JOURNAL OF MATERIALS PROCESSING TECHNOLOGY

In this study, the tribological behavior of Cr(2)O(3)/Ni(8.5)Cr(7)Al5Mo2Si2B2FeTiO(2) coatings for bearing materials was investigated in dry and acid conditions. Flame spray technique was used in order to deposit coating materials onto AISI 304L steel substrate. The coated samples were characterized by means of an optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), surface roughness and microhardness testers. The wear experiments were performed under dry and acid environments using a pin-on-plate configuration against AISI 303 counter material for different loads. It was found that in acid environment, the amount of wear loss is less than that of in dry condition and applied load level is more effective in dry condition. In SEM study, the effect of plastic deformation of adherent and compacted debris particles on friction of the coatings was investigated. (c) 2007 Elsevier B.V. All rights reserved

PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS

In this study, a generalized method based upon nonextensive statistics is presented for nucleation and growth processes in a thin layer between two interfaces. It is shown that the presented mathematical model, which uses an index called the entropic index that measures the nonextensivity of the physical system, successfully deals with the nucleation and growth processes, and works better than Johnson-Mehl-Avrami-Kolmogorov model. The presented model also contains Austin-Rickett model as a special case. (c) 2006 Published by Elsevier B.V

MATERIALS TESTING

The aim of this study was to investigate the influence of aging parameters and initial roughness on the wear properties of the aluminum alloy AA 6082 (Al-Mg-Si). For this purpose, various heat treatments were carried out. Afterwards, the solutionized samples and artificially aged samples (at 185 degrees C for 3 and 6 h) were prepared in terms of two different average surface roughnesses via various grades of grinding. The wear behavior of the samples was investigated by a pin-on-disc wear test apparatus under four different applied loads (5, 10, 15 and 20 N) and five different sliding distances (250, 500, 750, 1000, 1250 and 1500 m). The sliding velocity was 30 cm x s(-1). After the wear tests, the mass loss was measured for all samples and the worn surfaces were examined by scanning electron microscopy (SEM). The wear test results clearly show that with increasing hardness, the mass loss decreases, and the mass loss of the worn surfaces increases with increasing sliding distance, test load and initial roughness

INDUSTRIAL LUBRICATION AND TRIBOLOGY

Purpose - The purpose of this paper is to predict friction/wear properties of Al2O3-TiO2 coatings using artificial neural networks (ANN). Design/methodology/approach - Wear experiments were conducted in dry and acidic conditions. Wear loss values were determined and an ANN model was fixed in order to predict wear loss and friction coefficient values. Findings - Experimental and theoretical study results were well matched for wear loss and friction coefficient values. Research limitations/implications - The paper covers comparison of experimental and theoretical friction/wear results. Practical implications - A practical implication is that wear loss values can be predicted without further wear experiments. Originality/value - In this paper, the wear behavior of Al2O3-TiO2 coatings has been investigated, both experimentally and theoretically, for the first time

PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS

In this study, nucleation and grain growth was studied by using 2-dimensional generalized Monte Carlo simulations and experiments. As an attempt to improve the JMAK model, we proposed a new differential equation to be able to model nucleation and growth phenomena using nonextensive thermostatistics. One of the reasons that we would like to perform generalized Monte Carlo simulations in studying of nucleation and grain growth phenomena is that the generalized Monte Carlo algorithm was shown to be more effective than the standard Monte Carlo algorithm and also than the standard Molecular Dynamic algorithm in locating the minimum energy configuration. Therefore, for a given temperature, the fact that a configuration of the system with lower energy could be obtained by using the generalized Monte Carlo simulation means that a different textural configuration of grain growth could be also expected. In this respect, it is possible to say that the nonextensive statistics might be an appropriate tool in studying of nucleation and growth phenomena. (C) 2013 Elsevier B.V. All rights reserved

INTERNATIONAL JOURNAL OF MATERIALS RESEARCH

The fracture behavior of welded ductile iron is discussed by means of experimental and theoretical studies. Ferritic nodular cast irons were joined by cold arc welding in order to obtain over-matched weldment in which the yield strength of the weld metal is higher than that of the base metal. As a result of the welding process, various regions with different mechanical properties formed in the welded specimens. In the experimental part of the study, the mechanical properties of the different regions in the welded specimens were identified and J-Integral toughness values were determined by fracture toughness tests for different crack locations including the base metal, the heat affected zone and the weld metal. In the numerical part of the study, finite element analyses were conducted by fixing 3-D models precracked at different locations for different crack lengths. In these models, after stress-strain analysis, stress triaxiality and plastic deformation characteristics around the crack tip were determined for each crack location and different crack sizes. It was found that stress triaxiality values increase with growing crack length. Different regions with different strength levels in the weldment affect the extension of plastic deformation in the models. Hindrance to the extension of plastic deformation at the heat affected zone and diffusion line causes an extra increase in stress triaxiality at the crack tip

WEAR

Mo coated materials are used in automotive, aerospace, pulp and paper industries in order to protect machine parts against wear and corrosion. In this study, the wear amounts of Mo coatings deposited on ductile iron substrates using an atmospheric plasma-spray system were investigated for different loads and environment conditions. The Mo coatings were subjected to sliding wear against AISI 303 counter bodies under dry and acid environments. In a theoretical study, cross-sectional microhardness from the surface of the coatings, loads, environment and friction test durations were chosen as variable parameters in order to determine the amount of wear loss. The numerical results obtained via a neural network model were compared with the experimental results. Agreement between the experimental and numerical results is reasonably good. (c) 2006 Elsevier B.V. All rights reserved

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY

The main aim of this paper is to investigate the effect of yield strength mismatch of parent and weld metal on the fracture behavior of plain and heat-treated welded nodular cast iron. For this, experimental and theoretical studies were performed. Nickell electrode, which has lower yield strength value than that of the parent material, was use to join nodular cast iron by cold arc welding method. In experimental study, fracture toughness (J-integral) values were determined for various crack locations including base, weld metal and heat affected zone. In theoretical study, finite element analyses were performed for the same crack locations with different crack lengths. Stress triaxiality and equivalent plastic strain values were determined for all crack locations and various crack lengths. Finally, fracture toughness values of the base metal were determined as lower than those of the other regions including the weld metal and the heat affected zones. Stress triaxiality and equivalent plastic strain values used to clarify the effect of yield strength mismatch on the constraint around crack tip increased with growing crack length in annealed and under-matched models. In annealed models, stress triaxiality values became slightly lower but equivalent plastic strain values appeared higher than those of under-matched models. (C) 2007 Published by Elsevier B.V