Abstract

Most researches on doped ZnO thin films are tilted toward their applications in optoelectronics and semiconductor devices. Research on their tribological properties is still unfolding. In this work, nitrogen-doped ZnO thin films were deposited on 304 L stainless steel substrate from a combination of zinc acetate and ammonium acetate precursor by MOCVD technique. Compositional and structural studies of the films were done using Rutherford Backscattering Spectroscopy (RBS) and X-ray Diffraction (XRD). The frictional behavior of the thin film coatings was evaluated using a ball-on-flat configuration in reciprocating sliding under dry contact condition. After friction test, the flat and ball counter-face surfaces were examined to assess the wear dimension and failure mechanism. Both friction behavior and wear (in the ball counter-face) were observed to be dependent on the crystallinity and thickness of the thin film coatings.

Abstract

Natural fiber reinforced polymer composites have emerged as a potential environmentally friendly and cost-effective alternative to synthetic fiber reinforced composites. Therefore, in the past decade, a number of major industries, such as the automotive, construction and packaging industries, have shown a considerable interest in the progress of new natural fiber reinforced composite materials. The availability of natural fibers and the ease of manufacturing have tempted researchers to study their feasibility of their application as reinforcement and the extent to which they satisfy the required specifications in tribological applications. However, less information concerning the tribological performance of natural fiber reinforced composite material is available in the literature. Hence, the aim of this bibliographic review is to demonstrate the tribological behavior of natural fiber reinforced composites and find a knowledge about their usability for various applications that tribology plays a dominant role. This review presents the reported work on natural fiber reinforced composites with special reference to the type of fibers, matrix polymers, treatment of fibers and test parameters. The results show that composites reinforced with natural fibers have an improvement in tribological properties and their properties are comparable with conventional fibers. In addition, fiber treatment and fiber orientation are two important factors can affect tribological properties where treated fibers and normal oriented fibers exhibit better friction and wear behavior. This review is trying to evaluate the effect of test parameter including normal load and sliding speed on tribological properties, and the results vary based on type of reinforcement. Generally, due to their positive economic and environmental aspects, as well as their good tribological properties, natural composites are showing a good potential for employing in several applications.

Abstract

From a position of structural and power theory of friction and wear, it is possible to apply the method of Contact Electrical Resistance (CER) for a complex research of the processes in a-zone of frictional contact. The purpose of this paper is to present a construction of friction node and drive mechanism of friction machine. As a result of the reported study the regularities of changes the CER and tribomechanical indices for non-metal friction couples in dependence on loading parameters and lubricating media were received. Also, the method of determination the range and level of normal wear and critical points of transmission to damage in accordance with kinetics of wear changes is proposed. The interrelation between geometrical, physical and mechanical properties, processes of formation, transformation and destruction of secondary structures, tribotechnical indices and CER in dependence on operation regimes of friction couples.

Abstract

The purpose of this paper is to present a study aimed at creating a calculation-experimental method for calculating the wear of lubricated friction units of machines based on a two-factor wear model (contact pressure – sliding velocity) with identification of their wear resistance parameters. To achieve this purpose it was necessary to obtain theoretical dependences for identification of wear resistance parameters in the wear models based on laboratory tests with various geometrical contact diagrams of lubricated samples. Analysis of known studies has shown that existing approaches required solution of complex systems of integral-differential equations or numerical methods that are unacceptable in the engineering practice. In this study a model of the wear of lubricated friction units of machines in conditions of boundary friction was obtained in a form of dependence of the wear rate on the dimensionless complexes of contact pressure and sliding velocity. The basis was the solution of the inverse wear of the contact problem for various geometrical schemes of contact. The contact diagrams corresponded to the actual forms of contact of the friction units of the machines: rolling bearings and sliding bearings, gears and others. The following equations were taken as the defining equations: the equilibrium equation in the contact, the continuity equation in the contact, and the approximating experimental dependence for the wear of materials. As a result of the solution, simple algebraic formulas for calculating and identifying the parameters of the patterns of wear have been obtained. It was found that the installation has been developed for tests by means of program Solid Works and the numerical algorithm of the decision of a task on the basis of program MathCad. The findings of the study contribute explain the influence of determining factors of sliding velocity and load on bearing wear. The practical value of the research is that the obtained results were recommended for predicting wear of lubricated friction units of engines at the design stage and optimizing their design and operational parameters.

Abstract

"jats:p" Corrosion is one of the most common naturally occurring processes studied by thermodynamics, which includes oxidation process, metal disruption, and its chemical and electrochemical effects under environmental influence. Corrosion of metal and equipment accounts for a considerable proportion of total corrosion losses, thus providing the impetus for further investigation and developments related to corrosion protection in order to provide transport systems and industry with corrosion preventive materials and tools. Document type: Article