INVESTIGATION OF THERMAL-OXIDATIVE STABILITY OF COMPLEX CALCIUM GREASES BY THERMAL ANALYSIS AND IR SPECTROSCOPY.

This paper is concerned with a study of the thermal-oxidative stability of complex calcium greases that are intended for operation at high temperatures (200 degree C) with high specific loads. The complex calcium greases included in this study were prepared from various base oils. The thickening agent was a complex calcium soap of a C//1//0-C//2//0 fraction of synthetic fatty acids and acetic acid, with a 1:1. 2 molar ratio of the high- and low-mol. wt acids, and a total acid concentration of 15% by weight. In the work reported, the thermal-oxidative breakdown of complex calcium greases was studied through the use of DTA, DGA, and IR spectroscopy. The tests were performed with dynamic heating at temperatures increasing from 20 to 400 degree C in air or nitrogen medium. Measuring results are presented in tables and curves. The data show that the greases are less volatile than the dispersion media; the more volatile the dispersion medium, the greater the influence of the soap thickener in decreasing the weight loss of the grease. By comparing the TGA curves obtained in air and in nitrogen for each grease sample, two temperature intervals for weight loss can be established.