Ceramco manufactures both custom and stock fasteners out of alumina and zirconia, and although these are high performance materials, they are not going to have strength properties similar to your traditional fasteners. The tensile strength and/or torque values for these products have not been reported inasmuch we’ve only been able to advise customers on their usage, such as, be careful not to over-tighten them. And it was up to the customer to be able to translate the typical mechanical properties of these materials to evaluate the material limits.
This is no longer the case! We now have torque values to report to customers (we did actually provide a small chart with torque-to-failure values before, but those data were from in-house testing, and not to be confused with an installation torque). We also have tested the tensile strength, which previously had not been reported in any form. Individual papers on the torque strength and tensile strength will be published in the near future based on the test results.
In general, the fasteners performed as expected and in the case with torque values, were at least in correlation with previously measured values from over 10 years ago. The strength of the zirconia fasteners compared to the alumina fasteners was lower than expected, and has raised the question as to how fasteners made in ZTA (Zirconia Toughened Alumina) will perform. ZTA is a composite which combines the strength and toughness of expensive zirconia with the good performance and low cost of alumina. Testing of a ZTA fastener is underway and to be reported in a later paper.
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