Activated Sintering of ThO2 and ThO2-Y2O3 with NiO |
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Authors: | GEORGE P HALBFINGER MORRIS KOLODNEY |
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Affiliation: | Department of Chemical Engineering, The City College of New York, New York, New York 10031 |
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Abstract: | The effect of additives on the sintering of ThO2 and ThO2-Y2O3 compacts and loose powders was studied by isothermal shrinkage measurements and by scanning electron micrography. Small amounts of the oxides of Ni, Zn, Co, and Cu reduced the sintering temperature. The behavior of NiO at a concentration of 0.8 wt% (2.5 mol%) was studied in detail and found to yield high-density bodies at temperatures below 1500°C. The presence of Y2O3 as a separate phase increases the rate of sintering of ThO2, but smaller amounts of NiO are much more potent. The major portion of the densification occurs very rapidly and is followed by a much slower sintering process typical of volume diffusion. The fast early shrinkage may be caused by the capillary forces of a liquid, but since no evidence of melting was found, a solid-state mechanism may be responsible. |
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