Fengfan Trivalent Chromium Passivator for Blue Zinc Plating Trivalent Chromium Passivator TR-290HC

Product Overview

TR-290HC is a liquid trivalent chromium passivator for zinc-plated steel, chosen where a plain blue is not blue enough. On alkaline non-cyanide zinc it produces a blue-purple tone with good corrosion resistance, the combination that visible fasteners, brackets and decorative hardware need.

Because the passivation dip is the last wet step in the plating process, a change here shows up immediately on the finished part: color, coverage and how the surface survives handling afterwards. The step itself is short and sits at the end of the line, after the process of electroplating and the rinse that follows, and before drying, sealing or assembly.

Fengfan has supplied surface-finishing chemistry since 1984. Alongside this passivator we supply the brighteners, purifiers and sealants that sit around it on the line, plus the acid zinc plating chemicals for the tanks upstream, so a shop that offers plating services can source a whole zinc sequence from one place and get advice on how the steps interact. The same range covers the blue and black passivators used on zinc nickel plating, so a plant running more than one zinc system can keep them apart without going to several suppliers.

Key Features

• Blue-purple rather than flat blue. On alkaline non-cyanide zinc the film reads deeper than a standard blue passivation, which is what makes it worth specifying on parts a customer will actually look at.
• No hexavalent chromium. The bath is built on trivalent chromium, so the dip tank and the rinse behind it carry no Cr(VI) burden and the waste stream is simpler to handle.
• Forgiving on line timing. Ordinary variation in immersion and transfer time does not flip the color, and that is what makes day-to-day maintenance and management convenient on a busy line.
• Barrel, rack, automatic or manual. The same product runs in a barrel electroplating plant and on a rack tank, and it can go into a manual line while an automatic line runs beside it.
• A plating solution that stays predictable. Concentration and pH are the two numbers to watch in the metal plating process, and both move slowly enough to be corrected between shifts.
• Sealer-compatible. Used with a PN-series sealant it gives longer corrosion protection than the passivation step on its own.

Specifications

Process Sequence & Bath Control

1. Finish the zinc first. The passivator colors what the electroplating step left behind, so a bright, evenly plated surface is the starting point; no dip rescues a dull deposit.
2. Rinse thoroughly before the dip. Carry-over from alkaline or acid zinc plating chemicals shifts the pH of the passivator and dulls the finish.
3. Check the bath at the start of each shift. Concentration and pH are corrected then, not after a run has already gone pale.
4. Keep the parts moving in the tank. A still bath leaves streaks and unwetted patches, most visibly on flat rack work.
5. Move parts to the rinse without a pause. A slow transfer lets the film keep building on one face and not the other, and the difference only shows after drying.
6. Rinse cool, then hot, then dry. Parts should be dry before they are handled, sealed or packed, because a wet film marks easily.
7. Expect drag-out. It is normal in any metal plating process for the bath to leave the tank on the work, so concentration falls with throughput; top up from the make-up figure rather than by eye.
8. Keep the plating solution clean. Filter out solids and carried-over rinse water instead of letting them accumulate in the tank.

Applications

• Automotive manufacturing. Fasteners, clips, brackets and small pressings are zinc plated and passivated before assembly, and the finish has to survive handling, torque and the weather under the vehicle. The parts come straight off the process of electroplating, so a color problem shows up on the assembly line rather than in the plating shop, and batch-to-batch consistency counts as much as corrosion performance.
• Builders' hardware and general fasteners. Screws, hinges, anchors, chain and wire fittings, where a decorative blue is the expected finish and the part is judged on appearance as much as on protection.
• Appliance, HVAC and enclosure hardware. Brackets, fan housings and stamped panels that stay visible in service, and where handling marks show quickly.
• Job shops and captive lines. A shop selling plating services on mixed barrel loads needs one passivator that copes with whatever the metal plating process sends down the line — different shapes, sizes and dip times — without resetting the bath for every job.
• The neighboring steps. SZ-30B brightener for sulfate zinc, ZN 50 bright alkaline and ZN-500 cyanide-free alkaline brightener, Phoenix EB 204A-204B divalent tin coloring additive, Phoenix Seal 149-L and 149-T anodizing sealants, FI-970 bright acid copper, Nickel Purify P3, FF-116 chrome mist inhibitor and FF-4219 nano-protection for wood, stone and concrete all come from the same range and can travel on one order.

Blue-Purple Color Control

A blue-purple passivator does not paint color onto a part. It forms a thin chromium film by reaction with the zinc, and the color you see is that film sitting on the deposit the process of electroplating produced.

Two things follow. The zinc layer sets the ceiling on the shade: a bright, fine-grained alkaline non-cyanide deposit takes a deeper blue-purple than the same part run after acid zinc plating chemicals, which build a different surface. And film build sets the tone, with a short dip reading lighter and a longer one moving toward purple.

Once the color is where you want it, lock it. Write the dip time and the transfer speed into the plating process sheet, and treat pH and concentration as the two variables that can still move. A bath that is drifting shows up first as a pale, uneven tone on the parts that spend longest in the tank.

Geometry matters as much as chemistry. Recessed areas and the inside of a barrel load see less fresh solution, so heavily shaped parts come out lighter in the hollows than on the flats. Drying matters too: water left standing on a freshly passivated part leaves marks that a second dip will not level.

If a customer's drawing names a specific blue, approve a physical sample under the light they will inspect in and keep it with the batch record. That sample settles more arguments than any color description on a purchase order.

Ordering, Packing & Delivery

Automotive Corrosion Resistance Applications

In automotive manufacturing, the longevity and durability of metal components are critical. Parts such as brake calipers and engine components have to withstand harsh conditions, and metal plating services help ensure they do. Electroless nickel plating services give manufacturers uniform coatings that improve wear resistance and reduce friction. Passivation of stainless steel is also essential for preventing rust and corrosion in exhaust systems. The TR-290HC Trivalent Chromium Passivator from Fengfan Trade offers a reliable way to achieve a blue finish that improves aesthetic appeal while providing superior corrosion resistance, making it a suitable choice for automotive applications.

Technical Support & Model Matching

Choosing the right match is where most sourcing decisions stall. As a trading supplier, we keep one point of contact from first enquiry to after-sales: tell us what you are making and the conditions you work under, and we shortlist the closest matches from our supplier network, compare specifications and arrange samples before you commit to a bulk order. If something does not behave as expected, we work with the supplying partner on the cause and a practical fix, and stay with the case until it is settled. Email, WeChat or WhatsApp enquiries get a reply within 24 hours.

FAQ