Yao Guang-chun

Preparation and Characterization of Graphite Powder Covered with CeO2

Abstract In order to improve the wetting properties of graphite with Al melt and reduce the oxidation of the graphite, by which the segregation of components during the liquid-stir-casting process could be prevented. In this paper, a uniform thin nano-film of CeO 2 , about 20 nm thick, was successfully prepared onto graphite powder surface by heterogeneous nu-cleation process. The results show that an obvious chemical reaction did exit between CeO 2 film and graphite with the formation of Ce-O-C bond, leading to a shift of the binding energy of C and Ce. The cover with CeO 2 film illustrates a distinct change of surface state of graphite with a decrease of angle of contact.

纳米增韧NiFe 2 O 4 陶瓷惰性阳极烧结行为与性能的研究

采用粉末冶金法制备NiFe 2 O 4 纳米粉增韧NiFe 2 O 4 陶瓷铝电解惰性阳极, 研究了NiFe 2 O 4 纳米粉添加量对NiFe 2 O 4 陶瓷惰性阳极烧结行为和材料性能的影响。通过线收缩和SEM对NiFe 2 O 4 陶瓷的烧结性能和显微结果进行分析。研究结果表明: 随着NiFe 2 O 4 纳米粉添加量的增加, 烧结收缩程度逐渐增大, 烧结致密化开始温度和烧结初期活化能逐渐降低, 添加量为40%时试样从900℃开始大幅度收缩, 烧结初期表观活化能下降到291.43 kJ/mol。NiFe 2 O 4 陶瓷惰性阳极的体积密度、抗弯强度和断裂韧性随NiFe 2 O 4 纳米粉添加量的增加均呈现先上升后下降的变化趋势, 气孔率和静态腐蚀率呈先下降后上升的趋势, 均在30%达到极值, 断裂韧性达到最大值3.12 MPa?m 1/2 , 是未添加纳米粉试样的2.14倍。NiFe 2 O 4 纳米粉的添加能够明显增强晶界结合强度, 降低陶瓷材料气孔率, 从而提高断裂表面能实现增韧作用。