Plasma Oxidation of Alloys

为了弄清合金等离子体氧化的可能性及其机理，对Cu-Al、Ag-Cd和Ag-Al合金进行了低温等离子体氧化。在400 ~ 900℃的温度范围内，用常规氧化方法对Ag-Al合金在空气中的氧化行为进行了研究。在400 ~ 900℃的温度范围内，证实了ag -0.5 ~ 4.5at%Al合金在空气中氧化后，由于氧化而显著提高了硬度。这是由于分散的氧化铝沉淀的小尺寸。在这些合金中发现了两种类型的氧化行为：高温氧化和低温氧化。高温氧化时电阻率R减小，低温氧化时电阻率R增大。这是因为Al_2O_3析出物中有过量的氧用于低温氧化，并且在高温下形成了化学计量Al_2O_3颗粒。发现低温等离子体能够氧化Cu和Ag合金。在适当的等离子体氧化条件下，只形成内部氧化层而不形成外部氧化层。等离子体氧化的氧化速率和硬度比通常的气体氧化要高得多。

In order to make clear a possibility and the mechanism of plasma oxidation of alloys, Cu-Al, Ag-Cd and Ag-Al alloys were oxidized by low temperature plasma. For comperison, oxidation behavior of Ag-Al alloys in air by the usual oxidation method was also studied in the temperature range of 400-900 c.In Ag-0.5-4.5at%Al alloys oxidized in air at 400-900 C a marked increase in hardeness due to oxidation was confirmed. This results from dispersion of Al oxide precipitates small in size. In these alloys, two types of oxidation behavior were found : high temperature oxidation and low tempature oxidation. On the high temperature oxidation the electrical resistivity R decreases, while R increases at low temperatures. This is because Al_2O_3 precipitates have an excess amount of oxygen for the low temperature oxidation, and stoichiometric Al_2O_3 particles are formed at hith temperatures.Low temperature plasma was found to be enable to oxidize both Cu and Ag alloys. In adequate conditions of plasma oxidation, only the internal oxidation layer was formed without the formation of an external oxidation layer. The oxidation rate and the hardeness are much higher for plasma oxidation than for the usual gas oxidation.