| Nowadays,while people in our country are advancing by leaps and bounds in life,the requirements for air quality are becoming higher and higher.Therefore,with the continuous progress of industry,it is even more urgent to reduce air pollution.High-temperature dust filter materials are an important technology for reducing emissions.The direction of scientific research is from ceramics to porous Fe-Al alloys.The goals of these years have turned to nickel-based superalloys because of their good high-temperature oxidation resistance and excellent processing performance.To attract attention.Ni-Cr-Al porous materials are among the best.In this paper,Ni,Cr,Al,Y element powders are used as raw materials,and the porous materials Ni-Cr-Al and Ni-Cr-Al-Y are prepared by the principle of powder metallurgy and pressureless sintering,and the high temperature oxidation performance at 1000?is studied.The results of the research work are as follows:Ni-Cr-Al porous alloys with different porosities were obtained by changing the particle size of the powder and the sintering temperature.It was found in a series of oxidation time experiments of oxidation at 1000?for 100h that the powder particle size is??48?m?Ni and Cr The mass fraction ratio of Al powder sintered at1250-1300?for 3h is 75Ni-16Cr-9Al.The porous material has the highest open porosity and the best high temperature oxidation resistance,and the open porosity does not decrease significantly.Based on the above,adding rare earth Y,by changing the content of Y,prepared a series of mass fraction ratio of Ni-16Cr-9Al-x Y?x=0.5,1,1.5,2?and 75Ni-16Cr-9Al porous alloys.The oxidation mechanism and oxidation behavior at 1000?were studied by constant temperature oxidation and discontinuous weighing method,and the surface morphology and phase change analysis of samples oxidized at different times.Research surface:The oxidation process of Ni-Cr-Al-Y porous material is mainly divided into three stages,the transient oxidation stage in the early stage,the stable growth stage in the middle stage and the gradual oxidation growth stage in the later stage.It proves the different roles of rare earth Y in the three stages.The transient oxidation process in the early stage reduces the critical concentration of Al-lean phase oxidation;in the middle stage,it has a"pinning"effect on the oxides that have been generated to prevent the shedding of oxides;Reduce the contact of oxygen with the unoxidized elements of the matrix.However,the addition of Y with a mass fraction of 2%will cause Y2O3to segregate and reduce the high-temperature oxidation resistance of Ni-Cr-Al-Y.Comprehensive analysis shows that the Ni-Cr-Al-Y porous material has good formability,high open porosity and large pore size;it exhibits excellent anti-oxidation performance in the oxidation experiment,and the oxidation product is stable,and the oxidation kinetics is in line with Parabolic law.It can be applied to industrial production. |
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