Edelink Efrain Tinoco Falero

Abstract:

Assessments on the metallic iron phase morphology and carbon content, regarding the reduction of composite briquettes, were originally obtained. Targeting to appraise the nucleation, growth and the carburizing evolution of the metallic iron phase, the briquettes were firstly reduced in temperatures from 1000 to 1350�C, during times ranging from 5 to 45 minutes, under CO and N2 atmospheres. With the objective to define the microstructures formed along the briquette�s cross sections, they were examined in Optical and SEM microscopes and submitted to a Chemical Micro Analyzer. Four metallic iron phase morphologies were characterized: i) iron granules, generated during the initial reduction times and nucleated at both, the peripheral and core regions; ii) iron whiskers, occurring mainly at the briquette�s core and for short reduction times; iii) sintered and dense external continuous iron layer, located at the periphery and formed for longer times, and iv) iron globules, generated from previously molten carburized iron phases, sited at the briquette�s core for longer reduction times. The following carbon percentage were obtained in the main iron phases: i) iron globules: from 3.8 to 4.6%C, for CO atmosphere, and from 3.5 to 4.5%C, for N2; ii) continuous iron layer: from 0.5 to 1.3%C, for CO atmosphere, and from 0.7 to 0.9%C, for N2 furnace atmosphere. Finally, regarding the carburization kinetics of the liquid iron phase, the following parameters were calculated: i) 26.4 kJ/molC, for apparent activation energy; ii) 46.9 MHz, for frequency factor.