Atomic force microscope image of aluminum magnesium boride (AlMgB14) superhard coating as deposited. The coating has a surface roughness of 0.17 nm and a dry friction coefficient of 0.05.
Image Credit: DOE, Energy Efficiency and Renewable Energy Laboratory
Industrial energy efficiency is directly linked to the wear and degradation of materials used in processing applications such as pumps and tooling components. A new family of “superhard” (greater than 40 GPa) composites has emerged in which the hardness is derived from microstructural engineering of the constituent phases. Preliminary studies involving the primary constituent phase, aluminum magnesium boride (AlMgB14), have demonstrated the feasibility of producing thin film coatings of the compound on various substrates, including straight-grade cemented carbide.
Industrial energy efficiency is directly linked to the wear and degradation of materials used in processing applications such as pumps and tooling components. A new family of “superhard” (greater than 40 GPa) composites has emerged in which the hardness is derived from microstructural engineering of the constituent phases. Preliminary studies involving the primary constituent phase, aluminum magnesium boride (AlMgB14), have demonstrated the feasibility of producing thin film coatings of the compound on various substrates, including straight-grade cemented carbide.
Eaton Corporation (Southfield, MI) and Greenleaf (Saegertown, PA) researchers are developing and hope to commercialize nano-coatings of AlMgB14 and AlMgB1 4-TiB2, as degradation resistance materials applicable to both industrial hydraulic and tooling systems,. The coatings result in surface hardness exceeding 30 GPa. For hydraulic products, the degradation improvement targets for the new nano-coatings are 1) sliding friction reduction of 50%; 2) torque-to-turn reduction of 50%; 3) volumetric loss reduction over simulated lifetime of 50% (resulting in pumping efficiency improvement of 3 to 5%); and 4) start-up torque reduction of 75%. These coatings are also targeted at increasing coated cutting tool life by 50%. The technology advanced by this project is expected to result in U.S. energy savings of 31 trillion Btu/year by 2030 with associated energy cost savings of $179M/year.
The three year project is supported by a $2,929,600 federal grant with Eaton providing 30% cost share for its total costs for the award, including material, equipment, and labor, totaling $935,065 for the three budget periods of this award, with $142,500 of that cost share coming from its subawardee, Greenleaf. Eaton has also invested close to $2 million in coating and related equipment, as well as funded tribology research and modeling applicable to hydraulic products worth approximately $2.5 million. The goal of this project is to develop degradation-resistant nano-coatings of AlMgB14 and AlMgB14– (titanium diboride) TiB2 that result in improved surface hardness and reduced friction for industrial hydraulic and tooling systems.
Preliminary studies involving the primary constituent phase, aluminum magnesium boride (AlMgB14), have demonstrated the feasibility of producing thin film coatings of the compound on various substrates, including straight-grade cemented carbide. The coatings combine high hardness with a low friction coefficient, and have been shown to substantially reduce tool wear in lathe turning tests.
The objectives of the project will be achieved through: (1) establishing the mechanical and tribological properties of single-phase and composite boride thin films; (2) developing and optimizing various vapor deposition techniques for coating application; (3) verifying the energy efficiency advantage of boride thin film over baseline performance metrics; (4) assessing lifetime energy savings in industrial hydraulic and tooling systems; and (5) scaling up deposition technology for large scale applications, complex shapes, and industrial commercialization.
Major barriers include: Failure of existing coating solutions to combine durability with reduction in friction losses needed to improve energy efficiency in hydraulic pump components and tooling systems; high friction, low wear resistance, and over-specification of pump size, which lead to excessive energy use in industrial hydraulic systems: wear of the active components can decrease volumetric and mechanical efficiency by as much as 10% over the lifetime of a typical hydraulic pump; lack of long-term performance data to predict operating lifetime of the coatings under typical operating conditions; insufficient information on the correlation between vapor deposition processing method and surface properties.
Eaton is a worldwide leader in the design, manufacture, and marketing of a comprehensive line of reliable, high-efficiency hydraulic systems and components. Eaton manufactures hydraulic pumps for both industrial and mobile hydraulics, including aerospace hydraulics. In addition, Eaton also manufactures hydro-electric transmission controls and transmissions for automotive and truck markets, where the coating technology developed under this project may be utilized. Eaton’s 2005 sales in the fluid power business segment amounted to $3.24 billion, with about half of that derived from hydraulic products.
