Abstract
This study aimed to investigate the relationship between the surface mechanical properties and the grindability of Ti alloys. Binary Ti alloys containing 5 wt % concentrations of Al, Cr, Sn, or V were prepared using a vacuum arc melting furnace, and their surface properties and grindability were compared to those of commercially pure Ti (cp-Ti). Ti alloys containing Al and Sn had microstructures that consisted of only α phase, while Ti alloys containing Cr and V had lamellar microstructures that consisted of α + β phases. The Vickers microhardness of Ti alloys was increased compared to those of cp-Ti by the solid solution strengthening effect. Among Ti alloys, Ti alloy containing Al had the highest Vickers microhardness. At a low SiC wheel speed of 5000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the hardness values of Ti alloys decreased. At a high SiC wheel speed of 10,000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the tensile strength values increased. The Ti alloy containing Al, which showed the lowest tensile strength, had the lowest grinding rate. The grinding ratios of the Ti alloys were higher than those of cp-Ti at both wheel revolution speeds of 5000 and 10,000 rpm. The grinding ratio of the Ti alloy containing Al was significantly increased at 10,000 rpm (p < 0.05).
Highlights
Titanium (Ti) has been used in dental prostheses, such as dental crowns, bridges, denture frameworks, and implant materials, due to its high specific strength, low elastic modulus, and good biocompatibility.Generally, Ti is cast into a specially formulated investment mold using a pressure-vaccum or high vacuum centrifugal casting machine to fabricate a prosthesis in the desired form
This work aimed to investigate the effects of hardness and tensile strength on the grindability of binary Ti-5 wt % (Al, Cr, Sn, and V) alloys
(99.99%), Cr pieces (99.995%), Sn granules (99.99%), and V pieces (99.7%) were used as raw materials for the preparation of Ti alloys. All of these materials were purchased from Alfa Aesar (Ward Hill, MA, USA)
Summary
Ti is cast into a specially formulated investment mold using a pressure-vaccum or high vacuum centrifugal casting machine to fabricate a prosthesis in the desired form. Its high melting temperature (1668 ◦ C) and chemical reactions with investment mold during the casting process result in brittle and hard α case formation on the surface, which make the finishing and polishing procedures difficult. To avoid problems during the casting process of Ti-based prostheses, the CAD/CAM technique was introduced in dentistry in the 1970s and developed rapidly for the convenient manufacture of dental prostheses. The clinical limitation of the CAD/CAM technique is that it is difficult to obtain precise restoration due to clinical parameters such as saliva, blood, or movements of the patient during oral structure scanning [1]. The other limitation is that the flaws on Metals 2017, 7, 487; doi:10.3390/met7110487 www.mdpi.com/journal/metals
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