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NITINOL (NiTi) SURFACE FINISHING
ELECTROBRIGHT offers most comprehensive Nitinol (NiTi) finishing package in industry which includes:
- Magnetoelectropolishing (US patented process)
- Simultaneous intermetellic inclusion detection and superpassivation (US patent pending process)
Due to its remarkable mechanical (pseudoplasticity, shape memory) and biocompatible properties Nitinol have found it’s lasting and growing place in medical (stents) and dental (rotary files) applications. The gold industrial standard for finishing Nitinol for implantable devices (stents) is electropolshing process. Electrobright went to extend to improve Nitinol finish and developed magnetoelectropolishing process. The magnetoelectropolishing remarkably improves Nitinol properties compare to standard electropolishing:
- Improves fatigue resistance by removing residual hydrogen which create hydrogen embrittlement Fig 2. Fig 3. (this phenomenon was independently proven by two international laboratories).
- Improves corrosion resistance and halts Ni ion leaching by creating pure TiO2 layer absent of any Ni elements.
Any of Nitinol finishing process will improve its fatigue and corrosion resistance how long Nitinol isn’t free from surface intermetallic inclusions. The new patent pending process addresses this problem by chemically detecting surface inclusion and by this gives for first time ever very cheap and 100% reliable method for eliminating inferior parts. Concurrently (if part is free from intermetallic surface inclusion) superpassivation, which eliminates all Ni presence on the surface will take place.
Fig 2. Micrographs of Nitinol fracture
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Electropolished (visible peripheral hydrogenated band responsible for fatigue deterioration) |
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Magnetoelectropolished (without hydrogenated layer with improved fatigue resistance)
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Fig 3.
Picture of 0.7 mm thick surgical blades (from left to right: electropolished, electropolished – fracture during 180° bend test (fractured around 120°), magnetoelectropolished with full 180° bend)
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