Biomimetic Nanostructured Coating for Dry Machining

The goal of this research project is to develop an innovative nanostructured coating, with a unique integration of hard phases and lubrication phases, for dry machining of austenite steels for the automotive and aerospace industries. This novel coating will be synthesized using a combination of electrostatic spray coating, chemical vapor infiltration, and plasma etching. Unique biomimetic-inspired domes plus the reservoir surface morphology of the coating constantly refresh the surface of contact with lubricants, leading to significantly reduced friction and wear. In comparison, current state-of-the-art techniques for combining the hard phases and soft phases for dry machining usually are in layered structures, where the soft phases wear away quickly leaving only the hard phases behind. Dry machining eliminates cutting fluids and relieves environmental loading from sources. Cutting fluids, at a yearly consumption of more than 100 million gallons in the United States, represent a significant health and environmental problem for the nation’s manufacturers. NanoMech is working to realize a reliable and scalable coating process for the coating to achieve dry machining with significantly extended tool life. The following explorative work was carried out in Phase I: (1) optimization of the combination of hard phases of different average sizes for controlled dimensions of the domes and reservoirs; (2) deposition of nanostructured solid lubricants dispersion; (3) optimization of the plasma etching process; (4) evaluation of the coating (physica1, chemical, tribological, and machining performance); and (5) design considerations for scaling up the manufacturing process for batch production. All of the technical goals were successfully accomplished in Phase I. The desired surface morphology was achieved for integrating the hard phases and the lubricant phases. Preliminary tribological testing has demonstrated a lower coefficient of friction and a better resistance to wear than the industrial benchmark, a nanostructured solid lubricant coating (physical vapor deposition) combing the hard phases and the soft phases in a layered structure. These excellent results have solidly established the technical platform for Phase II. Upon completion of Phase II, deliverables including the coating, coating system, and coated tool inserts are anticipated. The application of the coating is expected to facilitate dry machining—a green technology—by offering a 300 percent increase of tool life as compared to the industrial benchmark, better energy efficiency, and longer tool shelf life, further contributing to cost savings and strengthening the U.S. manufacturing industries in worldwide competitive markets.