The corrosion products formed on Sn-Zn solder alloys were systematically studied to elucidate the corrosion mechanism of Sn-Zn alloys in chloridecontaining solution. Sn-Zn alloys were subjected to immersion and polarization treatment in a 0.5 M NaCl solution. Ex situ analysis, including surface and crosssection, of the corrosion products was carried out by scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). The corrosion products presented porous microstructure formed by a fine interlinked network. An increase of zinc content resulted in more pores and cracks of the corrosion products, indicating degradation of corrosion resistance. Intriguing is the finding that a gradient of chlorine concentration from the outer layer inwards the alloys through the Zn-rich precipitates is observed, which demonstrates the migration of chloride ions inwards the alloys. Based on the results, a corrosion mechanism was proposed and discussed that explains the observations. Particular attention was paid to the anodic dissolution of Zn-rich precipitates.

Silicon nitride ceramics with rare earth (Re) compound (5 wt-%) and MgO (3 wt-%) additives were fabricated by spark plasma sintering and following heat treatment. The Re compounds included two groups: ReF 3 ((Re5La,Nd,Gd) and Re 2 O 3 (Re5La,Nd,Gd). Specimens show the same tendency in the sintering shrinkage rate, relative density, grain size and bending strength with the increasing Re cation (Re 3z ) radius both in ReF 3 and Re 2 O 3 added samples. However, as to aspect ratios and thermal conductivity, the change rules are completely opposite between the two groups of specimens.