科研之友
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摘要
Titanium is biocompatible, has high specific strength and high corrosion resistance compared to other materials. Producing near-net shape parts by metal injection moulding (MIM) minimizes the need for secondary operations required for other metal-working processes such as casting, forging, and investment casting. Removing binder (debinding) from the MIM moulded part without disturbing the powder particles is a crucial stage. Titanium-MIM parts were manufactured from hydride-dehydride (HDH) titanium alloy powder Ti-6Al-4V (d(10), d(50) and d(90) of 12.8, 51.8 and 117.7 pm respectively) and various polyethylene glycol-polyvinyl butyral (PEG-PVB) based binder systems. The effect of binder composition, powder loading (55 and 60 vol%), debinding time and temperature on the debinding rate for removing PEG with water, and porosity and microstructure of moulded parts was investigated. Solvent debinding had dissolution-controlled and diffusion-controlled stages; increasing debinding temperature shortened the dissolution-controlled stage. The amount of PEG removed increased with initial PEG content, temperature and debinding time. Porosity of solvent debound Ti-MIM parts increased with debinding time and PEG content. Good quality parts were produced using larger particles than normally recommended for MIM. The best debinding characteristics and uniform particle packing were obtained by making parts with 60 vol% Ti-6Al-4V and 80:15:5 vol% PEG:PVB:SA binder then solvent debinding for 4 hat 35 degrees C or 3 hat 45 degrees C. These conditions are very cost-effective compared to conditions published (2001-2016) for other bio-compatible metals-based MIM systems.
- 出版日期2018-2-15
