ZINCHROMATE BLACK 163
A BRIGHT BLACK CONVERSION COATING PROCESS FOR ZINC AND ZINC PLATED PARTS.
ZINCHROMATE BLACK-163 PROCESS IS SPECIALLY DESIGNED FOR PRODUCING A BRIGHT LUSTROUS JET-BLACK CHROMATE CONVERSION COATING ON ZINC, ZINC DIE CASTINGS AND ZINC PLATED COMPONENTS. THE PROCESS CAN BE USED AFTER ALKALINE CYANIDE, NON-CYANIDE, AND ACID CHLORIDE ZINC PLATING WITH A MINIMUM OF 5-7 MICRON THICK ZINC DEPOSITS.THE COATING PRODUCED BY THE PROCESS AFFORD HIGH CORROSION AND ABRASION RESISTANCE WITH FREE FROM STAINS AND FINGER PRINTS. IT WITHSTAND IN EXCESS OF 80 HOURS OF STANDARD SALT SPRAY SOLUTION WITHOUT WHITE CORROSION, AND PROVIDES CONSIDERABLE LUBRICITY.
ZINCHROMATE BLACK-163 PROCESS IS CONSISTED OF TWO LIQUID COMPONENTS FOR BATH MAKE UP AND MAINTENANCE. THEY ARE SIMPLE TO USE, HAVE LONG LIFE AND REQUIRE ONLY ROUTINE MAINTENANCE.
OPERATING CONDITIONS :
ZINCHROMATE BLACK-163 A – 100 ML/LITRE
ZINCHROMATE BLACK-163 B – 100 ML/LITRE
TEMPERATURE – ROOM
TIME – 0.5 – 3.0 MINUTES
pH (ELECTROMETRIC) – 0.8 – 1.8
EQUIPMENT :
HDPE, PP OR PVC TANKS CAN BE USED FOR ZINCHROMATE BLACK-163 PROCESS.
SOLUTION MAKE-UP :
1) FILL THE CLEAN TANK WITH 2/3 FULL OF WARM (50-70 C)
CHLORIDE FREE DEIONIZED WATER.
2) ADD REQUIRED QUANTITY OF ZINCHROMATE BLACK-163 A AND STIR TO
ENSURE THOROUGH MIXING.
3) ADD REQUIRED QUANTITY OF BLACK-163 B SOLUTION WHILE
CONSTANTLY STIRRING.
4) ADD WATER TO FINAL VOLUME AND STIR OPERATING SOLUTION
THOROUGHLY FOR AT LEAST 5 MINUTES.
5) ALLOW SOLUTION TO COOL TO ROOM TEMPERATURE.
7) CHECK pH OF THE BATH SOLUTION, IT SHOULD BE 0.8 TO 1.8 WITH
AN OPTIMUM pH BEING 1.15.IF REQUIRED, IT CAN BE LOWERED BY
USING 50 % TECHNICAL GRADE SULFURIC ACID OR RAISED BY USING
25 % SODIUM HYDROXIDE SOLUTION.
PROCESS SEQUENCE :
1. ZINC PLATING WITH MINIMUM 5 MICRON THICKNESS.
2. COLD WATER RINSE.
3. DEIONIZED WATER RINSE.
4. ZINCHROMATE BLACK-163 PROCESS.
5. DEIONIZED WATER RINSE.
6. DRY.
MAINTENANCE :
REPLENISHMENT ADDITIONS OF ZINCHROMATE BLACK-163 A AND 163 B ARE EVIDENCED BY CHANGE IN COLOUR OF THE PROCESSED PARTS OR BY LONGER IMMERSION TIME REQUIRED TO PRODUCE ACCEPTABLE COLOUR. REGULAR ADDITIONS OF 163 A AND 163 B SHOULD BE MADE ON VISUAL OBSERVATION OF PARTS BEING PROCESSED, BY pH CONTROL OR BY ADOPTING ANALYTICALMEASURES.
ANALYTICAL CONTROL :
1 ML PIPETTE
25 ML MEASURING CYLINDER
50 ML BURETTE
250 ML ERLENMEYER FLASK.
PROCEDURE :
1. PIPETTE A 1 ML SAMPLE OF THE OPERATING SOLUTION INTO A 250
ML ERLENMEYER FLASK.
2. ADD 15 ML CONC. HCL AND DILUTE TO 100 ML WITH WATER.
3. ADD 2 GM. OF POTASSIUM IODIDE AND MIX TO DISSOLVE.
4. TITRATE WITH 0.1 N SODIUM THIOSULPHATE SOLUTION TO A LIGHT
YELLOW COLOUR, ADD 2 ML STARCH SOLUTION AND CONTINUE THE
TITRATION UNTIL BLUE BLACK COLOUR DISAPPEARS.
CALCULATION :
MLOF 0.1 N SODIUM THIOSULPHATE USED X 10 = ML/LIT. OF 163 A AND/
OR 163 B
WASTE TREATMENT :
ZINCHROMATE BLACK-163 PROCESS SOLUTION ARE ACIDIC AND CONTAI. HEXAVALENT CHROMIUM. SODIUM BISULPHITE, SULFUR DIOXIDE OR FERROUS SULPHATE ARE USUALLY USED FOR CHROME REDUCTION BELOW 2.5 pH FOLLOWED BY NEUTRALIZATION TO pH 8 USING ALKALI AND SETTLING OF SOLIDS IS REQUIRED BEFORE DISCHARGING TO SEWAGE.