Calibration method of synchronous thermal analyzer

Abstract

The invention belongs to the field of thermal analysis, and particularly relates to a calibration method of a synchronous thermal analyzer, temperature calibration, enthalpy calibration and thermogravimetric calibration of the synchronous thermal analyzer are carried out by adopting a standard substance with known melting point and enthalpy data, and high precision of each calibration step is ensured, so that the accuracy of measured data of the synchronous thermal analyzer is improved. The calibration method is suitable for various standard substances, can be widely applied to different types of synchronous thermal analyzers, and has good applicability and universality. The calibration coefficient and the temperature deviation are automatically calculated through an instrument, the calibration process is simplified, the experiment efficiency is improved, and personal errors are reduced. The method is verified through multiple experiments and has good repeatability, and it is ensured that measurement results are consistent when different instruments in different batches are used.

Description

Technical Field

[0001] The present application belongs to the field of thermal analysis, and specifically relates to a calibration method for a synchronous thermal analyzer. Background Art

[0002] Synchronous thermal analysis (STA) is a comprehensive analytical method that combines thermogravimetric analysis (TG) and differential thermal analysis (DTA) techniques, and is widely used to measure the mass change and thermal effect of materials at different temperatures. Synchronous thermal analyzers can simultaneously record the thermogravimetric changes and differential thermal effects of samples in the same experiment, thus providing strong support for studying the physical and chemical changes of substances.

[0003] In the process of synchronous thermal analysis, the accurate measurement of temperature, enthalpy and thermogravimetry is often affected by many factors, such as the position of the thermocouple, the thermal resistance of the crucible, etc. Since the synchronous thermal analyzer does not directly measure the true temperature and enthalpy of the sample, there is a large measurement error. Most of the studies that have been published so far directly use the synchronous thermal analyzer to measure the thermogravimetry, temperature and enthalpy of the sample, and lack an effective calibration method.

[0004] Application Contents

[0005] The technical problem to be solved by the present application is to provide a calibration method for a synchronous thermal analyzer, by measuring the thermal enthalpy change of a standard substance through differential thermal analysis, and obtaining a correction coefficient of the synchronous thermal analyzer, thereby improving the measurement accuracy.

[0006] The present application provides a calibration method for a synchronous thermal analyzer, comprising the following steps:

[0007] Perform temperature calibration of a simultaneous thermal analyzer:

[0008] S1. Quantitatively weigh a plurality of standard substances, place them in corresponding numbers of crucibles, and prepare empty crucibles as reference samples;

[0009] S2. Then use the synchronous thermal analyzer to measure the melting points of multiple standard substances respectively. There is a certain temperature difference ΔT between the measured value and the actual value. Test multiple standard substances with different melting points respectively to obtain the ΔT corresponding to multiple melting points in the instrument measurement temperature range. Then, a series of ΔT values ​​are curve-fitted to obtain a ΔT / T calibration curve. In the actual measurement process, for any measured temperature T, the corresponding deviation value ΔT is found on the calibration curve and deducted, and it can be converted into the actual temperature Ts of the sample, thereby completing the calibration of the instrument temperature data;

[0010] To perform enthalpy calibration of a simultaneous thermal analyzer:

[0011] S3, then using a synchronous thermal analyzer to measure the melting points of multiple standard substances respectively, and obtain a DTA-TG spectrum;

[0012] S4. Analyze the DTA curve peak area of ​​the standard substance by synchronous thermal analyzer, and automatically calculate the instrument correction factor K according to the derived Speil formula -1 , automatically draw K -1 -T curve;

[0013] S5, based on K -1 -T curve, the synchronous thermal analyzer obtains the corresponding heat correction coefficient K according to the temperature of the measured sample, and then automatically calculates the thermal enthalpy change value ΔH of the measured sample.

[0014] Optionally, the standard substances include at least three of indium, tin, lead, zinc and aluminum.

[0015] Optionally, the standard substances include indium, tin, lead, zinc and aluminum.

[0016] Optionally, in S1, the weighed weight of each standard substance is equal and is 8-12 mg.

[0017] Optionally, in S1, the weighed weight of each standard substance is equal and is 10 mg.

[0018] Optionally, in S1, when measuring each standard substance, the heating rate of the synchronous thermal analyzer is 8-12°C / min.

[0019] Optionally, in S1, when measuring each standard substance, the heating rate of the synchronous thermal analyzer is 10°C / min.

[0020] Optionally, in S1 , when measuring each standard substance, the temperature of the synchronous thermal analyzer is respectively increased to at least 80° C. higher than the melting point of the corresponding standard substance.

[0021] Optionally, the calibration method further comprises the following steps:

[0022] Perform thermal gravimetric calibration of a simultaneous thermal analyzer;

[0023] On the basis of S1 and S2, calcium oxalate monohydrate is quantitatively weighed as a standard substance and placed in a crucible, and then measured with a synchronous thermal analyzer to obtain the corresponding DTA-TG spectrum; the weight loss rate of each step of the TG curve and the total weight loss rate are analyzed; the three weight loss percentages of calcium oxalate monohydrate measured are calculated according to the formula: the weight loss rate of the last calibration + (the actual weight loss rate of this time - the theoretical weight loss rate) to calculate the weight loss data that needs to be modified, and the calculated weight loss data is input into the instrument to complete the weight loss data calibration.

[0024] Optionally, the heating rate of the synchronous thermal analyzer is 8-12°C / min, and the temperature is increased to 1000°C.

[0025] The beneficial effect of the present application is that by using standard materials with known melting points and thermal enthalpy data, the high precision of each calibration step is ensured, thereby improving the accuracy of the data measured by the synchronous thermal analyzer. The calibration method is applicable to a variety of standard materials and can be widely used in different types of synchronous thermal analyzers, with good applicability and universality. The calibration process is simplified by automatically calculating the correction coefficient and temperature deviation through the instrument, improving the experimental efficiency and reducing human errors. The method has been verified by multiple experiments and has good repeatability, ensuring that the measurement results of different batches and different instruments are consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The DTA-TG spectrum of metallic lead provided in this application;

[0027] Figure 2 The heat correction coefficient K-1-T curve diagram provided for this application;

[0028] Figure 3 DTA-TG spectrum of CaC2O4·H2O provided in this application;

[0029] Figure 4 This is the DTA-TG spectrum of quartz provided in this application. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0031] Extrapolated onset temperature T e The value usually refers to a temperature point determined by a specific method in a thermal analysis experiment. This temperature point marks the starting point where a certain thermal effect or physical change occurs in the material. In thermal analysis techniques such as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), T e Values ​​are often used to evaluate the thermal stability, thermal decomposition characteristics, etc. of materials.

[0032] The peak area of ​​the DTA (differential thermal analysis) curve is an important thermal analysis parameter, which represents the area surrounded by the baseline before and after the reaction. The peak area of ​​the DTA curve reflects the energy change corresponding to the temperature difference between the sample and the reference during heating or cooling. This energy change is closely related to the physical or chemical changes that occur in the sample, so the peak area can be used as an important indicator to evaluate these changes.

[0033] As shown in the figure, the present application provides a calibration method for a synchronous thermal analyzer, comprising the following steps:

[0034] Perform temperature calibration of a simultaneous thermal analyzer:

[0035] S1. Quantitatively weigh a plurality of standard substances, place them in corresponding numbers of crucibles, and prepare empty crucibles as reference samples;

[0036] S2. Then use the synchronous thermal analyzer to measure the melting points of multiple standard substances respectively. There is a certain temperature difference ΔT between the measured value and the actual value. Test multiple standard substances with different melting points respectively to obtain the ΔT corresponding to multiple melting points in the instrument measurement temperature range. Then, a series of ΔT values ​​are curve-fitted to obtain a ΔT / T calibration curve. In the actual measurement process, for any measured temperature T, the corresponding deviation value ΔT is found on the calibration curve and deducted, and it can be converted into the actual temperature Ts of the sample, thereby completing the calibration of the instrument temperature data;

[0037] To perform enthalpy calibration of a simultaneous thermal analyzer:

[0038] S3, then using a synchronous thermal analyzer to measure the melting points of multiple standard substances respectively, and obtain a DTA-TG spectrum;

[0039] S4. Analyze the DTA curve peak area of ​​the standard substance by synchronous thermal analyzer, and automatically calculate the instrument correction factor K according to the derived Speil formula -1 , automatically draw K -1 -T curve;

[0040] S5, based on K -1 -T curve, the synchronous thermal analyzer obtains the corresponding heat correction coefficient K according to the temperature of the measured sample, and then automatically calculates the thermal enthalpy change value ΔH of the measured sample.

[0041] Compared with the prior art, the calibration method of the synchronous thermal analyzer provided in the present application ensures the high precision of each calibration step by adopting standard substances with known melting points and thermal enthalpy data, thereby improving the accuracy of the measurement data of the synchronous thermal analyzer. The calibration method is applicable to a variety of standard substances and can be widely used in different types of synchronous thermal analyzers, with good applicability and universality. The calibration process is simplified by automatically calculating the correction coefficient and temperature deviation through the instrument, improving the experimental efficiency and reducing human errors. The method has been verified by multiple experiments and has good repeatability, ensuring that the measurement results of different batches and different instruments are consistent.

[0042] In one embodiment, the standard substances include at least three of indium, tin, lead, zinc and aluminum. If there are less than three standard substances, a DTA-TG spectrum cannot be obtained, and too many standard substances will increase the workload.

[0043] In one embodiment, the standard substances include indium, tin, lead, zinc and aluminum. The melting point range of the five standard substances is 156.6-660.0°C, covering a wide range, and the span from the ground melting point to the high melting point is relatively uniform. On the basis of ensuring the accuracy of the DTA-TG spectrum, the workload is moderate.

[0044] In one embodiment, in S1, the weight of each standard substance is equal and is 8-12 mg. Preferably, in S1, the weight of each standard substance is equal and is 10 mg.

[0045] In one embodiment, in S1, when measuring each standard substance, the temperature rise rate of the synchronous thermal analyzer is 8-12°C / min. Too slow a temperature rise rate will increase the test time, and too fast a temperature rise rate will have the following effects:

[0046] Impact on peak temperature and peak shape: Rapid heating will push the reaction to the high temperature zone at a faster speed, which will cause the peak temperature of the thermal analysis curve (such as the DTA curve) to increase, and the peak amplitude to narrow, showing a sharp peak shape. For multi-stage reactions, rapid heating may make the boundaries between stage reactions blurred and difficult to distinguish. On the contrary, slow heating is conducive to the separation of stage reactions, making the thermal analysis curve show separated multiple peaks.

[0047] Impact on mass loss rate: Higher heating rates result in faster mass loss because the sample loses volatile components or pyrolyzes more quickly at a faster rate. This results in an increased mass loss rate on the thermogravimetric analysis (TGA) curve, which becomes steeper.

[0048] Influence on temperature distribution: The heating rate will also affect the temperature distribution of various parts in the sample. When the heating rate is too fast, the temperature difference between the inside and outside of the sample will increase, which may lead to uneven temperature distribution inside the sample, thus affecting the accuracy of thermal analysis results. For example, in differential scanning calorimetry (DSC) measurement, if the heating rate is too fast, it may lead to a significant temperature difference between the inside and outside of the sample, thus affecting the accurate measurement of thermal effects.

[0049] Affecting the accuracy and reliability of the experiment: Since a too fast heating rate may lead to the above-mentioned effects, it will also indirectly affect the accuracy and reliability of the experiment. Inaccurate thermal analysis curves may lead to misjudgment of the thermal stability and composition of the sample, thus affecting subsequent material research and development and application.

[0050] Preferably, in S1, when measuring each standard substance, the heating rate of the synchronous thermal analyzer is 10°C / min.

[0051] In one embodiment, in S1, when measuring each standard substance, the temperature of the synchronous thermal analyzer is respectively raised to at least 80°C higher than the melting point of the corresponding standard substance. In this way, it can be ensured that the standard substance is completely melted during the measurement process, which is crucial for accurately evaluating the performance of the thermal analyzer, because partial melting may cause deviations in the measurement results. By ensuring complete melting, more stable and accurate thermal analysis data can be obtained. By rising to a higher temperature, the impact of this thermal hysteresis effect can be reduced, making the measurement results closer to the true value. By keeping it at a temperature above the melting point for a period of time, the stability of the thermal effect can be observed. This helps to evaluate the performance of the thermal analyzer under long-term high temperature conditions and the thermal stability of the sample at high temperatures.

[0052] Preferably, when measuring each standard substance, the temperature of the synchronous thermal analyzer is raised to 100° C. higher than the melting point of the corresponding standard substance.

[0053] In one embodiment, the calibration method further comprises the following steps:

[0054] Perform thermal gravimetric calibration of a simultaneous thermal analyzer;

[0055] On the basis of S1 and S2, calcium oxalate monohydrate is quantitatively weighed as a standard substance and placed in a crucible, and then measured with a synchronous thermal analyzer to obtain the corresponding DTA-TG spectrum; the weight loss rate of each step of the TG curve and the total weight loss rate are analyzed; the three weight loss percentages of calcium oxalate monohydrate measured are calculated according to the formula: the weight loss rate of the last calibration + (the actual weight loss rate of this time - the theoretical weight loss rate) to calculate the weight loss data that needs to be modified, and the calculated weight loss data is input into the instrument to complete the weight loss data calibration.

[0056] In one embodiment, the temperature rise rate of the synchronous thermal analyzer is 8-12°C / min, and the temperature rises to 1000°C.

[0057] Using calcium oxalate monohydrate standard substance and based on its theoretical weight loss data, thermogravimetric analysis was performed on the synchronous thermal analyzer to correct the thermogravimetric measurement data of the instrument to ensure measurement accuracy.

[0058] The above calibration method can effectively improve the accuracy of the synchronous thermal analyzer when performing TG-DTA analysis, especially when measuring the temperature, thermal enthalpy and thermogravimetry of the sample, and can more accurately reflect the true properties of the sample.

[0059] Example 1

[0060] Experimental reagents and instruments

[0061] Standard substances: indium, tin, lead, zinc, aluminum; sample: quartz; provided by Beijing Hengjiu Experimental Equipment Co., Ltd.

[0062] Experimental instrument: HCT-4 synchronous thermal analyzer (Beijing Hengjiu Experimental Equipment Co., Ltd.).

[0063] Experimental method: Accurately weigh the standard sample (10.0±0.2mg) and put it into an alumina crucible. The empty crucible is the reference sample. The temperature is raised from room temperature to a temperature about 100℃ higher than the melting point of the standard substance at a heating rate of 10℃ / min. The temperature is maintained for 5 minutes to obtain a DTA-TG spectrum (differential thermal-thermogravimetric analysis spectrum). Figure 1 Shown is the DTA-TG spectrum of metallic lead.

[0064] Temperature Calibration:

[0065] In a synchronous thermal analyzer, since the standard material is not in direct contact with the thermocouple, there is a certain difference between the actual temperature of the standard material and the measured temperature; furthermore, the thermal effect generated when heating and reacting often makes the temperature distribution around the standard material uneven, thus causing a large temperature measurement error. Due to factors such as the thermal resistance of the crucible, there is a certain temperature difference ΔT between the actual temperature of the sample and the temperature detected by the thermocouple. And since ΔT is a value that changes with temperature, the deviation value ΔT is not the same at different temperatures. Therefore, it is necessary to test multiple standard materials with different melting points separately to obtain ΔT at multiple temperature points in the instrument's measurement temperature range, and then fit a series of ΔT values ​​to a curve to obtain a ΔT / T correction curve. In the actual measurement process, for any measured temperature T, find the corresponding deviation value ΔT on the correction curve and deduct it, and it can be converted into the true temperature Ts of the sample, thereby completing the calibration of the instrument's temperature data.

[0066] According to the above experimental method, the DTA-TG spectra of each standard substance were analyzed and the extrapolated starting temperature T e Value, if T e If the value is within the error range compared with the theoretical temperature, no calibration is required. If it is outside the error range, calibration is required. Figure 1 Taking the DTA-TG spectrum of metallic lead as an example, we can deduce the T e The temperature is 327.33°C and ΔH is 21.43 J / g, which are within the error range compared with the theoretical values ​​in Table 1 below.

[0067] Table 1

[0068] Calibration object <![CDATA[Theoretical temperature T e / ℃]]> Allowable error / ℃ indium 156.6 ±4 tin 231.9 ±4 lead 327.5 ±4 Zinc 419.5 ±4 aluminum 660.0 ±4

[0069] Enthalpy calibration:

[0070] When the temperature of the standard substance undergoes thermal changes, part of the heat is transferred to the temperature sensing device, and the other part is transferred outside the temperature sensing device. Therefore, the enthalpy in the obtained DTA spectrum only represents the enthalpy change of the part transmitted to the temperature sensing device. Therefore, in order to obtain the true enthalpy change of the sample, necessary enthalpy correction is required.

[0071] According to the above experimental method, the DTA-TG spectrum of the standard substance is obtained, and the peak area of ​​the DTA curve of the standard substance is analyzed. The instrument automatically calculates the instrument correction factor K according to the following Speil formula (1-3) derived -1 As shown in Table 2 below, K is automatically plotted. -1 -T curve as Figure 2 The synchronous thermal analyzer obtains the corresponding heat correction coefficient K according to the temperature of the sample being tested, and then automatically calculates the thermal enthalpy change value ΔH of the sample being tested.

[0072] The differential thermal curve can obtain the temperature and peak area of ​​the physical and chemical changes of the measured substance. The peak area is directly related to the enthalpy change of the change process. Equations 1 and 2 are obtained from the Speil formula:

[0073]

[0074] K=(gλs) -1 (2)

[0075] From equations 1 and 2, we can deduce:

[0076] In the above equation, m is the mass of the standard substance; A is the peak area; g is the coefficient related to the instrument; λs is the thermal conductivity of the standard substance; ΔH is the enthalpy change of the substance; and K is the instrument correction coefficient. The K value usually increases with increasing temperature. A TK curve is made by measuring a series of standard substances, so that the instrument can automatically analyze the enthalpy change of the substance based on the TK curve and the above equation.

[0077] Table 2

[0078] Calibration object English name <![CDATA[T e / ℃]]> Theoretical enthalpy change (J / g) <![CDATA[K -1 / J(℃·s) -1 ]]> indium In 156.6 28.5 238.2318 tin Sn 231.9 60.7 296.1502 lead Pb 327.5 22.6 384.7418 Zinc Zn 419.5 113 479.1824 aluminum Al 660.0 396 644.0266

[0079] Thermal Recalibration:

[0080] Accurately weigh the calcium oxalate monohydrate (CaC2O4·H2O) standard substance and raise the temperature from room temperature to 1000℃. According to the above experimental method, the DTA-TG curve of calcium oxalate monohydrate is obtained as follows Figure 3 As shown, the weight loss rate of each step and the total weight loss rate of the TG curve are analyzed.

[0081] First step reaction: CaC2O4·H2O→CaC2O4+H2O

[0082] The second step reaction: CaC2O4→CaCO3+CO

[0083] The third step reaction: CaCO3→CaO+CO2

[0084] The three-step reaction corresponds to three weight loss steps. The difference between the three-step weight loss rate and the theoretical weight loss rate is no more than 2%, and the difference between the total weight loss rate and the theoretical weight loss rate is no more than 4%, indicating that the thermogravimetric data of the instrument is accurate. The three weight loss percentages of calcium oxalate monohydrate measured are calculated according to the formula: weight loss of the last calibration + (actual weight loss of this measurement - theoretical weight loss) to calculate the weight loss data that needs to be modified, and the calculated weight loss data is input into the instrument to complete the weight loss data calibration.

[0085] Quartz sample testing:

[0086] According to the known standard, 51.2 mg of quartz sample was accurately weighed and subjected to TG-DTA analysis. The DTA-TG spectrum obtained by analysis ( Figure 4 ), the crystal transition temperature of the sample and its corresponding enthalpy change can be obtained. For example, the quartz sample undergoes a crystal transition at 578.51°C, and the enthalpy change is 10.30 J / g.

[0087] As can be seen from the above embodiments, the present invention ensures the high precision of each calibration step by using standard substances with known melting point, thermal enthalpy and weight loss data, thereby improving the accuracy of the synchronous thermal analyzer measurement data. The calibration method is applicable to a variety of standard substances and can be widely used in different types of synchronous thermal analyzers, with good applicability and universality. The present invention simplifies the calibration process, improves experimental efficiency, and reduces human errors by automatically calculating the correction coefficient and temperature deviation through the instrument. The method has good repeatability after multiple experimental verifications, ensuring that the measurement results of different batches and different instruments are consistent.

[0088] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0089] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A method for calibrating a synchronous thermal analyzer, characterized in that: The following steps are involved: Perform temperature calibration of a simultaneous thermal analyzer: S1. Quantitatively weigh a plurality of standard substances, place them in corresponding numbers of crucibles, and prepare empty crucibles as reference samples; S2. Then use the synchronous thermal analyzer to measure the melting points of multiple standard substances respectively. There is a certain temperature difference ΔT between the measured value and the actual value. Test multiple standard substances with different melting points respectively to obtain the ΔT corresponding to multiple melting points in the instrument measurement temperature range. Then, a series of ΔT values ​​are curve-fitted to obtain a ΔT / T calibration curve. In the actual measurement process, for any measured temperature T, the corresponding deviation value ΔT is found on the calibration curve and deducted, and it can be converted into the actual temperature Ts of the sample, thereby completing the calibration of the instrument temperature data; To perform enthalpy calibration of a simultaneous thermal analyzer: S3, then using a synchronous thermal analyzer to measure the melting points of multiple standard substances respectively, and obtain a DTA-TG spectrum; S4. Analyze the DTA curve peak area of ​​the standard substance by synchronous thermal analyzer, and automatically calculate the instrument correction factor K according to the derived Speil formula -1 , automatically draw K -1 -T curve; S5, based on K -1 -T curve, the synchronous thermal analyzer obtains the corresponding heat correction coefficient K according to the temperature of the measured sample, and then automatically calculates the thermal enthalpy change value ΔH of the measured sample.

2. The calibration method according to claim 1, characterized in that: The standard substances include at least three of indium, tin, lead, zinc and aluminum.

3. The calibration method according to claim 2, characterized in that: The standard substances include indium, tin, lead, zinc and aluminum.

4. The calibration method according to claim 1, characterized in that: In S1, the weighed weight of each standard substance is equal and is 8-12 mg.

5. The calibration method according to claim 1, characterized in that: In S1, the weighed weight of each standard substance is equal and is 10 mg.

6. The calibration method according to claim 1, characterized in that: In S1, the heating rate of the synchronous thermal analyzer was 8-12°C / min when measuring each standard substance.

7. The calibration method according to claim 1, characterized in that: In S1, the temperature increase rate of the synchronous thermal analyzer was 10°C / min when measuring each standard substance.

8. The calibration method according to claim 1, characterized in that: In S1, when measuring each standard substance, the temperature of the synchronous thermal analyzer is respectively increased to at least 80° C. higher than the melting point of the corresponding standard substance.

9. The calibration method according to claim 1, characterized in that: The following steps are also included: Perform thermal gravimetric calibration of a simultaneous thermal analyzer; On the basis of S1 and S2, calcium oxalate monohydrate is quantitatively weighed as a standard substance and placed in a crucible, and then measured with a synchronous thermal analyzer to obtain the corresponding DTA-TG spectrum; the weight loss rate of each step of the TG curve and the total weight loss rate are analyzed; the three weight loss percentages of calcium oxalate monohydrate measured are calculated according to the formula: the weight loss rate of the last calibration + (the actual weight loss rate of this time - the theoretical weight loss rate) to calculate the weight loss data that needs to be modified, and the calculated weight loss data is input into the instrument to complete the weight loss data calibration.

10. The calibration method according to claim 9, characterized in that: The heating rate of the synchronous thermal analyzer is 8-12°C / min, and the temperature rises to 1000°C.

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