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#131 Chromate Treatment

Category : Electroplating
September21, 2012

Chromate treatment process [Figure] and types and characteristics [Table] applied over zinc plating (some cadmium plating also) are shown.

[Fig.] Zinc plating chromate treatment process

Fig.

[Table] Outline of various chromate treatments
VarietyTypeExterior color toneApplication area
Gloss chromateFor exterior appearanceSilver blue whiteUse where emphasis is on the aesthetics rather than the corrosion resistance as much.
Anti-corrosiveBlue~Light YellowUsed where the anti-corrosion property is most important.
Colored chromate　Gold, RainbowUsed where the anti-corrosion property is further emphasized.
Black chromateFor exterior appearanceBlackGood corrosion resistance. Often used for ornamental purposes. Used where anti-wear property is not of importance.
Anti-corrosiveBlackUsed where corrosion resistance and weather resistance are of importance.
Green chromate　Olive colorApplied on parts used in highly corrosive enbironments.

Corrosion resistance example of various chromate treatments are shown in the [Table] below. The "white rust" is zinc oxide.

[Table] Corrosion resistance of various chromate treatments (Number of white rust spots, Test specimen 5 pcs.)
　Salt water spray time (H)
Coating24487296120144168192216〜500
Gloss chromate0245　　　　　　　
Colored chromate0000245　　　　
Black chromate0000025　　　　
Green chromate00000000002

Fig.

MISUMI USA eCatalog

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