Showing papers by "Sirus Javadpour published in 2015"

Fabrication of novel fiber reinforced aluminum composites by friction stir processing

Abstract: In this study, chopped and attrition milled high strength carbon, E-glass, and S-glass fibers have been used as the reinforcing agents in an aluminum alloy (Al1100) considered as the matrix. The Surface Metal Matrix Composites (SMMCs) then are produced by Friction Stir Processing (FSP). Tensile and micro-hardness examinations represent a magnificent improvement in the hardness, strength, ductility and toughness for all of the processed samples. Scanning Electron Micrographs reveal a proper distribution of the reinforcements in the matrix and a change in the fracture behavior of the FSPed specimens. The synergetic effects of reinforcing by fibers and Severe Plastic Deformation (SPD) lead to an extra ordinary improvement in the mechanical properties.

Modification of corrosion and tribological properties of 316L stainless steel by cathodic plasma electrolytic deposition of zirconia

Abstract: Purpose – This paper aims to study the deposition of ZrO2 on 316L stainless steel surface using cathodic plasma electrolytic deposition (CPED) technique in potassium hexafluorozirconate (K2ZrF6) electrolyte solution to promote its corrosion and tribological properties. Design/methodology/approach – Plasma electrolytic oxidizing (PEO) technique is commonly used to form zirconium dioxide (ZrO2) on various substrates. But, in this paper, cathodic type of this technique (CPED) was used. Findings – Composition of the surface layer was analyzed by X-ray diffraction (XRD) and the formation of ZrO2 on the substrate was confirmed. Scanning electron microscope (SEM) was used to observe the unique morphology of the surface layer. The corrosion resistance of the coated surface was investigated by electrochemical methods involving cyclic voltammetery in Ringer’s solution. The treated sample showed a better pitting resistance. Pin-on-disk wear tests revealed that the friction coefficient of the coated sample is lower t...

Investigating the Effect of the Deep Cryogenic Heat Treatment on the Mechanical Properties and Corrosion Behavior of 1.2080 Tool Steel

Abstract: Deep cryogenic heat treatment is assumed as a supplementary heat treatment performed on steels before the final tempering treatment to enhance the wear resistance and hardness of the steels. In this study, the effects of the deep cryogenic heat treatment on the wear behavior and corrosion resistance of the 1.2080 tool steel were studied using the wear testing machine and polarization and impedance spectroscopy tests. Moreover, the microstructural changes of the deep cryogenically treated samples were clarified via the scanning electron microscope (SEM) and X-ray diffraction testing machine. The results showed that the deep cryogenic heat treatment eliminated the retained austenite and made a more uniform carbide distribution with higher percentages. Beyond this, it was clarified that the deep cryogenic heat treatment increased the hardness and improved the wear behavior of the 1.2080 tool steel, as well as decreasing the corrosion resistance, due to the higher chromium carbides produced during the deep cryogenic heat treatment.

Investigating the effect of holding duration at a deep cryogenic temperature on the wear behavior of DIN 1.2080 (D3) tool steel

Abstract: This work focused on the effect of the holding time in a deep cryogenic heat treatment on the wear behavior, microstructural changes, retained austenite percentage and microhardness of 12080(D3) tool steel These analyses were performed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and energy dispersion spectroscopy (EDS) to study the microstructure A pin-on-disk wear testing machine was employed to investigate the wear behavior The microhardness changes were measured by KOPA machine It was shown that the deep cryogenic heat treatment eliminates retained austenite and makes a more uniform carbide distribution with higher percentages Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples It was also observed that the deep cryogenic heat treatment improves the wear behavior and microhardness of samples with an increase in the holding duration up to an optimum value: beyond that duration, the wear resistance and microhardness decreases to a specific value, and changed specifically at longer holding durations It was also observed that the predominant wear mechanism was a combination of adhesive and tribochemical wear