Aerospace Manufacturing Technology Center, National Research Council Canada, 5145 Decelles Avenue, Montreal, QC, H3T 2B2, Canada.
School of Biomedical Engineering, The University of Sydney, Sydney, NSW, 2008, Australia.
Sci Rep. 2021 Mar 26;11(1):6951. doi: 10.1038/s41598-021-82365-3.
Brittleness is a major limitation of polymer-derived ceramics (PDCs). Different concentrations of three nanofillers (carbon nanotubes, SiN and AlO nanoparticles) were evaluated to improve both toughness and modulus of a commercial polysilazane (PSZ) PDC. The PSZs were thermally cross-linked and pyrolyzed under isostatic pressure in nitrogen. A combination of mechanical, chemical, density, and microscopy characterizations was used to determine the effects of these fillers. SiN and AlO nanoparticles (that were found to be active fillers) were more effective than nanotubes and improved the elastic modulus, hardness, and fracture toughness (J) of the PDC by ~ 1.5 ×, ~ 3 ×, and ~ 2.5 ×, respectively. Nanotubes were also effective in maintaining the integrity of the samples during pyrolysis. The modulus and hardness of PDCs correlated positively with their apparent density; this can provide a fast way to assess future PDCs. The improvement in fracture toughness was attributed to crack deflection and bridging observed in the micro-indentation cracks in the modified PDCs. The specific toughness of the modified PDCs was 4 × higher than that of high-purity alumina, and its specific modulus reached that of commercially available technical ceramics. These PDCs can also easily take different shapes and therefore are of interest in protective armor, propulsion, thermal protection, device packaging and biomaterial systems.
脆性是聚合物衍生陶瓷（PDC）的主要限制因素。评估了三种纳米填料（碳纳米管、SiN 和 AlO 纳米颗粒）的不同浓度，以提高商业聚硅氮烷（PSZ）PDC 的韧性和模量。PSZ 在氮气中进行等静压热交联和热解。采用力学、化学、密度和显微镜特性相结合的方法来确定这些填料的影响。发现 SiN 和 AlO 纳米颗粒（活性填料）比纳米管更有效，分别将 PDC 的弹性模量、硬度和断裂韧性（J）提高了约 1.5 倍、约 3 倍和约 2.5 倍。纳米管在热解过程中也能有效地保持样品的完整性。PDC 的模量和硬度与其表观密度呈正相关；这可以提供一种快速评估未来 PDC 的方法。断裂韧性的提高归因于在改性 PDC 中的微压痕裂纹中观察到的裂纹偏转和桥接。改性 PDC 的比韧性比高纯氧化铝高 4 倍，比模量达到商业上可用的技术陶瓷。这些 PDC 还可以很容易地采用不同的形状，因此在防护装甲、推进、热保护、器件封装和生物材料系统中具有很大的兴趣。
