Mechanical properties of our alloys
Grain size
The small grain size in our dental casting alloys positively influences their mechanical, melting, casting and finishing properties. It also adds to their excellent corrosion resistance.
The average grain size of our dental alloys is less than 7 microns. This is very small in comparison with other leading products on the market which appear to average over 30 microns.
The superior quality is because:
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The raw materials are supplied from the mine as pure charge ingredients in a very fine powder form. We do not recycle metal for orthopaedic and dental alloys.
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The advanced furnaces used to make our ingots ensure a homogeneous melt.
Many of the important mechanical properties of alloys, including yield strength, hardness, ductility and corrosion resistance can be improved by refining the grain size. This is one of the reasons why our alloys are so strong.
Strength
Due to their high strength, ALEXIUM W® and NIMON EXTRA™ ceramic bonding alloys are categorised as type 4 alloys according to the ISO (International Standards Organisation). Type 4 is the highest requirement for dental alloys intended for ceramic bonding. It means they can be recommended for long span bridge work.
ALEXIUM W® cobalt chrome ceramic bonding alloy has a tensile strength of 805 MPa and an elongation of 15 %. NIMON EXTRA has a tensile strength of 830 MPa and an elongation of 6%.
ALEXIUM 21 is categorised as a type 5 dental alloy according to the ISO (International Standards Organisation). Type 5 is the highest standard for partial denture alloys and means it can be reliably used in thin section. ALEXIUM 21 denture alloy has a tensile strength of 819 MPa and an elongation of 12%. This means it has premium bending control, elasticity and fracture resistance.
Corrosion resistance
Cobalt and nickel alloys are historically known as 'superalloys' and are famous for their resistance to the effects of corrosion, wear and high temperatures.
The International Standard for corrosion testing of dental alloys was changed in August 2011.
ISO 10271:2011 now requires a 40 day lactic acid immersion with multiple tests throughout this period for metal ions released as a result of corrosion. It also requires an enhanced electrolytic corrosion analysis.
Independent tests confirm all of our dental alloys conform to ISO 10271:2011. These results can be downloaded from individual alloy pages.
Porcelain bonding
Bond strength with compatible ceramic is excellent. See the product instructions for recommendations. ALEXIUM W® cobalt chrome bonding alloy has a CTE of 14.1, while NIMON EXTRA™ nickel chrome alloy has a CTE of 13.8. Most of our customers choose to bond their ceramics without completing an oxidation firing. This seems to vary depending upon trends in different countries. We suggest our customers continue with the methods to which they have become accustomed.
Solidus & fit
Cooling shrinkage is minimal and predictable. Correct sprue and reservoir design will ensure accuracy of fit.
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