Sains Malaysiana 42(9)(2013): 1311–1317

Pencirian Keseragaman Campuran dan Sifat Reologi Serbuk Alumina-Zirkonia

untuk Pengacuan Suntikan Seramik

(Characterisation of Mixing Uniformity and Rheological Properties of Alumina-Zirconia

Powder for Ceramic Injection Moulding)

Sarizal Md Ani, Andanastuti Muchtar*, Norhamidi Muhamad & Jaharah A. Ghani

Jabatan Kejuruteraan Mekanik dan Bahan, Fakulti Kejuruteraan dan Alam Bina, Universiti Kebangsaan Malaysia, 43600 UKM bangi, Selangor D.E., Malaysia

Diserahkan: 13 Ogos 2012/Diterima: 2 Februari 2013

ABSTRAK

Pencirian keseragaman campuran dan sifat reologi bahan suapan merupakan elemen penting dalam melaksanakan proses pengacuan suntikan seramik. Kesesuaian bahan suapan yang dibangunkan dapat mengurangkan masalah yang timbul ketika proses pengacuan suntikan, penyahikatan dan pensinteran. Justeru itu, kajian ini dijalankan untuk mengenal pasti pembebanan serbuk yang optimum berdasarkan kepada keseragaman campuran dan sifat reologi bahan. Pencirian keseragaman campuran ditentukan berdasarkan kepada nilai tork yang rendah dan berkeadaan mantap. Kajian reologi pula dilakukan dengan menggunakan mesin reometer rerambut. Ujian dijalankan pada julat suhu 150 dan 170^oC dengan beban kenaan antara 20 dan 90 kgf. Bahan suapan yang digunakan terdiri daripada kombinasi serbuk seramik alumina-zirkonia bersama bahan pengikat polietilena berketumpatan tinggi, lilin parafin dan asid stearik. Hasil kajian menunjukkan bahan suapan bersifat pseudoplastik dengan pencampuran bahan yang seragam dalam tempoh kurang daripada 30 min. Hasil keputusan juga mendapati pada pembebanan serbuk 57% isi padu adalah yang paling optimum untuk proses pengacuan suntikan seramik berdasarkan kepada nilai kelikatan, indeks hukum kuasa dan tenaga pengaktifan aliran yang rendah.

Kata kunci: Alumina-zirkonia; keseragaman campuran; pengacuan suntikan seramik; sifat reologi

ABSTRACT

The mixing uniformity and rheological properties of feedstock are crucial to the success of the ceramic injection moulding process. The suitability of developed feedstock may reduce the problems that arise during injection moulding, debinding and sintering. Therefore, this study is focused on identifying the optimum powder loading based on the mixing uniformity and rheological properties of materials. Uniformity characterisation of the mixture is determined based on the low torque value and at the steady state. Rheological studies were carried out using a capillary rheometer machine. The test was carried out at temperatures between 150 and 170^oC with the applied loads between 20 and 90 kgf. The feedstock used was a combination of alumina–zirconia powder with a binder that consisted of high density polyethylene, paraffin wax and stearic acid. The feedstocks are found to be pseudoplastic with uniform mixing achieved in less than 30 min. The powder loading of 57% by volume is found to be optimum for the ceramic injection moulding process based on the low values of viscosity, power law index and flow activation energy.

Keywords: Alumina-zirconia; ceramic injection moulding; mixing uniformity; rheological behavior

RUJUKAN

Azhar, A.Z.A., Ratnam, M.M. & Ahmad, Z.A. 2009. Effect of Al2O3/YSZ microstructures on wear and mechanical properties of cutting inserts. Journal of Alloys and Compounds 478: 608-614.

German, R.M. 1990. Powder Injection Molding. New Jersey: Metal Powder Industries Federation.

German, R.M. & Bose, A. 1997. Injection Molding for Metal and Ceramic. New Jersey: Metal Powder Industries Federation.

Ibrahim, M.H.I., Muhamad, N. & Sulong, A.B. 2009. Rheological investigation of water atomised stainless steel powder for micro metal injection molding. International Journal of Mechanical and Materials Engineering 4(1): 1-8.

Iriany. 2002. Kajian sifat reologi bahan suapan yang mengandungi stearin sawit untuk proses pengacuan suntikan logam. Tesis Ph.D., Universiti Kebangsaan Malaysia (tidak diterbitkan).

Krauss, V.A., Pires, E.N., Klein, A.N. & Fredel, M.C. 2005. Rheological properties of alumina injection feedstocks. Materials Research 8(2): 187-189.

Li, Y., Li, L. & Khalil, K.A. 2007. Effect of powder loading on metal injection molding. Journal of Materials Processing Technology 183: 432-439.

Liu, D.M. & Tseng, W.J. 2000. Rheology of injection-molded zirconia-wax mixtures. Journal of Materials Science 35: 1009-1016.

Liu, L., Loh, N.H., Tay, B.Y., Tor, S.B., Murakoshi, Y. & Maeda, R. 2005. Mixing and characterisation of 316L stainless steel feedstock for micro powder injection molding. Materials Characterization 54: 230-238.

Liu, W., Xie, Z., Bo, T. & Yang, X. 2011. Injection molding of surface modified powders with high solid loadings: A case for fabrication of translucent alumina ceramics. Journal of the European Ceramic Society 31: 1611-1617.

Liu, Z.Y., Loh, N.H., Tor, S.B. & Khor, K.A. 2003. Characterization of powder injection molding feedstock. Materials Characterization 49: 313-320.

Murtadhahadi. 2007. Parameter penyuntikan bagi proses pengacuan suntikan logam menggunakan bahan suapan daripada SS 316L, PEG, PMMA dan asid stearik. Tesis Sarjana Sains, Universiti Kebangsaan Malaysia (tidak diterbitkan).

Mutsuddy, B.C. & Ford, R.G. 1995. Ceramic Injection Molding. London: Chapman and Hall.

Roh, J.Y., Kwon, J., Lee, C.S. & Choi, J.S. 2011. Novel fabrication of pressure-less sintering of translucent powder injection molded (PIM) alumina blocks. Ceramics International 37: 321-326.

Sotomayor, M.E., Varez, A. & Levenfeld, B. 2010. Influence of powder particle size distribution on rheological properties of 316 L powder injection moulding feedstocks. Powder Technology 200: 30-36.

Supati, R., Loh, N.H., Khor, K.A. & Tor, S.B. 2000. Mixing and characterization of feedstock for powder injection molding. Materials Letters 46: 109-114.

Trunec, M. & Hrazdera, J. 2005. Effect of ceramic nanopowders on rheology of thermoplastic suspensions. Ceramics International 31: 845-849.

Vielma, P.T., Cervera, A., Levenfeld, B. & Varez, A. 2008. Production of alumina parts by powder injection molding with a binder system based on high density polyethylene. Journal of the European Ceramic Society 28: 763-771.

* Pengarang untuk surat-menyurat; email: muchtar@eng.ukm.my