ZINCHROMATE BLACK 164
BLACKENING PROCESS FOR ZINC :
THE ZINCROMATE BLACK-164 PROCESS IS A METHOD OF BLACKENING ELECTROPLATED ZINC, ZINCBASE DIE-CASTING COMPONENTS AND HOT DIP GALVANIZED COMPONENTS. IT PRODUCES AN ADHERENT ALLOYED TYPE BLACK COATING WHICH RESIST TEMPERATURE UPTO 175 C. THE THICKNESS OF THE ZINC COATING SHOULD BE ATLEAST 5 MICRONS. THE COATING IS A GOOD FINISH IN ITSELF AND ALSO SERVES AS A BASE FOR ORGANIC FINISHES SUCH AS LACQUERS OR ENAMELS. FOR FURTHER-PROTECTION AND BETTER COLORATION THE COATING CAN BE OILED, LAQUERED OR WAXED. IT INVOLVES CLEANING OR RINSING, IMMERSION IN THE BLACKENING SOLUTION AT ROOM TEMPARATURE FOR 2 TO 6 MINUTES, RINSING AND DRYING.
SOLUTION COMPOSITION AND OPERATION :
ZINCHROMATE BLACK – 164 100 GM/LITRE
TEMPERATURE 30-45 C.
DIPPING TIME 2-6 MINUTES
BATH PH 4.8.6.7.
AGITATION SLIGHT MECHANICAL MOVEMENT IS
MUST.
SOLUTION PREPARATION:
TO PREPARE THE SOLUTION THE ZINCROMATE BLACK – 164 SALT SHOULD BE DISSOLVED IN WARM WATER (40-45C). ADJUST THE VOLUME. ADD DILUTE HYDROCHLORIC ACID (10%) TO ADJUST THE PH VALUE TO 4.8(IF REQUIRED) DECANT CLEAR SOLUTION IN TO BLACKENING TANK.
EQUIPMENTS :
P.V.C. OR H.D.P.E. MOULDED PLASTIC CONTAINERS OR P.V.C. LINED M.S. TANK CAN BE USED.
PROCESS SEQUENCE:
(A) ZINC PLATED ARTICLES, AFTER ZINC PLATING –
1. WATER SWILL.
2. SWILL IN RUNING WATER.
3. IMMERSE IN ZINCHROMATE BLACK SOLUTION.
4. THOROUGHLY SWILL IN RUNNING WATER.
5. DRY IN WARM AIR OR IN CENTRIFUGE.
(B) ZINC BASED DIE-CASTING. –
1. HOT ALKALINE CLEAN.
2. WATER SWILL.
3. DILUTE ACID DIP (0.5 % V/V/ SULFURIC ACID) FOR 2-5 SECONDS.
4. RINSE WITH RUNING WATER.
5. IMMERSE IN ZINCHROMATE BLACK SOLUTION.
6. RINSE WITH RUNING WATER.
7. DRY IN WARM AIR OR IN CENTRIFUGE.
SOLUTION MAINTENANCE :
TO MAINTAIN THE EFFICIENCY OF THE SOLUTION THE PH VALUE SHOULD BE MAINTAINED NEAR TO 4.8 USING DILUTE HYDROCHLORIC ACID (10%) TIME TO TIME, WHEN THE IMMERSION TIME EXCEEDS 6 MINUTES TO GIVE PROPER BLACK COLOUR, AN ADDITION OF 10-20 GM/LITRE OF ZINCHROMATE BLACK- 164 SHOULD BE MADE. AFTER SOMETIMES IF FURTHER ADDITION OF 164 SALT OR PH ADJUSTMENT TO 4.8 HAVE NO EFFECT, PREPARE A NEW SOLUTION.
NOTE : OUR RECOMENDATIONS ARE MADE IN GOOD FAITH AND ARE BASED ON OUR SKILL AND EXPERIENCE. HOWEVER, SINCE THE CONDITIONS OF USE OF THESE PRODUCTS ARE BEYOND OUR CONTROL, THIS INFORMATION IS GIVEN ON THE EXPRESS CONDITION AND AGREEMENT THAT MAHAVIR CHEMICAL INDUSTRIES WILL NOT BE LIABLE TO ANY PERSON BY REASON THEREOF. NOTHING HERE IN SHALL BE DEEMED TO BE A RECOMMENDATION TO USE ANY PRODUCT IN VIOLATION OF ANY EXISTING PATENT RIGHT.