MAR CHROME PRO HC - 21 is a specially formulated High Speed Fluoride Chromium electroplating process which is a custom blend of the secondary fluoride type of catalyst with Chromic Acid. This high-speed capability is a function of the chemistry design, which allows higher current efficiencies over a large catalyst range. The system has the capability of processing at much higher current efficiencies as compared to conventional Chromic Acid systems. The increase in the constant deposition rate is a result of the consistent current efficiency.
The electroplated deposits from the MAR CHROME PRO HC-21 system exhibit a very shiny, bright and smooth surface at a large range of current densities. The deposition rate at 2 asi, 140 OF is approximately 1.15 mils per hour as compared to 0.8 mils per hour for conventional systems.
The MAR CHROME PRO HC-21 plating system is maintained with a liquid additive MAR CHROME PRO HC-21 RL which eliminates dusting and splash back from solid additions. The system consistency can be maintained using an amp-hour control system. Standard pretreatment cycles, anodes and equipment can be used as those in any hexavalent chromium plating systems.
A solid version, MAR CHROME PRO HC-21 RS of this system, is also available to minimize the transportation of water over a large distance. It contains all of the active components to maintain the working solution at optimum operating chemical parameters.
MAR CHROME PRO HC-21
|Chromic Acid||32 oz/USG (240 g/litre)|
|Sulphate radical||0.16 oz/USG (1.2 g/litre)|
|Temperature||120°F – 150°F (48°C – 66°C)|
|Cathode Current Density Range||1 – 6 ASI (15.5 – 93 ASD)|
Existing Chromium Solution Conversion
Most conventional plating solution could possibly be converted to the MAR CHROME PRO HC-21. An analysis of the impurities must be done to determine the level of metallic contamination prior to conversion. Fluoroboric type of systems can not be converted to the MAR CHROME PRO HC-21.
New Plating Solution Make-up
A new make-up can be accomplished by two methods. The use of MAR CHROME PRO HC-21 MU-L can be used. This liquid contains 490 g/litre of Chromic Acid and the required amount of MAR CHROME PRO HC-21 secondary catalyst. The second method of make-up would be the use of solid MAR CHROME PRO HC-21 MU-S which contains the correct amount of the secondary catalyst.
Using MAR CHROME PRO HC-21 MU-L
Dilute to volume with DI water.
Using MAR CHROME PRO HC-21 MU-L
Add DI water to ½ the volume
Bring the solution to the correct level with DI Water.
Heat the solution to the operating temperature of 140°F (60°C). At this time analyze the plating solution of sulphate. Add Sulphuric Acid to bring the sulphate content to 0.16 oz/USG (1.2 g/l) if required. Electrolyze the plating solution for 1 hours to form an equilibrium with all of the components.
The MAR CHROME PRO HC-21 plating solution can be maintained using the liquid MAR CHROME PRO HC-21 RL or the solid MAR CHROME PRO HC-21 RS. Both systems contain Chromic Acid and the Fluoride type secondary catalyst. The sulphate catalyst is monitored by analysis and adjustments are made with Sulphuric acid or Barium Carbonate if required.
The liquid MAR CHROME PRO HC-21 RL contains 450 g/l of Chromic Acid and the secondary fluoride type catalyst. Additions can be made at a rate of 350 ml per 1,000 amp-hours using an amp-hour controller with a feeder pump. Compensation for drag-out must be considered and added to the feed rate.
The solid MAR CHROME PRO HS RS contains the Chromic Acid and the secondary fluoride type catalyst and can be added to the plating solution at a rate of 15 KG per 100,000 amp-hours or by analysis of the Chromic Acid in the plating solution. Compensation for drag-out must be considered and added to the feed rate.
On occasions when reverse etching is performed in the plating tank, additions of the MAR CHROME PRO HC-21 CAT will be required to bring the Active Fluoride Catalyst to the correct range. This may be necessary to compensate for the depletion of the active fluoride by the formation of a complex of iron and fluoride. Additions will be recommended by analysis only.