Production of porous ceramic material using different sources of alumina and calcia

Author(s)

de Oliveira, Ivone Regina ^[1] ; Cesar Leite, Vitoria Marques ^[1] ; Vargas Porto Lima, Milene Paula ^[1] ; Salomao, Rafael ^[2]

Affiliation

^[1] Univ Vale Paraiba, Inst Res & Dev, Sao Jose Dos Campos, SP - Brazil

^[2] Univ Sao Paulo, Sao Carlos Sch Engn, Mat Engieering Dept, Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: MATERIA-RIO DE JANEIRO; v. 20, n. 3, p. 739-746, JUL-SEP 2015.
• Web of Science Citations: 7

Abstract

Numerous papers and publications report the use of microporous calcium hexaluminate (CaO.6Al(2)O(3); CA(6)) as a key raw material for high temperature insulating materials. This material has unique properties with respect to chemical purity and mineral composition. Another important property of CA(6) is its structure, which consists of platelet-shaped crystals that interlock. The free distance between the crystals defines the microporous structure. The low density in combination with the micropores hampers heat transfer by radiation at temperatures exceeding 1000 degrees C and results in a low thermal conductivity. Given the advantages presented by this material, it is necessary to understand the formation mechanism of CA(6) grains in order to better develop the potential applications of this material. CA(6) can be fabricated using organic binders to consolidate the Al2O3-CaCO3 powder mixture and to provide green strength so that a green body can be formed and retains the desired shape before heating. However, these organic binders must be completely thermally decomposed so that they do not remain in the sintered body as carbon or ash. Moreover, the use of organic binders releases large volumes of gases such as carbon dioxide from the green body during heating. Therefore, an eco-friendly ceramic fabrication process has been developed that employs an inorganic binder (hydraulic alumina). The aim of the present work was to study the synthesis of porous calcium-hexaluminate ceramics using calcined alumina or hydraulic alumina combined with different sources of calcia (CaCO3 and Ca(OH)(2)) at different temperatures. The materials produced were characterized by X-ray diffraction, scanning electron microscopy, apparent porosity and mercury intrusion porosimetry. The materials produced by hydraulic alumina presented higher porosity and larger pores compared to those produced from calcined alumina. (AU)

• FAPESP's process: 13/22502-8 - Production and characterization of composite biomaterials based on calcium aluminate cement for applications in medical-dental health
• Grantee: Ivone Regina de Oliveira
• Support Opportunities: Regular Research Grants