laser radio frequency unit.

[0026] The cooling circulation system mainly refers to the water chiller; the radio frequency unit needs to be cooled by the water chiller to ensure safe operation when it is operating at high power. When the temperature is higher than 30°C, the water chiller will automatically run, and circulating cooling water will flow into the radio frequency unit cavity to cool it down.

[0027] In a further preferred embodiment, the horizontal distance between the fiber optic lens of the infrared thermometer and the oxide ceramic raw material column is 15-25cm.

[0028] The fiber optic lens is connected to an infrared high-speed thermometer, which can emit a white LED light spot for aiming and temperature measurement without contacting the raw material column.

[0029] In a further preferred embodiment, the laser radio frequency device is a carbon dioxide laser radio frequency device.

[0030] Beneficial effects of the present invention

[0031] This method can detect the melting point and phase transition temperature of oxide ceramics in the range of 350-3500℃, enabling rapid and convenient detection of the melting point and phase transition temperature of ultra-high temperature oxide ceramics. Attached Figure Description

[0032] Figure 1This is a schematic diagram of the high-temperature phase transition measuring device of the present invention; in the figure: 1-carbon dioxide laser radio frequency device, 2-reflector group, 3-air inlet, 4-light output lens nozzle, 5-cooling circulation system, 6-stage, 7-oxide ceramic material, 8-fiber optic lens, 9-high-speed infrared thermometer, 10-computer system.

[0033] Figure 2 It is (Y2O3) of Embodiment 1 of the present invention. 95 Figure showing the results of the detection of melting point and phase transition temperature of (Nb2O5)5;

[0034] Figure 3 This refers to (ZrO2) in Embodiment 2 of the present invention. 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 Melting point and phase transition temperature test results graph. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] (Y2O3) 95 Determination of melting point and phase transition temperature of (Nb2O5)5

[0038] First, determine the emissivity of Y₂O₃ and Nb₂O₅:

[0039] Emission rate of Y2O3

[0040] Step 1: Y2O3 powder is pressed into shape and sintered to obtain a raw material column with a mass of 0.040g;

[0041] Step 2: Place the Y2O3 raw material column from Step 1 on the stage of the high-temperature phase transition measuring device, and align the red calibration spot emitted by the carbon dioxide laser radio frequency device with the white LED spot emitted by the fiber optic lens of the high-speed infrared thermometer. The carbon dioxide laser radio frequency device has a rated power of 400W and laser parameters including wavelength of 10.6μm, light output frequency of 5kHz, and duty cycle of 12%.

[0042] Step 3: The emissivity of Y2O3 is 0.5. The fiber optic lens of the high-speed infrared thermometer is about 20cm away from the raw material column. The temperature characteristic parameters include output current of 20mA, response time of 10μs, and measurement frequency of 10μs.

[0043] Step 4: Start the carbon dioxide laser radio frequency device for heating, and the raw material column Y2O3 in Step 3 begins to melt in the air;

[0044] Step 5: After the Y2O3 raw material column melts and tends to form a spherical shape in Step 4, the carbon dioxide laser radio frequency device is stopped. The temperature change is observed and recorded by the computer system using an infrared high-speed thermometer. The melting point is obtained as 2122℃. According to the known actual melting point of Y2O3, which is 2439℃, the emissivity of Y2O3 is re-determined according to the rule that the higher the emissivity, the lower the temperature. After repeating this process multiple times, the emissivity of Y2O3 is obtained as 0.420. The melting point obtained at this time is equal to the actual melting point of Y2O3.

[0045] Emission rate of Nb2O5

[0046] Step 1 involves pressing and sintering Nb2O5 powder to obtain a raw material column with a mass of 0.040g.

[0047] Step 2: Place the Nb2O5 raw material column from Step 1 on the stage of the high-temperature phase transition measuring device, and align the red calibration spot emitted by the carbon dioxide laser radio frequency device with the white LED spot emitted by the fiber optic lens of the high-speed infrared thermometer. The carbon dioxide laser radio frequency device has a rated power of 400W and laser parameters including wavelength of 10.6μm, light output frequency of 5kHz, and duty cycle of 12%.

[0048] Step 3: The emissivity of Nb2O5 is 0.5. The fiber optic lens of the high-speed infrared thermometer is about 20cm away from the raw material column. The temperature characteristic parameters include output current of 20mA, response time of 10μs, and measurement frequency of 10μs.

[0049] Step 4: Start the carbon dioxide laser radio frequency device for heating, and the raw material column Nb2O5 in Step 3 begins to melt in the air;

[0050] Step 5: After the Nb2O5 raw material column melts and tends to form a spherical shape in Step 4, the carbon dioxide laser radio frequency device is stopped. The temperature change is observed and recorded by a computer system using an infrared high-speed thermometer. The melting point is obtained as 1348℃. According to the known actual melting point of Nb2O5, which is 1492℃, the emissivity of Nb2O5 is re-evaluated according to the rule that the higher the emissivity, the lower the temperature. After repeating this process multiple times, the emissivity of Nb2O5 is obtained as 0.402. The melting point obtained at this time is equal to the actual melting point of Nb2O5.

[0051] Calculate (Y₂O₃) 95 Emissivity of (Nb2O5)5:

[0052] 0.95·0.420 + 0.05·0.402 = 0.419

[0053] (Y2O3) 95 Determination of the melting point and phase transition temperature of (Nb2O5)5:

[0054] Step 1: Apply ceramic oxide material (Y2O3) 95 (Nb2O5)5 powder was pressed, shaped, and sintered to obtain a raw material column with a mass of 0.040g;

[0055] Step 2: Take the raw material column (Y2O3) from Step 1. 95 (Nb2O5)5 is placed on the stage of the high-temperature phase transition measuring device, and the red calibration spot emitted by the carbon dioxide laser radio frequency device and the white LED spot emitted by the fiber optic lens of the high-speed infrared thermometer are aligned with the raw material column. The power of the carbon dioxide laser radio frequency device is 400W, and the laser parameters include wavelength 10.6μm, light output frequency 5kHz, and duty cycle 12%.

[0056] Step 3: Adjust the emissivity parameters of the high-speed infrared thermometer to match those of the raw material column (Y2O3) in Step 2 using the computer system. 95 The emissivity parameter of (Nb2O5)5 is 0.419. The horizontal distance between the fiber optic lens of the high-speed infrared thermometer and the raw material column is about 20cm. The temperature characteristic parameters include output current 0-20mA, response time 10μs, measurement frequency 10μs, and emissivity adjustable from 0-1.

[0057] Step 4: Start the carbon dioxide laser radio frequency device for heating, and heat the raw material column (Y2O3) from Step 3. 95 (Nb2O5)5 begins to melt in air;

[0058] Step 5: When the raw material column (Y2O3) in Step 4... 95 After (Nb₂O₅)₅ melted and tended to form a spherical shape, the carbon dioxide laser radio frequency was stopped. Temperature changes were observed and recorded using a computer system and a high-speed infrared thermometer. Each component was tested with three different samples, and each sample was measured at least five times to ensure accuracy. One of the obtained cooling characteristic curves is shown below. Figure 2 As shown in the cooling characteristic curves, the ceramic oxide material (Y2O3) obtained using this method can be observed. 95 The melting point of (Nb₂O₅)₅ is 2394±23℃; its eutectic reaction temperature (L→C-Y₂O₃+F-Y₃NbO₇) is 2312±34℃. It can be seen that the test results obtained using the method of Example 1 of this invention have a narrow range distribution, indicating that the test method of this invention is accurate and reliable.

[0059] Example 2

[0060] First, using the same method as in Example 1, the emissivity of ZrO2, Y2O3, and Nb2O5 was determined to be 0.399, 0.420, and 0.402, respectively.

[0061] Then, according to the formula: 0.182·0.399 + 0.409·0.420 + 0.409·0.402 = 0.409

[0062] (ZrO2) is obtained. 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 The emissivity parameter is 0.409.

[0063] Step 1: Apply ceramic oxide material (ZrO2) 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 The powder was pressed into shape and sintered to obtain a raw material column with a mass of 0.040g;

[0064] Step 2: Take the raw material column (ZrO2) from Step 1. 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 Placed on the stage of the high-temperature phase transition measuring device, the red calibration spot emitted by the carbon dioxide laser radio frequency device and the white LED spot emitted by the fiber optic lens of the high-speed infrared thermometer are aligned with the raw material column. The carbon dioxide laser radio frequency device has a rated power range of 400W and laser parameters including wavelength of 10.6μm, light output frequency of 5kHz, and duty cycle of 15%.

[0065] Step 3: Adjust the emissivity parameters of the high-speed infrared thermometer to match those of the raw material column (ZrO2) in Step 2 using the computer system. 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 The emissivity parameter is 0.422. The high-speed infrared thermometer is equipped with an optical fiber lens that is about 20cm away from the raw material column. The temperature characteristic parameters include output current of 20mA, response time of 10μs, measurement frequency of 10μs, and emissivity adjustable from 0 to 1.

[0066] Step 4: Start the carbon dioxide laser radio frequency device for heating, and heat the raw material column (ZrO2) from Step 3. 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 It begins to melt in the air;

[0067] Step 5: When the raw material column (ZrO2) in Step 4... 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 After the melt tends to form a spherical shape, the carbon dioxide laser radio frequency device is stopped. The temperature change is observed and recorded using a computer system and a high-speed infrared thermometer. Each component is tested with three different samples, and each sample is measured at least five times to ensure accuracy. One cooling characteristic curve is obtained, as shown below. Figure 3 As shown in the cooling characteristic curves, the ceramic oxide material (ZrO2) detected using this method can be seen from the cooling characteristic curves. 18.2 (Y2O3) 40.9 (Nb2O5) 40.9 The melting point temperature is 2012±13℃. It can be seen that the test results obtained using the method of Example 2 of this invention have a narrow range distribution, indicating that the test method of this invention is accurate and reliable.

[0068] Matters not covered in this invention are common knowledge.

[0069] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for determining the melting point and phase transition temperature of oxide ceramics based on laser heating, characterized in that: An oxide ceramic raw material column is placed on the stage of a high-temperature phase transition measuring device. Then, the light spots emitted by the laser radio frequency device and the infrared thermometer are aligned with the oxide ceramic raw material column. The laser radio frequency device is activated to heat the oxide ceramic raw material column until it melts into a spherical shape. The laser radio frequency device is then turned off, and the infrared thermometer is used to continuously measure the temperature of the oxide ceramic raw material column to obtain the melting point and phase transition temperature of the oxide ceramic. The ceramic in the oxide ceramic raw material column is a composite ceramic. The oxide ceramic raw material column is in block form, with a diameter of 2-5 mm and a mass of 0.04-0.05 g; When starting the infrared thermometer, first set the emissivity of the infrared thermometer. The emissivity is set by multiplying the emissivity of each end oxide in the composite ceramic by its mole fraction in the composite ceramic and summing the results. The emissivity of the terminal oxide is obtained as follows: First, preset an emissivity for the infrared thermometer. Then, melt the terminal oxide ceramic raw material column into a spherical shape as described above. Next, start the infrared thermometer to continuously measure the temperature of the terminal oxide ceramic raw material column to obtain the measured melting point. Then, based on the difference between the measured melting point and the actual melting point of the terminal oxide ceramic, and the rule that the higher the emissivity, the lower the measured temperature, reset the emissivity. Take another portion of the terminal oxide ceramic raw material column for measurement. Repeat the above operation until the measured melting point is the same as the known melting point of the terminal oxide. Then, take the set emissivity as the emissivity of the terminal oxide.

2. The method for determining the melting point and phase transition temperature of oxide ceramics based on laser heat source heating according to claim 1, characterized in that: The melting point of the composite ceramic is 350-3500℃.

3. The method for determining the melting point and phase transition temperature of oxide ceramics based on laser thermal source heating according to claim 1, characterized in that: The oxide ceramic raw material column is obtained by pressing and sintering oxide ceramic powder; or by directly pressing oxide ceramic powder.

4. The method for determining the melting point and phase transition temperature of oxide ceramics based on laser heat source heating according to claim 1, characterized in that: The laser radio frequency device has a power of 20-400W when heated, a laser wavelength of 10.6mm, an output frequency of 5-50kHz, and a duty cycle of 5%-50%.

5. The method for determining the melting point and phase transition temperature of oxide ceramics based on laser heat source heating according to claim 1, characterized in that: The infrared thermometer has an output current of 0-20mA, a response time of 10μs, a measurement frequency of 10μs, and an emissivity of 0-1.

6. The method for determining the melting point and phase transition temperature of oxide ceramics based on laser thermal source heating according to claim 1, characterized in that: The infrared thermometer is activated to continuously measure the temperature of the oxide ceramic raw material column, and a temperature curve is obtained. The melting point and phase transition temperature are obtained from the temperature curve.

7. The method for determining the melting point and phase transition temperature of oxide ceramics based on laser heat source heating according to claim 1, characterized in that: The high-temperature phase transition measuring device includes a stage, a laser radio frequency unit, a reflector group, a light-emitting nozzle, a fiber optic lens, an infrared thermometer, and a computer system. The laser radio frequency unit serves as a laser source for heating the oxide ceramic raw material column. The reflector group ensures that the laser source, after reflection, can perpendicularly irradiate the surface of the oxide ceramic raw material column. The light-emitting nozzle is located directly above the oxide ceramic raw material column and is used to adjust the focusing range of the laser. The infrared thermometer emits LED indicator white light through the fiber optic lens to measure the temperature of the oxide ceramic raw material column. The computer system is used to collect and process temperature data. An air inlet is also provided above the light-emitting lens nozzle, through which protective gas is introduced to prevent volatile samples from contaminating the light path; The high-temperature phase transition measuring device also includes a cooling circulation system for cooling the laser radio frequency unit; The horizontal distance between the fiber optic lens of the infrared thermometer and the oxide ceramic raw material column is 15-25cm. The laser radio frequency device is a carbon dioxide laser radio frequency device.

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