SilCor® CrN - The first choice for:

Chromium - Chromium Nitride - Multilayer coatings

According to different criteria it seems as if coatings of chromium and its modifications (CrN and multi-layers) are inferior in quality to DLC films. This is not correct in general. Hard coatings of chromium and chromium nitride are at different points of view a good alternative to DLC coatings:
  • There is, for example in medical technology, the explicit need for a film appearing metallic silver.
  • The coating must show a high reflectance.
  • The component coated has to withstand temperatures above 400 degree Celsius.
  • Due to lacking support of the base material (hardness below 400 HV), the film thickness must exceed 3 µm.
  • The coating is operated in a strongly oxidising environment.
  • There is strong abrasion of the coating due to particles (e. g., glassy powder).
Depending on specific requirements, SilCor® CrN is coated in form of chromium mono-layers Cr or chromium nitride mono-layers CrN or multi-layer systems. By the deposition of multi-layers, metallic and ceramic properties are combined within one coating. These coatings are of a dense, non-porous structure, what is quite in contrast to a variety of PVD CrN coatings available. They are free of mechanical tensions (stress). The multi-layered structure of the coatings offers a wide spectrum of properties, which can be adjusted according to the requirements of use.
  • coating thickness between 1 and 10 µm
  • adjustable hardness from 1000 to 2800 HV
  • minimum coefficient of friction against dry steel of 0,56
  • typical critical load of 100 N depending on the substrate
  • thermal stability under ambient air up to 700 degree Celsius
  • high corrosion resistance against acids, leaches and corrosive gases.
These properties guarantee a strong increase of life and efficiency of tools and machine components (This is proven for a variety of - especially - forming tools, stamping tools, tablet tools etc.). The coatings of chromium, chromium nitride or multi-layers reduce friction and abrasion. In addition, corrosion is suppressed. The decorative appearances of the coatings are between metallic silver (upper layer chromium) and silver grey (nitride upper layer). The coatings withstand high mechanical and thermal stress. They do not show micro-columns visible by electron microscopy. This homogenous micro-structure results in dense coatings, what is the origin of the high corrosion resistance.

The deposition of Silcor® CrN:
Chromium, nitride and multi-layer coatings are deposited by physical vapour deposition from solid cathodes (and nitrogen gas). This is performed employing the powerful arc evaporation sources developed by PT&B. On demand, Cr, CrN and multi-layers can be deposited by reactive magnetron sputtering. The deposition technology used leads to advantages of the hard coatings:
  • Good adhesion on every metallic surface due to interface mixing with the base material and reduced stress of the films
  • Deposition at temperatures as low as 100 degree Celsius
  • Variable surface roughness (from extra rough to extra smooth)
  • Adjustable microscopic structure and macroscopic properties as hardness, thickness, density, conductivity and coefficient of friction
In addition, there is the option for post-deposition polishing of the coatings. This can be done by a newly developed technique, which uses no wax ore grease.

The coating technology of PT&B will fulfil your requirements!

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