Ultra-hard low friction coating based on A1MgB.sub.14 for reduced wear of MEMS and other tribological components and system

Patent · Tue Jul 03 00:00:00 EDT 2007

OSTI ID:1531533

Cook, Bruce Allan; Tian, Yun; Harringa, Joel Lee; Constant, Alan Paul; Russell, Alan Mark; Molian, Palaniappa A.

Performance and reliability of microelectromechanical system (MEMS) components enhanced dramatically through the incorporation of protective thin film coatings. Current-generation MEMS devices prepared by the LIGA technique employ transition metals such as Ni, Cu, Fe, or alloys thereof, and hence lack stability in oxidizing, corrosive, and/or high temperature environments. Fabrication of a superhard, self-lubricating coating based on a ternary boride compound AlMgB.sub.14 is described in this letter as a potential breakthrough in protective coating technology for LIGA microdevices. Nanoindentation tests show that hardness of AlMgB.sub.14 films prepared by pulsed laser deposition ranges from 45 GPa to 51 GPa, when deposited at room temperature and 573 K, respectively. Extremely low friction coefficients of 0.04-0.05, which are thought to result from a self-lubricating effect, have also been confirmed by nanoscratch tests on the AlMgB.sub.14 films. Transmission electron microscopy studies show that the as-deposited films are amorphous, regardless of substrate temperature; however, analysis of FTIR spectra suggests that the higher substrate temperature facilitates formation of the B.sub.12 icosahedral framework, therefore leading to the higher hardness.

• Research Organization: Iowa State Univ. Research Foundation, Inc., Ames, IA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-82
• Assignee: Iowa State University Research Foundation, Inc. (Ames, IA)
• Patent Number(s): 7,238,429
• Application Number: 10/946,051
• OSTI ID: 1531533
• Country of Publication: United States
• Language: English