| 摘要 |
Prodn. comprises reacting an aq. soln. of Zr or Hf oxychloride with H2S04 at elevated temp. and subsequently adding hydroxide to produce very pure Zr or Hf sulphates in solid, practically insol. form; sepg. the solid sulphates from the remaining soln. and reacting the prod. with an aq. soln. of ammonium carbonate to form solid carbonates of Zr, or Hf; and sepg. the solid carbonates from the soln. and calcining these at ca. 700 deg.C to give the desired submicron oxide powder. Pref. the reaction of the Zr or Hf sulphates with ammonium carbonate soln. is carried out under vigorous stirring to break down loose agglomerates present in the sulphates. A stabiliser substance amy be added which coprecipitates with the solid carbonates of Zr, and Hf. In an alternative embodiment of the process, the solid sulphates of Zr or Hf are obtd. in the first stage by reacting an aq. soln. of a Zr or Hf slat with H2S04 and adding an alkaline substance to produce the solid practically insol. Zr or Hf sulphates. USE/ADVANTAGE - The process is cheap to carry out and gives high reactivity submicron powdered prods. of high purity which are free from hard agglomerated particles and which are esp. useful for the prodn. of sintered parts which can be made at relatively low sintering temps. and which have high density high mechanical strength and small grain size, useful in the fields of ceramics, electronics, and lasers, or as a precious stones.
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