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Processes for the surface treatment of tools and precision components
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Electro- or chemical plating (hard chromium, chemical nickel)
Advantages:
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Good corrosion resistance |
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Low processing temperature |
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Deposition also in bore holes, slots etc. |
Disadvantages:
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Limited selection of coating materials |
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Relatively soft coatings |
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Ecologically problematic treatment baths (include cyanide, heavy metals, fluorides, oils and greases) |
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Limited accuracy of surface replication |
Diffusion processes (Nitriding, nitrocarburisation, boronizing, phosphating, etc.)
Advantages:
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Good corrosion resistance |
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Good reproducibility |
Disadvantages:
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Relatively soft coatings |
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Limited selection of base material (must be suitable for nitriding) |
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Long processing times |
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Substances from processing are damaging to the environment and to health |
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Post-treatment required |
CVD (Chemical Vapour Deposition)
Advantages:
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High wear resistance |
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Economic production of thicker coatings |
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Also suitable for bore holes, slots etc. |
Disadvantages:
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High processing temperatures |
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Coatings with a several metals (e.g. TiAlN) are not possible |
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Edges become rounded (coating thickness) |
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Uses ecologically problematic, toxic metal chlorides |
PACVD (Plasma-Assisted Chemical Vapour Deposition)
Advantages:
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Significantly lower process temperatures are possible than for CVD |
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Precise coatings |
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Low temperatures |
Disadvantages:
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Only limited suitability for bore holes, slots etc. |
PVD (Physical Vapour Deposition)
Advantages:
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No environmentally damaging materials and emissions, no toxic reaction products |
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Great variety of coatings can be produced |
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Coating temperature below the fineal heat treatment temperature of most steels |
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Small, precisely reproducible coating thickness (accurate surface replication, true to size, |
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High wear resistance |
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Low frictional coefficient |
Disadvantages:
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Bore holes, slots etc. can only be coated down to a depth equal to the diameter or width of the opening |
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Corrosion resistant only under certain conditions |
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In order to achieve a uniform coating thickness, the parts to be coated must be rotated during processing |
P3e™ (Pulse Enhanced Electron Emission)
Advantages:
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All advantages of PVD technology |
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Great variety of oxide based coatings possible |
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First alpha-aluminium oxide based coating by a PVD process |
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Low deposition temperature (600°C) compared to CVD (1000°C) for deposition of alpha-aluminium oxide |
Disadvantages:
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Same as for PVD technology |
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