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AssigneeAdvanced Diamond Technologies, Inc.
InventorsHongjun Zeng, John Arthur Carlisle, Ian Wakefield Wylie
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A durable composite diamond electrode is disclosed which comprise at least a relatively thicker conductive UNCD (Ultrananocrystalline Diamond) layer, with low deposition cost, on a substrate underlying a relatively thinner conductive MCD (Microcrystalline Diamond) layer. The electrode exhibits long life and superior delamination resistance under extremely stressed electrochemical oxidation conditions. It is hypothesized that this improvement in electrode reliability is due to a combination of stress relief by the composite film with the slightly “softer” underlying UNCD “root” layer and the electrochemically durable overlying MCD “shield” layer, an effective disruption mechanism of the fracture propagation between the compositing layers, and thermal expansion coefficient match between the diamond layers and the substrate. The diamond composite electrode can be applied to any electrochemical application requiring extreme voltages/current densities, extreme reliability or biomedical inertness such as electrochemical systems to generate ozone, hydroxyl radicals, or biomedical electrode applications.
An electrochemical system comprising an anode containing a first underlying conductive ultrananocrystalline diamond layer prepared by a deposition technique including a methane to hydrogen ratio of at least 2 to about 10 percent and a pressure in the range of about 1 to about 10 Torr that is deposited directly onto at least one side of a substrate and having a first average thickness and a first average grain size that is less than about 100 nm, and an outermost conductive diamond layer overlying the first diamond layer, the outermost diamond layer having a second average thickness and a second average grain size, wherein the second average grain size is more than three times greater than the first average grain size and the average sp2 content of the first conductive diamond layer is at least five times greater than an average sp2 content of the outermost conductive diamond layer.
Dependencies are inferred from the claim text.