[Studies on the refractory coating materials for preventing scale formation (author's transl)].
In casting of high-fusing alloys such as cobalt-chrome and nickle-chrome alloys, the reaction between the investing mold and high-fusing molten alloys suffers the disadvantage of the scale formation. The various coating materials are used to prevent the scale formation. The experiments have been carried out to prove the effectiveness of seven commercialized coating materials. And the reaction between the coating materials and high-fusing molten alloys was analyzed by X-ray diffractometer. Results were as follows: 1) The refractory compositions of seven commercialized coating materials were composed of alpha-quartz (SiO2), zircon (ZrSiO4) and zirconium oxide (ZrO2). 2) Dainainvest (Ohara) mainly containing zircon indicated the reduction in surface roughness due to coating. Although zircon was slightly observed on the cast surface, the product of reaction was not detected. 3) Liquid investment (Nobilium) and Paint investment (Shofu) having about equal amounts of alpha-quartz and zircon showed as reduction in surface roughness as Dainainvest. The product of reaction was not observed and the cast surface was smooth. 4) Quick request (Shiken), Pre-coat (Niranium) and Ethymay B (Kamemizu) composed of alpha-quartz had not appreciably effectiveness. The cast surface was rough due to production of picrochromite (MgCr2O4) and eskolaite (Cr2O3)in the reaction between molten alloys and coating materials. 5) Hi-coat with zirconium oxide did not point out the advantage in spite of high refractory composition and showed little reduction in surface roughness due to coating.
D002858:Chromium Alloys; D001840:Dental Bonding / Q000592:standards*; D003734:Dental Casting Investment; D003764:Dental Materials / Q000592:standards*; D006358:Hot Temperature; D011791:Quartz / Q000592:standards*; D012822:Silicon Dioxide / Q000592:standards*; D013499:Surface Properties; D015040:Zirconium / Q000592:standards*
D002858:Chromium Alloys; D003734:Dental Casting Investment; D003764:Dental Materials; D011791:Quartz; D012822:Silicon Dioxide; D015040:Zirconium