The rapid development and widespread application of magnesium alloy bring about a significant amount of magnesium alloy scrap. Thus, we offer a feasible and simple way to realize the recycling of magnesium scrap in this work, applying it as a synergist in the intumescent fire-retardant coatings for steel structure. With the introduction of magnesium scrap, the fire resistance, thermal stability, and water tolerance of the as-prepared coatings significantly improved. According to ASTM E119 standards, the fire resistance of coatings was investigated in our laboratory. Adding only ~ 0.48 wt% of the scrap decreased the backside temperature of the coated steel from 310°C to 171°C, with a ~ 44.8% reduction, indicating obvious synergy. Moreover, the coating containing ~ 0.48 wt% scrap exhibited excellent thermal stability and water resistance, and its char yield at 800°C and water contact angle reached up to 27% and 80.6°, respectively. Based on the analysis of flame-retardant mechanism, the scrap and intumescent fire-retardant system jointly promoted the formation of an intumescent and compact char residue, thus suppressing the heat transfer and protecting the steel. Hence, using magnesium alloy scrap as a synergist contributed to realizing the recycling of waste and providing practical intumescent fire-retardant coatings for structural steel.

镁合金的快速发展和广泛应用带来了大量的镁合金废料。因此，我们提供了一种可行且简单的方法来实现镁废料的循环利用，并将其作为增效剂应用于钢结构膨胀型阻燃涂料中。随着镁废料的引入，所制备涂层的耐火性，热稳定性和耐水性得到显着改善。根据ASTM E119标准，在我们的实验室中对涂料的耐火性进行了研究。仅添加约0.48 wt％的废料，可使涂层钢的背面温度从310°C降至171°C，降低约44.8％，表明具有明显的协同作用。此外，含有约0.48 wt％废料的涂料具有出色的热稳定性和耐水性，在800℃和水接触角下的焦炭收率分别达到27％和80.6°。在对阻燃机理进行分析的基础上，废料和膨胀型阻燃体系共同促进了膨胀型致密炭渣的形成，从而抑制了热传递并保护了钢。因此，使用镁合金废料作为增效剂有助于实现废料的回收利用，并为结构钢提供实用的膨胀型防火涂料。