| The development of new clean energy is the fundamental way to solve my country’s energy shortage and ecological environment problems.The development of nuclear fusion energy is generally regarded by the public as an important issue to solve energy problems,and its application is also in line with the concept of green energy.Among the first wall materials(PFM)currently studied at home and abroad,tungsten has the characteristics of high melting point,low sputtering rate and high thermal conductivity,which meets the necessary characteristics of the first wall material,but for PFM,high temperature oxidation resistance is an important safety factor that needs to be considered in the future.Self-passivation tungsten alloy(SPTA)and its surface coating technology can form dense protective oxide scale after accident by adding some beneficial anti-oxidation elements(Cr、 Ti、 Zr、 Nb、 Y etc.)Or slow down W oxidation.In this paper,the dual-glow plasma surface alloying technology(dual-glow technology)is used to prepare a W-Cr-Y self-passivation alloy layer on the surface of pure tungsten,which is the main way to solve the possible risks of future nuclear fusion devices..In this paper,the double-glow plasma surface alloying technology(double-glow technology)is used to prepare the W-Cr-Y self-passivation alloy layer on the surface of pure tungsten with the W-Cr-Y alloy target prepared by powder metallurgy technology as the source electrode..In the experiment,different W-Cr-Y alloy layers were prepared by changing the workpiece temperature and the voltage difference between the source and the cathode.By means of scanning electron microscopy(SEM)and its accompanying energy dispersive spectrometer(EDS),X-ray diffraction(XRD),etc.The microstructure and composition of the-Cr-Y alloy layer were analyzed.The mechanical properties of the alloy layer were characterized by microhardness tester.The high-temperature oxidation resistance experiments of different W-Cr-Y alloy layers and pure tungsten substrates were carried out after 10 h of oxidation in a simulated future nuclear fusion power station water loss accident temperature of 1000 ℃ and in the atmospheric environment,and their oxidation kinetics were investigated.The science and antioxidant mechanism were analyzed,and the following results were obtained:(1)When the temperature is kept at 1000 °C,different composite W-Cr-Y self-passivation modified layers are obtained by changing the pressure difference.It is found that too high or too low pressure difference will cause the surface of the alloy layer to appear rough.In addition,the thickness of the composite layer is lower,and the overall quality is reduced.When the pressure difference is 300 V,a smooth,continuous and dense alloy layer with a thickness of up to 35 μm can be obtained.In the W-Cr-Y self-passivation alloy layers prepared at different temperatures with a pressure difference of 300 V,it was found that with the increase of preparation temperature,the surface smoothness and density of the alloy layer increased.However,except for the preparation temperature of 1000 ℃,the alloy layers prepared at other temperatures had different degrees of cracks with the matrix;when the preparation temperature was 1100 ℃,holes and cracks appeared in the alloy layer.EDS analysis shows that the content of Cr and Y elements on the surface of the alloy layer is less than that of the designed source target.XRD diffraction analysis shows that the W-Cr-Y self-passivation alloy layers prepared by all process parameters are BCC structures,only the diffraction peaks of W exist,and the phases corresponding to Cr and Y are not detected.(2)The peak value of the surface hardness of the W-Cr-Y self-passivation alloy layer prepared by different process parameters is twice the hardness of the substrate,and the surface hardness is also different with the thickness of the alloy layer;The surface hardness of the W-Cr-Y alloy layer was the highest when the voltage difference was 300 V and the temperature was 1000 ℃,and the hardness decreased slowly with the increase of load.(3)In the oxidation experiment after oxidation at 1000 °C and in the atmospheric environment for 10 h,the slope of the oxygen weight gain curve of the alloy layer prepared at a voltage difference of 200 V at a temperature of 1000 °C and a voltage difference of 300 V at a temperature of 800 ° C is close to that of the pure W substrate,large area penetrating cracks appear after oxidation.After the sample was oxidized with a voltage difference of 300 V and a temperature of 900 ℃,a few cracks appeared on the surface,and the oxygen absorption rate was slow;the sample prepared with a voltage difference of 300 V and a temperature of 1000 ℃ had the smallest oxidation weight gain and achieved the best anti-oxidation effect. |
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