Abstract
This study investigated the bio-corrosion response of spark plasma sintered zirconia reinforced titanium in an oral environment. Adding zirconia (Yttria-3mol% stabilized ZrO2 also referred to as YSZ) was expected for the improvement of the low resistance to corrosion and appalling wear property of Ti6Al7Nb. Subsequently, the underlying corrosion behaviour submerged in Hank’s solution was assessed as the Ti6Al7Nb matrix was fabricated via the spark plasma sintering technique whilst reinforcing with varying volumes of nanostructured Yttria-3mol% stabilized ZrO2. The Ti6Al7Nb and YSZ powders were mixed using the tubular mixer for 3 h at 49 rpm. At their various ratios, the admixed powders were sintered in vacuum using a 30 mm die, at a temperature of 1100 ℃ and 1300 ℃, a heating rate of 100 ℃/min, holding time of 10min, and applied pressure of 22 MPa. The relationship between sintering process parameters and formed composite characteristics was investigated. To examine the morphology of the bio-composites using a high-resolution Scanning Electron Microscope (HR-SEM), Optical Microscope (OM), and energy dispersive X-ray spectroscopy (EDS) were affixed to the HR-SEM to study the compositional analysis. At the same time, the phase changes and proportion of each crystalline phase were observed by means of X-ray diffraction (XRD), and the surface microhardness was assessed using the Vickers microhardness tester. Furthermore, the biocorrosion behaviour in Hank’s solution was investigated by making use of the Open circuit potential (OCP), Chronoamperometry, and potential dynamic polarization (PDP) electrochemical techniques. Electrochemical measurements were carried out using Princeton Applied Research: Versastat 4 Potentiostat. The results showed an improvement in corrosion resistance and mechanical properties with an increase in the wt.% of zirconia reinforcement. Also, SEM with EDS was used to examine the sintered samples after they had been subjected to bio-corrosion. The microstructural changes resulting from YSZ addition were considerably different from those seen in pure Ti6Al7Nb. The microstructure revealed that the
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surface modification was ascribed to corrosion resistance exhibited upon the incorporation of zirconia particles within the matrix, which aided the production of globular zirconia-rich agglomerates. Furthermore, the sample with the composition of Ti6Al7Nb + 15%YSZ sintered at 1300 ℃ exhibited the most enhanced hardness value of 1039.25 HV0.1. Sample Ti6Al7Nb + 5%YSZ sintered at 1100 ℃ having the highest resistance to corrosion, displaying the most positive Ecorr value of -0.25V.