کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7899547 | 1510348 | 2018 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Optimized synthesis of ambient pressure dried thermal insulating silica aerogel powder from non-ion exchanged water glass
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Silica aerogels are considered as promising materials for future energy saving buildings, however, their reliability remains questionable as commercially available aerogels can show relatively high standard deviations e.g. 22.2â¯Â±â¯1.4â¯mWâ¯mâ1â¯Kâ1. Therefore a synthesis protocol for silica aerogel powder with thermal conductivities having extremely reduced standard deviations was designed, compatible with mass production, i.e. reduced use of solvents and hydrophobization agents. Silica sols were prepared from non-ion exchanged water glass, while a combined solvent exchange, silylation and washing out of sodium ions was carried out using a hexane/trimethylchlorosilane/isopropyl alcohol solution with a molar ratio trimethylchlorosilane/pore water of only 0.11. The hexane amount was reduced 35 times compared to typical processes in literature. The aerogel powder was finally dried at ambient pressure at 150â¯Â°C. No notable shrinkage was observed for 8â¯wt% silica aerogel samples, having a thermal conductivity of 25.4â¯mWâ¯mâ1â¯Kâ1 with a standard deviation of only 0.1. The 6â¯wt% silica aerogels had a thermal conductivity of 23.4â¯mWâ¯mâ1â¯Kâ1 with a standard deviation of 0.3, but had shrunken 36%. By replacing trimethylchlorosilane with hexamethyldisiloxane, aerogels having a thermal conductivity of 22.4â¯mWâ¯mâ1â¯Kâ1 with a standard deviation of 0.3 were obtained.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 499, 1 November 2018, Pages 217-226
Journal: Journal of Non-Crystalline Solids - Volume 499, 1 November 2018, Pages 217-226
نویسندگان
Steve De Pooter, Steven Latré, Frederik Desplentere, David Seveno,