title: Characterization of Ni-Cr alloys using different casting techniques and molds.
abstract: This study differentiated the mechanical properties of nickel-chromium (Ni-Cr) alloys under various casting techniques (different casting molds and casting atmospheres). These techniques were sampled by a sand mold using a centrifugal machine in ambient air (group I) and electromagnetic induction in an automatic argon castimatic casting machine (group II). The specimen casting used a graphite mold by a castimatic casting machine (group III). The characteristics of the Ni-Cr alloys, yield and ultimate tensile strength, bending modulus, microhardness, diffraction phase, grindability, ability to spring back, as well as ground microstructure and pattern under different casting conditions were evaluated. The group III specimens exhibited the highest values in terms of strength, modulus, hardness, and grindability at a grind rate of 500 rpm. Moreover, group III alloys exhibited smaller grain sizes, higher ability to spring back, and greater ductility than those casted by sand investment (groups I and II). The main factor, "casting mold," significantly influenced all mechanical properties. The graphite mold casting of the Ni-Cr dental alloys in a controlled atmosphere argon casting system provided an excellent combination of high mechanical properties and good ability to spring back, and preserved the ductile properties for application in Ni-Cr porcelain-fused system. The results can offer recommendations to assist a prosthetic technician in selecting the appropriate casting techniques to obtain the desired alloy properties.
authors.affiliation: Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan. Electronic address: wencchen@fcu.edu.tw.
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Chen
authors.affiliation: Department of Dentistry, Kaohsiung Armed Forces General Hospital, Kaohsiung 802, Taiwan; School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
authors.forename: Fu-Yuan
authors.initials: FY
authors.lastname: Teng
authors.affiliation: School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
authors.forename: Chun-Cheng
authors.initials: CC
authors.lastname: Hung
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry*; D003735:Dental Casting Technique; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006244:Hardness; D008422:Materials Testing; D008669:Metallurgy / Q000379:methods*; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D002858:Chromium Alloys
keywords: Casting; Dental alloys; Graphite mold; Spring back (recovery angle)