Roman Nevshupa

Model of the effect of local frictional heating on the tribodesorbed gases from metals in ultra-high vacuum

In this paper, a model of thermal desorption of gases from the friction zone of metals in ultra-high vacuum is presented. Comparison of the model with the experimental data of tribodesorbed gases from AISI 304 steel shows that for mild friction the amount of desorbed gases owing to the local temperature increase is much lower than the experimentally obtained values. This finding supports the hypothesis that structural modification of material is the main driving process for tribodesorption. The study also shows that a significant volume of material around the friction zone contributes to the tribodesorption process.

Characterisation of tribocorrosion behaviour of multilayer PVD coatings

The effect of repassivation on tribocorrosion behaviour of two multilayer coatings of different structures is studied experimentally by measuring the variation of instantaneous open-circuit potential during friction. One coating consists of alternating Cr and CrN layers, while another consists of alternated layers of CrN and ZrN. Analysis of the results showed that friction force, i.e. the rate of the mechanical energy supplied to the material in the contact zone, has no direct influence on the tribocorrosion behaviour; however, the wear rate does strongly influence the tribocorrosion. A simple phenomenological model of repassivation of the multilayer coating is developed assuming “surface coverage” approach. This model establishes the relationship between the rate of mechanical activation of material by friction and the behaviour of the open-circuit potential.

Mechanically stimulated solution of adsorbed hydrogen and deuterium in steel

The results of the pioneer research of the phenomenon of a mechanically stimulated solution of gases (hydrogen and deuterium) in a bulk of balls made of carbon chromium steel (15% Cr, 1% C) are presented. The experiments have been performed in a vacuum chamber filled with deuterium at a pressure of 5 ×10 -1 Pa. The ball-bearing was loaded by an axial force of 34.3 N per ball and rotation was performed at a speed of 195 rpm. The phenomenon has been studied for both long (N 1 = 24 x 10 3 revolutions) and short (N 2 = 2 x 10 3 revolutions) rotation periods. An unloaded sample of the same steel was kept stationary in the chamber during the experiment as a reference. The measurements of the distribution of hydrogen and deuterium atoms in the depth of the ball, as well as in the bulk of the reference sample, were performed using SIMS.

Rolling‐sliding, scuffing and tribocorrosion behaviour of PVD multilayer coatings for gears application

Purpose – The aim of this work is the study the tribological behaviour and tribocorrosion resistance of newly developed multilayer PVD coatings Cr/CrN and CrN/ZrCN applied on nitrided F1272 steel for gear applications.Design/methodology/approach – Tribological characterization has been completed by several tribological tests performed under ball‐on‐disc configuration, extreme pressure tests to determine the maximum load before the films failure and rolling‐sliding tests under line‐contact conditions (35‐40 per cent of sliding). The response of the different coatings to sodium chloride aggressive environment has been simulated by accelerated tribocorrosion tests, combining simultaneously chemical and mechanical factors. The synergistic effect of wear on corrosion behaviour and vice versa, has been studied in order to compare the protective properties of the different PVD coatings developed.Findings – Cr/CrN PVD coating improves wear in almost a 90 per cent compared to the nitrided substrate, presenting a s...

Measurement uncertainty of a fibre-optic displacement sensor

The measurement uncertainty and linearity of a bundle fibre-optic displacement sensor were studied on a wide range of displacements using experimental and simulation approaches. The theoretical He–Cuomo distribution functions of light intensity yielded the simulated modulation characteristic that best fitted the experimental data in the range of dimensionless distances to the target surface from 0 to 50 but diverged beyond. The coefficient of variation of the output signal of the sensor varied non-monotonically with the distance to the target surface. This variation is suggested to stem from small randomly distributed imperfections on the mirror surface.

X-Ray Photoelectron Spectroscopy for Characterization of Engineered Elastomer Surfaces

© 2012 Nevshupa et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. X-Ray Photoelectron Spectroscopy for Characterization of Engineered Elastomer Surfaces

Innovative “Green” Tribological Solutions for Clean Small Engines

Since its invention in the last quarter of the nineteenth century and during all the twentieth century, two-stroke engines penetrated in many industrial, automotive and handheld appli‐ cations where engines with high specific power, simple design, light overall weight and low cost are required. Presently, two-stroke engines are commonly used in motorcycles, scooters, chainsaw, agricultural machinery, railways grinding machines, outboard applications, etc.

Force Measuring System for High-Precision Surface Characterization under Extreme Conditions

Force measuring is used in various surface characterization techniques such as indenta‐ tion, scratch tests, tribological analysis, determination of gas content, etc. The main problems related with force measurement under extreme conditions have been analysed. “ strategy that should be followed to solve these problems has been discussed and several examples of successive solutions that recently were developed by the authors are presented. The need to carry out the characterization under extreme conditions poses serious problems for the designers of the measuring systems that may include the incompatibility of the sensors with the test conditions, undesirable interactions with other components, stability, precision and uncertainty issues, the measurement range, etc. Resolving these problems must be based on a global approach in which the characteri‐ zation system is considered as a whole, while the designer must analyse and solve the possible conflicts between the subsystems. The way how an appropriate force measur‐ ing system can be selected is described. The proposed method is illustrated by an example in which an indirect force measurement using optical fibre displacement sensor was used. “nother example describes measuring system developed for vacuum high-tempera‐ ture nanoindentation. “t high temperature, proper heat management based on noncontact heating and laminar flow cooling system is mandatory to avoid experimental data being affected by external noise and thermal drift.