Evaluation on Adhesion Strength of Laser Induction Hybrid Rapid Cladding Cu-Fe-Based Coatings Using Scanning Kelvin Probe

2015 ◽  
Vol 1096 ◽  
pp. 103-106
Author(s):  
Xiao Qin Dai ◽  
Sheng Feng Zhou ◽  
Zheng Xiong
Keyword(s):  
Solid Solution ◽  
Tensile Strength ◽  
Work Function ◽  
Adhesion Strength ◽  
Electron Work Function ◽  
Nondestructive Method ◽  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Logarithmic Relationship ◽  
Laser Induction

It is very important to effectively evaluate the adhesion strength of coating. A nondestructive method to evaluate the adhesion strength of laser induction hybrid rapid cladding Cu-Fe-based coatings was investigated. The electron work function of coatings was measured by scanning Kelvin probe. It was demonstrated that the Fe-rich particles and solid solution of Fe can increase the EWF and the tensile strength. A logarithmic relationship between the ratio of EWF to dilution and the adhesion strength was established.

EFFECT OF GRAIN SIZE ON THE ELECTRON WORK FUNCTION OF Cu AND Al

2004 ◽  
Vol 11 (02) ◽  
pp. 173-178 ◽  
Author(s):  
WEN LI ◽  
D. Y. LI
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Grain Boundary ◽  
Work Function ◽  
Electron Work Function ◽  
Deformation Texture ◽  
Kelvin Probe ◽  
Surface Conditions ◽  
The Mean ◽  
Sophisticated Instrument

The Kelvin probe is a sophisticated instrument which is very sensitive to changes in surface conditions, such as deformation, texture, phase transformation and contamination. Efforts have been made to use this technique to diagnose wear. In this study, the effect of the grain boundary (GB) on the electron work function (EWF) was examined with the aim of investigating the contribution of changes in grain size to total changes in the EWF during wear. Copper and aluminum were studied as examples. It was demonstrated that the EWF dropped in the vicinity of GB's and the mean EWF decreased as the grain size decreased. The mechanism responsible for the changes in the EWF with respect to the GB is discussed.

scholarly journals Scanning Kelvin Probe Investigation of High-Strength Steel Surface after Impact of Hydrogen and Tensile Strain

2020 ◽  
Vol 1 (1) ◽  
pp. 187-197 ◽  
Author(s):  
Andrei Nazarov ◽  
Flavien Vucko ◽  
Dominique Thierry
Keyword(s):  
Tensile Deformation ◽  
Electron Work Function ◽  
High Strength Steels ◽  
High Strength ◽  
Potential Drop ◽  
Hydrogen Uptake ◽  
Surface Oxide ◽  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Cracking Mechanisms

Hydrogen in combination with mechanical stress can lead to rapid degradation of high-strength steels through environmentally assisted cracking mechanisms. The scanning Kelvin probe (SKP) was applied to automotive martensitic steel grade MS1500 in order to detect local reactivity of the surface after hydrogen uptake and tensile deformation. Hydrogen and stress distribution in microstructures can be characterized by SKP indirectly measuring the potential drop in the surface oxide. Thus, the links between electron work function, oxide condition, and subsurface accumulation of hydrogen and stress have to be investigated. It was shown that plastic strain can mechanically break down the oxide film creating active (low potential) locations. Hydrogen effusion from the steel bulk, after cathodic charging in aqueous electrolyte, reduced the surface oxide and also decreased potential. It was shown that surface re-oxidation was delayed as a function of the current density and duration of cathodic hydrogen pre-charging. Thus, potential evolution during exposure in air can characterize the relative amount of subsurface hydrogen. SKP mapping of martensitic microstructure with locally developed residual stress and accumulated hydrogen displayed the lowest potential.

Work function study of rhenium oxidation using an ultra high vacuum scanning Kelvin probe

2000 ◽  
Vol 88 (7) ◽  
pp. 4371 ◽  
Author(s):  
I. D. Baikie ◽  
U. Petermann ◽  
A. Speakman ◽  
B. Lägel ◽  
K. M. Dirscherl ◽  
...  
Keyword(s):  
Work Function ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Kelvin Probe ◽  
Function Study ◽  
Scanning Kelvin Probe

Work Function Study of Polycrystalline Metals using a UHV Scanning Kelvin Probe

2000 ◽  
Vol 615 ◽  
Author(s):  
U. Petermann ◽  
I.D. Baikie ◽  
B. Lägel ◽  
K.M. Dirscherl
Keyword(s):  
Work Function ◽  
Target Material ◽  
Kelvin Probe ◽  
High Work Function ◽  
Positive Ions ◽  
Polycrystalline Metals ◽  
Scanning Kelvin Probe ◽  
Flash Annealing ◽  
Different Temperatures ◽  
High Work

ABSTRACTWe have undertaken a study of high work function (φ) surfaces as part of an ongoing project searching for efficient target materials for use in Hyperthermal Surface Ionisation (HSI), a new mass spectroscopy ionisation technique. HSI relies on high work function surfaces for the production of positive ions. Polycrystalline metals as Re, W, Mo and Pt are particularly interesting materials in this respect as oxidation substantially increases their φ. We present and discuss the following experimental evidence: a) the magnitude and sign of φ changes in terms of adsorbate induced dipoles, b) the effect of molecular hydrogen exposure on the clean surface, and c) the effect of subsequent oxygen exposure.Using a novel UHV Scanning Kelvin Probe we have followed the oxidation kinetics of polycrystalline metals at different temperatures and examined the effects of oxidation, flash annealing and sputter-anneal cleaning cycles via high-resolution φ topographies. Our results indicate in particular Re as a suitable HSI target material exhibiting a φ increase of 1050 meV at 300 K increasing to 2050 meV at 900 K. Sputter-cleaned surfaces exhibit a dramatic change in the second oxidation phase.We have also examined φ changes associated with N2O and CO2 on Tungsten and Molybdenum. We observe that atomic oxygen gives similar results to O2 but has a much lower initial sticking coefficient. We report that CO2 actually lowers the φ for substrate temperatures under 650 K, the peak work function changes occurs at 850 K and is approximately 1/3 the height of the O2 or O peak.

Work Function Study for the Search of Efficient Target Materials for Use in Hyperthermal Surface Ionization Using a Scanning Kelvin Probe

2000 ◽  
Vol 623 ◽  
Author(s):  
U. Petermann ◽  
I.D. Baikie ◽  
B. Lägel ◽  
K.M. Dirscherl
Keyword(s):  
Work Function ◽  
Surface Ionization ◽  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Flash Annealing ◽  
Function Change ◽  
Work Function Change ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Ongoing Project

AbstractIn order to search for efficient target materials for use in Hyperthermal Surface lonisation (HSI), a new mass spectroscopy ionisation technique, we have performed a study of high and low work function (ø) surfaces as part of an ongoing project. HSI relies on high and low work function surfaces for the production of positive (pHSI) and negative (nHSI) ions, respectively.Using a novel UHV Scanning Kelvin Probe we have followed the oxidation kinetics of polycrystalline Re at different temperatures and examined the effects of oxidation, flash annealing and sputter-anneal cleaning cycles via high resolution work function topographies. Our results indicate that oxidised Re is the best candidate for pHSI in terms of ionisation efficiency and ø change. The peak work function change of 2.05 eV occurred at 900 K to 950K.For the nHSI materials Calcium exhibited the best performance with respect to the ionisation efficiency indicating a wf of 2.9 eV. We will present data in terms of mass fragmentation using an HSI-Time-of-Flight (TOF) system and time stability of the work function.

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