大尺寸二硅化钼棒材连续挤出成型技术的研究

Research on continuous extrusion molding of large-sized MoSi_2 bars

为了提高发热元件的使用寿命,消除二硅化钼棒材中的内部缺陷,对大尺寸棒材的连续挤出成型技术进行了研究,分析了粘接剂种类、添加量及加水量对泥料特性和坯体干燥特性的影响,并研究了粘接剂种类和脱脂条件等对二硅化钼棒材组织结构和力学性能的影响.实验结果表明,高粘度的粘接剂会导致高的内部缺陷和表面缺陷发生率,仅通过工艺条件的改变不能从根本上解决这一问题.而低粘度粘接剂虽然有利于消除内部缺陷,但棒材表面缺陷的发生率却与脱脂工艺密切相关.因此,只有粘度适中的粘接剂与适宜的脱脂工艺相配合,才能有效地抑制棒材内部缺陷和表面缺陷的发生.在本实验中,以B2的粘接剂与脱脂条件3相配合,可以制得高密度无缺陷的大尺寸二硅化钼棒材,将产品的成品率从原来的80%提高到了96%.

The lifetime of MoSi2 heating element, manufactured by continuous extrusion molding technology, can be extended via using defects free hot and cold ends. For preparing defects free MoSi2 rods, the influence of hinder viscosity and degreasing condition on the microstructure and mechanical properties of the rods was in- vestigated in this work. Experimental results indicate that the high incidence rates of interior and surface de- fects are generally resulted from high binder viscosity, which cannot be eliminated by changing the degreasing condition only. Using binder with low viscosity, the occurrence of interior defects can be controlled but that of surface defects is closely influenced by the degreasing condition. Therefore, defects free rods can be prepared by adopting binder with moderate viscosity and processing in suitable degreasing condition. Based on the ex- perimental data, the optimal technical parameters were established, which improved the rate of finished prod- ucts from 80% to 96%. This technology can also supply reference to the continuous extrusion molding of other ceramic bars.