Advantages of Diffusion Coatings
Example of tantalum diffusion coating on superalloy A-286
- Thin (1–3 µm) surface layer that grades from pure tantalum at surface to a mixture of tantalum and substrate elements
- High bond strength, because tantalum is diffused into the substrate surface and chemically mixes with substrate elements
- Precise replication of intricate substrate features that requires no postprocess machining or polishing
- Little or no change to the treated substrate physical dimensions
- Original surface roughness maintained
- High corrosion resistance
- Application to various steels, chromium-coated materials, and nickel-based superalloys
- Ability to combine effectively with a conventional chromium coating to substantially increase the lifetime of the chromium coating
- Application to net-shape products as a final production step
The diffusion coating process itself requires no costly equipment, is readily scalable to large batches, is rapid (deposition times of <1 hour), and is economical because little tantalum is required. Ultramet developed this process under NASA funding to protect space shuttle propellant valves.
The tantalum diffusion coating significantly enhances the corrosion resistance and lifetime of chromium-coated components. Tantalum fills the microcracks that inevitably exist in chromium coatings and prevents corrosive liquids from reaching the component surface.
Learn more about tantalum and corrosion protection at Ultramet CPT.