Sn-Bi solder was proposed as one of the most promising substitutes for lead solder due to its lower melting temperature, good wettability, good yield strength and cost efficiency. With Ag elements added, the mechanical properties of Sn-Bi solder were improved obviously. There are two ways that are commonly used to add the reinforced particles into the solder. The first way (Way I) is to blend the reinforced particles with solder powders together, and then followed by pressure forming, sintering, cooling, crystallization and serious machining methods under inert atmosphere to make the solder paste. Another way (Way II) is to directly add the reinforced nano or micro particles into the solder paste by sufficient mechanical-stirring. In this research we would like to get fully understanding on the effects of these two ways of Ag addition on the mechanical properties of Sn-Bi-Ag solder joints during aging. Sn57.6Bi0.4Ag solder stands for the Way I and the doped Sn58Bi ? 0.4Ag solder stands for the Way II. These two kinds of joints were compared via micromorphology observation, thermal failure analyses as well as balls shear strength measurement after different aging time (under 100°C, from 0 to 800 h). The mechanical properties of Sn57.6Bi0.4Ag and the doped Sn58Bi ? 0.4Ag solder joints during aging were shown to be associated with the changes of micromorphology, the dissolution of IMCs, as well as the flatness of the joints' interface. Before long-time aging, the doped Sn58Bi ? 0.4Ag solder joints showed better mechanical performance than Sn57.6Bi0.4Ag solder joints. During aging, Sn56.7Bi0.4Ag solder joints had better performance in preventing the dissolution of Ni-Sn IMCs into the solder side, having smoother interfaces, comparing with Sn58Bi ? 0.4Ag solder joints. The degenerated phenomenon of Ag nanoparticle reinforcement seriously happened in the doped Sn58Bi ? 0.4Ag solder joints. After longtime aging, Sn57.6Bi0.4Ag solder joints had better mechanical properties than the doped Sn58Bi ? 0.4Ag solder joints.
Boron in coal is of great interest, mainly because it can be used as paleosalinity indicator; it is also of environmental concern because of its toxic effects, especially on land plants. This paper describes a new method for determination of the boron concentration in coal by inductively coupled plasma mass spectrometry (ICP-MS) after closed-vessel microwave digestion. Samples of raw coal rather than coal ash were used for the determination to avoid the loss of volatile organically bound boron. Addition of H 3 PO 4 to the HNO 3 and HF used as reagents in the process could also significantly diminish boron volatilization during acid-drying after sample digestion. A 2% ammonia solution, which was injected into an ICP-MS spray chamber to eliminate the memory effect of boron, may reduce boron signals to blank levels (within 120 s) during ICP-MS analysis. The boron concentrations of National Institute of Standards and Technology (NIST) standard reference coal samples obtained using the ICP-MS in high-resolution mode and with 103 Rh or 115 In used as online addition internal standards are in good agreement with the certified values.
This paper reports the mineralogical compositions of super-low-sulfur (Yueliangtian 6-upper (YLT6U)) and high-sulfur (Yueliangtian 6-lower (YLT6L)) coals of the Late Permian No. 6 coal seam from the Yueliangtian coal mine, Guizhou, southwestern China. The mineral assemblages and morphology were detected and observed by X-ray diffractogram (XRD), optical microscopy and field-emission scanning electron microscope (FE-SEM) in conjunction with an energy-dispersive X-ray spectrometer. Major minerals in the coal samples, partings and host rocks (roof and floor strata) include calcite, quartz, kaolinite, mixed-layer illite/smectite, chlorite and pyrite and, to a lesser extent, chamosite, anatase and apatite. The Emeishan basalt and silicic rocks in the Kangdian Upland are the sediment source for the Yueliangtian coals. It was found that there are several modes of chamosite occurrence, and precursor minerals, such as anatase, had been corroded by Ti-rich hydrothermal solutions. The modes of occurrence of minerals present in the coal were controlled by the injection of different types of hydrothermal fluids during different deposition stages. The presence of abundant pyrite and extremely high total sulfur contents in the YLT6L coal are in sharp contrast to those in the YLT6U coal, suggesting that seawater invaded the peat swamp of the YLT6L coal and terminated at the YLT6U-9p sampling interval. High-temperature quartz, vermicular kaolinite and chloritized biotite were observed in the partings and roof strata. The three partings and floor strata of the No. 6 coal seam from the Yueliangtian coal mine appear to have been derived from felsic volcanic ash. Four factors, including sediment-source region, multi-stage injections of hydrothermal fluids, seawater influence and volcanic ash input, were responsible for the mineralogical characteristics of the Yueliangtian coals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.