In this study, Ti powders were fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method.The Ti powders were prepared from the spark plasma sintering (SPS) and their microstructure was investigated.Hydrogenation reactions of Ti scrap occurred at near 450oC with a sudden increase in the reaction temperature and thedecreasing pressure of hydrogen gas during the hydrogenation process in the furnace. The dehydrogenation process was alsocarried out at 750oC for 2 hrs in a vacuum of 10-4torr. After the HDH process, deoxidation treatment was carried out withthe Ca (purity: 99.5%) at 700oC for 2 hrs in the vacuum system. It was found that the oxidation content of Ti powder thatwas deoxidized with Ca showed noticeably lower values, compared to the content obtained by the HDH process. In orderto fabricate the Ti compacts, Ti powder was sintered under an applied uniaxial punch pressure of 40 MPa in the range of900-1200oC for 5 min under a vacuum of 10-4torr. The relative density of the compact was 99.5% at 1100oC and the tensilestrength decreased with increasing sintering temperature. After sintering, all of the Ti compacts showed brittle fracturebehavior, which occurred in an elastic range with short plastic yielding up to a peak stress. Ti improved the corrosionresistance of the Ti compacts, and the Pd powders were mixed with the HDH Ti powders.

In this study, Ti powder was fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH)method. Hydrogenation reactions of Ti scrap occurred at near 450oC with a sudden increase in the reactiontemperature and the decreasing pressure of hydrogen gas during the hydrogenation process in the furnace. Thedehydrogenation process was also carried out at 750oC for 2hrs in a vacuum of 10-4torr. After the HDHprocess, a deoxidation treatment was carried out with the Ca(purity: 99.5) at 700oC for 2hrs in the vacuumsystem. It was found that the oxidation content of Ti powder that was deoxidized with Ca showed noticeablylower values, compared to the content obtained by HDH process. In order to fabricate Ti compacts, Ti powderwas sintered at 1100~1400oC for 2hrs under a vacuum of 10-4torr. The relative density of compact was 94.9%at 1300oC. After sintering, all of the Ti compacts showed brittle fracture behavior, which occurred in an elasticrange with short plastic yielding up to a peak stress.

In this study, Ti powder was fabricated from Ti scrap by a hydrogenation-dehydrogenation (HDH)method. The Ti powders were compacted by Spark plasma sintering (SPS) and the microstructure andmechanical properties of the powders were investigated. A hydrogenation reaction of Ti scrap occurred attemperatures near 450oC with a sudden increase in the reaction temperature and a decrease in the pressureof the hydrogen gas as measured in a furnace during the hydrogenation process. In addition, a dehydrogenationprocess was carried out at 750oC for 2hrs in a vacuum of 10-4torr. The Ti powder sizes obtained byhydrogenation-dehydrogenation and mechanical milling processes were in the range of 1~90µm and 1~100µm,respectively. To fabricate Ti compacts, Ti powders were sintered under an applied uniaxial punch pressure of40 MPa at in a range of 900~1200oC for 5 min. The relative density of a SPSed compact was 99.6% at 1100oC,and the tensile strength decreased with an increase in the sintering temperature. However, the hardnessincreased as the sintering temperature increased.