Document Type : Original Article
Authors
1
Demonstrator, Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University. Cairo, Egypt
2
Associate Professor, Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University. Cairo, Egypt
3
Professor, Chemistry & Technology of Ceramic, Coating, Surface Treatment and Corrosion Control Department, Central Metallurgical Research and Development Institute (CMRDI). Cairo, Egypt
4
Professor, Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University. Cairo, Egypt
Abstract
This study aimed at developing a controlled method for the precipitation of nano-alumina coating on surface treated yttria partially stabilized tetragonal zirconia (Y-TZP). Thirty zirconia discs were prepared and divided into 2 main groups: Polished zirconia (I) and sulfuric acid treated zirconia surface (II). These were further subdivided into 3 subgroups (A, B, C) respectively: Control uncoated, surface coating with nano-structured alumina using aluminum nitride powder (AlN) as a reference method, and aluminum sulfate powder Al2(SO4)3 as an alternative aluminum ion source. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for specimen’s characterization. The XRD analysis revealed that IB, IIB exhibited wide peaks of nano-boehmite with peaks of unreacted AlN. After heat treatment, the lamellae transformed to nano-alumina. While IC, IIC groups revealed peaks of nano-boehmite only, transformed to nano-alumina by heat treatment. SEM of IB, IIB revealed bundles with nano-sized interlocked lamellae exhibiting large surface area. Groups IC, IIC had a leafy-like structure, randomly positioned nano-alumina crystals. Better retentive surface features were confirmed for IIB, IIC. It has been concluded that alumina precursors, pH, temperature and stirring time are sensitive parameters in the co-precipitation of nano-alumina on zirconia. Aluminum nitride precursor provides superior zirconia nano-alumina coating quality than aluminum sulfate. Sulfuric acid surface pre-treatment of zirconia improved the retentive quality of the nano-alumina coating.
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