Self-lubricating friction parts engineered for high-temperature applications
Current lubricants fail at high temperatures and numerous small- and medium-sized enterprises (SMEs) seek the competitive edge new technology could afford. Scientists developed novel solutions for dry-friction, high-temperature situations within the context of the EU-funded project HIGRAPH (Incorporation of solid lubricants into surface of friction parts engineered for high-temperature applications). The team encapsulated high-temperature solid lubricant (HTSL) particles in micro-reservoirs. This maintains operational integrity even at high temperatures and enables slow release of solid lubricant, generating a lubricating film at the frictional interface. The self-lubricating surface layers were prepared through powder metallurgy or modification of thermal spray coatings (TSC) by micromachining depending on industrial requirements. The parts proved to last three to four times longer due to an important reduction of friction coefficient. The slight increase in unit price will be completely offset by the enhanced service lifetimes for 40 to 60 % cost savings within 2 to 3 years. Researchers created a database of wear mechanisms of parts subjected to friction at high temperatures. This tool offers designers of machined parts the opportunity to determine the selection of materials, the properties of the surface layers, manufacturing technology and tribological properties. Together with their model of mixed lubrication, market analysis enabled the researchers to evaluate commercially available HTSL powders. They chose the most promising HTSL powders for the selected industrial applications. In addition, the team developed a laser micromachining process for TSC surface texturing that facilitates the encapsulation of solid lubricants into the micro-reservoirs. The new lubricant technology could be effectively applied to a variety of products, including tension and guide rolls for the steel industry, vanes and driving shaft for the aeronautics field, and valves for the petrochemistry field. The HIGRAPH team tested the technology on rail guide and rollers. A new monitoring and process control system allowed real-time control of the coating deposition process. HIGRAPH's novel solid lubricant technology for high-temperature applications will increase service lifetime and reduce the need for replacement, while decreasing the energy consumed by the machines to do their jobs. In addition to machining applications for SMEs, outcomes are expected to reach new markets, including various industrial sectors.
Keywords
Self-lubricating, friction parts, high-temperature applications, HIGRAPH, solid lubricants
