Zhe role of zirconia additions on the microstructure and corrosion behavior of Ni-Cr dental alloys

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 ZrO2 with 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 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.