UNCD^® Faces have consistently outperformed silicon carbide faces in rigorous testing. UNCD Faces have been successfully tested and evaluated in a variety of conditions, including:

•  Slurry applications (10% solid loaded diatomaceous earth)
•  Hot water (accelerated wear testing)

In addition to these dynamic evaluations, the coefficient of friction (CoF) of UNCD has been quantified against both carbon and SiC (silicon carbide). Summaries of the hot water testing and CoF evaluations are shown below.

Dynamic Hot-Water Testing

Advanced Diamond Technologies on-site seal testing

UNCD Faces have been evaluated and testing in over thirty 100 hour dynamic "hot water" tests. These tests included critically evaluating both the mating and primary faces before and after being exposed to a poorly lubricating environment of hot water at 250 °F-300 °F and 100-150 psig using ANSI 3196 (Goulds) pumps. These conditions have been shown to create very aggressive face wear which enables the comparison of different face materials. The 100 hour hot water test simulates over two years of normal operation. The evaluations were run using a conventional blister-resistant carbon primary running against either an alpha-phase, self-sintered SiC mating ring or the UNCD Face using the same SiC.

UNCD Faces within Type A05 Component Seals have neither failed nor leaked within this series of 100 hour evaluations. The UNCD faces have measured minimal wear (tens of micro inches) after completing the 100 hour test. Standard SiC rings, however, exhibit deep grooves measuring well over 4,000 micro-inches which developed in 50 to 75 hours. None of the standard SiC seals ran for the targeted test length of 100 hours due to seal leakage. The standard seals leaked so severely that the tests were consistently aborted. Below are photographs and radial traces of a UNCD face (left) and standard SiC face (right) after hot water testing. The full technical article detailing these results was published in "Using Ultrananocrystalline Diamond to Improve Mechanical Seal Performance" in the January 2008 issue of Maintenance Technology.

UNCD Seal Face	SiC Seal Face
Surface condition of a UNCD seal face after running in 250 °F water at 100 psig, showing almost no wear.	Surface condition of a silicon carbide seal face after running in 250 °F water at 100 psig, showing deep grooves.
Surface trace across the UNCD seal face demonstrating that minimal wear took place over 100 hours of operation in 250 °F water at 100 psig.	Surface trace across the silicon carbide seal face indicating heavy wear after 100 hours of operation in 250 °F water at 100 psig.

The extreme wear resistance of UNCD Seals has been confirmed by Argonne National Laboratory, Advanced Diamond Technologies, Inc. (ADT), and a major seal manufacturer. ADT has a hot water test rig and the necessary characterization equipment to conduct these tests in its facilities. This testing equipment is used to rigorously evaluate suppliers of silicon carbides and other seal elements that go into the Type A05 seal.

Coefficient of Friction (CoF)

The CoF of UNCD faces running against SiC primaries has been routinely measured between 0.018 and 0.04 (see figure below). The CoF test rig measures the resulting torque of a rotating 1.375 inch A05 seal at various face loads. The CoF is calculated from a series of data points considered representative of the data collected toward the end of the test when the dynamic events associated with the start up and load variations have stabilized. The same test using SiC running against SiC measured greater than 0.18 and SiC against resin-bonded carbon routinely measures between 0.08 and 0.1.

To validate the benefits of the friction measurements made on the CoF test rig, a slurry-rig was instrumented at Argonne National Laboratory to measure the temperature of seal chambers when pumping a 10 wt% solid abrasive in Goulds 3196 pumps. The seal chambers of the pumps using UNCD Seals were found to operate six degrees (Fahrenheit) cooler than those pumps using industry standard SiC face seals. The low friction enables UNCD faces to be paired with SiC primaries in applications that would otherwise require softer carbon faces due to intermediate dry operation or temperature sensitive media. UNCD's lower friction can provide more robust single seal solutions in applications that might otherwise require the added costs and maintenance issues associated with double seals.

Manufacturing Capabilities

CoF measurements of UNCD Seals result in an extremely low value of 0.018

ADT has the capability, equipment, staff, and business practices in place to supply seals in commercial quantities. ADT routinely processes seals with shaft diameters ranging from 0.375 to 10 inches. Processing capabilities exist to handle both contacting and non-contacting face designs. ADT also has the test and characterization capabilities to qualify seal face materials, evaluate seal wear resistance, and characterize specific end-use performance.

For additional information regarding UNCD Type A05 test results, technical capabilities, or to discuss your specific requirements please call ADT or fill out the contact form here.