Conformação de alumina porosa utilizando fios de seda por prensagem uniaxial e isostática

Abstract

Porous ceramics have a high potential for application in several areas, one of which is the production of thermal insulation, which was the subject of our study. Obtaining this type of material follows some classic routes, of which the following can be mentioned: burning of organic particles, replication, gelcasting of ceramic foams, among others. However, an alternative method would be to associate alumina with silk thread, which works as a pore generator, which during pyrolysis will be degraded, thus obtaining a porous ceramic. In the production of thermal insulators, porosity allows the material to decrease its thermal conductivity, making it difficult to dissipate heat, since the air present in the porosity is an excellent thermal insulator. This work presents a method for obtaining porous ceramics through the process of pressing alumina powder together with silk threads, eliminating the silk thread by degradation and subsequent sintering to obtain the final product. The silk thread was characterized by thermogravimetric analysis (TGA) to assess silk degradation temperatures. For the material obtained, a dilatometry analysis was performed, in which it was verified that the samples without the fiber presented a greater contraction, in comparison with the samples with fiber. Another analysis performed was the scanning electron microscopy (SEM), through which it was verified that due to the degradation of the silk fibers there was the formation of pores. Finally, to assess whether there was any change in the thermal conductivity of the material, a thermal conductivity meter was used, but the results obtained were similar between the samples with and without fiber, as the density of the samples did not vary, this can be explained due to the low generation of pores, providing inconclusive data on the difference in thermal conductivity.