2025 Volume 20 Issue 1 Pages 26-35
Using a controlled atmosphere cutting apparatus equipped with a mass spectrometer, this study investigated the influence of several additive compounds on grease decomposition and hydrogen generation caused by a nascent clean steel surface. The decomposing behavior of greases was found to be evaluated by examining the changes in the generation amount ratios, which were the ratios of ion intensity values during cutting to those before cutting, for the individual mass numbers. In base greases with no additive, fairly sharp and high generation amount ratios appeared in the vicinity of such periodical mass numbers corresponding to alkyl groups. Compared with the base urea grease, every additive could suppress the hydrogen generation and, in particular, polysulfide reduced the hydrogen generation most. Polysulfide also had the highest capability in providing thick reaction films on chip contact surfaces in both urea and PTFE greases. Further, unlike the others, the greases including polysulfide delivered unique decomposition behavior where most generation amount ratios increased in the nearly whole range of the mass numbers and there disappeared the features of high generation amount ratios at periodical mass numbers. Such unique behavior could possibly connect with the thick reaction film formation contributing to reduce the hydrogen generation.
