For high performance of hydrocarbon intumescent coatings, interactions between the acid source ammonium polyphosphate (APP) and inorganic fillers can be critical. In the present work, low-borate concentration (ie, 1 wt% zinc borate) intumescent coatings with different concentration ratios of CaCO₃ to APP were studied in an attempt to map the reaction mechanisms. The analysis of the coating performance was conducted using thermal insulation assessment according to the UL1709 fire curve (disregarding substrate load, geometrical diversity, and other full-scale implications of the complete standard), rheological measurements, thermogravimetric analyses, attenuated total reflection-Fourier transform infrared spectrometer (ATR-FTIR), and X-ray diffraction. Results show that a coating with a CaCO₃/APP mass ratio of 0.3 gives the best performance (ie, the longest critical time of steel substrates to reach both 400 and 550°C in the thermal insulation assessment). The dependency on the CaCO₃/APP ratio of the dynamic viscosity minimum points to significant interactions between CaCO₃ and APP during the softening state (ie, the intumescence process) of the coating. Due to an enhanced anti-oxidation property, the degradation zone of the intumescent char and the residual weight of the coating after exposure were both improved when increasing the CaCO₃/APP ratio. The compositional development of the intumescent char showed that CaCO₃ and APP react to form a new polymeric phase, calcium catena-polyphosphate (CaP₂O₆). This polyphosphate may contribute to the formation of a compact phase in the intumescent char and benefit the thermal insulation performance of low-borate concentration hydrocarbon intumescent coatings.

中文翻译：

---

低硼酸盐浓度烃膨胀涂料中碳酸钙和多磷酸铵的相互作用

对于碳氢化合物膨胀型涂料的高性能，酸源聚磷酸铵 (APP) 和无机填料之间的相互作用至关重要。_{在目前的工作中，研究了具有不同CaCO 3}与APP浓度比的低硼酸盐浓度（即1 wt% 硼酸锌）膨胀型涂层，以试图绘制反应机理图。根据 UL1709 防火曲线（不考虑基材负载、几何多样性和完整标准的其他全面影响）、流变测量、热重分析、衰减全反射-傅里叶变换，使用隔热评估对涂层性能进行了分析红外光谱仪（ATR-FTIR）和X射线衍射。结果表明，具有 CaCO _3的涂层/APP 质量比为 0.3 给出了最佳性能（即，在绝热评估中钢基材达到 400 和 550°C 的最长临界时间）。_{动态粘度最小值对CaCO 3} /APP 比率的依赖性表明在涂层的软化状态（即膨胀过程）期间CaCO ₃和APP之间存在显着的相互作用。由于增强的抗氧化性能，当增加CaCO ₃ /APP 比率时，膨胀炭的降解区和暴露后涂层的残余重量均得到改善。膨胀炭的组成发展表明，CaCO ₃和 APP 反应形成新的聚合物相，链状聚磷酸钙 (CaP ₂6 ₎。这种多磷酸盐可能有助于在膨胀炭中形成致密相，并有利于低硼酸盐浓度烃膨胀涂层的隔热性能。