Effect of Graphene Nanosheets on the Microstructure and Mechanical Properties of Sn-20Bi Solder.

The application of Sn-Bi series solder is limited due to the brittleness of Bi phase. Sn-20Bi solder with less Bi element content has great research prospects, but it needs modification to make it a substitute for traditional Sn-Pb solder. In this article, we mixed graphene nanosheets with nanometer Sn powder by means of ultrasonic oscillation, and Sn-20Bi-qGNS (q = 0.01, 0.02, 0.04, 0.06, and 0.1 wt.%) solder alloys were prepared by the melt-casting method. The effects of graphene nanosheets (GNSs) on the microstructure, physical properties, mechanical properties, and corrosion resistance of solder alloys were investigated. Scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to determine the microstructural morphology and composition. The results showed that the melting point, density, and wettability of the solder decreased slightly with the addition of GNSs. The addition of GNSs as a second phase refined the solder structure and improved the tensile strength of the molten Sn-20Bi composite solder to 99.6 MPa, while elongation decreased with the addition of GNSs. Furthermore, GNSs prevented the MC Sn-20Bi-qGNSs/Cu intermetallic compound layers' growth by interfering with atomic diffusion and grain boundary movement. In addition, the addition of 0.02 wt.% GNSs enhanced the shear strength of MC Sn-20Bi solder joints to 46.3 MPa. The electrochemical experimental results show that the surface corrosion products of MC Sn-20Bi-qGNSs under 3.5% NaCl solution were Sn3O(OH)2Cl2, with MC Sn-20Bi-0.01GNSs exhibiting the best corrosion resistance.

Effect of Aluminum Addition on the Microstructure and Properties of Non-Eutectic Sn-20Bi Solder Alloys.

This study investigates the effect of aluminum (Al) on the microstructure, micro-hardness, and wettability of environmentally friendly Sn-20Bi-xAl (x = 0, 0.1, 0.3, 0.5 (wt.%)) solder alloys. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) analysis, and X-ray diffraction (XRD), were used to identify the microstructure morphology and composition. The spreading area and contact angle of the Sn-20Bi-xAl alloys on Cu substrates were used to measure the wettability of solder alloys. The results indicate that Al increased the hardness to a maximum value of ~27.1 HV for x = 0.5. When the content of Al was more than 0.3 wt.%, the hardness change value gradually flattened. From the spreading test results, Al reduced the wettability of solder alloys. When the content of Al was 0.1 wt.%, the change was slight. When more than 0.3 wt.%, the wettability of Sn-20Bi-xAl solder alloys sharply dropped. The corrosion resistance of Sn-20Bi-0.1Al alloy was the best, and the corrosion rate was at the lowest value at 0.092 mm/a due to the dense corrosion products.

Solid State Phase Equilibria of an Al⁻Sn⁻Y Ternary System.

A complete understanding of the solid-state phase equilibria of the ternary Al⁻Sn⁻Y system is essential for the development of both Al-based structural materials and Sn-based lead-free solders. In this work, the phase relationships in the Al⁻Sn⁻Y ternary system at 473 K were investigated mainly by means of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) with energy disperse spectroscopy (EDS) analysis. The existence of 12 binary compounds, namely Sn3Y, Sn5Y2, Sn2Y, Sn10Y11, Sn4Y5, Sn3Y5, AlY2, Al3Y5, Al2Y3, AlY, Al2Y and α⁻Al3Y, was confirmed. Controversial phases (Sn5Y2 and Al3Y5) were found in this work. This isothermal section consisted of 15 single-phase regions, 27 two-phase regions and 13 three-phase regions. No ternary compounds were found and none of the other phases in this system revealed a remarkable solid solution at 473 K.

[Simultaneous determination of ten organotin compounds in polyvinyl chloride plastics using gas chromatography-mass spectrometry].

A rapid and effective gas chromatography coupled with mass spectrometry method has been developed systematically and studied for the simultaneous determination of 10 organotin compounds, dibutyltin-dichloride (DBT), n-butyltin-trichloride (MBT), triethyltinchloride (TET), fentin-chloride (TPhT), chlorotributylstannane (TBT), tri-n-propyltinchloride (TPrT), diphenyltin-dichloride (DPhT), tetrabutyltin (TeBT), di-n-octyltin-dichloride (DOT), phenyltin trichloride (MPhT)), in polyvinyl chloride (PVC) plastics. The PVC sample was dissolved with tetrahydrofuran and the polymer in the sample was precipitated with methanol, and then the target compounds were derivatized with sodium tetraethylborate and extracted with hexane under ultrasonication. The qualitative and quantitative analysis were carried out by GC-MS and the total ion chromatogram and selected ion chromatogram were obtained. The derivatization and extraction conditions, such as the derivatization time, derivatization pH value, dosages of derivatization reagent and precipitation reagent were optimized. The good linearities, recoveries and precisions were obtained. The linearity ranges were 0.5 - 50 mg/L. The linearity correlation coefficients of 10 organotin compounds were between 0.997 8 and 0.999 7. The average recoveries were 84.23% - 109.1% with relative standard deviations of 4.24% - 10.75%. The established method has been successfully applied to the determination of organotin compounds in PVC plastics.

The Current Status of Hospital Information Systems in Yanbian, China / 대한의료정보학회지

PURPOSE: The purpose of this study was to analyze the current status of Hospital Information system in Yanbian, China. METHODS: Structured self-administered questionnaires were sent to hospitals in Yanbian to survey the issues and six hospitals answered. Data were analyzed by using Windows SPSS 12.0. RESULTS: All facilities were second-grade national hospitals with 100~500 beds, kept about 40 computers and all used internet. Four of them had information exclusive department, and the other two had the implementation plans. All of the hospitals had Patient Billing System and some features of Medication Administration System. Four hospitals had administration systems, and the other two had no plans to develop or adopt administration system in the next three years. Two hospitals used the packages composed of Electronic Data Interchange System, Amount Receivable Management System and Laboratory Information System. One hospital used the Picture Archiving and Communication System, Telemedicine System, Radioactive Examination. CONCLUSIONS: Compared with Korea, the results showed relevant explanation on the delays of implementing HIS and its current status in Yanbian. In order to develop Hospital Information System, various strategies must be developed and active international support and research was required to provide the appropriate experiences.