Design guidelines for titania-silica-alumina ceramics with tuned anatase to rutile transformation
authors Feltrin, J; De Noni, A; Hotza, D; Frade, JR
nationality International
journal CERAMICS INTERNATIONAL
author keywords Anatase; Rutile; Phase transformation; Taguchi planning
keywords PHOTOCATALYTIC ACTIVITY; PHASE-TRANSFORMATION; THERMAL-STABILITY; POWDER MIXTURES; TIO2; DENSIFICATION; NANOPARTICLES; KINETICS; TEMPERATURE; INCLUSIONS
abstract Titania-based ceramics with adjustable anatase-rutile fractions were obtained by milling of anatase, quartz and corundum precursors, uniaxial pressing and firing at 1100 degrees C. The influence of silica and alumina, combined with milling time and compaction pressure, was studied by design of experiments. The L9 orthogonal array with a three-level noise factor was employed. Firing of pure titania at 1100 degrees C yielded complete anatase to rutile transformation (ART), whereas stabilized samples show that an optimum amount of 9% silica and 33% alumina reduces phase transformation to only about 5 wt% rutile. An extended correlation matrix combined with analysis of variance (ANOVA) was applied to assess the combined effects of quartz, alumina, milling time and uniaxial compressing pressure on relative density, and anatase to rutile transformation. Results show absence of ART after milling, and controlled partial conversion of anatase to rutile after firing. Very good fitting was obtained by multivariate analysis on considering first and second order terms for dependence on silica contents and interactions between silica and each of the remaining factors, including milling time. This empirical dependence could be interpreted on a sound physicochemical basis, allowing the prediction of suitable compositions and processing conditions to obtain rutile-free samples by conventional ceramic processing, and to design ceramic samples with controlled fractions of anatase and rutile.
publisher ELSEVIER SCI LTD
issn 0272-8842
year published 2019
volume 45
issue 5
beginning page 5179
ending page 5188
digital object identifier (doi) 10.1016/j.ceramint.2018.12.026
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000459365500001
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