Injection Molding of Inconel718 Parts for Aerospace Application Using Novel Binder System Based On Palm Oil Derivatives

Authors: R. Ibrahim, M. Azmirruddin, M. Jabir, N. Johari, M. Muhamad, A. R. A. Talib

Abstract:

Inconel718 has been widely used as a super alloy in aerospace application due to the high strength at elevated temperatures, satisfactory oxidation resistance and heat corrosion resistance. In this study, the Inconel718 has been fabricated using high technology of Metal Injection Molding (MIM) process due to the cost effective technique for producing small, complex and precision parts in high volume compared with conventional method through machining. Through MIM, the binder system is one of the most important criteria in order to successfully fabricate the Inconel718. Even though, the binder system is a temporary, but failure in the selection and removal of the binder system will affect on the final properties of the sintered parts. Therefore, the binder system based on palm oil derivative which is palm stearin has been formulated and developed to replace the conventional binder system. The rheological studies of the mixture between the powder and binders system have been determined properly in order to be successful during injection into injection molding machine. After molding, the binder holds the particles in place. The binder system has to be removed completely through debinding step. During debinding step, solvent debinding and thermal pyrolysis has been used to remove completely of the binder system. The debound part is then sintered to give the required physical and mechanical properties. The results show that the properties of the final sintered parts fulfill the Standard Metal Powder Industries Federation (MPIF) 35 for MIM parts.

Keywords: Binder system, rheological study, metal injection molding, debinding and sintered parts.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1072409

References:

[1] Hu Youhua, Li Yimin, He Hao, Lau Jia and Tang Xiao, "Preparation and Mechanical Properties of Inconel 718 Alloy by Metal Injection Molding, Rare Metal Materials and Engineering, 2010, 39(5):0775- 0780.
[2] G. Appa Rao, M. Srinivas, D. S. Sarma, "Influence of Modified Processing on Structure and Properties of Hot Isostatically Pressed Superalloy Inconel 718", Materials Science and Engineering A 418 (2006) 282-291.
[3] Davies, P.; Dunstan, G.; Hoyward, A. Powder Metallurgy World Congress & Exhibition. Shrewsbury: European Powder Metallurgy Association, 2004: 6.
[4] Bose, A.; Valencia, J.; Spirko, J. Advances in Powder Metallurgy and Particulate Materials, 1997, 18(5): 99.
[5] German R. M., Bose A., Injection Molding of Metals and Ceramics. Metal Powder Industries Federation; 1997.
[6] Merhar J. R., Overview of Metal Injection Molding. Metal Powder Report 1990; 45(5):339-42.
[7] Chung C. I., Rhee B. O.,"Requirements of Binder for Powder Injection Molding. Compending Metal Injection Molding 1987;2(5):269-77.
[8] Norhamidi M., Muhammad H. I., Nor H. M. N., Ahmad K. A. M. I. and Jaafar S., "Improtance of Rheological Behaviour in Metal Injection Moulding for Prediction of Injected Parts", ICAST 2000, pg. 169-174.
[9] Norhamidi M., Iriany, Ahmad K. A. M. I. and Jaafar S., "Rheological Study of Feedstock for Metal Injection Molding Process", ICAST 2000, pg. 97-106.
[10] Wenjea J. T., Ïnfluence of Surfactant on the Behaviors of Injection- Molded Alumina Suspensions", Material Science & Engineering A289 (2000) 116-112 .
[11] Baiyun H., Shuquan L. and Xuanhui Qu,"The Rheology of Metal Injection Molding", Journal of Materials Processing Technology 137 (203) 132-137.
[12] M.Khakbiz, A.sinchi, R.Bagheri, Analysis of the rheological behavior and stability of 316L stainless steel Ti.C powder injection molding, Elsevier Materials Science and Engineering A 407 (2005) 105-113.
[13] Z.Liu, N.H.Loh, S.B.Tor, K.A Khor, Characterization of powder injection molding feedstock, lsevier Materials Characterization 49 (2003) 313- 320.
[14] R.M. German, A.Bose , " Injection molding of metal and ceramics" , MPIF, New Jersey,1997.
[15] C. Muttsuddy, R.G.Ford, ceramics injection molding, Champion Hall, London 1995.
[16] L.V. Dihoru, L.N. Smith, R. Orban, R.M. German, Mater. Manuf. Process. 15 (3) (2000) 419-438.
[17] L.V. Dihoru, L.N. Smith, R.M. German, Powder Metall. 43 (1) (2000) 31-36.
[18] H.A. Barnes, J.F. Hutton, K. Walters, An Introduction to Rheology,Elsevier.
[19] Wei-Wen Yang, Kai-Yun Yang, Min-Hsiung Hon, Effect of PEG molecular weights on rheological behavior of alumina injection molding feedstock, Elsevier Materials Chemistry and Physics 78 (2002) 416-424.