Experimental Study of the Antiactivation of Reduced Pellets at Low Temperatures
Transactions of the Iron and Steel Institute of Japan
It is generally "ecognized Ihat iron oxide IJellels reduced by hydrogen at lower temlJeratures are easily reoxidized in an air almoslJhere even at room lemperalu reo However, IJellels slighlly reoxidized by Ih e inert gas if a lower oxygen /lOlential showed inactive behaviours. I'ery Ihin oxide layer of the thickneH less Iha ll .') A was formed 011 Ihe /Jore sUlface oj Ihe /Jellet during reoxidalion wilh nitrogen-oxygen gas mixture of below 1"0 oxygen. When Ih e ox)'gen con tent in Ihe gas
... ent in Ihe gas mixture was below 1° (I, Ihe degree q! reoxidatioll was nearly 0.9° 0 independent oj the ox)'gen /JOtelltial. But if the oxygell content exceeded J%, Ihe degree oj reoxidation increased ra/Jidly wilh the oxygen contell t. It was also shown that Ihe rale of reoxidatioll was controlled by Ihe diffusioll of oxygen Ihrough Ihe boundary alld Ihe reacted shell layers. Therifore, Ihe eX/Josure time necessa!), for alltiactivalioll couid be calculaled alld it was de/Jendellt 011 the ox)'gen /lOtential. Fu rlhermore, when Ihe resislallce of Ihe ga. 1 110I1.I/lOrt was IlCl?ligibly small, Ihe rale of reoxidatioll was re/JI'esented by Ihe logarilhmic rale law. * Originall y pub lished in T elsll-lo- !-lagani. 58 ( 1972), 375, in J apanese. Eng lish version rece ived D ecem ber 12, 19 72 .