Weis Frederik, Seipenbusch Martin, Kasper Gerhard
Institute for Mechanical Process Engineering and Applied Mechanics, Karlsruhe Institute of Technology (KIT), Strasse am Forum 8, 76131 Karlsruhe, Germany.
Institute of Chemical Process Engineering, University of Stuttgart, Böblinger Strasse 78, 70199 Stuttgart, Germany.
Materials (Basel). 2015 Mar 6;8(3):966-976. doi: 10.3390/ma8030966.
Silica core-shell nanoparticles of about 60-120 nm with a closed outer layer of bismuth or molybdenum oxide of 1-10 nm were synthesized by an integrated chemical vapor synthesis/chemical vapor deposition process at atmospheric pressure. Film growth rates and activation energies were derived from transmission electron microscopy (TEM) images for a deposition process based on molybdenum hexacarbonyl and triphenyl bismuth as respective coating precursors. Respective activation energies of 123 ± 10 and 155 ± 10 kJ/mol are in good agreement with the literature and support a deposition mechanism based on surface-induced removal of the precursor ligands. Clean substrate surfaces are thus prerequisite for conformal coatings. Integrated aerosol processes are solvent-free and intrinsically clean. In contrast, commercial silica substrate particles were found to suffer from organic residues which hinder shell formation, and require an additional calcination step to clean the surface prior to coating. Dual layer core-shell structures with molybdenum oxide on bismuth oxide were synthesized with two coating reactors in series and showed similar film growth rates.
通过常压下的化学气相合成/化学气相沉积集成工艺，合成了粒径约为60 - 120 nm的二氧化硅核壳纳米颗粒，其氧化铋或氧化钼的封闭外层厚度为1 - 10 nm。基于六羰基钼和三苯基铋分别作为涂层前驱体的沉积过程，通过透射电子显微镜（TEM）图像得出薄膜生长速率和活化能。123 ± 10和155 ± 10 kJ/mol的各自活化能与文献数据高度吻合，并支持基于前驱体配体表面诱导去除的沉积机理。因此，清洁的基底表面是实现保形涂层的前提条件。集成气溶胶工艺无溶剂且本质上清洁。相比之下，发现商用二氧化硅基底颗粒存在有机残留物，这会阻碍壳层形成，并且在涂层之前需要额外的煅烧步骤来清洁表面。通过串联两个涂层反应器合成了氧化钼在氧化铋上的双层核壳结构，其薄膜生长速率相似。
