Metal finishing Q&As since 1989

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Ultrahard Coating/Plating for Titanium?

I'm working with titanium alloy base material for a casing. The stiffness and impact resistance relative to weight is the most compelling factor for my application. My casing application requires a thin (1 mm or less), stiff, moderately impact resistant (neither denting nor fracturing), and - most importantly - extremely hard / abrasion resistant. The goal is abrasion resistance against even very minor scratches from everyday materials ranging from sand to steel.

Titanium alloys clearly lack sufficient hardness and abrasion resistance. Chromium plating is not sufficient either. Tungsten carbide plating may work, but the thinnest I've seen done (0.3 mm) is heavier than the material I'd plate. A 0.3 mm titanium carbide plating is about 0.48 g/cm^2, while 0.7 mm thick titanium alloy weighs maybe 0.34 g/cm^2.

Ultrathin PVD coatings (usually 1-4 microns) of say titanium aluminum nitride are simply too thin. While they have great properties, the extreme thinness means that it does wear through in some places before the material's lifetime is complete. In regular use, I would not concerned about micron-level abrasions, but that's all it takes to break through the coating to the base material, where much deeper abrasion can occur.

What other plating approaches & materials are out there? Could I plate with something like titanium carbide? Are there suggestions as to companies who could handle this kind of process? Are there platings which might be suitable here, but are incompatible with titanium?

A final note: I am plating onto a partially irregular surface. While it is not highly detailed, some portions are curved, etc.

Galen Zink
Product Designer - Portland, Oregon, USA
December 22, 2008