Electrolytic Corrosion Behavior of 20 Cu-20 Ni-54 NiFe2O4-6 NiO Cermet with Interpenetrating Structure at 880 °C and 960 °C.

Here, 20 Cu-20 Ni-54 NiFe2O4-6 NiO (wt%) cermets were prepared via the powder metallurgy process, and the electrolytic corrosion behavior of the cermets at 880 °C and 960 °C was studied through the microstructure analysis by SEM and EDS. Results show that the ceramic phase is seriously affected by chemical corrosion at 880 °C electrolysis, and it is difficult to form a dense ceramic surface layer. A dense ceramic surface layer is formed on the bottom of the anode electrolyzed at 960 °C, and the dense layer thickens with the extension of the electrolysis time. The formation of the dense surface layer is mainly caused by the oxidation of Ni. The oxidation rate of the metallic phase and the corrosion rate of the ceramic phase have an important effect on the formation of the dense layer. In the corrosion process of NiFe2O4 phase, preferential corrosion of Fe element occurs first, and then NiO phase is precipitated from NiFe2O4 phase. After the NiO is dissolved and corroded, the NiFe2O4 grains collapse and the ceramic phase peels off from the anode.

Deposition and regional distribution of HCHs and p,p'-DDX in the western and southern Tibetan Plateau: records from a lake sediment core and the surface soils.

Tibetan Plateau is the world's highest plateau, which provides a unique location for the investigation of global fractionation of organochlorine pesticides (OCPs). In this study, deposition and regional distribution of HCHs and p,p'-DDX in the western and southern Tibetan Plateau were investigated by the records from a sediment core of Lake Zige Tangco and 24 surface soils. Concentration of ΣHCHs in the surface soils of the western Tibetan Plateau was much higher than that of the southern part. Maximum fluxes of α-, ß-, and δ-HCH in the sediment core were 9.0, 222, and 21 pg cm(-2) year(-1), respectively, which appeared in the mid-1960s. Significant correlations were observed between concentrations of α- and ß-HCH in both the surface soils and the sediment core. Concentrations of both α- and ß-HCH increased with the inverse of the average annual temperature of these sites. γ-HCH became the dominant isomer of HCHs after the late 1970s, and reached the maximum flux of 160 pg cm(-2) year(-1) in the early 1990s. There were no significant correlations between concentrations of γ-HCH and the other isomers in both the surface soils and the sediment core. The results suggested that there was input of Lindane at scattered sites in this area. In contrast to ΣHCHs, concentration of Σp,p'-DDX in the surface soils of the southern part was much higher than that of the western part. Maximum flux of Σp,p'-DDX was 44 pg cm(-2) year(-1), which appeared in the mid-1960s. Local emission of p,p'-DDT was found at scattered sites. This study provides novel data and knowledge for the OCPs in the western and southern Tibetan Plateau, which will help understand the global fractionation of OCPs in remote alpine regions.