Abstract
Recently the rare earth metal-cobalt magnets, namely Sm-Co, have been developed. The properties of this magnet are much better than that of the previous ones, such as alnico or ferrite magnet. By using the Sm-Co magnet, good results have been gained in the field of dental science, especially in the prosthetic dentistry. Lately Pd-Co-Ni casting alloys which have soft ferromagnetic properties have been developed. At present time, it has been understood by many clinicians that the alloy was very useful in the mouth to use the magnetic force of the Sm-Co magnet. I this paper, the new Au-Co-Ni casting alloys for dental magnetic appliance have been studied. Ranges of solidification temperature, mechanical properties, magnetic properties, microstructures and corrosion resistance have been examined. Results were as follows: 1) Au-Co-Ni alloys have satisfied soft ferromagnetic properties for dental use.Especially, increasing Co content, high magnetic saturation (10〜13kG) was gained. 2) Low melting temperature (1035〜1040℃) were obtained on the high karat compositions. On the other compositions, melting points were less than 1270℃. 3) Mechanical properties were enough for dental use. 4) Corrosion resistance of Au-Co-Ni alloys were not so good for a solution of 1%NaCl.
