Vermikülitlerin Mikrodalga Genleşme Özellikleri

Abstract

In this study, microwave exfoliation characteristics of eight vermiculite and one phlogopite sample were determined using a kitchen type microwave oven considering power and reaction time. Same samples were also expanded at flame and the results obtained were compared so as to determine the differences between the exfoliation behaviours. Samples prepared at sizes -3,35 +2 mm and phlogopite sample at 2 mm were expanded at flame using a portable torch. These tests were conducted at the same flame conditions (maximum temperature 1060ºC) for 30 seconds and for some samples up to 65 seconds if the exfoliation continued. Experimental results were evaluated by determining the bulk densities (BD) before and after exfoliation. In the flame expansion tests, BD values proceeding towards higher values were determined in the order U-1 < C-3 < T-1 < SA-1 < In-1 < SA-2 < C-2 < C-1 < SA-3. Best expansion was observed with vermiculite sample of U-1 with a BD of 80 kg/m3. Increase of phlogopite content in vermiculite or hydrobiotitic vermiculites was observed to affect the expansion behavior and the reaction time negatively. BD values of the expanded samples were in better agreement with the loss on ignition values of the raw samples compared to the weight loss values during the expansion. Microwave exfoliation tests were conducted at 450W, 600W and 800W for reaction times of 1, 3, 5 seconds. BD values obtained after microwave exfoliation were different from flame expanded samples (T-1 < C-3 < SA-1 < U-1 < SA-2 < In-1 < C-2 < C-1 < SA-3) and the best result was obtained for sample T-1 with a BD of 100 kg/m3. Increase of phlogopite content in vermiculite or hydrobiotitic vermiculites was also observed to decrease the microwave exfoliation characteristics. BD values of the microwave exfoliated samples, contrary to flame expansion, were in better agreement with the weight loss values during the exfoliation compared to the loss on ignition values of the raw samples. Also, pure phlogopite sample (SA-3) showed almost no reaction both for flame and microwave treatments.