材料期刊网

以氢氧化钾、氢氧化钠和氢氧化锂为分解剂对氧化铪靶材废料进行了碱分解的对比实验.结果表明:反应温度在500 ～800℃范围内,分解剂与氧化铪摩尔比3∶1,反应时间2h,氧化铪粒度38 ～ 45μm时,选择KOH为碱分解剂,氧化铪的分解率明显高于选用其他两种分解剂的分解率,因此选择氢氧化钾为分解剂进行氧化铪靶材废料的碱分解实验.实验研究了反应温度、配比、原料粒度和反应时间等因素对氧化铪分解率的影响.结果表明:提高反应温度、物料配比、反应时间和减小原料粒径均能提高氧化铪的分解率,在温度为800℃,氢氧化钾与氧化铪的摩尔比2.7∶1.0,原料粒度45～53 μm,反应时间2h的实验条件下,氧化铪的分解率可达到96％以上.研究配比对产物影响表明:当KOH/HfO2摩尔比为3∶1,高于理论值(2∶1)时,发生反应:HfO2+2KOH=K2HfO3;KOH/HfO2摩尔比为1∶1时,在反应的初始阶段,氢氧化钾与氧化铪反应生成K2HfO3,K2HfO3包裹在颗粒表面与氧化铪继续发生反应:K2HfO3+ HfO2=K2Hf2O5,生成K2Hf2O5.

The contrast experiment of alkali decomposition for HfO2 scrap was performed with KOH,NaOH and LiOH as decomposition agent under the same conditions.The results showed that when selecting KOH as decomposition agent,the decomposition rate of hafnium oxide was significantly higher than the other two kinds of decomposition agent with molar ratio of alkali to hafnia of 3∶ 1,particle size of 38 ～45 μm,reaction temperature of 500 ～800 ℃ for 2 h.Consequently,potassium hydroxide was selected as the decomposition agent.The effects of reaction temperature,mole ratio of alkali to hafnium oxide,particle size and alkali fusion time on the decomposition of hafnium oxide were primarily investigated.The investigation showed that decomposition rate of hafnia increased with the reaction temperature,mole ratio of alkali to hafnium oxide,alkali fusion time increasing and the particle size decreasing,the decomposition rate was over 96％ when KOH/HfO2 molar ratio was 2.7∶ 1.0,particle size of hafnia was 45 ～ 53 μm at 800 ℃ for 2 h.The study of effects of molar ratio (KOH/HfO2) on decomposition rate showed that when KOH/HfO2 molar ratio was 3∶ 1,higher than the theoretical value (2∶1),HfO2 + 2KOH =K2HfO3 occurred;when the KOH/HfO2 molar ratio was 1∶ 1,in the initial stage of reaction,the reaction of potassium hydroxide and hafnia generated K2HfO3,which was wrapped in particle surface,and then reacted with hafnia:K2Hf2O5 ∶ K2HfO3 + HfO2 =K2Hf2O5.