Non-chromate conversion films are formed on the surface of an Al-Z n-Mg-Cu alloy using a two step cerium salt treatment. The corrosion resistance of the alloy in chloride solution has been studied after the non-chromate treatment. It was found that the conversion film could greatly improve the corrosion resistance of the alloy to pitting and uniform corrosion in a chloride environment. The non-chromate film can retard both the anodic and cathodic processes. The treated alloy is not sensitive to the changes in the concentration of chloride ions and the pH value of the chloride solution.
Low-temperature vitreous materials fluxed with lead (and barium) appeared in the early Warring States period (c.fifth century BCE) in ancient China. A range of lead vitreous products fluxed with the same agent, including faience/glass beads, glazed pottery and Chinese blue (purple) pigment, were developed subsequently. This study carries out scientific analysis of six vitreous beads unearthed from the Zhaitouhe cemetery site in northern Shaanxi dating to the early and middle Warring States period to investigate their chemical composition, microstructure and coloration. The lead (and barium) vitreous beads identified here are some of the earliest lead vitreous materials discovered in China so far, and therefore important for the study of the development of lead vitreous technologies in ancient China. This paper also points out that it is meaningful to evaluate the lead glass, glazed pottery and barium copper silicate pigments as a whole technological assemblage given their close relationships.
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