气氛对氧化铬材料烧结的影响

Effect of atmosphere on sintering behavior of chromium oxide materials

以Cr2O3微粉为主要原料,TiO2微粉为烧结助剂,聚乙烯醇为结合剂,经制浆、喷雾造粒、机压和等静压二次成型后,分别在空气(氧分压为2.1×104Pa)、工业氮气(氧分压为1×103Pa)、纯氮气(氧分压为10 Pa)和高纯氮气(氧分压为0.1 Pa)中以及埋炭(氧分压为2.3×10-12Pa)条件下,于1 500℃保温3 h烧成制备了氧化铬试样,研究了烧成气氛的氧分压对氧化铬材料烧结的影响。结果表明:氧分压在0.1～2.1×104Pa之间,氧分压对添加有3%(w)烧结助剂TiO2的氧化铬材料烧结影响显著,随着氧分压的降低,试样的体积密度增加,显气孔率下降;但未添加烧结助剂TiO2时,即使在0.1 Pa这一较低氧分压下,氧化铬材料也未能实现致密化烧结;而在埋炭造成的极低氧分压下,无论是否添加烧结助剂TiO2,均能使氧化铬材料烧结致密。

The chromium oxide materials were prepared using Cr2O3 micropowder as main starting material and TiO2 micropowder as sintering aid,polyvinyl alcohol as binder,by a series of processes such as pulping,spraying granulation,machine moulding and cold isostatic pressing,and firing at 1 500 ℃ for 3 h in air（oxygen partial pressure was 2.1×104 Pa）,industrial nitrogen（oxygen partial pressure was 1×103 Pa）,pure nitrogen（oxygen partial pressure was 10 Pa）,high pure nitrogen（oxygen partial pressure was 0.1 Pa）,and carbon embedded atmosphere（oxygen partial pressure was 2.3×10-12 Pa）.Effects of oxygen partial pressures on the sintering behavior of Cr2O3 materials were investigated.The results show that：（1）for 3 wt% TiO2-doped specimens,there is a substantial dependence of sintering on oxygen partial pressure（0.1 Pa-2.1×104 Pa）,and the bulk density increases and apparent porosity decreases with oxygen partial pressure decreasing;（2）even if the oxygen partial pressure is 0.1 Pa,the specimen without TiO2 cannot reach densification sintering;（3）under very low oxygen partial pressure of carbon embedded atmosphere,Cr2O3 materials containing TiO2 or not can attain densification.