Gorokhovsky V.I.,University of Texas at San Antonio |
Gannon P.E.,Montana State University |
Wallace J.,Arcomac Surface Engineering LLC |
Vanvorous D.,Arcomac Surface Engineering LLC |
And 3 more authors.
Journal of the Electrochemical Society | Year: 2011
When Solid Oxide Fuel Cells (SOFCs) are operated in the temperature range from 750 to 800°C, it becomes possible to use inexpensive ferritic steels as interconnects (ICs). Due to the demanding SOFC-IC operating environment, protective coatings are gaining attention as a way to increase long-term stability. In this study, the large area filtered arc deposition (LAFAD) process was used to deposit nano-structured coatings from the (Co,Mn)TiCrAlY(O,N) system. Both nano-laminated as well as nano-composite coating architectures were studied and compared. Coatings were deposited on ferritic steel with the aid of an ultra-thin, adhesion-promoting bond-coat, and were subsequently annealed in air for various time intervals. Surface oxidation was investigated using RBS, SEM, and EDS analyses. Cr-volatilization was evaluated using a modified transpiration apparatus and Area Specific Resistance (ASR) was studied as a function of time using a four-point technique. Significant improvement in oxidation resistance, Cr volatility, and ASR were observed in the coated samples. In addition, a set of sample IC plates were subjected to LAFAD coatings and tested in a SOFC stack. Transport mechanisms for various oxidizing species and coating diffusion barrier properties are discussed, as are the trades-offs between ionic diffusion and electronic conductivity. © 2011 The Electrochemical Society.
Cheng Y.H.,American Eagle Instruments Inc. |
Browne T.,American Eagle Instruments Inc. |
Heckerman B.,American Eagle Instruments Inc. |
Bowman C.,Arcomac Surface Engineering LLC |
And 2 more authors.
Surface and Coatings Technology | Year: 2010
A large area filtered arc deposition (LAFAD) technique was used to deposit TiN/Ti multilayer coatings with fixed TiN layer thickness and different Ti layer thickness. Nanoindention and pin-on-disk tribometer were used to characterize the hardness, elastic modulus, plasticity, friction coefficient, and wear rate of the multilayer coatings. The dependence of the mechanical and tribological properties of the coating on the Ti interlayer thickness was systematically studied. It was found that the increase in the Ti layer thickness resulted in a decrease in the effective hardness and elastic modulus, and an increase in the wear rate, plasticity, and toughness. The coatings with a Ti layer thicknesses of 0, 25. nm and 50. nm possess an excellent combination of high effective hardness (> 20. GPa), high plasticity (> 69%), low friction coefficient, and high wear resistance. © 2010 Elsevier B.V.