title: Gypsum-bonded alumina dental investment for high-fusing casting.
abstract: In this study, we developed a new gypsum-bonded investment for high-fusing alloys. The investment was composed of gypsum as a binder and alumina as a refractory. Effects of type of alumina powder and gypsum content on characteristics of the gypsum-bonded alumina investment were investigated. Obtained characteristics of this experimental investment were as follows: fluidities ranged from 48.8 to 88.9 mm; setting times ranged from 21.2 to more than 120 minutes; setting expansions ranged from 0.4 to 1.3%; green strengths showed 0.5 to 4.5 MPa; fired strengths ranged from 0.2 to 1.7 MPa; thermal expansions after firing were -1.60 to 2.16%. Thermal expansion occurred because of the chemical reaction between Al2O3 and CaO decomposed from gypsum. These results suggest that this gypsum-bonded alumina investment with 20 or 25 mass% gypsum content possessed the fundamental properties for high-fusing alloy casting.
authors.affiliation: Department of Dental Technology 1, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yan
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry*; D019245:Compressive Strength; D003722:Dental Alloys / Q000737:chemistry; D003734:Dental Casting Investment / Q000737:chemistry*; D003735:Dental Casting Technique; D004055:Differential Thermal Analysis; D008422:Materials Testing; D010316:Particle Size; D012212:Rheology; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D003722:Dental Alloys; D003734:Dental Casting Investment; D000537:Aluminum Oxide; D002133:Calcium Sulfate