No abstract

aIn order to investigate the gold coin's tarnish mechanism, the tarnish and corrosion mechanism on Chinese gold coins was investigated by optical microscopy (OM), scanning electron microscope energy dispersive spectrometry (SEM-EDS), electron microprobe analysis (EMPA), XPS and X-ray diffraction (XRD). The results indicated that the tarnish on the gold coin was caused by silver on its surface. The main component of the tarnish stain on the gold coin was silver sulfide and silver sulfate. The stain and the contamination originate from the polishing procedure, which accelerated the tarnish process. Two measures can be taken to prevent the gold coin's tarnish. First, the mintage of gold and silver coins should be separated and, second, a chemical cleaning procedure should be introduced.

A fast and large scalable process to produce TiC powder was obtained using a horizontal rotary ball mill within 60 min via a mechanically induced self-propagating reaction (MSR). The as-synthesized TiC particles have well-defined crystals structure and the median diameter of ∼1 μm with less impurity due to short duration of milling. The mechanism for the acceleration of MSR was investigated in detail. The graphene nano-platelets are exfoliated from graphite by ultra-high-energy of the horizontal rotary ball mill after less than 30 min of milling, which plays a crucial role in formation of leaf-like nanoplatelets with Ti lamella by ball collision. At the same time, the ultra-highenergy of ball milling can boost self-prorogating reaction in a short duration of milling.

As the main coolant piping from the steam generator to the reactor pressure vessel, cold leg is an important part of the primary circuit. During a LOCA accident in the cold leg, the parameter sensitivity has a crucial influence for the containment response. PAREO program is used to analyze the sensitivity of the pressure response of HPR1000 containment. Quantitatively evaluated the influence of free volume, area of thermal components, spray flow rate and internal atmospheric temperature on the pressure and temperature of containment under the condition of LOCA. The results show that the area of thermal components is the most sensitive parameter to the pressure response process of containment. The research results could provide technical support for containment design, safety analysis and assessment.