Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954
Microhardness of Hydroxyapatite Doped ZrO2 using Sol-Gel Method22 S. Helen1, A. Ruban Kumar1, a 1– Centre for Crystal Growth, VIT University, Vellore, India a – arubankumar@vit.ac.in DOI 10.2412/mmse.48.98.680 provided by Seo4U.link
Keywords: hydroxyapatite, zirconium oxide, sol-gel method, micro-hardness.
ABSTRACT. Calcium Phosphate based bio-ceramics in the form of hydroxyapatite (HA) with high biocompatibility in hard tissues. In this work HA mixed with ZrO2 using Sol-gel method. Calcium nitrate with Di-ammonium hydrogen phosphate used for the formation of HA, which exhibited less mechanical property. To overcome these problems ZrO2 were used to increase its mechanical strength.XRD and FTIR confirmed the phases and functional groups and its hardness was analysed and confirmed it is a soft material used in various medical applications especially in orthopaedics field.
Introduction. Hydroxyapatite is an inorganic material with minerals present in bone and teeth which have low mechanical property, which does not support for load bearing applications. To sustain these problems, HA incorporates with different composites to increase mechanical strength in the field of implants. The combination of hydroxyapatite with composites improves hardness and fracture toughness .YSZ/HA used to improve wear resistance, strength of HA using co-precipitate method [1]. For load-bearing applications various metals, as alloys were used but using of metals has some drawbacks such as corrosion, negative tissue reactions, the slack of implants and stress due to high stiffness, which used in various medical applications. To prevent the decomposition of HA doped ZrO2 must less than 10% unless specific sintering temperature should apply.ZrO2 has an eminent potential to used in bone implantations which are tougher than Al2O3.And the stable phase of HA produced with some OH- bond. However, while sintering the H2O vapour and decay at 1300°C, which produces secondary phases. ZrO2 has tetragonal or cubic in structure at room temperature.ZrO2 has high mechanical strength and low toxicity for living organisms. The HA synthesized using ZrO2 which can use in various applications in both dentistries and in orthopedics which has the mechanical strength greater than the cortical bone [2].Zirconium oxide is known as ceramic which has a high thermal expansion with high resistance to crack propagation. HA improves bending strength and coatings for medical applications by adding the small amount of ZrO2.The hardness and flexural strength for HA were 5.4GPa and 94MPa; ZrO2 has 14.2GPa and 929MPa [3]. As catalytic ZrO2 has the potential application due to less toxicity, less volatile and more stable at high temperature and eco-friend with environmental.ZrO2 and Al2O3 are bioinert materials with high fracture strength and high toughness. Ceramics such as ZrOCl2 and AlCl3 using a precipitate method using calcium nitrate with di-ammonium hydrogen phosphate to improve both bending strength and disintegration toughness [4]. Composites synthesized using sol-gel with polymers to ceramics in that ZrO2 with PEG used as a plasticizer for medical applications. The polyethylene glycol (PEG) added with Zirconium oxide (ZrO2) which increase the coating ability and films were more homogeneous [5]. HA added with PEG/ZrO2 as the bioactive material used widely in wear resistance in joint applications using the sol-gel method. The aim of this paper is about the micro hardness of HA with inorganic (PEG) and ceramic (ZrO2) combinations using sol-gel method which does not report yet. 22
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