This paper presents the effect of saline environment on the fatigue behaviour of high-velocity oxygen fuel thermal-sprayed WC-CrC-Ni coatings. These coatings are used to improve the surface hardness, corrosion and wear resistance of components or products, in the place of hard chrome plating. Although so far many tests on the wear and corrosion of coating behaviour were carried, the conduct of the joint action fatiguea corrosive environment is not fully identified. In the frame of the experimental programme, similar axial fatigue tests at room temperature, on air or on specimens immersed in 3% NaCl solution and also chemical composition, structural analysis of the fracture surface were performed, using SEM and EDX. The saline environmentcauses material corrosion, generation of voids and microcracks on the specimen surface and their propagation through the specimen cross-section, accelerating the specimen failure.
The heat generated during friction stir welding (FSW) process depends on
plastic deformation of the material and friction between the tool and the
material. In this work, heat generation is analysed with respect to the
material velocity around the tool in Al alloy Al2024-T351 plate. The slip
rate of the tool relative to the workpiece material is related to the
frictional heat generated. The material velocity, on the other hand, is
related to the heat generated by plastic deformation. During the welding
process, the slippage is the most pronounced on the front part of the tool
shoulder. Also, it is higher on the retreating side than on the advancing
side. Slip rate in the zone around the tool pin has very low values, almost
negligible. In this zone, the heat generation from friction is very low,
because the material is in paste-like state and subjected to intensive
plastic deformation. The material flow velocity around the pin is higher in
the zone around the root of the pin. In the radial direction, this quantity
increases from the pin to the periphery of the tool shoulder. [Projekat
Ministarstva nauke Reublike Srbije, br. TR 35002 i br. IP
451-03-2802/2013-16/69]
The paper presents investigations performed on WC-CrC-Ni coatings, deposited by High Velocity Oxygen Fuel (HVOF) thermal spraying, in order to assess the corrosion behaviour of coatings obtained using WOKA 7504 powder. Mechanical tests, structural and electrochemical analyses have been performed in order to determine the degree in which material composition, powder production method and technological parameters of HVOF process affect the corrosion resistance of the deposited layers. For the corrosion resistance, assessment electrochemical methods were used. Samples immersed in 3% NaCl solution and open-circuit potential (OCP) method were used to examine the potential change and creation of a protective layer on the surface. The best results, in terms of corrosion resistance and adherence resistance of the coating layer, were obtained for layer thickness of 110 to 220 μm. It was found that surface processing, after layer deposition through HVOF process, increases the corrosion rate about 1.5 times compared to unpolished ones, as a result of the protective passivated film removal that forms on the coating layer surface or due to the possibility of additional defects inducing in the deposited layer during the surface finishing operation.
This paper highlights the changes of polyethylene behaviour during various loading rates as well as the influence of test temperature on the material characteristics. Passive infrared thermography method and a high speed infrared camera were used to observe the temperature changes of the sample surface during the tests. The experimental program was carried out on samples taken from PE80 polyethylene gas pipes with simulated imperfections with bilateral V-notch, U-notch, and central hole. Samples have been tensile tested and the results are correlated with the temperature distribution of the samples surface.
Experimental measurement and analytical calculation of preheating, i. e. interpass temperature during multi-pass repair welding has been presented. Analytical calculation is based on heat transfer analysis, whereas measurements have been performed by thermovision camera. Repair welding was performed on crane wheels in the Steelworks Smederevo. Comparison of results indicated that analytical calculation is good enough as the first approximation, but it needs further elaboration, e. g. taking into account the radiation component of heat dissipation and/or temperature dependence of material thermomechanical properties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.