The diversity of multidisciplinary approaches suggests that fundamentals of scuffing require systemic, complex multi-scale and multi-physics analysis of an irreversible process as it is postulated in present study. That is probably one of the reasons of lack of unequivocal model of this irreversible transitional process from stable more or less lubricated wear to scuffing described only by one or few authors in equation(s) form. Therefore, it is useful to characterize the tribological surface properties in frame of systemic approach looking simultaneously for the optimal compromise between rheological, morphological and physicochemical features of contacting surface's layer. Hypothetical role connected to any group of features in the topological approach is elucidated and experimentally confirmed via the wettability, strongly combined with surface roughness and surface free energy. Due to the fact that the free energy is directly related to the surface wettability it can as well affect the scuffing activation process. For scientific and rhetoric reasons some selected results of limited boundary lubrication investigations under double blind trial conditions in case of gear oil with anti-wear (AW) and extreme pressure (EP) additives are elucidated here. The results issued from scuffing tests on AISI 4140 ground steel burnished under different forces in order to generate different surface roughness, residual stresses and surface energy are analysed. It was stated and numerically correlated that the wettability by lubricating medium influences the scuffing resistance. Additionally, the dependence of wettability on selected parameters of roughness and a time to scuffing activation have been stated. On that basis, it is proposed to reinforce concept of "oleophilic" and "oleophobic" properties of metallic surfaces as autonomous invariants determining the activation of catastrophic wear process under boundary lubricated conditions. Keywords: Scuffing; Wettability; Boundary lubrication; Surface roughness. This is an eprint of paper published by Elsevier in Tribology International (2015) kris@kubiak.co.uk http://dx Nomenclature:

AbstractThe article contains an analysis of charging electric cars as a way to increase the use of energy produced from a photovoltaic system. A photovoltaic system is described, consisting of two micro installations, with a power output of up to 40 kWp each, supplying two sectors of the building of the Lublin Science and Technology Park. An internet platform for monitoring the operation of a photovoltaic system is presented. Next, an innovative system for monitoring, consumption and production analysis of electric energy in individual building sectors is described. A surplus of energy produced in one of the sectors was found. It was proposed that this excess energy would be used to charge electric vehicles. An analysis of the surplus power generated by the photovoltaic system in excess of the energy consumed by the building sector was used to determine the power available to the wall charger. The surplus of energy produced was used for calculations related to the amount of charging the electric vehicle required and the cost of traveling 100 km. Charging an electric car not only provides a faster return on investment in the installation, but also presents drivers with a very ecological and economical transport solution.

No abstract

Waste management is still one of the leading global challenges in the 21st century. From the European Union’s point of view, the Waste Framework Directive obliges businesses and households to recycle at least 55% of their municipal waste by 2025 and to reach 65% in 2035. Hence there is a great need to seek new solutions for the reuse of various waste materials. One of the most widely used wastes is their utilization as fillers or reinforcements in the metal- or polymer-based composites. The reuse of wastes for the production of tribological materials gives not only environmental benefits related to the transformation of waste into raw materials but also may improve the mechanical and tribological properties of such materials. Moreover, the use of waste reduces the production costs resulting from the lower price of filler materials and longer service life of developed products. The purpose of the current review is, therefore, aimed at the evaluation of the reuse of agricultural, industrial and postconsumer wastes as reinforcements in the composites used for tribological applications. The tribological performance (wear rate, coefficient of friction) of both monolithic and hybrid composites reinforced with waste materials was a particular subject of interest in this review.

No abstract