Dai Xiaobing, Qian Jueshi, Qin Jihui, Yue Yanfei, Zhao Yushan, Jia Xingwen
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China.
Materials (Basel). 2022 Jun 10;15(12):4134. doi: 10.3390/ma15124134.
Magnesium phosphate cement (MPC) is a potential inorganic binder for steel coating due to setting and hardening rapidly, and bonding tightly with steel. NHHPO-based MPC as a fire-retardant coating for steel was investigated in this work. MPC coatings were prepared from MPC paste and MPC mortar with expanded vermiculite (EV). The physical-mechanical properties and fireproof performance of MPC coatings were investigated in detail. An infrared thermal imager was employed to collect the temperature distribution and temperature rise with time on the coating samples automatically. The X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analyses were carried out on the MPC coating after the fireproof test. Re-fire test and corrosion resistance were performed preliminarily on the MPC coating. The results showed that the fireproof performance of MPC coating met the fire protection requirement for steel as long as the thickness of the MPC paste coating was up to 10 mm, while the thickness of MPC mortar coating decreased to 4 mm when adding 40% EV (by mass). Dehydration and decomposition of reacted products in the hardened MPC coating were, to some extent, contributed to the excellent fireproof performance during the fire test. The slight ceramic formation and integration of MPC coating during the fire test would compensate for the decreasing of strength due to the dehydration and decomposition, so that the MPC coating would keep certain fireproof performance when undergoing fire again. MPC is suitable for a fire-retardant coating, while higher tensile bonding strength with steel and potential corrosion resistance on steel, as well as rapid surface drying and hardening can be achieved.
磷酸镁水泥（MPC）因其凝结硬化迅速且与钢材紧密粘结，是一种用于钢材涂层的潜在无机粘结剂。本文研究了以NHHPO为基础的MPC作为钢材防火涂料的性能。采用膨胀蛭石（EV）制备了MPC涂料浆体和MPC砂浆。详细研究了MPC涂层的物理力学性能和防火性能。利用红外热成像仪自动采集涂层样品的温度分布和随时间的温升情况。对防火试验后的MPC涂层进行了X射线衍射（XRD）和扫描电子显微镜（SEM）分析。对MPC涂层初步进行了复烧试验和耐腐蚀性试验。结果表明，只要MPC涂料浆体涂层厚度达到10mm，其防火性能就能满足钢材的防火要求；而添加40%（质量分数）EV时，MPC砂浆涂层厚度可降至4mm。硬化MPC涂层中反应产物的脱水和分解在一定程度上有助于其在火灾试验中表现出优异的防火性能。火灾试验过程中MPC涂层轻微的陶瓷化形成和结合能够弥补因脱水和分解导致的强度降低，从而使MPC涂层在再次遇火时仍能保持一定的防火性能。MPC适用于防火涂料，同时它与钢材具有较高的拉伸粘结强度，对钢材具有潜在耐腐蚀性能，并且表面干燥硬化迅速。
