Study on the Production of extra-low-oxygen titanium by Calcium -halide flux method

在钙和它的氧化物共存的情况下，钛中的平衡氧含量在1273K^&lt；2)&gt；从热力学角度考察了获得较低氧气水平的先进方法。卤化钙熔剂可以有效地降低副产物CaO的活性，因此实验上采用了Ca-CaCl2和Ca-BaCl2熔剂对钛进行脱氧。在1273K下，用CaCl2熔剂和钙蒸气对含数百质量ppm的钛丝和小块钛进行了脱氧，脱氧质量低至几十质量ppm。讨论了影响钛进一步提纯效率的氧源，认为其中之一是熔剂中的氧污染。采用电化学技术对高纯钛进行了脱氧处理，并对得到的近无氧钛进行了表征。高纯钛阴极和碳阳极在1223K左右浸泡在熔盐(如CaCl2)中，电极之间施加外部直流电压。将含110质量PPMO的高纯钛阴极丝脱氧至20ppm以下。用痕量元素分析(如辉光放电质谱仪)、显微维氏硬度测量和电阻率测量对脱氧钛样品进行了表征。电化学脱氧制备的高纯钛具有高的残余电阻率比(Rho&lt；298&gt；/Rho&lt；4.2&gt；=155)和较低的显微维氏硬度值(64kgf/mm^2)。还研究了用BaCl2和MgCl2等熔盐脱氧的可行性，并用这些熔盐将含氧量约为1000ppm的钛脱氧到100-300ppm级。

Under co-existence of calcium and its oxide, the equiliblium oxygen content in titanium is 500 mass ppmO at 1273K^<1)2)>. The advanced methods were examined to attain the lower oxygen level from the thermodynamic viewpoints. Calcium-halide fluxes may decrease the activity of by-product CaO so efficiently that Ca-CaCl_2 and Ca-BaCl_2 fluxes were experimentally applied for the deoxidation of titanium.Titanium wires and small pieces containing a few hundreds mass ppm were deoxidized as low as a few tens mass ppm by use of CaCl_2 flux and calcium vapor at 1273K. The oxygen sources to make worse the efficiency of the further purification of titanium were discussed and one of them was suggested to be the oxygen contamination in the flux.Deoxidation of high purity titanium using an electrochemical technique and characterization of the obtained nearly oxygen-free titanium were carried out. High purity titanium cathode and carbon anode were immersed in molten salt (e.g. CaCl_2) at around 1223 K, and external DC voltages were applied between the electrodes. High purity titanium cathode wires containing 110 mass ppmO were deoxidized to less than 20 ppm. Trace element analysis(e.g. glow discharge mass spectrometry), micro Vickers hardness measurements, and electrical resistivity measurements were carried out to characterize the deoxidized titanium samples. The electrochemical deoxidation produced high purity titanium with a high residual resistivity ratio (rho_<298>/rho_<4.2>=155) and a low micro Vickers hardness value (64kgf/mm^2). Feasibility of deoxidation by using various molten salts such as BaCl_2 and MgCl_2 was also examined, and titanium containing about a thousand mass ppm oxygen were deoxidized to 100 - 300 ppm level by using these salts.