Experimental Investigation on Microstructure and Mechanical Properties of Nd:YAG Laser treated CP-Ti and Ni-Cr Alloys for Dental Applications

摘要

Commercial pure titanium (CP-Ti) has been The material of choice in several disciplines of dentistry due to its excellent biocompatibility, high resistance to corrosion, good oxidation resistance, strength-weight ratio and low mass-to -volume ratio. Despite a number of favourable characteristics, CP-Ti possess low mechanical strength, low surface hardness and poor wear resistance. The aim of the study was to investigate the effect of laser surface treatment on the mechanical properties of cast titanium and to compare with Ni-Cr alloys. Dumbbell and round shaped investment cast specimens were prepared for commercial pure Titanium (Grade-2) and Ni-Cr alloys. The cast specimens were laser treated on the surface using a Nd; YAG Laser machine with argon shielding. Tensile testing was conducted to obtain the tensile strength, percentage elongation and modulus of elasticity. The data were statistically analysed by ANOVA/post hoc test (p<0.050). Microstructures of fractured surfaces were evaluated using scanning electron microscopy and changes in crystal orientation were evaluated by X-ray diffraction (XRD) analysis. The highest tensile strength was obtained for laser treated titanium specimens with 450J/cm~2，followed by control groups. The results of the experiment showed that laser treated CP-Ti has better mechanical properties than laser Treated Ni-Cr alloy. The laser treatment has modified the micro structure, enhanced the tensile strength and surface hardness. This inference of improvement widens the scope of use laser application in dentistry and beyond.