Porous Ceramic Made from Powders Prepared by Chemical Dispersion of Alloy Al–Mg (20 wt.%)

Abstract

Scanning electron microscopy and x-ray phase analysis results are presented for powders prepared by chemical dispersion of alloy Al-Mg (20 wt.%) and specimens of porous ceramic materials made from these powders. Different powder fractions are obtained during chemical dispersion of aluminum-magnesium alloy. A powder fraction finer than 50 mm is selected for study. Ceramic specimens are prepared by semidry compaction. Features of phase composition and structure of heat-treated powders and ceramic prepared with a high magnesium content in the original alloy are described.Keywords: porous ceramic, chemical dispersion, alloy Al-Mg (20 wt.%), fracture surface fractogram.Currently in industrial production it is necessary to use different ceramic material objects, in particular porous permeable materials for creating new forms of filter elements and highly efficient heat insulation objects. Therefore preparation of porous ceramic material with a high level of operating parameters and prescribed pore space structure is important.The aim of this work is to study the microstructure and properties of powder prepared by chemical dispersion of Al-Mg (20 wt.%) alloy and ceramic material based upon it. STUDY PROCEDURE FOR CHEMICAL DISPERSION OF ALLOY Al-Mg (20 wt.%)The starting powder of mixed hydroxides was prepared by chemical dispersion of Al-Mg alloy by treating it with 20% aqueous caustic soda solution. The powder obtained from mother liquor was fired, repeatedly washed with distilled water by filtration under vacuum, and calcined at 1250°C for 1 h [2].A distinguishing feature of the powder obtained is the fact that it consists of two fractions, finer than 50 mm, and from 315 to 630 mm. The fraction finer than 50 mm was selected for study. Ceramic specimens were prepared by semidry pressing (150 MPa) followed by sintering (1450°C, holding 1 h). After sintering specimens had an apparent density of 1.72 g/cm 3 , open porosity 58.41%, and ultimate strength in compression 175 MPa.