Study on forming of titanium powder

• Main Author: Tan, Sir Seng.
• Other Authors: Loh Ngiap Hiang
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Materials::Metallic materials
• Online Access: http://hdl.handle.net/10356/46068
• Institution: Nanyang Technological University

Due to the relatively high strength, excellent corrosion resistance of titanium against many medium, and bio compatibility, there is wide interest in the usages for titanium. However, the high cost of processing titanium has hindered its farther applications. Net/near-net shaping, including powder metallurgy and powder injection molding, is an effective method to reduce the cost. The object of this study attempts to investigate the forming of titanium powder via conventional powder metallurgy. With commercially pure titanium powder, the formability of the powder was tested by cold compaction with different parameters. Cold pressing without binder shows defects like delamination and crack in the pressed parts with a little high aspect ratio. The binder of PVA will help to eliminate those defects and good green parts could be formed. After debinding of pressed parts and green PIM parts produced in SIMTech, dilatometer study showed all the parts starts to shrink at around 650°C. However, the max shrinkage is different among parts. Some parts have the tailor up phenomenon during cooling stage, likely due to the phase transformation of titanium. After sintering, microstructure examination showed some large pores in the sintered pressed parts and the pressing condition will affect the size and porosity. The pores are smaller, fewer and more homogeneous in the sintered PIM parts. The EDX of some parts detected high amount of iron element in the grain boundaries, leading to second beta phase in the sintered pure titanium. The results of the study showed the forming of titanium powder is plausible. However, the processes need to be refined to improve final properties.