Wear behavior of in-situ oxide dispersion strengthened Fe-8Ni alloy with Zr additions

MakaleWOS:000959908100001In this study, in-situ oxide dispersion strengthened (ODS) Fe91Ni8Zr1 and Fe88Ni8Zr4 alloys were produced by combination of high energy mechanical alloying (HEMA) and high temperature equal channel angular extrusion (HT-ECAE). The wear behaviors of the consolidated samples were investigated under different loads from 1 N to 4 N by reciprocating wear tests at room temperature. The Scanning electron microscopy (SEM) was used to examine the wear tracks to analyze the wear characteristics as a function of applied loads. The relative comparison of the wear results showed that under the lower loads of 1 N and 2 N, Fe88Ni8Zr4 alloy has lower wear rate than Fe91Ni8Zr1 alloy whereas under the higher loads of 3 N and 4 N, it is vice versa. Additionally, the friction coefficient of Fe91Ni8Zr1 alloy was found to be lower than that of Fe88Ni8Zr4 alloy under all the applied loads. The results were comparatively discussed with respect to microstructural features of 1 at% Zr and 4 at% Zr containing ODS alloys produced by HEMA followed by ECAE. The obtained results of ODS alloys with different grain size, precipitate size, and number density of the precipitates, may disclose a new sight for using such alloys in wear applications just as cutting tools, turbine blades, and discs

Characterization and In Vitro Bioactivity of Calcium and Phosphorous Containing Titania Layer on Ti6Al4V Alloy

Calcium and phosphorous containing titania layers on Ti6Al4V biomedical alloy were formed by micro arc oxidation (MAO) in an electrolyte containing calcium acetate and sodium phosphate, and then subjected to hydrothermal treatment (HT) in order to achieve improved biocompability with modified titania layer. Samples were hydrothermally treated in water solution whose pH was adjusted to 11.0-11.5 by adding NaOH, at 230 °C for 10 h and cooled in the autoclave. Surface morphology, microstructure, and phase composition of titania layer were investigated systematically before and after HT. Their biomimetic apatite inducing ability in a simulated body fluid (SBF) was investigated. The bioactivity tests of modified MAO surface on Ti6Al4V alloy showed a considerable improvement compared to the unmodified MAO surfac

Characterisation and corrosion behaviour of plasma electrolytic oxidation coatings on high pressure die cast Mg-5Al-0.4Mn-xCe (x=0, 0.5, 1) alloys

In the present study, the influence of minor cerium (Ce) additions (up to 1 wt.%) to AM50 magnesium alloy on the plasma electrolytic oxidation (PEO) process and the corrosion performance of the PEO coatings were studied. Therefore, a silicate-based PEO coating was deposited on AM50 containing 0, 0.5 and 1 wt.% Ce under the same processing conditions. The resulting surface morphology, cross-sectional microstructure, phase and chemical compositions of the coatings were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analyses (XRD). The corrosion behaviour of the coatings was evaluated by salt spray and electrochemical corrosion tests. The results show that the growth rate of the coating is reduced, but the thickness is becoming more uniform if cerium is added to AM50 alloy. However, the phase composition and coating morphology are hardly influenced, but the corrosion properties reveal large differences suggesting that the porous PEO coatings have to be considered as a system of coating and substrate. A more uniform corroding substrate such as the cerium alloyed AM50 provides much better protection in combination with a PEO coating than the pure AM50. Flaking-off of large coating areas was observed due to the volume increase caused by corrosion products forming in the interface. Such a severe localised corrosion in the interface causing delamination of the coating can be suppressed by cerium addition. (C) 2014 Elsevier B.V. All rights reserved

Surface modification of Ti6Al4V by micro-arc oxidation in AgC2H3O2-containing electrolyte

This study focuses on the biological properties of Ti6Al4V after employing micro-arc oxidation in sodium phosphateand calcium acetate-containing electrolyte with and without addition of silver acetate. After micro-arc oxidation process, structural features of the surfaces were analyzed by using an energy dispersive X-ray spectrometer equipped scanning electron microscope, an X-ray diffractometer and a Fourier transform infrared spectroscope. The micro-arc oxidation process generated multilayer coatings composed of carbonated hydroxyapatite and titanium oxide layers, while addition of 0.001 mol/l silver acetate into the electrolyte caused incorporation of 0.7 wt.% silver into the coating. The antibacterial activity of the coatings was analyzed by using the Streptococcus mutans American Type Culture Collection 25175 strain. The metabolic activity of the multilayers was evaluated in cultures of a human primary osteogenic sarcoma cell line (Saos-2). In short, incorporation of 0.7 wt.% silver in the form of agglomerated particles, mostly around the micropores of the titanium oxide layer, enhanced the antibacterial efficiency of the fabricated coating to some extent without altering the cell proliferation considerably

Surface modification of Ti6Al4V by micro-arc oxidation in AgC 2

This study focuses on the biological properties of Ti6Al4V after employing micro-arc oxidation in sodium phosphateand calcium acetate-containing electrolyte with and without addition of silver acetate. After micro-arc oxidation process, structural features of the surfaces were analyzed by using an energy dispersive X-ray spectrometer equipped scanning electron microscope, an X-ray diffractometer and a Fourier transform infrared spectroscope. The micro-arc oxidation process generated multilayer coatings composed of carbonated hydroxyapatite and titanium oxide layers, while addition of 0.001 mol/l silver acetate into the electrolyte caused incorporation of 0.7 wt.% silver into the coating. The antibacterial activity of the coatings was analyzed by using the Streptococcus mutans American Type Culture Collection 25175 strain. The metabolic activity of the multilayers was evaluated in cultures of a human primary osteogenic sarcoma cell line (Saos-2). In short, incorporation of 0.7 wt.% silver in the form of agglomerated particles, mostly around the micropores of the titanium oxide layer, enhanced the antibacterial efficiency of the fabricated coating to some extent without altering the cell proliferation considerably

Optimisation of micro-arc oxidation electrolyte for fabrication of antibacterial coating on titanium

This study has been carried out to optimise the silver (Ag) content of the coating synthesised on commercially pure titanium (Cp-Ti, Grade 4) for biomedical applications by micro-arc oxidation (MAO) process. The MAO process has been conducted in electrolytes containing silver acetate (AgC2H3O2) at different concentrations between 0 and 0.002 mol L-1. When compared to the base electrolyte, coatings synthesised in >= 0.001 mol L-1 AgC2H3O2 added electrolytes exhibited an antibacterial efficiency of 99.8% against Staphylococcus aureus (S. aureus). Detailed examination revealed that the presence of 0.01 mol L-1 AgC2H3O2 in the electrolyte resulted in incorporation of 1.4 wt-% Ag into fabricated coating consisting mainly of outer hydroxyapatite (HA) and inner titanium oxide (TiO2) layers. In comparison to the Ag-free coating, 1.4 wt-% Ag in the coating lowered the proliferation of SAOS-2 cells, which still tended to grow at a relatively low rate with increasing culturing time