Hyun-Kuk Park

Fabrication and Mechanical Properties of ultra fine WC-6wt.%Co by Spark Plasma Sintering Process

Using the spark plasma sintering process (SPS process), the WC-6wt.%Co hard materials were densified using an ultra fine WC-Co powder. The WC-Co was almost completely dense with a relative density of up to 100% after the simultaneous application of a pressure of 60 MPa and the DC pulse current for 3 min without any significant change in the grain size. The average grain size of WC that was produced through this experiment was about 0.2~0.8 μm. The hardness and fracture toughness were about 1816 kg/mm and 15.1 MPa·m, respectively, for 60 MPa at 1200°C. (Received September 30, 2010)

Property Evaluation of Ti Powder and Its Sintered Compacts Prepared by Ti Scrap

Abstract In this study, Ti powders were fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method.The Ti powders were prepared from the spark plasm a sintering (SPS) and their m icrostructure was investigated.Hydrogenation reactions of Ti scrap occurred at near 450 o C 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 750 o C for 2 hrs in a vacuum of 10 -4 torr. After the HDH process, deoxidation treatment was carried out withthe Ca (purity: 99.5%) at 700 o C 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 of900-1200 o C for 5 min under a vacuum of 10 -4 torr. The relative density of the compact was 99.5% at 1100 C 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.Key words Ti, Ti alloys, HDH process , spark plasma sintering , potentiodynamic polarization.

Fabrication and Property Evaluation of Cu-Mn Compacts for Sputtering Target Application by a Pulsed Current Activated Sintering Method

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are and , respectively. The heating directly progresses up to with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to .