气氛条件下氧化铬材料的烧结性能研究

Sintering behavior of chromium oxide materials at varying firing atmospheres

以Cr2O3微粉为原料、TiO2微粉为助烧结剂、聚乙烯醇为结合剂,通过制浆、喷雾造粒、机压和等静压二次成型制备试样,分别在埋炭和不同氧分压气氛条件下,经过1 500℃保温3 h烧成制得Cr2O3材料。分析了氧分压对Cr2O3材料烧结性能的影响。结果表明,在埋炭条件下,无论是否添加TiO2,均能使Cr2O3材料烧结致密。在控制气氛条件下,未添加TiO2的Cr2O3材料在不同氧分压下均未能实现致密化烧结;氧分压对添加TiO2的Cr2O3材料烧结性能影响显著,随着氧分压降低,试样的体积密度增大、显气孔率减小。在添加助烧结剂的条件下,通过调节氧分压,可以控制Cr2O3材料的烧结程度,形成晶粒发育较好、结合程度较高、气孔多呈圆形且孤立分布的致密结构。

The chromium oxide materials were prepared using Cr2O3 micropowder and TiO2 micropowder as the main starting materials, polyvinyl alcohol as the binder, by a series of processes such as pulping, spraying granulation, machine molding and cold isostatic pressing, and sintering at 1 500℃ for 3 h in atmosphere furnace and carbon bed. The effect of oxygen partial pressure on the sintering behavior of Cr2O3 material was investigated. The results show that all specimens which have TiO2 or not attain densification in carbon bed; for 3wt%TiO2-doped specimens there is a substantial dependence of sintering on oxygen partial pressure （0.1 Pa ～2.1×10^4 Pa） ; the bulk density increases very rapidly and apparent porosity decreases quickly with the decreasing oxygen partial pressure; however, even if the oxygen partial pressure decreases to 0.1 Pa, there is little densification for specimens not containing TiO2. With the aid of sintering agent, the microstructure of the sintered Cr2O3 specimen could be controlled by adjusting oxygen partial pressure, forming densed structure with well-devel- oped and tightly-bonded crystals, and isolatedly-distributed rounded pores.