Preparation And Properties Of Zr And Zr-Er Alloyed Layer On TC11 By Double Glow Plasma Surface Alloying Technology

TC11 titanium alloy is a kind of α+β titanium alloy with good comprehensive performance. But some disadvantages limit its further application in aerospace components. It should be due to the low surface hardness, poor tribology property and high temperature oxidation resistance. To solve these problems, the Zr alloyed layer and Zr–Er alloyed layer were prepared TC11 alloy using the double glow plasma surface alloying(DGP) technology. At the beginning of the experiment, the process parameters were investigated. And then the micro-hardness of layer and binding force between layer and substrate were tested to value the quality of the alloyed layers. The analysis in this issue focused on the effect of load, speed and temperature on the tribology property as well as effect of temperature on the high temperature oxidation resistance.The process parameters of Zr alloyed layer were listed follow: source voltage: 600~650V, cathode voltage: 450~500V, air pressure: 30 Pa, time: 3h, the distance between target and substrate: 15 mm. The optimum process parameters of Zr–Er alloyed layer were listed follow: source voltage: 550~600V, cathode voltage: 400~450V, air pressure: 35 Pa, time: 3h, the distance between target and substrate: 15 mm. The alloyed layer formed in the optimum process parameters combine with the substrate metallurgical. It can be observed that the gradient distribution of alloy elements. The thickness of Zr alloyed layer is approximate 5μm. It was composed of Zr and α-Ti solid solution phases. The thickness of Zr-Er alloyed layer is approximate 10μm. It is composed of Zr, Al3 Er and Er2O3 phases. The test results of micro-hardness and nano indentation hardness showed that the hardness and deformation resistance of alloyed layers were higher than TC11 substrate.Wear tests under different process parameters indicated that the friction coefficient, wear volume, the wear scar width and depth of both Zr alloyed layer and Zr–Er alloyed layer were much lower than TC11 substrate. The tribology property was improved.After the high-temperature oxidation of 100 h,the oxidation products of TC11 substrate was composed of Ti O2 and Al2O3.The oxidation particle was bulky and its structure is porous. Under the temperature of 650 and 750 degree, the oxidation products of Zr alloyed layer and Zr–Er alloyed layer were composed of Zr O2, Er2O3 and a small quantity of Ti O2. The oxide film was density and intact which could effectively prevent oxygen into substrate. Under the temperature of 850 degree, the oxide film of Zr alloyed layer peeled off the substrate which leaded to the decrease of the oxidation resistance. The Zr–Er alloyed layer can still maintain good high temperature oxidation resistance under the same temperature.