Synthesis of nanoporous ceramic materials for filtration of liquids and gases by technological combustion method

Abstract

Experimental and analytical studies on the synthesis of a Ti-Al-based ceramic material with a nanoscale porous structure were conducted. The results of previous studies conducted by the authors showed that it is reasonable to obtain porous ceramic materials designed for filtration of liquids and gases by thermal explosion (throughout the sample) rather than by layer-by-layer combustion. Self-propagating high-temperature synthesis (SHS) was used to obtain nanoporous ceramic membranes from a mixture of powders, wt.%: 40Ti + 60Al in one stage with the TiAl3 formation. It was found that the synthesized material consists of the main phase TiAl3 with a small amount of aluminum oxidized into Al 2 O 3 and unreacted. The microstructural analysis of the sample fracture showed that the resulting material has a developed surface and high open porosity. Empirically investigated open porosity is up to 48%, and the pore size ranges from 0.1 to 0.2 цт. The efficiency of the porous material obtained for the Ti-Al-based ceramic SHS filter reaches 99.999 %, gas flow resistance is 100 mmHg, filtration index is 0.062. Gas ultrafiltration capacity is up to 40 l/(cm 2 •h) at a pressure drop on the filter of 2 kPa, and water ultrafiltration capacity ranges from 2 to 10 l/(cm 2 •h) at a pressure drop on the filter of 0.1 MPa. Membranes made of ceramic materials with a gradient nanoporous structure by this method can be used as filter elements for small units providing fine water cleaning from bacteria, viruses, dissolved organic carbon, as well as for fine cleaning of air, process gases from dispersed micro-impurities and radioactive aerosols. The membrane SHS filters developed can also be used in units operating in aggressive environments and/or at high temperatures (up to 1000 °C).