High Temperature Oxidation Of Cu-S, Cu-Se And Cu-Te Alloys

Copper is a traditional, yet modern and important metals. Effect of copper on themajor civilizations in human history cannot be compared to any other materials in allhuman used, so there are two stages in the history of human civilization, bronze ageand mild bronze age, were named after the copper alloy. Copper and gold, silverbelonging to the same family in the periodic table of elements, and thus has a preciousmetal similar in excellent physical and chemical properties.Copper and its alloys have been widely used in the welding electrode substrate,silicon chip, contact switches and other fields, because they have excellent electricalconductivity, thermal conductivity, corrosion resistance and easy processing, and soon. But it is inevitable that copper would be oxidation in the actual work. The hole inthe copper connector is often still appear at the interface. Adding a certain amount ofalloying elements to pure copper is one of the more common methods of improvingthe ability of high temperature oxidation resistance of alloys. But adding alloyingelements also maybe improve the resistance of copper alloys, thereby affecting theability of conducting.Not only the alloying elements can affect ability of high temperature oxidationresistance, impurity elements also have some impact on the stability of copper underhigh temperature conditions. There are80%copper extracting from the coppercontaining Cu₂S, and in the refining process will react with the gases which containthe sulfur element, copper alloys would contain a trace of S elements. Se and Tewould easily be imported in the copper smelting process.The effect of adding S, Se and Te to copper on high temperature oxidationresistance of copper has not yet reached a unified conclusion. We need to study theeffect of S, Se and Te to pure copper in high temperature oxidation for promoting theapplication of copper and rich the knowledge of high temperature oxidation.It was found that the oxidation resistance of the alloys were improvedremarkablely compared to thant of Cu at673K with the following order: Cu-Se alloy> Cu-Te alloy> Cu-S alloy>6N Cu. When the alloy elements increase, theoxidation resistance of alloy is better. After adding the trace elements, significantlyimprove antioxidant of copper alloys, mainly due to the increase of oxide activationenergy of copper, reflected in the trace elements blocking oxygen diffusion in oxidesand alloys. In the oxide layer, S, Se, and Te occupy the location of oxygen lattice,reducing the Cu vacancies, improving oxidized activation energy of Cu in oxide.Sulfur, selenium, and tellurium aggregate and form a impurities interface as well asCu-S, Cu-Se, Cu-Te key in alloy impede the diffusion of copper to oxide. Traceelements not only did not increase the alloy oxidation resistance, but decreased at1073K. Cu-0.1Se alloy have the fastest oxidation rate, the worst oxidation resistance,when increase the trace elements, the oxidation resistance of alloy would even worse.It is because that S, Se, Te and Cu produces Cu₂S, Cu₂Se, Cu₂Te and othercompounds, these oxides can react with O₂, also can react with CuO, reduces theoxidation resistance of alloy.