Our processes in detail

1. Acidic bright zinc bath

Thick layer passivation (transparent, chromium-VI-free)

Bright, colourless to light yellow, light reddish-blue passivation layer (depending on zinc electrolyte) with excellent corrosion protection
Chrome-VI-free passivation, contains no chromate
Suitable for passivation of zinc-plated products from slightly acidic and alkaline zinc baths

Trivalent blue passivation (chromium-VI-free)

Good gloss effect with haze-free brilliant blue tone and extremely good corrosion resistance
Suitable for passivation of zinc-coated products from slightly acidic and alkaline zinc baths

Yellow chromating (contains chromium VI)

Produces a yellowish, multicoloured iridescent protective layer on electro-deposited zinc
Chromate layer meets elevated corrosion-protection requirements
Enhanced chromating adhesion for painting, coating or powder coating

Sealing

Extra-high corrosion resistance thanks to higher input of special inorganic micro-silicon compounds in combination with polyacrylates
Assures enhanced sliding properties
Suitable for sealing of zinc-plated, passivated, yellow-chromed and phosphated surfaces

2. Alkaline zinc processes

Thick layer passivation (transparent, chromium-VI-free)

Bright, colourless to light yellow, light reddish-blue passivation layer (depending on zinc electrolyte) with excellent corrosion protection
Chromium-VI-free passivation, contains no chromate
Suitable for passivation of zinc coated products from slightly acidic and alkaline zinc baths

Trivalent blue passivation (chromium-VI-free)

Good gloss effect with haze-free brilliant blue tone and extremely good corrosion resistance
Suitable for passivation of zinc-plated products from slightly acidic and alkaline zinc baths

Black passivation (chromium-VI-free)

Applies black passivation layers to alkaline deposited zinc coatings
Extremely suitable for coating of rack parts
Trivalent chromium (III) passivation
Completely free of chromium (VI)
Very good corrosion protection in combination with subsequent sealing"

3. Hard chrome plating (fluoride-free)

Exceptional hardness (900 to around 1000 HV), high wear resistance, good resistance to tarnishing and corrosion under atmospheric exposure
Layer thicknesses up to 0.1 mm possible
Gaining in importance in the mechanical, automotive and hydraulic engineering industries

4. Bright chromium plating

Used for deposition of bright decorative layers of chromium onto bright nickel
Excellent hiding power

5. Semi-bright nickel

High adhesion, high ductile formability, good levelling
Used for deposition of semi-bright nickel coatings
Primarily for the production of double-nickel layers on surfaces severely exposed to corrosive attack
Also available in semi-bright sulphur-free form as double-nickel plating for copper

6. Bright nickel

Process for deposition of uniform high-gloss and light nickel coatings
Extremely well suited for subsequent bright chrome plating

7. Manganese phosphating

The tightly bonded phosphate layer assures constant coefficients of friction after a short running-in period
High-quality corrosion protection when combined with anti-rust oiling, giving the components a decorative anti-reflective appearance
Chemical immersion phosphating, assuring a very fine crystalline, almost totally black layer of manganese phosphate

8. Bright copper

For high-speed deposition of thick bright copper coatings on iron, steel, brass and zinc die-castings
Copper coating can then be passivated, nickel coated, tin coated or chrome plated

9. SurTec 650 chromitAL TCP

Excellent corrosion protection, comparable to hexavalent passivation treatments
Chromium-VI-free, trivalent passivation
Suitable for high-alloy aluminium, castings and forgings, extremely suitable as an adhesion-enhancing substrate for paints, coatings and adhesives
Meets corrosion-protection requirements in accordance with MIL 5541 and MIL-DTL-81706 (336h salt-spray test in accordance with DIN 50021 SS)
Low surface resistance (<0.8 mOhm/cm²)

10. Compact Fe/zinc-nickel system

Highly corrosion-resistant layers meet automotive industry requirements
Alkaline alloying process, deposits layers with a nickel content of 12 to 15%

11. Our Niro-look process

Corrosion protection in accordance with DIN EN ISO 9227 NSS
"Niro-look" is a thick layer passivation process. It delays the formation of white rust (corrosion of the zinc layer) and can replace yellow chromating for corrosion protection purposes. The two processes scored equally good corrosion ratings when tested on identical component surfaces. Protection can be further enhanced by additionally applying post-dip solutions or top coats on the thick-layer passivation (depending on the geometry of the component). Alkaline, acidic or abrasive cleaning products and mechanical cleaning pads must under no circumstances be used. These would damage the layer and permanently destroy the finish and the corrosion-protection function.

Colour
The colour of a "Niro-look" finish is inherently restricted to the intrinsic colour. The colour of passivation finishes (without additional application of post-dip solutions or top coats) is an intensive iridescent red-green. Application of post-dip solutions or topcoats onto the thick-layer passivation produces a "silk-gloss" finish, because the silk-gloss metallic substrate of the zinc is visible. A slight iridescence of the surface will remain apparent despite application of post-dip solutions or topcoats. Quality thick-layer passivation treatments produce a layer thickness of >30µm.

Layer thickness range:
Rack finishing: 8-25µm
Drum finishing: 8-20µm

Our processes in detail – GMH Gruppe