Display omitted
► The native film on the alloy surface contains TiO2, Nb2O5, ZrO2, Ta2O5 as was demonstrated by XPS. ► After 2000h, XPS revealed the same oxides and calcium, phosphorous ions ...deposited as hydroxyapatite. ► Impedance data exhibited a passive film with two layers: an inner, barrier and an outer, porous. ► In Ringer and Ringer–Brown solutions, the new alloy presented low corrosion rates.
A new quaternary Ti–20Nb–10Zr–5Ta alloy with β-near microstructure was obtained. Its native passive film composition and its modification and corrosion resistance after 2000 immersion hours in simulated biofluids were studied. The native film on the alloy surface contains TiO2, Nb2O5, ZrO2, Ta2O5 protective oxides as was demonstrated by XPS. After 2000h, XPS revealed the presence of same oxides and calcium, phosphorous ions deposited from physiological solutions as hydroxyapatite. In Ringer and Ringer–Brown solutions, the new alloy presented low corrosion rates. Impedance data exhibited a passive film with two layers: an inner, barrier layer and an outer, porous layer.
•OL44, OL52, S.4571, Monel 400 and Uranus B6 stainless steels were studied.•Steels were exposured by corrosion action of choline chloride solutions.•Structural and magnetic properties were determined ...and compared.•Is revealed a high corrosion resistance of structure and specific magnetization.
An influence of corrosion action based on choline chloride ionic liquids on magnetic properties of various grades of stainless steels has been studied. OL44, OL52, S.4571, Monel 400 and Uranus B6 stainless steels were exposured by action of ChCl-Oxalic Acid (1:0.5) M and ChCl-Malonic Acid (1:2) M solutions at 80 °C during 1 month. The temperature dependences of the specific magnetization before and after corrosion action were studied by ponderomotive method in 0.86 T magnetic field in the temperature range of 77–1000 K. Comparative analysis of temperature dependence of specific magnetization before and after ionic liquids exposure confirmed a high corrosion resistance of magnetic characteristics of the investigated stainless steels under conditions of long-term contact with based on choline chloride ionic liquids at 80 °C. Images obtained with an metallographic microscope showed a surface of the steel in an initial state contains defects which become centers of pointed corrosion. Corrosion resistance of stainless steels in contact with solutions based on choline chloride ionic liquids at moderate temperatures is satisfactory for a practical application of these materials.
Experiments deal with the solidification pattern of FeSiCaMgRE-treated and un-inoculated and inoculated Ca,Ce,S,O-FeSi three ductile iron compositions 2.5%Si; 4%Si and 4%Si-1.6%Mo (Si:Mo = 2.5). ...Structure analysis is performed in 20mm diameter bar, resin sand mould solidification. Increasing of the Si content leads to increasing the graphite amount. Mo addition in high Si-iron limits the graphitizing effect of Si, but the graphite amount remains higher compared with conventional iron. A similar evolution is registered for graphite nodule count, while Si-Mo iron has lower nodule count compared with referred iron. For the same production conditions, graphite nodularity according to ISO 945 evaluation is negatively affected by Si and Si-Mo: it decreases from 95% up to 80% value, but remains at the accepted level, which means that the selected inoculant seems to be effective in these irons. For high Si-ductile irons, the nodularity evaluation must be more carefully considered, by including a minimum limit of the accepted sphericity shape factor. Increasing of the Si content leads to a prevalent ferritic matrix. Supplementary addition of Mo at the upper limit in Si-Mo affects the ferritic effect of Si, resulting an intermediary ferrite and pearlite mixture. It is found that inoculation is important for high-Si, and particularly for Si-Mo alloyed irons, requiring a high efficiency inoculation procedure.
PDF
