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Full-Text Articles in Engineering Science and Materials

Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic Jan 2008

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 Jan 2008

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.


Structural Characteristics Of Some Ternary Ag-In-Sn Alloys, Zeljko J. Kamberovic Jan 2008

Structural Characteristics Of Some Ternary Ag-In-Sn Alloys, Zeljko J. Kamberovic

Zeljko J Kamberovic

The Ag-In-Sn system, as one of potential lead-free solder materials, was studied in this paper. The investigated alloys were chosen from two sections, with molar ratio of In:Sn equal to 1:4; 1:2. DTA, XRD, SEM and microhardness investigations were used in order to determine structural characteristics of chosen Ag-In-Sn ternary alloys.


Structure And Kinetics Of Internal Oxidation In Ag-Sn Alloys, Zeljko J. Kamberovic Dec 2007

Structure And Kinetics Of Internal Oxidation In Ag-Sn Alloys, Zeljko J. Kamberovic

Zeljko J Kamberovic

Internal oxidation in Ag-Sn-In-Te and Ag-Sn-Cu-Bi alloys was tested. Microstructures of casted and homogenized samples, as well as after internal oxidation were followed by optical microscopy. The structure of Ag-Sn-Cu-Bi alloy was found finer, and the oxidation rate is considerably higher compared to the Ag-Sn-In-Te type alloy sheets. It seems that the size and volume fraction of secondary phase particles (probably ζ type) can influence the process of internal oxidation. In the Ag-Sn-In-Te alloy type “wavy oxidation” was noticed with oxide free regions.