scholarly journals Interfacial superstructures and chemical bonding transitions at metal-ceramic interfaces

2021 ◽  
Vol 7 (11) ◽  
pp. eabf6667
Author(s):  
Can Yang ◽  
Chongze Hu ◽  
Congying Xiang ◽  
Hongbo Nie ◽  
Xinfu Gu ◽  
...  
Keyword(s):  
Chemical Bonding ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Solute Concentration ◽  
Model Systems ◽  
Metal Ceramic ◽  
Anisotropic Formation ◽  
Strong Segregation ◽  
Electron Energy Loss ◽  
Ceramic Interfaces

Metal-ceramic interfaces are scientifically interesting and technologically important. However, the transition of chemical bonding character from a metal to a nonoxide ceramic is not well understood. The effects of solute segregation and interfacial structural transitions are even more elusive. In this study, aberration-corrected electron microscopy is combined with atomic-resolution energy-dispersive x-ray and electron energy loss spectroscopy to investigate Ti-, V-, and Cr-segregated WC-Co interfaces as model systems. The experiments reveal the general anisotropic formation of reconstructed trilayer-like superstructures with segregant-specific compositional profiles that facilitate the transition from covalent to metallic electronic structures. Density functional theory calculations confirm the gradual increasing metallicity from WC to Co in the interfacial trilayers via increasing metallic solute concentration. This study uncovers unprecedented details of the sophisticated interfacial superstructures at metal-ceramic interfaces. It sheds light on how a metal transits to a ceramic at a “general” interface with strong segregation.

A flat-lying dimer as a key intermediate in NO reduction on Cu(100)

2021 ◽  
Author(s):  
Kenta Kuroishi ◽  
Muhammad Rifqi Al Fauzan ◽  
Ngoc Thanh Pham ◽  
Yuelin Wang ◽  
Yuji Hamamoto ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Density Functional Theory ◽  
Scanning Tunneling Microscope ◽  
Density Functional ◽  
No Reduction ◽  
Density Functional Theory Calculations ◽  
Scanning Tunneling ◽  
Functional Theory ◽  
Tunneling Microscope ◽  
Electron Energy Loss

The reaction of nitric oxide (NO) on Cu(100) is studied by scanning tunneling microscope, electron energy loss spectroscopy and density functional theory calculations. The NO molecules adsorb mainly as monomers...

Investigation of chemical bonding at metal-ceramic interfaces

2012 ◽  
Vol 38 ◽  
pp. 012014 ◽  
Author(s):  
A Bakulin ◽  
S Kulkova ◽  
S Hocker ◽  
S Schmauder
Keyword(s):  
Chemical Bonding ◽  
Metal Ceramic ◽  
Ceramic Interfaces

Understanding Mechanical Integrity of Metal/Ceramic Interfaces Through In-Situ Micro Mechanical Testing and Multiscale Simulations

2018 ◽  
Author(s):  
Xiaoman Zhang ◽  
Yang Mu ◽  
Shuai Shao ◽  
Collin Wick ◽  
Ramu Ramachandran ◽  
...  
Keyword(s):  
Mechanical Testing ◽  
Density Functional ◽  
Ceramic Coating ◽  
Minimum Energy ◽  
Shear Loading ◽  
Interfacial Region ◽  
Loading Conditions ◽  
Metal Ceramic ◽  
Ceramic Interfaces

Mechanical failures of interfacial regions of ceramic-coating/metal-adhesion-layer/substrate systems were measured quantitatively and observed concurrently through instrumented microscale mechanical testing in-situ a scanning electron microscope (SEM). Failure of the interfacial regions of coating/interlayer/substrate systems was observed in micro-pillar specimens in-situ under different loading conditions, including shear, compression, and tension. Under shear loading, shear failure of the interfacial region was observed to occur in two stages: an initial uniform shear plastic deformation of the entire metal interlayer followed by an unstable shear-off close to the metal/ceramic interface. Additional testing under compression loading conditions suggests that the unstable shear-off is concomitant with the metal/ceramic interface going from being “locked”, with no relative displacement between materials on the two sides of the interface, to being “unlocked”, with significant relative displacements. Failure of the interfacial region was also observed under tensile loading conditions. Density functional theory (DFT) and molecular dynamics (MD) studies on one particular metal/ceramic interface, namely Ti/TiN, showed that a weak interaction plane exists in the metal layer near the chemical interface in a coherent Ti/TiN structure. Consequently, the free energy and theoretical shear strength of the semi-coherent Ti/TiN interface is found to depend on the physical location of the misfit dislocation network (MDN). The minimum energy and strength of the interface occur when the MDN is near, but not at the chemical interface. The present work gives new insight into the nature of mechanical failure of metal/ceramic interfaces, is relevant to materials-based engineering of metal/ceramic interfaces, and has applications to engineering of ceramic coating/substrate systems.

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