Synthesis of Yttria-stabilized zirconia from local sands / Nur Fatinhanani Fatimah Norsham

Amang zircon sand is abundant in Malaysia due to the large tin mining industry and resources in Malaysia especially around Perak and Selangor. However, no comprehensive study has been dedicated to Amang zircon sand. This study transformed the by-product in tin mining industry into something valuable like zirconia. The study aimed to evaluate the influence of temperature on zirconia powder synthesised from Amang zircon sand and the effect of yttrium oxide concentration as the doping agent in stabilizing Amang zirconia powder. The raw Amang zircon sand obtained from Kilang Amang Onn Sdn. Bhd. (Onn Mineral Company) at Kampar, Perak was analysed with Malvern Panalytical Epsilon and the analysis showed major zirconium composition of 60.17 wt.% with 5.22 wt.% silicon and impurities. Alkali fusion of Amang zircon sand with 6M sodium hydroxide (NaOH) was employed in this study followed with thermal treatment at 670 °C for 2 hours. Sodium zirconate and sodium silicate obtained from the fusion was subjected to leaching with deionized water and 8M hydrochloric acid (HCl). Sodium silicate and unreacted NaOH and zircon were leached out, leaving zirconium oxychloride (ZrOCl2) for further hydrolysis process. Zirconium oxychloride was neutralized and hydrolysed by ammonium hydroxide at pH of 10-10.5 to produce zirconium hydroxide (Zr(OH)4). Zirconium hydroxide powder was then calcined at varied temperature of 400-800 °C for 4 hours to obtain Amang zirconia. The effect of temperature on Amang zirconia was observed in term of increased zirconium composition at 81.28 wt.% coupled with low impurities when calcined at high temperature of 800 °C. Agglomerated monoclinic zirconia powder with a small fraction of tetragonal and cubic phase, particle size of 150.2 μm and specific surface area of 0.314 m2/g was observed by Rigaku Ultima IV diffractometer, Brunauer-EmmettTeller, Malvern Panalytical Mastersizer and Hitachi SU3500 microscopy. Subsequent stabilization of zirconia with yttrium oxide as doping agent at concentration of 3-5 wt.% revealed an enhanced crystallinity of monoclinic yttria stabilized zirconia powder with smaller particle size of 88.97 μm. The composition of yttria zirconium oxide increased with the addition of yttrium oxide. 71.01 wt.% of zirconium composition when stabilized at 5 wt.% demonstrated the material’s potential for locally synthesised yttriastabilized zirconia. In conclusion, this comprehensive study highlighted the potential of zirconium oxychloride (ZrOCl2) produced from Amang zircon sand as precursor to synthesized yttria stabilized zirconia powder at designated parameters. The finding not only highlighting the potential of locally available Amang zircon sand but also opening the probability to utilized Amang zirconium oxychloride and zirconia for tailored application in various industries such as textile, oil and also nuclear.