Über die Oxydation von Silber‐Kupfer‐Legierungen

Abstract

Geschmolzene AgCu‐Legierungen mit 0 bis mindestens etwa 30% Ag lassen sich bei 1230° durch Sauerstoff vollständig oxydieren, Bei mehr als 30% Ag in der Legierung verbleibt ein Ag‐reicher Regulus, neben der entstandenen Ag2OCu2O‐Schmelze. Der gleiche Zustand ergibt sich durch Dissoziation, wenn Gemische aus Ag2O und CuO auf 1230° erhitzt werden. Cu2O löst im geschmolzenem Zustand in Luft von Atmosphärendruck bis zu 44 Gew.% Ag2O. Der Schmelzpunkt von Cu2O wird hierdurch um etwa 170° erniedrigt.

Selective oxidation of copper from liquid copper-silver alloys

“…Thus, the oxide mixture would contain 66 mass pct copper and 34 mass pct silver. The copper-to-silver ratio in this oxide mixture is somewhat higher than the value of 1.1 (49.7 mass pct copper and 41.0 mass pct silver) reported by Kohlmeyer and Sprenger [11] and the average value of 1.30 (48.44 mass pct copper and 37.28 mass pct silver) reported by Barbante et al [9] The scatter in the copper-tosilver ratios could be attributed to the entrainment of one phase within another and also differences in the experimental conditions. Figure 7 shows the effect of the borax-to-silica mass ratio of the slag on the copper content of the metal after 15 minutes of refining.…”

“…Applying X Cu O 2 this equation to the data given in Kohlmeyer and Sprenger's article, [11] and using a heat of fusion of cuprous oxide of 56.07 kJ/mole [17] gives an activity of cuprous oxide which is close to unity. It is assumed that the composition of the oxide for copper contents of the metal, varying in the range of 0.42 to 1.33 mass pct, would be close to that observed by Kohlmeyer and Sprenger.…”

“…[11] The results showed that, with oxygen injection at 1230 ЊC, molten alloys containing less than 30 mass pct silver were completely converted to silver oxide and copper oxide. Cuprous oxide could dissolve up to 44 mass pct silver oxide in the liquid state, and this resulted in a 170 ЊC depression in the melting point of the cuprous oxide.…”

“…Also, data from Kohlmeyer and Sprenger indicate that for silver-copper alloys containing 1.5 to 2.5 mass pct copper at 1473 K, the equilibrium composition of the oxide is 44 mass pct Ag 2 O ( ϭ 0.327) X Ag O 2 and 56 mass pct Cu 2 O ( ϭ 0.673) for oxygen injec-X Cu O 2 tion. [11] This mixture has a liquidus temperature which is about 170 K lower than the melting point of pure Cu 2 O. [11] The approximate equation for the activity of cuprous oxide on the liquidus is…”

“…[11] This mixture has a liquidus temperature which is about 170 K lower than the melting point of pure Cu 2 O. [11] The approximate equation for the activity of cuprous oxide on the liquidus is…”