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
Diserahkan: 14 Disember
2017/Diterima: 23 Februari 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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*Pengarang untuk surat-menyurat; email: muchtar@ukm.edu.my