Characterization of Tricresylphosphate Lubricating Films by Micro-Fourier Transform Infrared Spectroscopy

Abstract

The characterization of tricresylphosphate (TCP) lubricating film by use of micro-Fourier Transform Infrared Spectroscopy (μ-FTIR) is reported. The study uses a combination of test methods to establish the qualitative sequence of chemical reactions that result in the formation of the observed anti-wear film. A four-ball wear tester, using a 6 μl test procedure, was used to generate the tribochemical films. A static pressurized Differential Scanning Calorimeter (DSC) was used at several temperatures to obtain TCP-iron reaction products similar to those formed under rubbing conditions. The wear contact temperatures can be estimated by comparison of the μ-FTIR spectra of the static reaction products to the spectra from the wear tests conducted at room temperature. The combination of the FTIR and DSC proved to be a powerful, rapid and reliable analytical tool. The use of DSC as a static reactor and the four-ball wear tester as a sequential test procedure provided the necessary materials for FTIR analyses. The unique capability of the μ-FTIR microscope enabled the identification of chemical species without disturbing the surface films on wear surfaces.