LIGHT-ELEMENTS ANALYSIS USING HE-3 MICROBEAM

Coatings containing light elements such as carbon, nitrogen or oxygen play actually an important role in surface engineering as a means to improve the tribological performance. In this paper, we have studied the wear tracks on a diamond coating after a fretting test against a Cr steel ball. The microprobe facility of the LARN has been used to determine light elements concentration in the wear tracks because the size of the tracks was less than 100 mu m and the transfer layer from the Cr steel counterbody was not uniform. Quantitative analysis of oxygen has been performed using the 2.392 MeV resonance of the O-16(He-3, alpha(0))O-15 reaction at 90 degrees, while carbon has been measured simultaneously with the C-12(He-3, p(1))N-14* reaction at 175 degrees. The cross sections and the Q-value of this reaction are so high that an absorber is not required, so we can also measure the backscattered He-3 particles in the same detector. A correlation between carbon, oxygen and iron has been made to investigate the possibility of interdiffusion between the diamond coating and the transferred material due to the fretting test.