Conventional and microwave sintering of condensed silica fume

Abstract

Condensed silica fume, a by-product from the production of silicon alloys, was sintered by (i) conventional heating in a dilatometric furnace, both at constant heating rate and isothermal heating, and (ii) by the microwave heating. The dense products with relative density up to 95% of theoretical can be obtained only by short runs at high heating rates, preferentially accomplished by the microwave treatment. Prolonged heating leads to the devitrification of the original glassy phase to cristobalite, accompanied by an arrest of densification.

Microstructure and Electromagnetic Properties of Microwave Sintered CoCuZn Ferrites

“…The microwave sintering technique also has unique advantages over conventional sintering technique. The main advantage of microwave sintering is high post sintering density and low heat losses during the ferrite formation and rare possibility of formation of microstructural defects like inter and intra granular pores and cracks due to micro-strain or stress, which is otherwise more probable to occur in conventional sintering [7][8][9][10]. The essential difference in the microwave and conventional sintering process is in the heating mechanism.…”

Microwave sintering of high-permeability (Ni0.20Zn0.60Cu0.20)Fe1.98O4 ferrite at low sintering temperatures

“…For microwave sintering, however, the materials themselves absorb microwave energy, and then transform it into heat within their bodies. The advantages of microwave sintering were found to include higher energy efficiency, higher postsintering density [13][14][15][16], and lower sintering temperatures [17,18], compared with conventional sintering. So the microwave sintering technique is expected to prepare the high-permeability NiZn ferrites at relatively low sintering temperatures.…”

Control of pore size by metallic fibres in glass matrix composite foams produced by microwave heating

“…15 In other papers, uncontrolled porosity formation has been seen as one of the disadvantages of microwave densification. 1,3,4 The interrelationship between the processes of pore formation and crystallisation in glass-ceramics heated under microwaves has been also investigated. 16 Some of the main advantages of using microwave radiation include very short processing times obtainable due to rapid, selective and volumetric heating.…”