Abstract
The effect of several kinds of inhibitors against the deterioration of quenching oils was examined experimentally. It is concluded, from the results, that most of oxidation inhibitors examined here seem to elongate the initial stage (induction, period) of deterioration and to accelerate the oxidation of oil in the later stage (polymerizing period) by a catalytic action of the oxidation products of inhibitors. Although for quenching oil the inhibitor should be effective not only in the initial stage but also in the later stage of oxidation process, there was a difficulty in finding such inhibitor. But, some good effects were observed in certain cases, that is, n-phenyl-α-naphthyl-amine in soya-bean oil, di-phenyl-amine and di-tert.-buthyl-para-cresol in 110-dynamo oil and di-tert. -buthyl-para-cresol in 120-cylinder oil, when the concentration was about 0.5%.
