一种可紫外光固化新型耐烧蚀涂料研究

A New UV Curable Ablation-Resistant Coating

基于巯基-乙烯基光引发逐步聚合机理,以含有乙烯基的液态硅氮烷预聚物与多元巯基化合物为基体,辅以某种陶瓷微粉作为填料,研制了一种可紫外光固化的新型耐烧蚀涂料。采用等温差示光量热扫描(DPC)和测试固化度研究了填料添加量对紫外光固化放热行为和一次成型厚度的影响关系。结果表明:在制备0.5 mm厚的涂层时,填料添加量逐渐从0增至5%(质量分数,下同),固化放热峰值和放热量随添加量的增大而逐渐减小,且固化放热峰从尖锐逐渐趋于平坦,这是由于填料的加入使得涂料变为不透明,对入射的紫外光线产生了衍射/反射作用,从而减弱了辐照强度;填料添加量大于10%时,明显阻碍光固化反应的发生,涂层的一次成型厚度随填料添加量的增加而降低,可采用多次涂敷的措施解决涂层厚度不足的问题。当填料添加量从0增至20%,对于1.0 mm厚的涂层而言,在800℃质量保持率从61.2%增至73.5%。填料含量20%的涂层具有较为优异的耐烧蚀性能,氧-乙炔烧蚀的线烧蚀率为0.252 mm/s,质量烧蚀率为61.7 mg/s。

A new UV curable ablation-resistant coating for supersonic aircrafts was described in this paper. The step-growth thiol-vinyl silizane UV curable system was used as resin matrix and a micron inorganic powder as filler. Reaction exothermic behavior and thickness forming for one time were explored by Differential Photo Calorimeter （DPC） and curing degrees were also measured. The results show that when 0. 5 mm thick coating formed, the maximum value of exothermic peak in DPC curve is decreased and shape of exothermic peak is changed from sharp to broaden one with the increase of filler used from none to 5wt% due to the diffraction or/and reflection of filler which makes the transparent copolymer opaque and UV light intensity reduced. When the content of filler is more than 10wt%, UV cure process is hindered. The thickness of one time formation is also decreased with the increase of filler. However, this limit can be overcome by the multilayer-coating technology. For fabricating 1.0 mm thick polymer ceramic precursor films, the curing degrees are decreased from 89.8% to 38.3% with incorporation filler from none to 20wt% ,but the yields of ceramics measured by TGA from room temperature to 800℃ is enhanced from 61.2% to 73.5%. The linear ablation rate and mass ablation rate are decreased obviously with the increased amount of filler and the coating containing 20wt% filler has excellent ablation-resistant property with linear ablation rate and mass ablation rate being 0. 252 mm/s and 61.7 mg/s respectively.