等离子烧结制备CNTs增强Nb/Nb_5Si_3复合材料

Preparation of CNTs Reinforced Nb/Nb_5Si_3 In-situ Composites by Spark Plasma Sintering

采用放电等离子烧结(SPS)技术,在烧结温度为1 500℃,升温速度为150℃/min下,制备了CNTs含量分别为1%、2%和3%的Nb/Nb5Si3复合材料。研究了不同CNTs含量的放电等离子烧结Nb/Nb5Si3复合材料的组织与性能。结果表明,复合材料的组织主要由Nb、α-Nb5Si3和γ-Nb5Si3相组成,当CNTs含量超过2%时复合材料中出现了新相Nb4C3,可能是因为CNTs结构在球磨或烧结的过程中被破坏,与Nb粉发生了化学反应。在烧结工艺参数相同的条件下,随着CNTs含量的增加,复合材料的致密度有所下降,硬度(HRC)先增加,当CNTs的含量约为2%时达到最大为66,含量超过2%时,复合材料的界面结合能力差,致密度降低较多,硬度下降。延长保温时间和增加压力,会使得复合材料的致密度和硬度增大。

CNTs/Nb-20Si composites with 1% ,2 % and 3 % CNTs addition were prepareo at 1500 ℃/rain by spark plasma sintering （SPS）, and effects of CNTs content on microstructures and prop- erties of Nb/Nb5Si3 in situ composites were investigated. The results show that the in-situ composites consist of Nb, a-Nb5 Si3 and Y-Nb5 Si3 phase. With CNTs content addition more than 2 %, the new phase Nb4C3 can be observed in the composites, which may be attributed to CNTs structure being destroyed in a ball or sinl;ering process to take place the chemical reaction. At the same sintering process parameters, the densities of the composites are decreased obviously with the increase of CNTs content. The maxi- mum hardness（ HRC） 66 of the composites prepared can be presented with 2%addition of CNTs. Howev- er, with CNTs addition more than 2 %, the relative densities and hardness are decreased as a result of poor interracial adhesion. The relative densities and hardness of the composites are increased with the in- crease of holding time and pressure.