27 research outputs found
Shear Strength of Copper Joints Prepared by Low Temperature Sintering of Silver Nanoparticles
In this work, mechanical properties of Cu-to-Cu joint samples prepared by low temperature sintering of Ag nanoparticle paste have been investigated. The silver nanopaste was prepared by a controlled thermal decomposition of an organometallic precursor. The as-synthesized Ag particles were spherical, with an average diameter of 8.5 nm. The Cu-to-Cu joint samples were made by placing a small amount of Ag nanopaste between two polished Cu plates and sintering at 150C, 200C, 220C and 350C in air. A normal load was applied to aid sintering. Mechanical properties were measured by imposing a uniform stress across the sample bond area and measuring the corresponding strain. The application of external load was found to have a positive effect on the material’s mechanical properties. Furthermore, interestingly high values of shear strength were observed.Byly zkoumány mechanické vlastnosti Cu-to-Cu spojů připravených nízkoteplotní sintrací pasty Ag nanočástic. Ag nanopasta byla připravena řízeným tepelným rozkladem organokovových prekurzorů. Syntetizované Ag NPs byly kulovité, o středním průměru 8,5 nm. Cu-to-Cu spoje byly vyrobeny umístěním malého množství Ag nanopasty mezi dvě leštěné Cu desky a sintrováním při 150C, 200C, 220C and 350C na vzduchu. Zatížení bylo použito na k podpoře sintrace. Mechanické vlastnosti byly měřeny stanovením napětí lomu a deformace. Bylo zjištěno, že aplikace vnějšího zatížení má pozitivní vliv na mechanické vlastnosti spoje
Electrochemical corrosion of Al-Pd alloys in HCl and NaOH solutions
The corrosion performance of as-solidified Al-Pd alloys in HCl and NaOH
aqueous solutions is investigated in this work. Four different alloys
(Al88Pd12, Al77Pd23, Al72Pd28 and Al67Pd33, element concentrations are given
in at.%) were prepared from high purity Al and Pd lumps by arc-melting in Ar.
Subsequently, the alloy microstructure and phase occurrence were investigated
by a combination of scanning electron microscopy and room-temperature powder
X-ray diffraction. The assolidified Al-Pd alloys were found to consist of
several single-phase microstructure constituents with various structures and
chemical compositions, including structurally complex intermetallic phases.
The polished surfaces of the Al-Pd alloys were subjected to electrochemical
polarization in aqueous HCl and NaOH solutions (0.01 mol.dm-3) at 21±2°C. The
corrosion experiments were conducted in a standard 3-electrode cell
controlled by potentiostat. The corrosion potentials and corrosion current
densities were determined by Tafel extrapolation of the experimental
polarization curves. Phase dissolution has been observed on the alloy
surfaces and some of the phases were preferentially corroded. The effects of
the alloy microstructure and the phase occurrence are evaluated. The local
nobility of individual intermetallic compounds is discussed. Finally, the
conclusions for the alloys corrosion performance in acidic and basic
solutions are provided