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

Received: 13 August 2012/Accepted: 2 February 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

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* Corresponding author; email: muchtar@eng.ukm.my