Long Carolyn T, Wang Ruisong, Shoalmire Charles, Antao Dion S, Shamberger Patrick J, Grunlan Jaime C
Department of Mechanical Engineering, Texas A&M University, 3123 TAMU, College Station, Texas 77840, United States.
Department of Materials Science and Engineering, Texas A&M University, 3123 TAMU, College Station, Texas 77840, United States.
ACS Appl Mater Interfaces. 2021 Apr 28;13(16):19369-19376. doi: 10.1021/acsami.1c03781. Epub 2021 Apr 16.
In an effort to protect metal substrates from extreme heat, polymer-clay multilayer thin films are studied as expendable thermal barrier coatings. Nanocomposite films with a thickness ranging from 2 to 35 μm were deposited on steel plates and exposed to the flame from a butane torch. The 35 μm coating, composed of 14 deposited bilayers of tris(hydroxymethyl)aminomethane (THAM)-buffered polyethylenimine (PEI) and vermiculite clay (VMT), decreased the maximum temperature observed on the back side of a 0.32 cm thick steel plate by over 100 °C when heated with a butane torch. Upon exposure to high temperature, the polymer and amine salt undergo pyrolysis and intumesce, subsequently forming a char and blowing gas. The char encases the nanoclay platelets, and a ceramic bubble is formed. The macro-scale bubble, in tandem with the nanocomposite coating properties, increases resistance to heat transfer into the underlying metal substrate. This heat shielding behavior occurs through radiative effects and low aggregate through-plane conductivity resulting from multilayer nanodomains and intumesced porosity (i.e., conduction through the gas as the film expands to form a ceramic bubble). These relatively thin and lightweight films could be used to protect important metal parts (in automobiles, aircraft, etc.) from fire-related damage or other types of transient high-temperature situations.
为了保护金属基材免受极端高温的影响，聚合物 - 粘土多层薄膜作为可消耗的热障涂层进行了研究。将厚度在2至35μm范围内的纳米复合薄膜沉积在钢板上，并暴露于丁烷喷枪的火焰中。由14个沉积双层的三（羟甲基）氨基甲烷（THAM）缓冲聚乙烯亚胺（PEI）和蛭石粘土（VMT）组成的35μm涂层，在用丁烷喷枪加热时，可使0.32cm厚钢板背面的最高温度降低超过100°C。在暴露于高温时，聚合物和胺盐发生热解并膨胀，随后形成炭层并产生气体。炭层包裹着纳米粘土片层，形成陶瓷气泡。宏观尺度的气泡与纳米复合涂层的特性共同作用，增加了对热传递到下层金属基材的阻力。这种热屏蔽行为是通过辐射效应以及由多层纳米域和膨胀孔隙率导致的低总体面内电导率（即当薄膜膨胀形成陶瓷气泡时通过气体的传导）发生的。这些相对薄且轻质的薄膜可用于保护重要的金属部件（如汽车、飞机等中的部件）免受火灾相关损坏或其他类型的瞬态高温情况的影响。
