Sol-Jel Yöntemiyle Üretilen Alümina Alkojelin Fizikokimyasal ve Yapısal Özellikleri Üzerine Kurutma Türünün Etkisi

Year 2020, , 657 - 669, 01.09.2020

Dilek Cantürk Öz Nihan Kaya

https://doi.org/10.2339/politeknik.456871

Cited By: 1

Abstract

Üstün termal ve mekanik
özellikleri sebebiyle başta uzay teknolojisi olmak üzere pek çok alanda
kullanılmakta olan alkojeller, düşük yoğunluğa ve yüksek gözenekliliğe sahip
süper yalıtkan ve çevre dostu malzemeler olarak bilinmektedir.  Genel olarak inorganik tuzlar ya da metal
alkoksitlerin hidrolizi ve kondenzasyonu olarak bilinen sol-jel tekniği
kullanılarak, üç aşamada üretilmektedirler. Son aşama hazırlanan ıslak jellerin
kurutulması olup,  ıslak jelin
gözenekliliği ve jel ağının korunması için en uygun kurutma tekniğinin
seçilmesi büyük önem arz etmektedir. Bu çalışmada, sol-jel yöntemiyle
sentezlenen alümina alkojellerden süperkritik şartlarda, atmosfer basıncında ve
dondurarak olmak üzere üç farklı kurutma koşullarında elde edilen gözenekli
malzemelerin fizikokimyasal ve yapısal özellikleri XRD, TGA/DSC, FT-IR ve BET
analizleri ile karakterize edilmiştir. Farklı kurutma koşullarında aerojel,
kriyojel ve ambijel ismini alan amorf yapıya sahip bu jellerin fizikokimyasal
özellikleri ve ısısal davranışlarındaki değişimler dikkate alındığında, ıslak
jellerin kurutulmasında en uygun kurutma tekniğinin ön işlem yapılmadan dondurarak
kurutma olduğu sonucuna ulaşılmıştır. 

Keywords

Sol-jel yöntemi, alümina alkojel, aerojel, ambijel, kriyojel

Effect of Drying Method on the Physicochemical and Structural Properties of Alumina Alcogel Produced by Sol-Gel Method

Abstract

Because of its superior thermal and mechanical
properties, alcogels, which are mainly used in space technology, are known as
super insulation and environment friendly materials with low density and high
porosity. Generally, they are produced in three stages using sol-gel technique
known as hydrolysis and condensation of inorganic salts or metal alkoxides. The
final stage is the drying of the wet gel, and it is of great importance to
select the most suitable drying technique to protect the porosity and structure
of wet gel. In this study, the physicochemical and structural properties of
porous materials obtained by using sol-gel technique under three different
drying conditions which are supercritical conditions, atmospheric pressure and
freezing, were characterized by XRD, TGA/DSC, FT-IR and BET analyzes. Taking
into account the physicochemical properties and thermal behavior of these gels,
which have amorphous structure and named aerogel, cryogel and ambigel in
different drying conditions, it is concluded that the best drying technique for
drying wet gels is freeze drying without pretreatment.

Keywords

Sol-gel method, alumina alcogel, aerogel, ambigel, crygogel

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