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Full-Text Articles in Mechanical Engineering
Adhesion At Diamond /Metal Interfaces: A Density Functional Theory Study, Haibo Guo, Yue Qi, Xiaodong Li
Adhesion At Diamond /Metal Interfaces: A Density Functional Theory Study, Haibo Guo, Yue Qi, Xiaodong Li
Faculty Publications
To understand the basic material properties required in selecting a metallic interlayer for enhanced adhesion of diamondcoatings on the substrates, the interfaces between diamond and metals with different carbide formation enthalpies (Cu, Ti, and Al) are studied using density functional theory. It is found that the work of separation decreases, while the interface energy increases, with the carbide formation enthalpy ΔHf (Tiys (Ti>Cu>Al), is needed to achieve a higher overall interface strength. In addition, when the surface energy is larger than the interface energy, a wetted diamond/metal interface is formed during diamondnucleation, providing the strongest adhesion …
Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li
Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li
Faculty Publications
Hydrogen atmosphere can significantly change the tribological behavior at diamond and diamondlike carbon (DLC) surfaces and the friction-reducing effect depends on the partial pressure of hydrogen. We combined density functional theory modeling and thermodynamic quantities to predict the equilibrium partial pressures of hydrogen at temperature T, PH2 (T), for a fully atomic hydrogen passivated diamondsurface. Above the equilibrium PH2 (T), ultralow friction can be achieved at diamond and DLC surfaces. The calculation agrees well with friction tests at various testing conditions. We also show that PH2 (T) …