The Preparation Of Porcelain-fused-to-metal Material For Dental Use

Porcelain-Fused-to-Metal restorations (PFM) sinter the ceramic powder on alloy substrates at high temperature, which makes the restorations have high strength as well as aesthetically pleasing appearance. They are the preferred restorations in the repair of clinical edentulous. The current PFM materials increase their strength through internal precipitation of leucite, which can also adjust the thermal match between the ceramic and the alloy. However, the strength is still not enough and the bonding between the ceramic and the alloy is not firm.Research included leucite preparation and ceramic frit preparation matching leucite. Solid phase reaction was used to prepare leucite.By adjusting the content of additives and changing heating conditions, the influential factors in leucite synthesis were explored. XRD, FTIR, Raman spectroscopy, SEM and quartz expansion instrument were used to test the microstructure and physical properties of leucite. The result shows the best recipe was K₂O 1.0 mol, Al₂O₃ 1.0 tool, SiO₂4.0 mo and TiO₂ 0.05 mol, Li₂O 0.1mol, SnO₂ 0.03mol, Na₂O 0.4mol.SiO₂-Al₂O₃-K₂O-Na₂O system was selected as a glass matrix. Through a series of physical performance tests, the best recipe matching leucite was identified. Two ways were used to prepare PFM powders, one was to add different proportions of leucite to the ceramic frit, and the other was to grain-process the ceramic frit. The experimental results show that with the increase of leucite in the ceramic frit, the thermal expansion coefficient and chemical stability of the material also increase, but bending strength decreases; After crystallization, the physical and chemical properties of ceramic frit are superior to the properties before crystallization, and their bending strength are generally higher than that of the ceramic frit adding leucite,which indicates that leucite precipitated in ceramic frit itself can enhance the strength of materials better than the additive introduced leucite into the ceramic frit. The test results also show that the bending strength and chemical stability of laboratory-developed ceramic powder meet the ISO standards. This paper also discussed the bonding between metal substrate and the ceramic powder. Experiments show that adding a certain amount of cobalt-nickel mixture to ceramic powder can enhance bonding strength between metal substrate and ceramic; the smaller the thermal expansion coefficient difference between metal substrate and ceramic is, the higher the bonding strength between them will be.