Scale Effects and the Molecular Origins of Tribological Behavior

Nanotribology ◽  
2003 ◽  
pp. 29-44 ◽  
Author(s):  
Gang He ◽  
Mark O. Robbins
Author(s):  
Renan Magnol ◽  
Marciano Macedo ◽  
Marcelo de Macêdo ◽  
Cherlio Scandian

2018 ◽  
Vol 84 (12) ◽  
pp. 68-72
Author(s):  
A. B. Maksimov ◽  
I. P. Shevchenko ◽  
I. S. Erokhina

A method for separating the work of impact into two parts - the work of the crack nucleation and that of crack growth - which consists in testing two samples with the same stress concentrators and different cross-sectional dimensions at the notch site is developed. It is assumed that the work of crack nucleation is proportional to the width of the sample face on which the crack originates and the specific energy of crack formation, whereas the work of the crack growth is proportional to the length of crack development and the specific crack growth energy. In case of the sample fracture upon testing, the crack growth length is assumed equal to the sample width. Data on the work of fracture of two samples and their geometrical dimensions at the site of the notch are used to form a system of two linear equations in two unknowns, i.e., the specific energy of crack formation and specific energy of crack growth. The determined specific energy values are then used to calculate the work of crack nucleation and work of crack growth. The use of the analytical method improves the accuracy compared to graphical - extrapolative procedures. The novelty of the method consists in using one and the same form of the notch in test samples, thus providing the same conditions of the stress-strain state for crack nucleation and growth. Moreover, specimens with different cross-section dimensions are used to eliminate the scale effects. Since the specific energy of the crack nu-cleation and specific energy of the crack growth are independent of the scale factor, they are determined only by the properties of the metal. Introduction the specific energy of crack formation and growth makes possible to assign a specific physical meaning to the fracture energy.


2020 ◽  
Vol 2020 (9) ◽  
pp. 13-17
Author(s):  
Yuriy Ryzhov ◽  
Svetlana Abramova

There is carried out a number of experiments with the purpose of analyzing SOTS impact upon both finishing productivity, and physical-chemical state and tribological behavior of surfaces machined, and also a possibility for creation according to the results of the investigations carried out a relatively universal micro-emulsion SOTS based on existing in the Ukraine the line of oils, PAV, corrosion inhibitors, alloying additives etc. As SOTS samples there were used both well-known compouds, for example, Camix, Nope Right (USA), and carbamide having in its structure boron, boron-phosphorus-containing additive, water-solvable phosphate, tributyl phosphate (oil-solvable), concentrate SOTS tribol, having in its structure compounds of boron, nitrogen and phosphorous; ethylic ether of fatty acids; methyl ether of colza oil; Sarkozyl-O having in its structure easily-decomposable chlorine compounds. From the results obtained it is possible to draw a conclusion that during finishing in the environment of water-compatible SOTS an important role in the formation of the properties of the surface worked is played by hydrocarbon components and additives which contribute to the formation of the thinnest surface layers modified with carbon and oxygen.


2020 ◽  
Vol 62 (12) ◽  
pp. 1243-1250
Author(s):  
Fahri Vatansever ◽  
Alpay Tamer Erturk ◽  
Erol Feyzullahoglu

2019 ◽  
Vol 61 (6) ◽  
pp. 543-548
Author(s):  
Aslı Gunay Bulutsuz ◽  
Mehmet Emin Yurci ◽  
Kadir Ozaltin ◽  
Witold Chrominski ◽  
Malgorzata Lewandowska

2010 ◽  
Vol 1 (2) ◽  
pp. 123-128
Author(s):  
Mohammad A. Chowdhury ◽  
Dewan M. Nuruzzaman ◽  
Mohammad L. Rahaman

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