Papers by Keyword: Nitrogen Atmosphere

Abstract: The subject of this work was to study the photoluminescence characteristics of nanoZnO and SiO₂ powders into Zn₂SiO₄ phosphor, and to achieve better control on grain size and grain shape than traditional powder. The manganese elements were used to replace Zn₂SiO₄ defects and to achieve better control on grain size and grain shape than traditional powder. With different sintering atmosphere conditions, the effect of the photoluminescence intensity due to sintering temperature and the concentration of activator were be discussed by the X-Ray diffraction, SEM and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles.

Abstract: Reliability and life-time of electric/electronic products is still a highly actual and discussed topic. Every electric/electronic product is heterogeneous system which consists not only from components and constructional parts, but also from many interconnections. Basic segments of interconnection are solder joints, recently created by lead-free materials. The passing from well-proven lead solders to lead free compositions brought many new aspects in reliability and life-time of electronic systems. Some of the negative factors are their poor electro-mechanical properties, which are based on complicated microstructure of interlayer interface. This fact causes defects in solder joints and consequential failure of the function. This article is focused on an investigation of mechanical properties of lead-free solder joints. There are investigated various properties of common lead-free solder paste depending on various concentrations of O₂ by reflow process and on various components size. Next, there are shown microstructures by micro sections for various concentrations of O₂. Mechanical properties (mechanical strength) are tested by shear test equipment DAGE 2400.

Abstract: The effect of sintering atmosphere and nitrogen pressure on microstructure of Ti(C, N)–12WC–16Ni–4Mo₂C cermet were investigated by scanning electron microscopy (SEM) and optical microscopy (OM), the transverse rupture strength (TRS), porosities, volume fractions of phases and grain sizes were determined. Results show that nitrogen pressure has a significant impact on TRS, appropriate nitrogen pressure could improve TRS. Vacuum sintering promotes the densification of sintered body, however, nitrogen atmosphere sintering could gain maximal TRS. Nitrogen atmosphere sintering facilitates the formation of inner rim phase and reduces the dissolution of TiC and TiN, small grain size is gained.