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以纯铪粉为原料,采用真空烧结的方法,制备疏松、多孔且孔隙均匀的铪块,以能满足碘化的要求,防止铪粉在摩擦和碰撞的过程中易燃,不利于碘化装炉和出炉;同时高温烧结还可除去铪中的部分杂质,防止碘化过程发生中毒现象。利用SEM、电感耦合等离子体质谱分析法和EDS能谱分析等测试手段,主要研究了烧结温度对烧结后铪块的孔隙结构和成分变化的影响。实验结果表明:在真空度为6.7×10-3Pa、烧结温度1000℃(保温2 h)的条件下,所得试样的孔隙分布均匀,孔径大小基本一致,为150 nm,孔隙边缘光滑,形状由不规则倾向于圆形,且随温度的升高,粘结面不断扩大,逐渐形成烧结颈,颗粒边缘继续钝化,表面由粗糙变光滑,烧结颈由细变粗,大孔隙收缩,有的烧结颈出现熔化,小孔消失。烧结后的铪块中杂质元素W,Mo,Fe,O等含量不受温度的影响,H的含量随着烧结温度的升高而减少,由真空炉的压强分析知,氢含量的减少主要是由水分的蒸发和试样中的氢化铪高温分解产生氢气所造成的。
Taking pure hafnium powder as raw material and adopting vacuum sintering method to prepare loose and porous hafnium block with uniform pore so as to meet the requirement of iodization and prevent the hafnium powder from being flammable in the process of friction and collision and not conducive to iodination loading furnace and Baked; at the same time high-temperature sintering can remove some impurities in hafnium to prevent iodination poisoning phenomenon. The influence of sintering temperature on the pore structure and composition of sintered hafnium block was studied by SEM, ICP-MS and EDS EDS. The experimental results show that under the conditions of vacuum degree of 6.7 × 10-3 Pa and sintering temperature of 1000 ℃ for 2 h, the pore size distribution of the obtained sample is uniform and the pore size is basically the same with a diameter of 150 nm. The pore edge is smooth and the shape is from The irregularities tend to be round, and as the temperature increases, the bonding surface expands to form a sintering neck gradually. The edge of the particles continues to passivate, the surface becomes smooth and rough, the sintering neck is narrowed and coarsened, the macropores shrink, and some Sintering neck appears melting, the hole disappears. The contents of W, Mo, Fe and O in the sintered hafnium blocks are not affected by the temperature. The content of H decreases with the increase of the sintering temperature. According to the pressure analysis of vacuum furnace, the decrease of hydrogen content is mainly It is caused by the evaporation of moisture and the decomposition of hydrogen fluoride in the sample by hydrogen.