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Surface Modification of Self-Consolidated Microporous Ti Implant Compacts Fabricated by Electro-Discharge-Sintering in Air

Jo Y. J., Yoon Y. H., Kim Y. H., Chang S. Y., Kim J. Y., Lee Y. K., Van Tyne C. J., Lee W. H.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1287--1291

EN

A single pulse of 0.75-2.0 kJ/0.7g of atomized spherical Ti powders from 300 mF capacitor was applied to produce a microporous Ti implant compact by electro-discharge-sintering (EDS). A solid core in the middle of the compact surrounded by a microporous layer was found. X-ray photoelectron spectroscopy was employed to study the surface characteristics of the EDS Ti compact and it revealed that Ti, C and O were the main constituents on the surface with a smaller amount of N. The surface was lightly oxidized and was primarily in the form of TiO2 resulting from the air oxidation during EDS processing. The lightly oxidized surface of the EDS compact also exhibited Ti nitrides such as TiN and TiON, which revealed that the reaction between air constituents and the Ti powders even in times as short as 128 msec.

2

Porowata elektroda niklowa przeznaczona do utleniania metanolu

Jaroń A., Żurek Z.

Ochrona przed Korozją

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2016

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nr 4

98--101

PL

W pracy badano proces utleniania metanolu na porowatych elektrodach niklowych wytworzonych nad drodze wysokotemperaturowej obróbki kulistych ziaren Ni. Morfologia tak otrzymanych elektrod była analizowana z wykorzystaniem techniki SEM. Charakterystykę elektrochemiczną porowatych elektrod niklowych przeprowadzono w 0,5-molowym roztworze KOH zawierającym metanol o stężeniu 0,05÷0,25 mola. W badaniach wykorzystano techniki woltamperometrii cyklicznej i liniowej.

EN

The process of methanol oxidation on porous nickel electrodes formed by means of high-temperature processing of spherical Ni grains was studied in the research work. The morphology of such obtained electrodes was analyzed with the use of the SEM technique. Electrochemical characteristic of porous nickel electrodes was performed in a 0.5M KOH solution containing methanol at a concentration of 0.05-0.25M. Techniques of cyclic and linear sweep voltammetry were used in the research.

3

Effects of piezoelectricity on bulk waves in monoclinic poro-elastic materials

Gupta V., Vashishth A. K.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 2

571--577

EN

Piezoelectric materials are materials which produce electric field when stress is applied and get strained when electric field is applied. Piezoelectric materials are acting as very important functional components in sonar projectors, fluid monitors, pulse generators and surface acoustic wave devices. Wave propagation in porous piezoelectric material having crystal symmetry 2 is studied analytically. The Christoffel equation is derived. The phase velocities of propagation of all these waves are described in terms of complex wave velocities. The effects of phase direction, porosity, wave frequency and piezoelectric interaction on the phase velocities are studied numerically for a particular model.

4

Self-Consolidation Mechanism Of Porous Ti-6Al-4V Implant Prototypes Produced By Electro-Discharge-Sintering Of Spherical Ti-6Al-4V Powders

Lee W. H., Jo Y. J., Kim Y. H., Jo Y. H., Seong J. G., Van Tyne C. J., Chang S. Y.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1185--1189

EN

Electro-Discharge-Sintering (EDS) was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 – 150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 – 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.

5

Deposition of a polymeric porous superhydrophobic thin layer on the surface of poly(vinylidenefluoride) hollow fiber membrane

Ahmad A. L., Mohammed H. N., Ooi B. S., Leo C. P.

Polish Journal of Chemical Technology

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2013

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Vol. 15, nr 3

1-6

EN

Porous superhydrophobic layer of low-density polyethylene (LDPE) was created by a simple approach on the Poly(vinylidenefluoride) (PVDF) hollow fiber membranes. Acetone and ethanol mixtures with different volume ratios were used as the non-solvent on the coating surface. A 5:1 (v/v) acetone/ethanol ratio provided a porous surface with a 152° ± 3.2 water contact angle. The high contact angle could reduce membrane wettability for better carbon dioxide capture when the membrane was used as gas-liquid contactor in absorption processes. To assess the effect of the created superhydrophobic layer, the pristine and modified membranes were tested in a CO2 absorption system for ten days. The results revealed that the absorption flux in the modified membrane was higher than that of pristine membrane.

6

Study of circular crested waves in a micropolar porous medium possessing cubic symmetry

Kumar R., Panchal M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2011

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Vol. 59, nr 1

103-110

EN

The paper is concerned with the propagation of circular crested Lamb waves in a homogeneous micpropolar porous medium possessing cubic symmetry. The frequency equations, connecting the phase velocity with wave number and other material parameters, for symmetric as well as antisymmetric modes of wave propagation are derived. The amplitudes of displacement components, microrotation and volume fraction field are computed numerically. The numerical results obtained have been illustrated graphically to understand the behavior of phase velocity and attenuation coefficient versus wave number of a wave.

7

Reflection and transmission of plane waves between two different fluid saturated porous half spaces

Kumar R., Miglani A., Kumar S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2011

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Vol. 59, nr 2

227-234

EN

The present study is concerned with the reflection and transmission of plane waves between two different fluid saturated porous half spaces when longitudinal and transversal waves impinge obliquely at the interface. Amplitude ratios of various reflected and transmitted waves are obtained .The variations of amplitude ratios with angle of incidence are depicted graphically. A particular case of reflection at the free surface in fluid saturated porous half spaces has been deduced and discussed. A special case of interest has also been deduced from the present investigation.

8

Magnetic fluid based porous inclined slider bering with velocity slip

Shah R. C., Bhat R.

International Journal of Applied Mechanics and Engineering

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2003

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Vol. 8, no 2

331-336

EN

A theoretical study was made of a porous inclined slider with a magnetic fluid as lubricant considering velocity slip. Expressions were obtained for pressure, load capacity, friction on the moving slider, the coefficient of friction and the position of the centre of pressure. Computed values showed that load capacity and friction decreased when the slip parameter increased. The coefficient of friction attains an optimum for a certain value of the slip parameter which affects a little the position of the centre of pressure.

9

Sound absorption properties of recycled polyester fibrous assembly absorbers

Lee Y., Joo C.

Autex Research Journal

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2003

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Vol. 3, no. 2

78--84

EN

Sound absorption materials are generally classified into three types, porous, resonator, and panel. All of these three types are based on the theory of energy transforming from sound energy to thermal energy. In this paper, we examined the sound absorption coefficient of recycled polyester nonwovens for the purpose of substituting the conventionally used materials such as glasswool and rockwool. The use of recycled polyester nonwovens has many advantages compared to conventional sound absorbers, including reduced product cost, good handling, and environmental protection. The sound absorption coefficient of the recycled polyester nonwovens was determined by a two-microphone impedance measurement tube; the determination of the noise absorption coefficient is nothing more than the absorption energy rate of the material against the incidence energy. We have determined the relationship between the acoustic absorption values measured and the nonwoven parameters including fibre properties and web properties.

10

Parametry struktury modelowych materiałów porowatych

Łukowski J., Kołodziej J.

Zeszyty Naukowe. Mechanika / Akademia Techniczno-Rolnicza w Bydgoszczy

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2002

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Z. 53(241)

129-137

PL

Przedstawiono wyniki modelowania analityczno-numerycznego przepływu prądu jonowego przez układ złożony z wiązki równoległych prętów zanurzonych w elektrolicie wykorzystując metodę kolokacji brzegowej. Analizowano przepływ prądu jonowego wzdłuż, oraz w poprzek prętów. Wyznaczono parametry opisujące architekturę wewnętrzną układu: współczynnik uformowania i krętość w funkcji porowatości dla trzech różnych regularnych konfiguracji prętów.

EN

The paper presents the results of analytic-numerical modeling of ionic current flow through an array composed of a bundle of parallel rods, submerged in electrolyte, using the boundary collocation method. The flow o ionic current along and across the rod was analyzed. The parameters were determined, describing internal architecture of the array: formation coefficient and tortuousity relative to three varied regular rod configurations.