Análise do comportamento mecânico de espumascerâmicas a base de alumina obtidas pelo método daréplica

摘要

Ceramics with porous cellular structure, called ceramic foams, have a potential use in severalapplications, such as: thermal insulation, catalyst supports, filters, and others. Among thesetechniques to obtain porous ceramics the replication method is an important process. Thismethod consists of impregnation of a sponge (usually polymer) with ceramic slurry, followedby a heat treatment, which will happen the decomposition of organic material and sinteringthe ceramic material, resulting in a ceramic structure which is a replica of impregnatedsponge. Knowledge of the mechanical properties of these ceramics is important for thesematerials can be used commercially. Gibson and Ashby developed a mathematical model todescribe the mechanical behavior of cellular solids. This model wasn´t for describing theceramics behavior produced by the replica method, because it doesn´t consider the defectsfrom this type of processing. In this study were researched mechanical behavior of porousalumina ceramics obtained by the replica method and proposed modifications to the model ofGibson and Ashby to accommodate this material. The polymer sponge used in processing wascharacterized by thermogravimetric analysis and scanning electron microscopy. The materialsobtained after sintering were characterized by mechanical strength tests on 4-point bendingand compression, density and porosity and by scanning electron microscopy. From theseresults it was evaluated the mechanical strength behavior compared to Gibson and Ashbymodel for solid cellular structure and was proposed a correction of this model through a factorrelated to struts integrity degree, which consider fissures present in the structure of thesematerials besides defects geometry within the struts