Abstract
Aims: is to evaluate the castability of titanium alloy and compare it with that of nickel-chromium and cobalt-chromium alloys by measuring castability and porosity values. Materials and methods: A total of 30 samples were prepared for castability and porosity tests. Castability was measured by castability test according to Hinman method by measuring the numerical number of the reproduced segments of casting samples . Porosity value was measured by determined the porosity percentage according to (Archimedes) method . ANOVA and Duncun, s multiple range test were carried out to determine the significant difference at p ≤ 0.05% . Results: the results showed that titanium alloy has a lowest value of castability and the highest value of porosity percentage, While cobalt-chromium alloys has intermediate values. Nickel-chromium alloy has highest value of castability and the lowest value of porosity. Conclusion: there is a significant differences between the castabilty and porosity values among different casting alloys used. The differences between the catability values are related to variance between the melting temperature of the different casting alloys, the higher the melting temperature the less castability value
Highlights
Cobalt Chromium (Co-Cr) based alloys was introduced in 1930 and is well known for its high Young’s modulus, fatigue strength, wear resistance and corrosion resistance
The aims of this study is to evaluate the castability of titanium (Ti) casting alloy and comparing it with that of nickel-chromium (Ni-Cr) alloy and cobalt- chromium (Co-Cr) alloy
The result showed that the mean value of castability of nickel-chromium alloy (Ni-Cr) was (84.36 %), which is higher than for cobalt-chromium alloy (Co-Cr) alloy (78.086 %), For Titanium alloy (Ti) the castability value was the least
Summary
Cobalt Chromium (Co-Cr) based alloys was introduced in 1930 and is well known for its high Young’s modulus, fatigue strength, wear resistance and corrosion resistance. [1,2,3] Co–Cr alloys are hard, rigid and mostly corrosion resistant; the retainer arms have often lacked adequate flexibility. As used in dentistry, 99.6% of commercially pure titanium is nontoxic, hypoallergenic, one half the weight of cobalt-chromium, radiograph translucent, inexpensive, and price stable. Along with these significant benefits, it is important to note that titanium can be used for partial denture frameworks, complete denture bases, metalceramic restorations, and implant suprastructures. [7-10] Despite the low density of titanium (4.50 g/cm2), a titanium framework supplies excellent strength and favorable hardness. High elongation and a low fatigue value allow titanium clasps to accommodate deep undercuts. [11]
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