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Effects of NH₄VO₃ on Properties and Structures of Cordierite Ceramics

W. Ning, Z. Tang, Z. Han, S. Ding, C. Xu, P. Zhang

Journal of Ceramic Science and Technology, Vol. 9, No. 1 (2018), pp. 47-52

DOI: 10.4416/JCST2017-00063

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Abstract

To obtain cordierite ceramics with superior properties, different proportions of NH4VO3 were added to a preferred basic ceramic formula, the main raw materials of which included talc, kaolin, calcined kaolin, alumina, aluminum hydroxide and amorphous SiO2. The cordierite ceramics were manufactured by means of high-temperature sintering. The results show that the coefficient of thermal expansion of the cordierite ceramics is significantly reduced with the addition of 4 % NH4VO3; water absorption rate, apparent porosity and flexural strength of the ceramics were increased. The results of FT-IR, XRD and SEM analyses show that V ion entered the lattice of the cordierite crystals and formed V-O bonds and V-O-Si bonds by replacing Mg2+ and Si4+, the strength of the chemical bonds was enhanced during the sintering process. The cell parameters of the cordierite were changed from a = 9.7638 Å, c = 9.3152 Å to a = 9.6851 Å, c = 9.2923 Å. The microcracks in the ceramics disappeared while the pores were increased and uniform. Because of this, the coefficient of thermal expansion is decreased, and the other properties of cordierite ceramics are increased.

Keywords

NH4VO3, cordierite, thermal expansion, structure

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