【作者】 崔春娟；

【导师】 张军；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2005， 硕士

【摘要】 当前场致发射材料研究的热点主要有半导体硅、金刚石薄膜以及碳纳米管等。Si-TaSi2共晶自生复合材料作为半导体金属共晶材料(SME)之一,具有较低的功函数、良好的电传输特性和自生肖特基结等特点,被认为是具有良好的应用前景的场发射材料之一。本文采用电子束区熔(EBFZM)定向凝固技术制备Si-TaSi2共晶自生复合场发射材料。借助金相技术、电镜技术、图象处理技术等多种分析测试手段,考察了Si-TaSi2共晶定向凝固组织演化规律和Si-TaSi2共晶自生复合材料的场发射性能。 首先研究了不同的凝固速率下制得的Si-TaSi2自生复合材料的凝固组织特征,随着凝固速率的增大,组织明显得到细化:TaSi2纤维的直径d变小,纤维间距λ变小,与此同时面密度Nr增大,体积分数V%增大;采用波谱分析和金相分析的方法对共晶体中相的组成进行了研究:在透射电镜上进行选区电子衍射,明确了Si基体和TaSi2纤维之间的位相关系为【011】Si//[0001】TaSi2。(022)Si//(012 0)TaSi2;采用零功率法固定试样凝固过程中的固液界面,得到了固液界面的演化规律,即随着凝固速率的增大,固液界面经历从平界面→胞状界面→平界面的演化过程。并对小平面相/非小平面相的共生动力学和TaSi2相的小平面-非小平面转变机理进行了研究。 依据选择性刻蚀原理,探索了Si基尖锥形TaSi2场发射阵列的制作工艺,并测试了样品的场发射性能,初步明确了材料性能、凝固组织、工艺参数之间的关系。更多还原

【Abstract】 Nowadays the research of field emission display materials is mostly focused on semiconductor Si , diamond film , carbon nanotubes and so on. Si-TaSi2 eutectic in situ composite for field emission is one of the Semiconductor Metal Eutectic materials(SME), which has so many characters such as the relatively low work function, good electricity conduction, Schottky junctions grown spontaneously into the matrix etc, and it is regarded as one of the excellent field emission materials . In this paper, the directionally solidified Si-TaSi2 eutectic in situ composite for field emission is prepared with the electron beam floating zone melting (EBFZM) technique. Microstructure of directionally solidified Si-TaSi2 eutectic in situ composite and the characters of field emission are investigated by the help of metallograph, electron micrograph, imagine management technology and other analysis test methods.Microstructure of directionally solidified Si-TaSi2 eutectic in situ composite is investigated at the different solidification rates. Microstructure is obviously thinned as the solidification rate increases. With the increasing of the solidification rate, the diameter and the inter-fiber spacing of the TaSi2 fibers decrease, while the fiber density and the volume fraction increase. The phases composition of the eutectic is investigated by the help of spectrum. Precinct electronic diffraction is manipulated on the transmission electron micrograph, which demonstrates that the locationrelationship between Si matrix and TaSi2 fibers is [011]Si//[0001]TaSi2,(022)Si//(0120)TaSi2. The evolvement principle of solid/liquid interface is obtainedas the solid/liquid interface is fixed during solidification process by the method of zero power. With the increasing of the solidification rate, solid/liquid interface changes from planar interface to cell interface then transits to planar interface again. Intergrowth dynamics of facet/non-facet and transformation mechanism of TaSi2 phase are investigated as well.Facture technique of Si matrix cone-shaped field emission array is explored according to optional corrode theory, and field emission property of the samples is tested at the same time. So the relationship among materials’ property,microstructure and technical parameters is confirmed primarily.更多还原