热重分析Thermogravimetric analysis

热重分析仪核心是高灵敏度的热天平（可达 0.1 μg），样品放在坩埚中，在设定的气氛（氮气、氩气、空气或氧气）下以一定速率（常用 10 °C/min）升温。所得热重曲线（TG）显示质量损失台阶，其一阶导数（DTG）的峰对应最大失重速率温度。常与差示扫描量热法（DSC）同步联用（TG-DSC），或与红外、质谱联用分析逸出气体。

At its heart is a sensitive thermobalance, reading to about 0.1 μg; the sample sits in a crucible and is heated at a set rate, commonly 10 °C/min, in nitrogen, argon, air or oxygen. The TG curve shows steps of mass loss, and peaks in its first derivative (DTG) mark temperatures of fastest loss. It is often run simultaneously with DSC (TG-DSC) or coupled to infrared or mass spectrometry to identify evolved gases.

一水合草酸钙 CaC₂O₄·H₂O 的热重曲线有三个台阶：约 100–200 °C 失去结晶水（失重 12.3%），约 400–500 °C 分解为 CaCO₃ 并放出 CO（19.2%），约 600–800 °C 分解为 CaO 并放出 CO₂（30.1%）。它常被用作热重仪器的校准标准。

Calcium oxalate monohydrate, CaC₂O₄·H₂O, loses mass in three steps: water of crystallisation at about 100–200 °C (12.3%), CO on decomposing to CaCO₃ at about 400–500 °C (19.2%) and CO₂ on decomposing to CaO at about 600–800 °C (30.1%). It is often used to calibrate thermogravimetric instruments.

1915 年日本东北大学的本多光太郎制造了第一台热天平。1950 年代起商品化仪器出现。TGA 用于测定高分子的热分解温度和填料含量、药物和晶体的结晶水与溶剂含量、催化剂积碳量、煤和生物质的水分灰分挥发分、金属有机框架的热稳定性、锂电池材料的组成，以及研究反应动力学。

Kotaro Honda at Tohoku University built the first thermobalance in 1915, and commercial instruments appeared from the 1950s. TGA measures decomposition temperatures and filler content of polymers, water and solvent of crystallisation in drugs and crystals, coke on catalysts, moisture, ash and volatiles in coal and biomass, thermal stability of metal–organic frameworks and the composition of battery materials, and is used in kinetic studies.