Mekanisme Penyerakan Zarah dalam Pemprosesan Berkoloid Oksida Seramik (Al₂O₃–ZrO₂–MgO) Menggunakan DAXAD 19^TM

Abstract

Dalam kajian ini, kesan agen penyerak komersil Daxad 19TM terhadap sifat reologi dan pemadatan ampaian seramik alumina–zirkonia–magnesia telah dikenalpasti. Komposisi serbuk yang digunakan adalah berasaskan kepada 85% isipadu alumina (ketulenan 99.99%) dan 15% isipadu zirkonia (ketulenan 99.5%). Penambahan serbuk magnesia (ketulenan 99.99%) pula adalah pada kuantiti yang kecil iaitu 0.25% berat daripada jumlah berat alumina dan zirkonia. Untuk mengelakkan masalah pengaglomeratan zarah, teknik pemprosesan berkoloid dipilih dalam pembikinan sampel. Untuk ini, Daxad 19TM dicampurkan ke dalam ampaian dengan tujuan untuk menyerakkan zarah. Kuantiti penyerak Daxad 19TM yang digunakan ialah dalam julat 0 hingga 0.60% berat. Kajian reologi menggunakan alat meter kelikatan dilakukan bagi mengenalpasti kuantiti Daxad 19TM yang optimum bagi penyerakan zarah. Setelah itu, sampel anum dihasilkan melalui proses penuangan buburan. Sampel diprasinter pada suhu 800°C selama 45 minit sebelum disinter pada suhu 1600°C selama 2 jam. Kajian ini secara keseluruhannya telah mendapati julat penggunaan optimum penyerak Daxad 19TM di dalam ampaian seramik yang dihasilkan adalah di antara 0.4875% hingga 0.525% berat daripada berat keseluruhan serbuk seramik yang digunakan. Kertas ini juga membincangkan mekanisme penyerakan zarah dalam ampaian alumina–zirkonia–magnesia melalui penggunaan Daxad 19TM. Kata kunci: Penyerakan zarah, reologi, ketumpatan, alumina, zirkonia The effects of a commercially available dispersant, Daxad 19TM, on the rheology and densification characteristics of alumina–zirconia–magnesia suspensions have been investigated. The compositions of powders used are based on 85% volume of alumina (99.99% purity) and 15% volume of zirconia (99.95% purity). The addition of a small amount of magnesia is based on 0.25% weight of the combined weight of both alumina and zirconia powders. In an effort to avoid the agglomeration of particles, colloidal processing technique is used to produce samples. For this, Daxad 19TM is added to the suspensions to disperse the oxide particles. The Daxad 19TM addition is within the range of 0–0.60% weight. Rheological investigation is carried out using a rotational viscometer to determine the optimum quantity of dispersant (Daxad 19TM) that can best disperse the powders. Green samples are then prepared using the slip casting process. The sample are pre–sintered at a constant temperature of 800°C for 45 minutes before being sintered at 1600°C with a holding time of 2 hours. The optimum concentration of Daxad 19TM for a successful dispersion of powders is found to be between 0.4875–0.525% weight of the combined weight of alumina and zirconia powders. This paper also discusses the mechanisms for particle dispersion in alumina–zirconia–magnesia suspensions. Key words: Particle dispersion, rheology, density, alumina, zirconia

Effect of Dispersant Agent Amount in Colloidal Processing of Zirconia Dental Ceramic

“…The viscosity of the suspension with 0.5 wt% PEI slightly increased in the beginning, but its viscosity remained low as the shear rate was increased. Based on previous studies, the best dispersing properties can be obtained when the slurry viscosity is minimum [9,10]. This result could be attributed to a decreased particle agglomeration, which enables the suspension to flow easily.…”