scholarly journals Elemental composition of the surface layers formed on titanium at the cathodic treatment in chitosan-containing aqueous-dimethyl sulfoxide solutions of phosphate-molybdate electrolyte

2021 ◽  
Vol 21 (1) ◽  
pp. 32-48
Author(s):  
Svetlana S. Popova ◽  
◽  
Hussein Ali Hussein ◽  
Lyubov’ N. Olshanskaya ◽  
Sergei V. Arzamastsev ◽  
...  
Keyword(s):  
Surface Layer ◽  
Phosphoric Acid ◽  
Organic Solvent ◽  
Dimethyl Sulfoxide ◽  
Electrolyte Solution ◽  
Aqueous Electrolyte ◽  
Sodium Molybdate ◽  
Volume Ratio ◽  
Surface Layers ◽  
Potentiostatic Mode

It was established that at the cathodic treatment of titanium in aqueous dimethyl sulfoxide solutions of sodium molybdate, containing phosphoric acid, at the potential of the cathodic incorporation of sodium (Ec = −2.6 V) in the potentiostatic mode, the composition formed on the electrode surface layer depended not only on the composition of the solution, but also on the volume ratio of the aqueous electrolyte solution and the organic solvent (dimethyl sulfoxide).

scholarly journals SEM And EDS Analysis Of Nitinol Surfaces Treated By Plasma Electrolytic Oxidation

2015 ◽  
Vol 15 (3) ◽  
pp. 41-47 ◽  
Author(s):  
K. Rokosz ◽  
T. Hryniewicz ◽  
Ł. Dudek ◽  
W. Malorny
Keyword(s):  
Surface Layer ◽  
Phosphoric Acid ◽  
Plasma Electrolytic Oxidation ◽  
Copper Nitrate ◽  
Layer Versus ◽  
Surface Layers ◽  
Electrochemical Processes ◽  
Electrolytic Oxidation ◽  
Micro Arc Oxidation ◽  
Plasma Electrolytic

Abstract In the paper, the surface layers formed on nickel-titanium alloy during Plasma Electrolytic Oxidation (PEO), known also as Micro Arc Oxidation (MAO), are described. The mixture of phosphoric acid and copper nitrate as the electrolyte for all plasma electrochemical processes was used. Nitinol biomaterial was used for the studies. All the experiments were performed under the voltage of 450 V and current density of 0.3 A/dm2. The main purpose of the studies was to achieve the highest amount of copper in the surface layer versus amount of the copper nitrate in phosphoric acid. The highest copper concentration was found in the surface layer after the PEO treatment in the electrolyte consisting of 150g Cu(NO3)2 in 0.5 dm3 H3PO4. The worst results, in case of the amount of copper in the NiTi surface layer, were recorded after oxidizing in the solution with 5 g Cu(NO3)2.

Investigation of the accumulation of alloying elements (Mn, Ni, Mo) on the surface of high-alloy steel in acid medium

2020 ◽  
Vol 25 (3) ◽  
Keyword(s):  
Surface Layer ◽  
Sulfuric Acid ◽  
Phosphoric Acid ◽  
Alloy Steel ◽  
Holding Time ◽  
Alloying Elements ◽  
Surface Layers ◽  
High Alloy ◽  
High Alloy Steel ◽  
High Concentrations

The formation of corrosion products in the surface layers of steel 15KH12VNMF brand was investigated in solutions of hydrochloric, sulfuric, phosphoric, and nitric acids. Comparative data were obtained on the accumulation of impurity alloying elements in surface layers of high-alloy steel 15KH12VNMF brand. The content of alloying elements was defined in the surface layer of steel and corrosion products when holding samples in solutions with a certain concentration for 1 hour. The obtained data indicate that the accumulation of manganese, molybdenum and nickel in the surface layer does not occur in the sulfuric acid solution. The surface layers in the solution of phosphoric acid accumulate intensively alloying impurities, whereas in nitric and hydrochloric acids there is a selective accumulation. The surface films on the steel 15KH12VNMF brand in solutions of hydrochloric, sulfuric, phosphoric, nitric acids were Identified at high concentrations and times of incubation. It was established that the rate of manganese accumulation in hydrochloric acid is constant, regardless of the acid concentration. For nickel and molybdenum, the rate of accumulation increases at initial concentrations, and tends to its constant value at high concentrations. In sulfuric acid solutions, the amount of manganese on the surface depends not only on the concentration, but also on the holding time. The accumulation of nickel and molybdenum on the surface of the plate depends as on the concentration and the time. It was determined that in solutions of phosphoric acid the accumulation of manganese occurs only at the primary time, in the future remains constant. The accumulation of nickel and molybdenum on the surface depends as on the concentration and the time and has a similar character. The data are obtained that the accumulation of manganese, nickel, molybdenum on the surface of the sample in solutions of nitric acid with increasing concentration occurs regardless of the holding time of the sample.

The concerted use of SEM, TEM, and SCM for examination of resin-dentin interfaces

1994 ◽  
Vol 52 ◽  
pp. 476-477
Author(s):  
B. Van Meerbeek ◽  
L. J. Conn ◽  
E. S. Duke
Keyword(s):  
Surface Layer ◽  
Stress Distribution ◽  
Phosphoric Acid ◽  
Bonding Mechanism ◽  
Restorative Dentistry ◽  
Dental Adhesive ◽  
Low Viscosity ◽  
Dentin Adhesives ◽  
Acid Etch ◽  
Tooth Tissue

Restoration of decayed teeth with tooth-colored materials that can be bonded to tooth tissue has been a highly desirable property in restorative dentistry for many years. Advantages of such an adhesive restorative technique over conventional techniques using non-adhesive metal-based restoratives include improved restoration retention with minimal sacrifice of sound tooth tissue for retention purposes, superior adaptation and sealing of the restoration margins in prevention of caries recurrence, improved stress distribution across the tooth-restoration interface throughout the whole tooth, and even reinforcement of weakened tooth structures. The dental adhesive technology is rapidly changing. An efficient resin bond to enamel has already long been achieved. Its bonding mechanism has been fully elucidated and has proven to be a durable and reliable clinical treatment. However, bonding to dentin represents a greater challenge. After the failures of a dentin acid-etch technique in imitation of the enamel phosphoric-acid-etch technique and a bonding procedure based on chemical adhesion, modern dentin adhesives are currently believed to bond to dentin by a micromechanical hybridization process. This process is developed by an initial demineralization of the dentin surface layer with acid etchants exposing a collagen fibril arrangement with interfibrillar microporosities that subsequently become impregnated by low-viscosity monomers. Although the development of such a hybridization process has well been documented in the literature, questions remain with respect to parameters of-primary importance to adhesive efficacy.

Electrokinetics, Adsorption and Colloid Study of Simulated Nuclear Waste Glasses Leached in Aqueous Solutions

1984 ◽  
Vol 44 ◽  
Author(s):  
Cheng T. Lee ◽  
D. E. Clark
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Glass Surface ◽  
Charged Particles ◽  
Electrostatic Repulsion ◽  
Surface Layers ◽  
Short Term ◽  
Chloride Solutions ◽  
Zeta Potentials ◽  
Glass Surfaces

AbstractZeta potentials of SRL-131-29.8% TOS simulated nuclear waste glasses leached in D.I. water, Al, Ca, Mg, and Zn chloride solutions at 90°C were measured as a function of leaching time. For short term leaching, the adsorption of Ca, Mg, Zn and Al reverses the glass surface potential from negative to positive. Colloids were found to be stable in D.I. water and AICl3 solutions after leaching, presumably due to the electrostatic repulsion between the glass surface and similarly charged particles. Colloids were not found in Mg, Zn or Ca chloride solutions after leaching; instead, a relatively thick metasilicate surface layer was formed on glass surfaces leached in these solutions. The concentration of Si in solution is reduced by the formation of these surface layers.

Stresses in the Surface Layer and Hydrogen Absorption and Diffusion in Cavitation Condition

2014 ◽  
Vol 225 ◽  
pp. 131-138
Author(s):  
Jarosław Chmiel ◽  
Jolanta Baranowska ◽  
Roman Jędrzejewski ◽  
Arkadiusz Rzeczycki
Keyword(s):  
Surface Layer ◽  
Stress State ◽  
Hydrogen Absorption ◽  
Surface Layers ◽  
Fem Modeling ◽  
And Diffusion

Cavitation attack in liquids generated a various states of stresses in surface layers of metals. Differences in stress state effects on hydrogen absorption activated by the cavitation implosion. Results of XRD investigation and FEM modeling shows on inhomogenity of process.

About U(t) form of pH-dependence of glass corrosion rates at zero surface to volume ratio

2015 ◽  
Vol 1744 ◽  
pp. 153-161 ◽  
Author(s):  
Michael I. Ojovan ◽  
William E. Lee
Keyword(s):  
Nuclear Waste ◽  
Low Temperatures ◽  
Ph Dependence ◽  
Effective Diffusion ◽  
Volume Ratio ◽  
Surface Layers ◽  
Near Surface ◽  
Numerical Examples ◽  
Corrosion Rates ◽  
Glass Corrosion

ABSTRACTThe pH-dependence of glass corrosion rates has a well-known U-shaped form with minima for near-neutral solutions. This paper analyses the change of U-shaped form with time and reveals that the pH dependence evolves even for solutions that have pH not affected by glass corrosion mathematically corresponding to a zero surface to volume ratio. The U(t) dependence is due to changes of concentration profiles of elements in the near-surface layers of glasses in contact with water and is most evident within the initial stages of glass corrosion at relatively low temperatures. Numerical examples are given for the nuclear waste borosilicate glass K-26 which is experimentally characterised by an effective diffusion coefficient of caesium DCs = 4.5 10-12 cm2/day and by a rate of glass hydrolysis in non-saturated groundwater as high as rh = 100 nm/year The changes of U-shaped form need to be accounted when assessing the performance of glasses in contact with water solutions.

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