| Efficacy of Acid Cleaning on the Deoxidation of Titanium Powder Using Calcium |
| Chon-Il Hong, Jae-Won Lim |
| Division of Advanced Materials Engineering and Research Center for Advanced Materials Development, College of Engineering, Chonbuk National University, Jeonju 54896, Republic of Korea |
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Received: 23 October 2017; Accepted: 29 December 2017. Published online: 6 March 2018. |
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| ABSTRACT |
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The optimum acid cleaning conditions for removing CaO formed by the reaction of Ca with Ti powder were investigated in this study. In this experiment, we used Ti powders composed of irregular polygonal Ti particles with average sizes of 125 mm and 250 μm. Ca granules were charged at 50% of the Ti mass into a deoxidation pot with Ti powder, and then the Ti powder with the Ca granules was deoxidized at 800 °C in a vacuum atmosphere of 5.0 × 10-4 torr. It was confirmed that subsequent acid cleaning with 10% HCl for 5 minutes reduced the initial oxygen concentration of the 125 μm-sized Ti powder from 2,000 ppm to 1,105 ppm. In the case of the non-contact deoxidation using Ca vapor at 900 °C, it was established that the non-contact deoxidation effect was higher than the contact type under the optimum acid cleaning condition of 10% HCl for 5 minutes. XRD and SEM analyses detected some Ca particles, and residual CaO on the Ti powder surface was confirmed without acid cleaning, but the acid cleaning process completely removed the residual CaO. It was also found that the deoxidation and acid cleaning decreased the c/a axial ratio of the Ti powder from 1.5885 to 1.5851. |
| Keywords:
titanium, powder, deoxidation, acid cleaning, calcium |
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