**Al2O3 and Al2O3-ZrO2 Fibers Obtained by Biotemplete with Low Thermal Conductivity**

Tiago Delbrücke, Rogério A. Gouvêa, Cristiane W. Raubach, Jose R. Jurado, Faili C.T. Veiga, Sergio Cava, Mario L. Moreira and Vânia C. Sousa

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59011

**1. Introduction**

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Certain porous materials have special properties and functions that cannot normally be obtained by conventional dense counterparts. Therefore, porous materials are now used in many applications such as final products and in various technological processes. Macroporous materials are used in various forms and compositions in everyday life; e.g. polymeric foams, packaging, lightweight aluminum structures in buildings, aircraft, and as a porous ceramic for water [1,2].

A growing number of applications that require advanced ceramics have appeared in recent decades, especially in environments where high temperatures, extended wear and corrosive environments are present. Such applications include the filtration of molten metals, high temperature insulation, support for catalytic reactions [3], filtration of particulates from exhaust gases of diesel engines and filtration of hot gases in various corrosive industrial processes, for example [4-6]. The advantages of using porous ceramic for these applications are generally a high melting point, suitable electronic properties, good corrosion resistance and wear resistance in combination with the characteristics acquired by the replacement of the solid material by voids in the component. Such characteristics include low thermal mass, low thermal conductivity, permeability control, high surface area, low density, high specific strength and a low dielectric constant [1,7]. These properties can be tailored for each specific application by controlling the composition and microstructure of the porous ceramic [8,9].

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According to the type of application different microstructures and thus different preparation methods are required for porous ceramic bodies. For thermal or acoustic insulators materials with closed porosity are preferred, whereas membranes and filters require open pores with exactly defined pore size, for example. Are currently used some specific techniques to obtain pores with polymer and cotton for use in thermal insulation [10,11]. On the other hand, for application to environmental issues sodium hydroxide is used to pore formation [12].

This work uses a simple and versatile methodology to prepare sintered porous ceramic bodies obtained by replica method using organic fibers. The porous bodies of Al2O3 and Al2O3-ZrO2 were synthesized through co-precipitation method [11] and replica [1,11] aiming to achieve a porous ceramic structure with thermal properties in agreement to the application of refractory materials.
