Quality Lab Test Instrument & TLD Dosimetry Factory

With the increasing demand from the new energy materials industry, lithium hydroxide hydrate, as an important intermediate in lithium salt chemistry, is widely used in cathode material preparation, coating additives, lubricants, glass and ceramics industries. Its dehydration and decomposition behavior not only affects material purity but also directly relates to sintering temperature settings, storage processes, and composition control. This paper, based on synchronous thermal analysis results, outlines the decomposition mechanism and key temperature range of lithium hydroxide monohydrate in an oxygen atmosphere, providing data support for enterprise production and engineering applications. I. Experimental Procedure 1. Measuring Instrument: STA400 Synchronous Thermal Analyzer 2. Sample: Lithium hydroxide monohydrate 3. Experimental Parameters: Ambient: Oxygen Heating Rate: 5℃/min Temperature Range: 25℃ to 800℃ Note: Data under an oxygen atmosphere more closely reflects actual sintering and oxidation processes. 4. Measurement Spectra 5. Measurement Spectrum Analysis: Stage 1: Removal of Water of Crystallization Temperature Range: 31.8℃ to 130.3℃ Weight Loss: ≈11.31% Thermal Effect: Obvious endothermic peak (≈90℃) LiOH·H2O→LiOH+H2O↑ Implication: Complete dehydration can only be achieved at drying temperatures above 130℃; below this temperature, long-term storage does not easily result in water loss. Stage 2: Thermal Decomposition of Lithium Hydroxide Temperature Range: 198.9℃ to 456.4℃ Weight Loss: ≈12.53% Thermal Effect: Second endothermic peak (≈276℃) Core Reaction: 2LiOH→Li₂O+H₂O↑ Implication: 200℃ to 450℃ is the critical decomposition range. If the sintering temperature of the cathode material covers this range, the proportion change caused by water evaporation needs to be considered. Excessive residence time in this range may lead to lithium loss, stoichiometric deviations, and high oxygen content in the product. Stage 3: High-Temperature Stability Temperature Range: 590.7℃ to 744.4℃ Weight Loss: ≈0.32% Explanation: No significant reaction; the system tends to stabilize. II. Experimental Conclusions Temperatures above 600℃ can be considered a relatively stable range for Li₂O, suitable for maintaining the stability of the lithium source structure in subsequent high-temperature stages. This thermal analysis provides the complete route of LiOH·H₂O→LiOH→Li₂O and the key temperature control points, serving as an important reference for material formulation and sintering temperature setting.

Thermogravimetric Analysis of Resin Polyvinyl chloride (PVC) resin, as a core variety of general-purpose plastics, is widely used in key areas such as building pipes, electronic and electrical insulation, and packaging materials. Its thermal stability directly determines the feasibility of product processing and its service safety. During high-temperature processing or long-term use, PVC is prone to dehydrochlorination chain degradation, leading to discoloration, embrittlement, and even failure. Therefore, accurately characterizing thermal degradation behavior is a core requirement for formulation optimization and quality control. Thermogravimetric analysis (TGA) can monitor the quality changes of PVC under programmed temperature rise in real time, providing key parameters such as initial decomposition temperature and maximum degradation rate, providing a scientific basis for PVC resin research and development, stabilizer screening, and quality control in the production process. I. Experimental Procedure 1. Measuring Instrument: TGA200 Thermogravimetric Analyzer 2. Sample Preparation Procedure: This experiment uses industrial-grade PVC resin as the test object, focusing on the optimization of TGA test conditions and the analysis of thermal degradation behavior. 2.1 Pretreatment: The PVC resin was dried in an 80°C drying oven for 4 hours to remove moisture interference. 2.2 Preparation Method: The sample was pulverized using a grinding machine and sieved to ensure uniform particle size. 2.3 Sample Amount: 10-20 mg of sample was weighed and placed in a ceramic crucible. Too large a sample amount would lead to uneven heat transfer, while too small a amount would result in a weak signal, affecting data accuracy. 3. Software Parameter Settings: Temperature, heating rate, and atmospheric environment were set through the equipment's operating software. Cut-off temperature: 700°C, heating rate: 20°C/min, nitrogen atmosphere throughout. 4. Spectral Analysis: From the data in the above figure, we can see that the thermal degradation of PVC resin under a nitrogen atmosphere exhibits a typical two-stage characteristic: 1. Dechlorination Stage (200-350℃): Unstable chlorine atoms on the PVC molecular chain initiate a chain reaction, releasing HCl gas and forming a conjugated polyene structure. This stage accounts for approximately 70% of the total mass loss. 2. Main Chain Breaking Stage (300-700℃): The conjugated polyene structure further decomposes into low-molecular-weight hydrocarbon compounds, with the residue ultimately forming carbonaceous residue. The DTG peak in the first stage (around 300℃) verifies the concentrated occurrence of the dechlorination reaction; coupled with infrared spectroscopy, the characteristic absorption peak of HCl can be detected. The peak broadening in the second stage indicates a more complex carbon chain degradation reaction. Furthermore, from this figure, we can also obtain the initial decomposition temperature of the PVC sample, i.e., Toneset, which is 246.83℃. The peak values ​​of the DTG curve correspond to the maximum degradation rate Tmax for each stage, with the maximum decomposition rate temperature being 303℃. II. Experimental Conclusions Thermogravimetric analysis (TGA), as a core technology for evaluating the thermal stability of PVC resin, can quantitatively characterize degradation stages, heat resistance levels, and reaction mechanisms by accurately analyzing the characteristic parameters of the TG-DTG curve. It effectively distinguishes the differences in thermal stability among PVC formulations. Even resins with similar appearances can be identified by the thermogravimetric analyzer through parameters such as initial decomposition temperature and maximum decomposition rate temperature, providing crucial support for production consistency and reliability control. Furthermore, by coupling TGA with infrared spectroscopy or mass spectrometry, the chemical mechanisms of PVC degradation can be further revealed, providing a microscopic basis for stabilizer molecule design.

In today's era of rapid technological advancement, various instruments and equipment are constantly emerging, bringing greater convenience and safety to our lives and work. Among them, fixed radiation alarm devices, as an important monitoring tool, have gradually come into the public eye. Radiation, this invisible "force," is always present around us. It includes natural radiation from the natural environment, such as cosmic rays and radioactive materials in soil and air, as well as radiation generated by human activities, such as X-ray examinations in the medical field and certain processes in industrial production. While moderate amounts of radiation do not cause obvious harm to the human body, when the radiation dose exceeds a certain limit, it may pose a potential threat to human health. Therefore, accurate and timely monitoring of radiation is particularly important, and fixed radiation alarm devices play a crucial role in this. The working principle of fixed radiation alarm devices is based on radiation detection technology. Through a built-in high-sensitivity detector, it can capture radiation signals in the surrounding environment. When a radiation source is present, the detector senses the energy changes of the radiation particles and converts them into electrical signals. After a series of amplifications, analyses, and processing, if the radiation intensity exceeds a pre-set threshold, the alarm will immediately emit an audible and visual alarm, attracting the attention of staff or relevant personnel. This rapid and accurate detection and alarm mechanism can identify potential radiation anomalies at the first moment, buying valuable time for appropriate protective measures. In practical applications, the installation location of the equipment is crucial. It is typically placed in areas where radiation leaks or risks may exist, such as around nuclear power plant reactors, at the entrance of hospital radiology departments, or near industrial irradiation facilities. Taking a nuclear power plant as an example, its internal reactors produce a large amount of radioactive material during operation, and even under strict safety measures, there is still a small probability of radiation leakage. In this case, the equipment distributed in various critical areas acts like loyal guardians, always on duty. Once excessive radiation is detected, it can quickly notify staff to take action, preventing further escalation of the accident and ensuring the safety of the surrounding environment and personnel. It is also an important piece of equipment for hospital radiology departments. When patients undergo radiological examinations such as X-rays and CT scans, although the radiation dose from the examination equipment is within safe limits, real-time monitoring of ambient radiation is still necessary. The alarm system ensures that radiation does not accidentally leak out of the examination room during the examination process, protecting other patients and medical staff from unnecessary radiation exposure. It also provides strong data support for the hospital's radiation safety management, helping the hospital develop more scientific and reasonable radiation protection systems. In the industrial sector, many companies involved in the production, processing, or use of radioactive materials are also equipped with it. For example, in some factory workshops using radioactive sources for non-destructive testing, the alarm system can monitor the radiation level of the working environment in real time, preventing workers from developing occupational diseases due to prolonged exposure to excessive radiation. Furthermore, for areas storing radioactive materials, the alarm system provides 24-hour uninterrupted monitoring; any abnormal radiation fluctuations will not escape its notice, effectively preventing safety accidents such as loss or theft of radioactive materials. To fully realize its function, regular maintenance and calibration are necessary. Due to environmental factors, equipment aging, and other reasons, the detection performance of the alarm system may gradually decline, leading to deviations in measurement results. Therefore, professional technicians meticulously inspect, clean, and calibrate the alarm devices at prescribed intervals to ensure they maintain optimal working condition and provide accurate and reliable data for radiation monitoring. Fixed radiation alarm devices, as a crucial line of defense in radiation monitoring, play an irreplaceable role in protecting human health, environmental safety, and industrial production safety. With continuous technological advancements, it is believed that their performance and application scope will continue to improve and expand, creating a safer radiation environment for us, ensuring that radiation is no longer an "invisible killer" lurking around us, but rather firmly controlled within safe limits.

Accurate measurement of radiation dose is crucial in fields such as nuclear radiation protection, medical radiotherapy, environmental monitoring, and scientific research. Thermoluminescent dosimeters, as a classic radiation dose measurement device, play an irreplaceable role in these fields due to their high sensitivity, wide measurement range, and good stability. This article will delve into the core technologies of the device, including its detection principle, and explore optimization schemes to improve reading accuracy. 1. Analysis of Detection Principle Thermoluminescent dosimeters utilize the property that certain materials, after being exposed to ionizing radiation, can absorb and store energy, and release photons when heated again. This process can be divided into three stages: 1.1 Irradiation Stage: When a thermoluminescent material is exposed to ionizing radiation, such as X-rays, gamma rays, or neutrons, the radiation particles interact with the material, exciting electrons within the material to higher energy levels, forming bound electrons in "traps." 1.2 Storage Stage: These trapped electrons remain relatively stable at room temperature and do not immediately release energy, thus preserving radiation information for a long time. 1.3 Readout Stage: By heating the detector to a specific temperature, the trapped electrons gain enough energy to escape the trap and release energy as photons as they return to their ground state—a phenomenon known as thermoluminescence. The intensity of the released light is proportional to the original received radiation dose. This light is converted into an electrical signal by a photomultiplier tube or other light detection device, allowing the radiation dose to be calculated. 2. Reading Accuracy Optimization Scheme Although thermoluminescent dosimeters have many advantages, their reading accuracy is affected by various factors, including the selection of detector materials, the design of the heating program, the efficiency of light signal collection, and the data processing algorithm. The following are some key optimization strategies: 2.1 Selecting High-Quality Detector Materials: Using high-purity, homogeneous, and radiation-response-stable thermoluminescent materials can effectively improve the detector's sensitivity and consistency. 2.2 Controlling the Heating Process: Controlling the heating rate and the temperature is crucial for the release of the thermoluminescent signal. A microprocessor-controlled heating system enables temperature profile setting, ensuring consistent measurement conditions and reducing sources of error. 2.3 Enhanced Optical Signal Collection Efficiency: Optimized optical design, such as using mirrors, lens focusing systems, and selecting appropriate filters to remove background noise, improves optical signal collection efficiency and signal-to-noise ratio. 2.4 Intelligent Data Processing: Introduced signal processing algorithms, such as peak identification, background subtraction, and nonlinear correction, effectively improve the accuracy and stability of readings. Simultaneously, establishing a calibration database and regularly calibrating the instrument is crucial for ensuring long-term measurement accuracy. 2.5 Environmental Factors Consideration: Considering that environmental factors such as temperature and humidity may affect detector performance, the design should incorporate a temperature and humidity control system or add appropriate correction factors during data analysis. In summary, the thermoluminescent dosimeter, through its unique detection principle, exhibits unique advantages in radiation dose measurement. Continuous optimization of detector materials, heating control, optical signal processing technology, and data processing algorithms can significantly improve reading accuracy and meet increasingly stringent radiation safety monitoring requirements. With the advancement of science and technology, it will play an even more important role in more fields in the future, contributing to human health and environmental protection.

In the field of radiation protection, thermoluminescent personal dosimeters are core tools for monitoring the radiation dose received by workers, and their accuracy directly affects occupational health management and safety assessment. However, due to environmental interference, equipment aging, and other factors, thermoluminescent personal dosimeter readings may deviate or become abnormal. This article will elaborate on the regular calibration process and strategies for identifying and handling abnormal data, providing actionable solutions for relevant organizations. 1. Regular Calibration: Ensuring the Reliability of Measurement Reference Standards Calibration is a crucial step in maintaining the accuracy of thermoluminescent personal dosimeters. It is recommended to conduct a standard source comparison experiment quarterly—using a metrologically certified cesium-137 or cobalt-60 radioactive source as a reference standard, covering the energy range that may be encountered in daily work. During operation, care should be taken to place the dosimeter chip in the center of the source to ensure geometric consistency; at the same time, ambient temperature and humidity parameters should be recorded, as these factors can affect the crystal luminescence efficiency. Standardized annealing procedures are equally important. According to national standards, lithium sodium fluoride (LiF) detectors should be burned at a constant temperature of 240℃±2℃ for 30 minutes to eliminate residual signals. Using a precision temperature-controlled muffle furnace with a programmed temperature rise curve can prevent overheating and sensitivity degradation. Regularly creating calibration curves using components irradiated with standard doses is also an effective means of compensating for individual component differences. 2. Outlier Screening: Multi-dimensional Analysis and Source Tracing Technology When outlier data appears, it is essential to first distinguish between systematic errors and random fluctuations. Statistical tests of the dataset are performed using the Grubbs criterion to eliminate suspicious values ​​with a probability below 5%. Then, a comparative analysis of parallel samples worn by multiple personnel in the same position is conducted to determine if it is an individual's specific exposure. Environmental electromagnetic interference is a significant factor. A spectrum analyzer is used to scan the electromagnetic noise distribution in the workplace, focusing on investigating harmonic components generated by high-frequency medical equipment. For areas with strong magnetic fields, fiber optic transmission is recommended instead of traditional cable connections. Component performance degradation can also lead to chronic drift. By observing the historical data trajectory of a single dosimeter through trend charts, a gradual upward or downward trend may indicate that aging components may need to be replaced. 3. Preventive Maintenance: Building a Closed-Loop Management System Establishing a complete traceability chain is crucial. Original calibration certificates should be retained starting from the procurement stage, and electronic files should be updated and identification codes generated after each calibration. Personnel training should include both practical exercises and theoretical assessments. Emphasis should be placed on training the correct wearing position (e.g., at the chest and collar) and avoiding the mixing of different types of components; the working principle of the dosimeter and common fault manifestations should also be explained. Management of thermoluminescent personal dosimeters requires a systematic engineering approach. Through standardized calibration procedures, scientific data analysis methods, and a rigorous quality control system, not only can the reliability of radiation protection data be guaranteed, but it can also provide strong support for occupational health management. With the development of IoT technology, real-time remote monitoring and intelligent early warning of dosimeter status can be realized in the future, promoting the transformation of radiation protection towards proactivity and intelligence.