Cai Guoshuai, Wu Jiaxuan, Guo Jiayi, Wan Yange, Zhou Qingjun, Zhang Pengyu, Yu Xiaolei, Wang Mingchao
School of Safety Science and Engineering, Civil Aviation University of China, 2898 Jinbei Road, Tianjin 300300, China.
College of Science, Civil Aviation University of China, 2898 Jinbei Road, Tianjin 300300, China.
Materials (Basel). 2023 Jun 21;16(13):4498. doi: 10.3390/ma16134498.
Currently, most thin-layer expandable coatings are polymer-based, with very few inorganic expandable coatings. Due to the high environmental friendliness of inorganic coatings, studying new types of inorganic coatings is of great significance. A novel amorphous aluminum phosphate-based flame-retardant coating was prepared by modifying it with nano-silica, hollow silica beads, hollow glass microspheres, and boron carbide. A comprehensive study was conducted on the flame retardancy and thermal insulation performance, composition and structural evolution under flame and physical and chemical properties, and the mechanisms of flame retardancy and thermal insulation were elucidated. Large-plate combustion testing, bonding strength testing, XRD, IR, TG-DSC, and SEM testing were all applied in this work. The synergistic effect of the four fillers was very obvious, and a series of AP22XY (nano-silica/silica beads/hollow glass microspheres/boron carbide = 2:2:0:4, 2:2:1:3, 2:2:2:2, 2:2:3:1, 2:2:4:0) coatings were prepared. The change in the ratio of glass microspheres to boron carbide had a significant impact on the composition and structural evolution of the coating, thus reflecting its effectiveness as a flame retardant and thermal insulation. Although decreasing the ratio would promote the formation of borosilicate glass and AlBO and improve the thermal stability of coatings, the structure inside of the coating, especially the skeleton, would be dense, which is not conducive to thermal insulation. When the ratio of glass microspheres to boron carbide is 3:1, AP2231 shows the best fire resistance. Under the combustion of butane flame at about 1200-1300 °C, the backside temperature reaches a maximum of 226 °C at 10 min, and then the temperature gradually decreases to 175 °C at 60 min. This excellent performance is mainly attributed to three aspects: (1) the foaming and expandability of coatings when exposed to fire, (2) the multiple endothermic reactions the coating undergoes, and (3) the improvement effect of boron carbide. Additionally, AP2231 shows the best bonding performance with a strength of close to 4.5 MPa after combustion, because of the appropriate content matching between borosilicate glass, AlBO, and hollow glass microspheres. The coating has potential application prospects in the construction and transportation fields, such as the protection of structural steel, fire prevention in subways and tunnels, and the prevention of lithium battery fires.
目前，大多数薄层可膨胀涂料是以聚合物为基础的，无机可膨胀涂料很少。由于无机涂料具有高度的环境友好性，研究新型无机涂料具有重要意义。通过用纳米二氧化硅、空心二氧化硅珠、空心玻璃微珠和碳化硼对其进行改性，制备了一种新型的非晶态磷酸铝基阻燃涂料。对其阻燃性和隔热性能、火焰作用下的组成和结构演变以及物理化学性质进行了全面研究，并阐明了阻燃和隔热机理。本工作采用了大板燃烧试验、粘结强度试验、XRD、IR、TG-DSC和SEM试验。四种填料的协同效应非常明显，制备了一系列AP22XY（纳米二氧化硅/二氧化硅珠/空心玻璃微珠/碳化硼=2:2:0:4、2:2:1:3、2:2:2:2、2:2:3:1、2:2:4:0）涂料。玻璃微珠与碳化硼比例的变化对涂层的组成和结构演变有显著影响，从而反映了其作为阻燃和隔热材料的有效性。虽然降低该比例会促进硼硅酸盐玻璃和AlBO的形成并提高涂层的热稳定性，但涂层内部结构，尤其是骨架会变得致密，不利于隔热。当玻璃微珠与碳化硼的比例为3:1时，AP2231表现出最佳的耐火性。在约1200-1300℃的丁烷火焰燃烧下，10分钟时背面温度最高达到226℃，然后在60分钟时温度逐渐降至175℃。这种优异性能主要归因于三个方面：（1）涂料遇火时的发泡和膨胀性，（2）涂料所经历的多次吸热反应，（3）碳化硼的改善作用。此外，AP2231表现出最佳的粘结性能，燃烧后强度接近4.5MPa，这是因为硼硅酸盐玻璃、AlBO和空心玻璃微珠之间的含量匹配得当。该涂料在建筑和交通领域具有潜在的应用前景，如结构钢的保护、地铁和隧道的防火以及锂电池火灾的预防。
