The basic components : 69%Co ; 23%Cr ; 5%Mo.
Nicel free cobalt-chromium alloys is a cast material produced by alloying of commercially pure metals, namely cobalt, chromium, molybdenum and others in vacuum induction furnaces. The alloy is characterized with required level of technological, physical and chemical and mechanical properties in accordance with requirements of the international standards ISO 6993 "Stomatology ceramic for dental appliance". It has high corrosion resistance and meets to toxicology and sanitary requirements for stomatology materials.
Heightened fluidity of the alloys makes it possible to cast thin-walled parts having thickness up to 0.3 mm. The products made from this alloy are well workable by abrasive tools and polishing means. Alloys properties ensure a reasonably high strength of metal-ceramic bonds on application of porcelain masses, i.e. it may be used for metal-ceramic dentures producing.
The main properties of alloy:
|Density||- 8,4 g/cm-3|
|Recommended casting temperature||- 1470-1550 *Ñ|
|Tensile strenght||- no less than 550 MPa|
|Yield strenght||- no less than 370 MPa|
|Elongation||- no less than 5%|
|Brinell hardness||- no less than 2300 MPa|
|Thermal factor of linear expansion in an interval of temperatures 20-500 *Ñ||- 14.2*10-6 K -1|
|PREPARATION OF THE DENTURE CASTING FOR FACING PORCELAIN MASS |
Unit-cast denture frame made from "Zellit-K" alloys needs to work thoroughly with abrasive tools, to clear by sandblaster and to degrease, and then to cover with an oxide film. For this purpose denture frame is placed in furnace for ceramic burning under temperature about 650 *Ñ. Then it is set vacuum in furnace, temperature is risen to 980 *Ñ, and denture frame is held for 1 minute under these conditions. After that the furnase is opened, and denture frame is cooled on the furnace table for 5 to 7 minutes. Then one is removed from the table and cooled to room temperature.
Ground and other ceramic mass layers are faced in accordance with instruction for use of the particular mass.