The high temperature corrosion resistance of α‐phase bronzes

摘要

AbstractThe oxidation of Cu‐Sn alloys containing up to 13 wt Sn in oxygen (1 atm) has been studied in the temperature range 550 °C to 800 °C at 50 °C intervals; the investigation involved the study of the kinetics and of the morphology and structure of the scales by appropriate physical methods, with the aim of correlating the two aspects of the oxidation behaviour. The oxidation rate of a 3 wt Sn alloy is lower than for pure Cu at 550 and 600 °C, but higher above 600°C. The effect of the tin addition is related to the interplay of many different factors affecting the reaction rate, the overall result depending on temperature. The rate of oxidation of the more concentrated alloys, however, is always lower than that of pure Cu. This result is attributed to the formation of an SnO2layer at the base of the scale which, although thin and usually discontinous, slows down the outward diffusion of copper. The highest tin concentration allowed by its high temperature solubility in copper is not sufficient to produce a continous thick healing layer of SnO2at the alloy surface, but nevertheless it produces a pronounced decrease of the oxidatio