添加Ti对C/C复合材料渗NiAl金属间化合物的影响

Influence of adding Ti on molten NiAl intermetallic infiltration into C/C composites

通过铺展实验研究添加Ti对NiAl金属间化合物与C/C复合材料润湿性的影响,发现添加Ti元素可改善熔融NiAl与C/C复合材料基体的润湿性。以低密度C/C复合材料为坯体,采用真空熔渗法制备C/C-NiAl复合材料,利用X射线衍射(XRD)和扫描电镜(SEM)对材料进行分析。结果表明:添加的Ti粉含量(质量分数)为15%时,C/C复合材料熔渗NiAl金属间化合物的效果最佳,且TiC颗粒与NiAl熔体在C/C复合材料内部呈网状分布;渗NiAl后材料的密度从1.35 g/cm3提高到2.47 g/cm3,开孔率从27%下降到15.1%,沿平行纤维排布面方向的洛氏硬度较未渗NiAl的C/C复合材料提高约30.7%。添加Ti能改善C/C复合材料渗NiAl性能的主要原因是Ti与C反应形成的TiC改善了NiAl在C/C复合材料中的化学吸附和物理吸附特性。

The influence of adding titanium on the wettability of molten NiAl intermetallic on the surface of C/C composites was investigated by spreading experiment. It is indicated that adding Ti can improve the wettability between C/C composites and NiAl intermetallic. Using the low-density C/C composite perform the C/C-NiAl composites were prepared by the vacuum molten infiltration. The composites were analyzed by X-ray diffraction（XRD） and scanning electronic microscope（SEM）. The results show that NiAl with about 15%Ti（mass fraction） possesses good wettability on the surface of C/C composites. The TiC particles and NiAl melt present network distribution in C/C composites internal. The density increases from 1.35 g/cm3 to 2.47 g/cm3 while the porosity decreases from 27% to 15.1% after the infiltration of NiAl. On the other hand,the Rockwell hardness of C/C-NiAl composites increases by 30.7% in the direction parallel to fiber fabric plane compared with that of C/C composites. The improvement of adding Ti for molten NiAl infiltration into the C/C composites results from the improvement of the chemical and physical adsorption characteristics of NiAl alloy on the composites,which is caused by TiC from reaction of Ti and C.