Effects of Metal Work Function and Contact Potential Difference on Electron Thermionic Emission in Contact Electrification

2019 ◽  
Vol 29 (29) ◽  
pp. 1903142 ◽  
Author(s):  
Cheng Xu ◽  
Binbin Zhang ◽  
Aurelia Chi Wang ◽  
Wenzhe Cai ◽  
Yunlong Zi ◽  
...  
Keyword(s):  
Work Function ◽  
Contact Potential Difference ◽  
Thermionic Emission ◽  
Potential Difference ◽  
Contact Potential ◽  
Metal Work Function ◽  
Contact Electrification ◽  
Metal Work

Changes of Contact Potential Difference Induced by Frictional Damage in Ultrahigh Vacuum

1999 ◽  
Vol 558 ◽  
Author(s):  
L. Zhang ◽  
K. Nakayama
Keyword(s):  
Atomic Force Microscope ◽  
Work Function ◽  
Contact Potential Difference ◽  
Ultrahigh Vacuum ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Light Load ◽  
Atomic Force ◽  
The Difference

ABSTRACTThe work function is one of the most fundamental properties of a metal surface. To clarify frictional electrification phenomena, the effects of frictional damage on the contact potential difference (CPD), which is defined by the difference between the work functions of two contacting surfaces, were investigated. Au(111) and Si(111) surfaces were scratched in an ultrahigh vacuum under a light load with the Si cantilever tip of an atomic force microscope. The contact potential difference between the scratched surface and the tip whose work function was known was measured using an ultrahigh vacuum scanning Kelvin probe force microscope (SKPM). Simultaneously, the noncontact atomic force microscope (NC-AFM) images were observed in situ. The CPD images showed clear changes between the areas with and without scratching, corresponding to the scratching track on the NC-AFM images.

scholarly journals The measurement of contact potential difference

1936 ◽  
Vol 155 (885) ◽  
pp. 218-234 ◽  
Keyword(s):  
Work Function ◽  
Metal Surfaces ◽  
Contact Potential Difference ◽  
Potential Difference ◽  
Peltier Effect ◽  
Dissimilar Metals ◽  
Theoretical Relation ◽  
Contact Potential ◽  
Work Functions ◽  
Clean Metal

A number of measurements of the contact potential difference between pairs of dissimilar metals has been made during the last few years. The interest and importance of such measurements arise chiefly in connexion with the theoretical relation which exists between the contact potential difference and the work functions of the surfaces considered. This relation, due to Richardson, may be written V c = Φ 1 - Φ 2 + P, (1) where P is a correction for the Peltier effect which, in practice, is negligibly small. If Φ 2 > Φ 1 , the sign of V c will be such that surface 1 is positive with respect to surface 2. It has been pointed out by Compton and Langmuir that equation (1) cannot hold for surfaces which are not homogeneous, since contact potential measurements would yield average values for the whole surfaces, while the magnitude of the work function, measured either by the photoelectric or the thermionic method, would be determined principally by the most electropositive portions of the surface. Farnsworth and Rose have shown that these considerations may apply even for clean metal surfaces, since recent measurements by Rose§ indicate that comparatively large contact potential differences may exist between different faces of crystals of the same metal, so that polycrystalline surfaces cannot necessarily be considered as homogeneous.

scholarly journals Contact potential difference of alloy steel after heat treatment

2020 ◽  
Vol 20 (3) ◽  
pp. 289-294
Author(s):  
L. P. Aref`eva ◽  
A. G. Sukiyazov ◽  
Yu. V. Dolgachev ◽  
L. S. Shakhova
Keyword(s):  
Heat Treatment ◽  
Work Function ◽  
Alloy Steel ◽  
Contact Potential Difference ◽  
Electron Work Function ◽  
Potential Difference ◽  
Polished Surface ◽  
Contact Potential ◽  
Tempering Temperature ◽  
Non Destructive

Introduction. The paper considers an actual issue of the development and application of a non-destructive method for controlling the quality of surfaces of steel products (Kelvin probe method). The work objective is to establish the magnitude of the contact potential difference (CPD) of steel 107WCR5 after heat treatment.Materials and Methods. The object of study is alloy tool steel 107WCR5. The chemical composition of the samples was refined through the optical emission analysis method. To carry out the statistical processing, there were three samples in three series. We chose different heat treatment modes for each series, i.e., quenching with low tempering, strengthening and normalization. The end surfaces of the samples were polished and then one of them was treated with a solution of nitric acid. Further, the measurement of the contact potential difference and statistical data processing were carried out. Results. The data obtained show that the CPD value of steel 107WCR5 samples changes after heat treatment. With an increase in tempering temperature, the contact potential difference of the polished surface and the hardness, decrease almost linearly. Exposure to acid causes a significant decrease and equalization of the contact potential difference for all structures. The contact potential difference of steels 107WCR5 and CT105 is compared. Alloying steel by the elements with the work function values of the electron higher than that of iron causes a decrease in the CPD between the standard and the sample. The CPD behavior under a change in the composition of the steel depends strongly on the presence of alloying elements. The dependence of CPD on the dispersion of the structure is seen in both cases; however, it is more pronounced for 107WCR5 steel. The electron work function of the martensite, troostite, and sorbitol structures obtained as a result of heat treatment of steels 107WCR5 and CT105 is calculated. Discussion and Conclusions. The dependence of the contact potential difference on the structure, chemical and phase composition was experimentally established; the electron work function of steels 107WCR5 and CT105 was calculated. This technique is more sensitive to alloy steel samples than to carbon steel. It seems possible to conclude that the measurement of the contact potential difference can be used to control surfaces exposed to active media or elevated temperatures as a non-destructive express diagnostic method.

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