Abstract This study investigates the effect of zirconia addition with different percentages on Ni-Cr alloy using a powder metallurgy technique. The scanning electron microscope with energy dispersive spectroscopy is used to analyze the microstructure of Ni-Cr and Ni-Cr-x ZrO2 (where x is 3, 6, 9 wt.%) alloys. The x-ray diffraction method is used to determine the phases for Ni-Cr and Ni-Cr/ZrO2 alloys. The corrosion and ion release tests were also achieved using potentiodynamic polarization and atomic absorption spectroscopy. According to the microstructural investigation, the results found that the Ni-Cr alloy’s grain size tends to reduce with the addition of ZrO2with obtaining the smallest grain size with 6 wt.% addition. The potentiodynamic polarization exhibited that the modified alloys are more resistant to corrosion in the saliva medium than the Ni-Cr alloy. Furthermore, the role of ZrO2 in the dissolution test shows the development in the passive layer’s resistance compared to unmodified alloys with reducing the Ni release from 2.5 ppm to 0.2 ppm. It can conclude that the addition of ZrO2 has significantly improved Ni-Cr’s biocompatibility and extend the area of implementations.
Conclusions
Based on the obtained results, the following conclusions were drawn:
1. The Ni-Cr alloy’s grain size was tending to decrease as the ZrO2 addition increase with exhibiting the smallest grain size with 6 wt.% addition; however, with a further addition to 9 wt.%, the grain size actually increased.
2. The Ni-Cr alloy’s corrosion rate reduced from 73.28 mpy to 0.487 mpy as the ZrO2 was added with an optimum percentage of 6 wt.%.
3. Ni and Cr’s highest ion release was obtained with the unmodified alloy with 2.5 ppm and 1 ppm, respectively. Conversely, the addition of ZrO2with 6 wt.% presented the lowest ion release with an average value of 0.3 ppm and 0.2 ppm for the Ni and Cr, respectively.