原料配比对多孔MgO/Fe-Cr-Ni复合材料性能的影响

铁铬镍合金具有良好的高温强韧性和抗蠕变性,广泛应用于航空发动机、工业燃气轮机等设备中。利用原位合成和无压烧结工艺制备nano-MgO(34.9%)/Fe-Cr-Ni(质量分数,下同),micro-MgO(34.9%)/Fe-Cr-Ni,micro-MgO(25.7%)/Fe-Cr-Ni,micro-MgO(17.0%)/Fe-Cr-Ni 4种多孔复合材料。采用DTA,XRD和SEM等测试方法,研究不同MgO晶粒大小和含量对多孔金属基复合材料的常温和高温抗弯强度、高温抗氧化性能的影响。结果表明,在相同的烧结工艺条件下,不同原始粉末引起不同的反应热焓,导致烧结后得到的试样具有不同的气孔率和相组成。制备出的多孔复合材料主要由Cr_0.7Fe_0.36Ni_2.9,Cr-Fe固溶体的金属基体和MgO陶瓷增强相组成。当温度从室温升至1000℃左右,4种复合材料的抗弯强度值均随着温度的升高而降低,但其抗氧化性能优异。在4种多孔复合材料中,多孔nano-MgO(34.9%)/Fe-Cr-Ni复合材料的高温抗氧化能力优于其他3种多孔复合材料。

Effect of raw materials ratio on performances of porous MgO reinforced Fe-Cr-Ni composites

Fe-Cr-Ni alloys are widely applied to aero-engine,industrial gas turbine and other equipment because of their high temperature strength and toughness and creep resistance.Four kinds of porous MgO reinforced Fe-Cr-Ni matrix composites,which are nano-MgO(34.9%)/Fe-Cr-Ni(mass fraction,the same below),micro-MgO(34.9%)/Fe-Cr-Ni,micro-MgO(25.7%)/Fe-Cr-Ni,micro-MgO(17.0%)/Fe-Cr-Ni,were prepared by powder sintering and in situ synthesis method.Effect of the particle sizes and content of MgO on bending strength at room or high temperature and oxidation resistance of porous metal matrix composites at high temperature were investigated by XRD,DTA and SEM.The results show that different raw materials lead to the different enthalpy,resulting in the different porosities and phase compositions for the sintered samples.The porous composites consist of Cr0.7Fe0.36Ni2.9,Cr-Fe and MgO phases generally.The bending strength of these porous composites decreases with the increase of the temperature.The high temperature oxidation resistance of nano-MgO(34.9%)/Fe-Cr-Ni composites is the best of the four kinds of porous composites.