Effects of binder system and processing parameters on formability of porous Ti/HA composite through powder injection molding

Micro powder injection molding has been accepted as a potential forming technology for large-scale production of miniature components in industries. However, mold filling capability is often poor due to the blind hole structure of the die cavity, which restricts the widespread application of this technique. In this paper, ZrO2 micro gears with addendum circle ranging from 900μm to 200μm were studied. Instead of using traditional PW-HDPE-SA binder as in powder injection molding, thermoplastic binder system is optimized here for better replication of micro gear. It is found that the dimensional accuracy and demold after injection molding can be improved by utilizing proper binder system. ZrO2 feedstock with a powder loading of 46vol.% and the binder system consisting of BW, HDPE and SA was successfully injection molded and demolded, which indicates good mold filling capability and sufficient demolding strength. The binder system was successfully removed by debinding process in two steps, solvent debinding followed by thermal debinding. Debound components free of defects were obtained. Keywords: Micro powder injection molding, ZrO2 feedstock, Binder system, Molding filling capability, Demolding strength

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Effects of Binder and Processing Parameters on Processability of Porous Ti/HA Composite through Powder Injection Molding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1133.90 ◽

2016 ◽

Vol 1133 ◽

pp. 90-94

Author(s):

Muhammad Rafi Raza ◽

Abu Bakar Sulong ◽

Norhamidi Muhammad ◽

Majid Niaz Akhtar ◽

Javad Rajabi

Keyword(s):

Injection Molding ◽

Heating Rate ◽

Water Immersion ◽

Research Work ◽

Weight Ratio ◽

Powder Injection Molding ◽

Powder Injection ◽

Mixed Powder ◽

Space Holder ◽

Porous Ti

Powder injection molding (PIM) process is suitable for both metal and ceramic materials to produce parts with high volume and accuracy at low cost. In this research work, 90wt. % of Ti6Al4V was dry mixed with 10wt. % of Hydroxyapatite (HA). The resultant mixture was further mixed with different space holders in weight ratio 8:2. The feedstock was prepared by mixing the final mixed powder with PEG and PW based binder systems. The dumbbell shape parts were produced using DSM Xplore injection molding machine. The molded samples were debound into two stages i.e solvent extraction followed by thermal debinding. The debinding parameters were optimized for different binder with space holders. The major binders’ paraffin wax (PW) extracted in haptane and PEG in water immersion at temperatures of 60 °C and 50 °C for 5 hrs respectively. The thermal de-binding was performed successfully at 500 °C by varying the heating rate from 3 °C/min-5 °C/min with holding time 1hr in argon atmosphere followed by the sintering in vacuum. During molding short shot defects and cracks were observed while during debinding, collection of binder, swelling and holes were noted. These types of defects may be due to space holder, improper binder, heating rate, temperature and dwell time at each processing step. The sintered test specimens were analyzed for porosity and microstructure. The results showed that the PEG based binder system with NaCl space holder is more effective to produce porous Ti/HA composite through PIM. Porous Ti/HA composite showed interconnected pores with average size of 90µm.

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Fabrication of zirconia-toughened alumina parts by powder injection molding process: Optimized processing parameters

Ceramics International ◽

10.1016/j.ceramint.2013.05.134 ◽

2014 ◽

Vol 40 (1) ◽

pp. 273-280 ◽

Cited By ~ 19

Author(s):

Sarizal Md Ani ◽

Andanastuti Muchtar ◽

Norhamidi Muhamad ◽

Jaharah A. Ghani

Keyword(s):

Injection Molding ◽

Processing Parameters ◽

Powder Injection Molding ◽

Powder Injection ◽

Injection Molding Process ◽

Molding Process ◽

Zirconia Toughened Alumina

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Investigation of Deibinding and Sintering of 3Y-ZrO2 Gear Fabricated by Micro Powder Injection Molding

Materials Science Forum ◽

10.4028/www.scientific.net/msf.749.378 ◽

2013 ◽

Vol 749 ◽

pp. 378-386

Author(s):

Lin Liu ◽

Yu Chen ◽

Xin Lei Ni ◽

Hai Qin Yin ◽

Xuan Hui Qu

Keyword(s):

Injection Molding ◽

Petroleum Ether ◽

Rapid Development ◽

Powder Injection Molding ◽

Powder Injection ◽

Binder System ◽

Anhydrous Alcohol ◽

Ether Mixture ◽

Thermal Debinding ◽

Influence Of Solvent

The rapid development of micro-system and its related products has caused an upsurge of micro components, and the micro powder injection molding is potential for its mass production. In this work, the solvent debinding mechanism of the in-house feedstock was studied. The influence of solvent debinding, thermal debinding and sintering on the micro gears was investigated. The weight loss of 3Y-ZrO2 micro gears ranging from 200 to 900μm were compared by using six types of solvent including ether mixture withanhydrous alcohol, petroleum ether, chloroform and are hexane etc. The thermal debinding scheme was determined based on the DSC and TGA results of the binder system. The effect of the heating rate on the micro gears was investigated. The experimental results showed that the petroleum ether mixture with anhydrous alcohol yielded the best debinding effect for the micro gears, which was controlled by diffusion and dissolution. Using the established debinding and sintering schedule, the defect free micro gears were successfully fabricated.

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