Ronuk Industries

TRIPASS YELLOW: 203

INTRODUCTION: The Plating Industry requires complying with pollution control norms of banning hexavalent. The Tripass Yellow 203 is especially developed to produce iridescent yellow conversion coatings on zinc-plated components.

The process employs two additives or a two-pack system for make up and for maintenance.

After processing and rinsing, waxes, seals and coats can be applied to further enhance the corrosion resistance.

EQUIPMENT:

Tanks:Lined with koroseal, PVC, polypropylene or polythene, steel or ceramic tanks may also be used.

Coils : Stainless Steel

Agitation : Mild from the filtered low-pressure blower.
Air agitation must be uniform and directed under the plated parts.

CHEMICALS REQUIRED:

TRIPASS YELLOW: 203 A for make-up and maintenance
TRIPASS YELLOW: 203 B for make up and maintenance

Sodium Hydroxide or Nitric Acid for pH control

Adjustment: OPERATING CONDITIONS

Iridescent yellow on zinc

	Optimum	Range
TRIPASS	203 A	90 ml/l 80 – 100 ml/l
TRIPASS	203 B	12 ml/l 10 – 15 ml/l
PH (electronic)	2.0	1.8 – 2.2
Immersion time	60 sec.	15 – 90 sec
Temperature	28°C	25°C – 35°C
Drying temperature	100°C	70°C – 110°C

* Fresh solutions may require a shorter immersion time of 15 – 30 secs. as per thickness of the zinc electrocoat.

MAKE-UP PROCEDURE:

Add water to the tank to ¾ of the desired final volume.

Add the required quantity of Tripass 203 A

Add the required quantity of Tripass 203 B

Adjust to the final volume with water.

Check pH and if necessary adjust with nitric acid or sodium hydroxide.

PROCESS SEQUENCE:

The following sequence is recommended for the application of Tripass 203 on zinc deposits.

Zinc plate
2 x cold water rinse Predip in 0.25% nitric acid
Tripass 203 A & 203 B x cold water rinse
Apply sealants, coats and waxes as per requirement of specification.
Dry.

Avoid long transfer times. Discoloration might occur; Drying should be carried out using hot air (60 – 80°C).

Intermediate drying between passivation and sealing has a favorable influence on corrosion resistance for rack applications (60 – 80°C).

SEALERS:

Different options for sealing are available. To obtain excellent corrosion performance Tripass 203 process can be combined with final sealers, waxes etc., for higher corrosion resistance.

CONTROL PROCEDURE:

In most instances it will be possible to control the Tripass 203 solution by visual observation of the work.

MAINTENANCE:

The consumption of the Tripass 203 additives is mainly dependent on the geometry of work to be processed.

An addition rate of 0.4 – 0.8 liter Tripass 203 A and 0.8 to 1.0 liter Tripass 203 B per 100 m2 can be used as guide.

ANALYTICAL PROCEDURE:

Reagents required

Sulphuric acid, reagent grade
Ammonium persulphate
0.1 N silver nitrate solution
Ammonium bifluoride
Potassium Iodide solution 10%
Starch solution (5 g/l)
Sodium Thiosulphate 0.1 N

Equipment:

1 Burette – 50 ml
1 conical flask – 300 ml
Measuring cylinder 10 ml or graduated pipette – 10 mls

Procedure:

Pipette 10 mls of the bath solution into the conical flask.

Dilute to 100 mls with demineralised water.

Add 3 mls of sulphuric acid – caution; this is a heat producing reaction.

Add 2 g ammonium persulphate.

Add 25 mls silver nitrate solution, with a pipette.

Add glass beads and boil for a minimum of 15 minutes.

Cool to room temperature

Add approximately 0.25 g of ammonium bifluoride.

Add 15 mls of potassium iodide solution.

Stand for 5 minutes

Titarate with sodium thiosulphate 0.1 N solution.

When the yellow colour fades, add 3 mls of the starch solution, continue titrating until the colour changes to green

Mls of sodium thiosulphate x 6.0 = ml/l Tripass 203 A

Waste disposal:

Please note that all waste materials must be discarded in accordance with local authority regulations, and therefore it is essential to ensure that the method suggested will produce effluent of a standard acceptable to the local authority concerned.

Tripass 203 solutions are acidic and contain trivalent chromium. The pH should be raised to 8 or 9 with an alkali such a soda ash or lime, the solids removed by settlement or filteration before discharging the solution. The sludge will contain heavy metals and must be disposed of in accordance with the local regulations.

HANDLING AND SAFETY INSTRUCTIONS:

For detailed information consult the material safety data sheets for this product.
Please read material safety data sheets carefully before using this product.

DISCLAIMER:

All recommendations and suggestions in this bulletin concerning the use of our products are based upon tests and data believed to be reliable. Since the actual use by others is beyond our control, no guarantee expressed or implied, is made by supplier, its subsidiaries of distributors, as to the effects of such use or results to be obtained, nor is any information to be construed as a recommendation to infringe any patent.