Sains Malaysiana 47(7)(2018): 1591–1597

http://dx.doi.org/10.17576/jsm-2018-4707-30

Improvement of Colloidal Stability in Colloidal Processing for Highly Translucent, Nanosized Zirconia

(Peningkatan Kestabilan Koloid dalam Pemprosesan Koloid bagi Zirkonia Berkelutcahayaan Tinggi, Bersaiz Nano)

CHUIN HAO CHIN¹, ANDANASTUTI MUCHTAR¹*, CHE HUSNA AZHARI¹, MASFUEH RAZALI² & MOHAMED ABORAS¹

¹Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

²Periodontology Department, Faculty of Dentistry, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Federal Territory, Malaysia

Received: 14 December 2017/Accepted: 23 February 2018

ABSTRACT

This study aimed to improve the colloidal stability of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) suspension through colloidal processing to obtain highly translucent Y-TZP. Agglomeration is often the main complication in the processing of nanosized Y-TZP as it deteriorates mechanical and optical properties. Thus, colloidal processing is necessary to mitigate the agglomeration in Y-TZP. The colloidal stability of Y-TZP suspension plays a key role for the success of colloidal processing. In this study, colloidal processing was conducted at several stages, namely, dispersant addition, pH adjustment and sedimentation. Changes in particle size and zeta potential at various stages were recorded. The suspensions were then slip-casted to form green bodies. Green bodies were sintered and characterized for density and translucency. The results showed that dispersant addition followed by pH adjustment effectively dispersed soft agglomerates by introducing electrosteric stabilization, whereas sedimentation successfully segregated hard agglomerates and contributed excellent colloidal stability. With high colloidal stability, the translucency of Y-TZP was improved by approximately 30%. This study demonstrated different colloidal processing stages and proved that high colloidal stability and fine particle size are vital to produce highly translucent Y-TZP.

Keywords: Colloidal stability; slip casting; translucency; zirconia

ABSTRAK

Kajian ini bertujuan meningkatkan kestabilan koloid polihablur zirkonia tetragonal separa stabil oleh yttria (Y-TZP) melalui pemprosesan berkoloid untuk menghasilkan Y-TZP berkelutcahayaan tinggi. Pengaglomeratan merupakan satu masalah dalam pemprosesan Y-TZP bersaiz nano kerana pengaglomeratan sentiasa menjejaskan ciri mekanik dan optik. Justeru, pemprosesan berkoloid diperlukan untuk mengurangkan pengaglomeratan dalam Y-TZP. Kestabilan koloid ampaian Y-TZP telah memainkan peranan yang penting dalam menjayakan pemprosesan berkoloid. Dalam kajian ini, pemprosesan berkoloid telah dijalankan melalui beberapa peringkat iaitu penambahan bahan penyerak, pelarasan pH dan pemendapan. Perubahan dalam saiz zarah dan keupayaan zeta pada tahap yang berbeza telah dicatat. Ampaian Y-TZP telah diguna untuk menghasilkan jasad anum melalui kaedah tuangan slip. Jasad anum telah disinter dan seterusnya ketumpatan dan kelutcahayaan spesimen diuji. Keputusan uji kaji menunjukkan aglomerat lembut telah berjaya dipisah melalui penstabilan elektrosterik dengan penambahan bahan penyerak dan pelarasan pH. Proses pemendapan yang seterusnya berjaya memisahkan aglomerat keras dan meningkatkan kestabilan koloid. Dengan kestabilan koloid yang baik, kelutcahayaan Y-TZP telah ditingkatkan sebanyak 30%. Kajian ini telah menunjukkan peringkat pemprosesan berkoloid yang berbeza dan membuktikan kestabilan koloid yang tinggi dan saiz zarah yang kecil adalah penting untuk penghasilan Y-TZP berkelutcahayaan tinggi.

Kata kunci: Kelutcahayaan; kestabilan koloid; tuangan slip; zirconia

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