Extreme Environment Tribological Characterization of Advanced Bearing Materials

In extremenbsp;temperatures withnbsp;variable atmospheresnbsp;in space exploration, traditional oil lubricants and greases are infeasible. To develop and verify the correct bearing materials/lubricants for these environments, we will use a special instrument for tribological study at extreme temperate conditions with a controlled gas atmosphere. We propose preliminary testing of one tribo-pair of advanced high temperature bearing materials (PS/PM400 sliding against BAM) that are suitable for Venusian surface conditions: PS/PM400 composite was developed by NASA scientists and it is a self-lubricatingnbsp;composite coating for high temperature applications up to 927˚C; boron-aluminum-magnesium (BAM - Al0.75Mg0.75B14), which is a high temperature, high wear resistance, low friction ceramic material. For lower temperature ranges, we propose to use a tribo-pair of advanced polymer bearing coatings sliding against each other for wide temperature range (cryogenic to 300˚C) applications: the coatings are based on aromatic thermosetting copolyesters (ATSP), which has demonstrated excellent tribological performance. This concept of polymer coating sliding on polymer coating yields the beneficial effects of ldquo;transfer layerrdquo;, which can efficiently reduce friction. In other words, one of the polymer coatings will work as a ldquo;pre-deposited transfer layerrdquo;, thus reducingnbsp;friction. In addition, because the cosmic environment radiation, mainly a combination of protons and alpha rays, might deteriorate the bearing materials after long time service in space exploration, we will study radiation exposure effects on the bearing materials. This study will be invaluable in qualifying tribological materials for mechanical devices (e.g., drills, electric motors, bearings) for use in extended deep space missions.