Activated carbon and ceramic powder heterodefloculation for porous structure manufacturing

Reference Presenter Authors
17-060 Lucas Freitas Berti Berti, L.F.(Federal University of Technology of Parana); Rambo, C.R.(Federal University of Santa Catarina); Reimbrecht, E.G.(Federal University for Latin American Integration); Bazzo, E.(Federal University of Santa Catarina); Hotza, D.(Federal University of Santa Catarina); Porous structures have been applied in several areas of industry, such as filtration, support for application in biomaterials, capillary structures, etc. There are several techniques for producing porous structures such as freeze casting, gel casting, replica of polymeric and wood structures, sacrificial phase, among others. The sacrificial phase technique has a wide range of possibility of pore size production and porosity values. In applications where residues are not tolerated, the sacrificial phase must be completely removed during the processing steps of the porous structure. Activated carbon is an option because of the fact that when it undergo a heat treatment in an oxidizing atmosphere it forms COx species during the processing. The objective of this work was to produce a porous ceramic structure consisting of mullite and alumina, using the activated carbon as the sacrifice phase, conforming it by slip casting. The production of an aqueous slurry of the ceramic powder mixture with the addition of activated carbon as sacrifice phase falls within the classification of heterodeflocculation. For that, a rheological study was carried out to determine the ideal pH, deflocculant concentration and solids concentration points of the slurry. With the slurry stabilized, the milling time was varied between 9h and 72h and the amount of sacrifice phase was also varied. The samples were heat at 1450 °C for two hours in oxidizing atmosphere. With samples produced, the morphological- and physical characterization of the materials were carried out. Samples presented porosity values between 40 and 80% and compressive strength values between 7 and 14 MPa. The SEM micrographs showed microstructures with well-defined corners grains, which is characteristic of the temperature used for the evaluated materials. After the determination of the mass variation during processing, it is possible to state that less than 1% of residues remained in the final component.
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