The improvement of DLC film lifetime using silver nanoparticles for use on space devices

Abstract

This paper reports the results of incorporating silver nanoparticles in DLC films to improve the solid lubricant's lifetime when atomic oxygen bombardment is present in high vacuum environments as are encountered in space. For this, etching experiments were performed in oxygen plasma operated at low pressure. DLC films were deposited on different metallic substrates and on silicon (100) with thin amorphous silicon interlayer by using a Pulsed DC-PECVD discharge. The main goals were to obtain a low etching rate in an atomic oxygen atmosphere, a low friction coefficient, a low total stress, a high degree of hardness, and very high adherence to the substrate in depositions. During etching experiments, the films were submitted to oxygen ions with energy of ∼ 84 eV in order to evaluate the process of wear of the surface in a short period (4 min). The mass spectrometry analysis shows a reduction of the volatile product species (C +, CO + and CO 2 +) in the etching environment for samples with more silver nanoparticles. The results were in agreement with profilometry measurements. The results confirm DLC films are more wear resistant against oxygen attack when silver nanoparticles are incorporated. Also, a consistent method for obtaining nanoparticle size and density control will be discussed.