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Full-Text Articles in Engineering Science and Materials
Effect Of Concentration On Electrospun Polyacrylonitrile (Pan) Nanofibers, Ji-Huan He, Yu-Qin Wan, Jian-Yong Yu
Effect Of Concentration On Electrospun Polyacrylonitrile (Pan) Nanofibers, Ji-Huan He, Yu-Qin Wan, Jian-Yong Yu
Ji-Huan He
Abstract: An allometrical scaling relationship between the diameter of electrospun nanofiber and solution concentration is established, the scaling exponent differs greatly between different polymers and the same polymer with different molecules or the same molecules with different properties. The diameter of electrospun polyacrylonitrile (PAN) nanofibers increases approximately linearly with solution concentration.
Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic
Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic
Zeljko J Kamberovic
This paper is a contribution to characterization of Cu-Al2O3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.
Determination Of Al2o3 Particle Size In Cu-Al2o3 Nanocomposite Materials Using Uv Spectrophotometry, Zeljko J. Kamberovic
Determination Of Al2o3 Particle Size In Cu-Al2o3 Nanocomposite Materials Using Uv Spectrophotometry, Zeljko J. Kamberovic
Zeljko J Kamberovic
In order to achieve improved mechanical properties of dispersion strengthened nanocomposite, without influencing electrical and thermal conductivity it is necessary for dispersoide to be nano sized and uniformly distributed in base metal matrix. In this paper are presented the results concerning possibility of using UV spectrophotometry for determination of alumina particle size in Cu-Al2O3 system. Presented results show that this method is unefficient as method for determination of dispersoide particle size, due to the coalescence of particles false results are obtained, i.e. particle size significantly higher then one determined by image analysis.
Sintering Of Cu–Al2o3 Nano-Composite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Sintering Of Cu–Al2o3 Nano-Composite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Zeljko J Kamberovic
This paper presents the synthesis of nano-composite Cu–Al2O3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu–Al2O3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA–TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20–50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by …
Synthesis And Sintering Of Cu-Al2o3 Nanocomposite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Synthesis And Sintering Of Cu-Al2o3 Nanocomposite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Zeljko J Kamberovic
By hydrometallurgy and powder metallurgy along with prognosis of physical- chemical properties, a synthesis of new improved materials can be successfully performed with in advance pre-set properties which is conditioned by a quality of starting powders i.e. by improving their structure. In accordance with that, this paper presents synthesis of the nanocomposite Cu-Al2O3 powder by thermochemical method and sintering with a comparative analysis of the mechanical and electrical properties of obtained solid samples. Nanocrystaline Cu-Al2O3 powders were produced by thermochemical method through following stages: spray-drying, oxidation of precursor powder, reduction by hydrogen and homogenisation. Characterization of powders included differential-thermal and …
Bubble Electrospinning For Mass Production Of Nanofibers, Yong Liu, Ji-Huan He
Bubble Electrospinning For Mass Production Of Nanofibers, Yong Liu, Ji-Huan He
Ji-Huan He
A new bottom-up gas-jet electrospinning process for mass production is presented. A bubble-induced cone on the surface of polymer solution is equivalent to the Taylor cone in traditional electrospinning, which is a must for producing nanofibers. In this study bubbles are produced by compressed air or nitrogen through a nozzle settled in the bottom of the solution. Multiple jets are observed during the electrospinning process as predicted for it is easy to many bubble-induced cones on the solution surface. The new electrospinning mechanism can be used for mass production of nanofibers.
The Synthesis Of Ultrafine And Nanocomposite Powders Based On Copper, Silver And Alumina, Zeljko J. Kamberovic
The Synthesis Of Ultrafine And Nanocomposite Powders Based On Copper, Silver And Alumina, Zeljko J. Kamberovic
Zeljko J Kamberovic
Contemporary materials with predetermined properties can be successfully synthesized by utilising the principles of hydrometallurgy and powder metallurgy. The results of developing a new procedure for the synthesis of ultrafine and nanocomposite powders based on copper, silver and alumina are presented in this paper. A two-component nanocomposite powder, Cu-Al2O3, was synthesized by a thermochemical procedure, by deposition from an aqueous solution of soluble metal salts, Cu(NO3)2 and Al(NO3)3. A three-component Cu-Ag-Al2O3 powder was produced by mechanically alloying nanocomposite Cu-Al2O3 powder and Cu-Ag powder, synthesized by the thermochemical procedure. The produced powders were characterized by determining the particle specific area, pouring …