Zinc electroplating protects metal architectural and structural elements against corrosion and adds to their aesthetic appeal.
Architects are specifying and your construction crews are probably installing more plated metal structural and decorative elements in commercial, office and hospitality projects these days. Here are some things you need to know about the benefits of plating these elements with zinc, which makes them both more functional and aesthetically appealing, and popular with architects.
For more information, please visit Ruisite.
The fundamental purpose of zinc plating is to protect the metal against corrosion that can affect the strength of structural elements. But zinc plating is also a valuable technique to enhance the visual appeal of decorative metal surfaces in both interior and exterior settings, particularly when a varied, imperfect industrial look is required.
Superior Protection
Electroplated zinc plating provides a metal structural component with a clear, thin coating (approximately 5-25 microns) that protects the underlying surface without interfering with its functionality or its decorative features. This contrasts with thicker (100-150 microns) coatings applied by hot-dip galvanizing, which can fill in threads and holes and blur the appearance of decorative features. Also, the heat of the hot-dip process can warp long metal structural items and large steel panels.
In addition, zinc plating provides a “sacrificial coating.” This means that, if the plating is later scratched — even to the depth that the underlying bare metal is exposed — the surrounding zinc coating will “sacrifice” itself and continue to protect the exposed metal from corrosion. This level of protection can give interior decorative elements like wall panels a longer useful and attractive life.
In outdoor settings, standard zinc plating tends to weather and corrode, but still protect. If a weathered look is not the desired goal for a project, a zinc-nickel alloy plating will provide even greater protection — up to 10 times that of zinc alone — giving steel structures a longer corrosion-free working life comparable to the protection offered by hot-dip galvanizing, but without the thick coating and potential for warping.
Though most regularly used with carbon steel, zinc plating works equally well to protect other metals, including brass and copper.
Aesthetic Appeal
But beyond its ability to protect metals, a less-recognized benefit of zinc plating is its ability to alter the surface appearance of a metal element to enhance its aesthetic appeal. The subtle unevenness of surface color that zinc plating produces on larger metal panels, for example, gives the surface a somewhat industrial look, enhancing an “industrial chic” design. Architects we have worked with have used this look to create eye-catching storefronts and interior wall surfaces in restaurants, retail spaces and offices.
In addition to the standard clear zinc plating, plating can also produce coatings in black, iridescent and olive drab. This is possible because zinc plating is a two-step process. A clear chromate finish is traditionally applied to further reduce the corrosion of the zinc plating. This can be replaced by a yellow hexavalent chromate that results in an iridescent surface finish, a black chromate that produces a black appearance or an olive drab chromate that results in a military look.
In one project, industrial-look panels were combined with unfinished wood slabs to create vintage-looking countertops and a bar in a restaurant. In another, large polished steel panels were coated with yellow hexavalent chromate to form a dramatic iridescent wall, as seen in the adjacent image.
Meet the King
For those less familiar with electroplating and the finishes and protections its processes can provide, it is essential to consult with a knowledgeable plater. Some effects may not be achievable with plating but may be possible with other processes. Powder coating, for example, will be more effective for outdoor installations, especially when zinc plating is used as the base coating.
Also, not all platers are equal in terms of their capabilities. Can the plater plate a large wall installation in one piece, for instance, or would it have to be done in sections, necessitating welds or other joints that might affect the finished appearance? Is the plater capable of applying the chromates needed to produce the desired finish color?
Our company’s operations boast the nation’s largest zinc tanks. Our “King Kong” plating line can service very large components reaching 27 feet long, 7½ feet deep, 46 inches wide and weighing 7,500 pounds. This makes it unnecessary to work with smaller components that would need to be assembled after plating.
Because of zinc-plated materials’ structural and aesthetic benefits, architects are likely to continue to specify these elements for building projects while working with platers to make sure the finished products last for years.
Dry IBC Tote Technology allows you to make liquid chromic acid yourself. Removing all the hassles such as lifting heavy cans, dumping cans / dealing with chromic acid dusting, and triple rinsing multiple cans of hexavalent chrome a year! This technology greatly reduces the risks associated with hexavalent chromium-both from a safety and environmental perspective. Better for your employees, better for the environment, and better for your bottom line.
Benefits of Making Liquids using Dry IBC Totes vs Manufacturing Internally
Ability to manufacture liquid chromic acid in minutes rather than hours
Substantial Reduction in “PEL” (Permissible Exposure Limits)
Adjustable Concentrations for All Applications
No Cans to Rinse or Dispose of as Hazardous Material
Same Low Cost for Chromic Acid
Plating International. Inc. also offers Drop-In Tank Liners and Secondary Containment for your Chrome Plating Facility. Contact Us Today!
Did you know companies are finding the benefits of One-Plate® are even greater as one component is easier to order, ship, and stock than three components.
Shops are finding this very convenient especially now that supply chains are strained by transport issues.
Shops with short labor or split shifts are reporting how One-Plate® is easier to operate with less workers and lab analysis.
And for those shops where their business level is lower due to the pandemic, they are appreciating the savings in time, energy, labor, and costs.
One-Plate® is now in 15 countries on 5 continents.
Plating International has increased our manufacturing capacity to meet the growing demand.
Single component One-Plate® EN versions are now available in low, mid, high phos and composites with Teflon, diamond, silicon carbide and boron nitride.
Just as the cold weather is coming, Plating International has verified the freeze resistance of the most popular One-Plate® Q solution. Attached please see a photo with a typical "A" solution on the left and One-Plate® Q on the right. After two weeks in a 5 degree F (-15 C) freezer, the "A" solution is frozen solid. The One-Plate® solution was just very cold. We then tested the One-Plate® solution and it plated as well as it always does, so there was no negative affect from the cold storage.
New technical articles and case studies are in the works..
Also, in this Covid-19 time when travel is limited, we have been having frequent video conference meetings to support plating shops and prospective customers to answer any questions they have, please don’t hesitate to reach out to set up any calls like this.
Want more information on zinc plating line? Feel free to contact us.
Traditionally, most “polypro” tanks are made with what is called “propylene homopolymer,” or “natural polypropylene.” This type of polypropylene has a high strength-to-weight ratio and is known for its stiffness and rigidity. In the plating industry, this natural polypropylene is the go-to material for most plastic-type tanks.
There is, however, another material, called “polypropylene copolymer” which is a less common material but is nonetheless superior in many ways. This copolymer polypropylene is a type of polypropylene that has a modified polymer chain which includes a different, “random” monomer molecule (for instance, ethylene). This molecular change results in some serious changes in physical property.
Compared to homopolymer PP, copolymer PP has a much higher impact resistance, increased flexibility and durability, and a lower melting point (which results in a lower heat-sealing temperature). Copolymer PP also tends to have a better stress crack resistance and lower temperature toughness than homopolymer. At the same time they exhibit essentially the same chemical resistance, water vapor permeability, and organoleptic properties (low tatste and odour contribution).
Given the comparative advantage of copolymer PP, it seems like a no-brainer to have a copolymer PP tank over a natural polypro tank. Because the copolymer is much more flexible and less stiff than the homopolymer, it will have a longer life than a natural polypro tank, and will be more resistant to stress and impact (for example, if a heavy anode or cathode falls of the bussing to the bottom of the tank). This means they are also less likely to get damaged during delivery. Copolymer PP also has a moderately better impact strength at temperatures down to 0°C, and have limited utility down to -25°C.
Plating International offers rigid plating tanks in both propylene homopolymer and copolymer polypropylene materials. Contact us for a quote today.
Traditionally, most chrome baths use lead anodes. When we think of lead anodes, we usually just think about the lead part, but in fact the lead anodes that are used are never made of pure lead. Chromic acid in the bath eats away at pure lead, especially when there is no current. Pure lead is also quite soft, does not hold its shape very well and sags under its own weight. This is why lead is alloyed with other metals in order to give it specific properties. Various amounts of antimony, tin and silver are added to the lead depending upon the application.
Antimony: Provides hardness, rigidity and resistance to curling or sagging and is used whenever strength is required. High antimony contents, however, tend to produce excessive surface scale and a less than optimum trivalent control. Antimony has a density of 0.24 lbs. per cubic inch and a melting temperature of degrees F.
Tin: Provides improved corrosion resistance and conductivity, reduces surface scaling and improves trivalent control. Used primarily in high fluoride baths. Tin has a density of 0.26 lbs. per cubic inch and a melting temperature of 450 degrees F.
Silver: A small amount of silver (0.5 - 1%) greatly extends the corrosion resistance and increases the conductivity. Due to the additional cost, this is used only where an extended anode life is required such as in very high fluoride baths.
C. P. Grade Lead: CP grade lead (99.9 % chemically pure) is the basic material that is used to make the various alloys. CP lead has a density of 0.41 lbs. per cubic inch and a melting temperature of 620 degrees F.
Lead Alloys: The anode materials are purchased from a smelter already alloyed per specification. These materials are available in ingots, cast mats, rolled sheet & bars, extruded pipe and extruded rods or wire in various sizes. Extruded and rolled forms are much denser than cast materials are and will therefore hold up much longer and are better suited for large anodes or ones that need to last for long periods of time.
It is good practice to standardize alloys and use only one type per bath. If several alloys are used then the each type should be marked so they are not accidentally mixed. Lead alloys should never be obtained from a scrap dealer as the quality is unknown. Most lead alloys used for chrome plating have a density of around 0.40 lbs. per cubic inch and a melting point of 580 – 600 degrees F.
6% antimony - 94% lead: This is a very common alloy that is used for a majority of chrome plating anodes. The antimony provides both hardness and rigidity and is particularly well suited for large or heavy anodes. The surface film from this alloy provides reasonable control of the trivalent, but the scaling is heavier than if tin were present.
7% tin – 93% lead: Used in all type baths including high fluoride solutions. This alloy is softer than 6/94 is and may sag if too heavy or too large. This alloy has an improved peroxide surface film for better trivalent control and reduced scaling.
2% tin – 4% antimony – 94% lead: This alloy provides a combination of improved rigidity and corrosion resistance. It has a better surface film than 6/94 does, but not quite as good as the 7/93 alloy is. It is used where a combination of optimum strength, resistance to distortion and surface film is needed.
0.5% silver – 4% tin – 2% antimony – 93.5% lead: The addition of a small amount of silver greatly improves the surface film and increases the corrosion resistance. The silver content is typically 0.5%, although it can be as high as 1% for even greater benefit. This alloy typically lasts 2-3 times longer than the others do. Obviously, the cost of the silver must be weighed against the value of the additional benefits obtained. This alloy is used primarily in very high fluoride baths.
A fire on the plating lines is always a disaster, but one that can be avoided by taking the proper precautions. One of the most common causes of these fires is electrical heaters, which often set fire to plastic tanks because of a drop in the solution level.
A common misconception is that the thermostat will stop the heater. However, this is not the case. Why doesn't the thermostat stop the heater? It’s because the thermostat relies on the liquid to transfer heat from the heater to the probe/sensor. If there is a sudden loss of liquid and the sensor is no longer covered by the liquid, then no heat is transferred. The thermostat detects this as a drop in temperature and keeps the heater operating. With no liquid to transfer heat away from the heating element it begins to overheat and sets the plastic tank on fire.
Properly passivated stainless steel will not plate unless contacted by a plating part or the bath is not properly maintained. They must be passivated from time to time according to the procedures established (by STI) for safety and effective passivation without contaminating the solutions or rinse tanks. Stainless steel is composed of iron (Fe); nickel (Ni); chromium (Cr) and several other minor components. Stainless steel is not resistant to chemical or physical attack. The corrosion resistance of stainless steel depends on the formation of a ‘passive surface film’ composed of nickel and chromium oxides (Cr2O3 & Ni0).
Procedure:
1. Pump bath out into the corresponding drums, tote, or tank.
2. Spray rinse the tank & plumbing, then drain any leftover bath into corresponding drums or tank.
3. Pump in 40% Nitric for Passivation from the tote into empty tank.
4. Once tank is filled with “40% Nitric for Passivation” do the following 3 things.
A. Turn on all pumps to tank.
B. Set temperature of the “40% Nitric for Passivation” to 90o F.
C. After you have completed Set 1 and 2 set timer for 3 hours.
One of the major decisions that plating shops have to deal with is “what kind of plating tank should I get for my plating line?” Of course, we wish the answer was as simple as the question, but the truth of the matter is it depends on a lot of different things. What are you plating? Plating chromic acid is a completely different process than zinc or cadmium plating. How much are you plating? 300 gallons or gallons? What method are you using to plate? There are so many questions to ask and factors to consider, we thought it would be nice to see it in the form of a pros/cons table:
As you will see in the diagram above there are many different things to consider when choosing a plating tank. Polypropylene tanks are great for smaller bath sizes and they are well-suited for the harsh conditions provided by plating shops. Polypropylene tanks are also very durable and they are great for use with acids and alkalies, which is why you can sometimes avoid buying a liner for your tank (unless you’re plating chromic acid, which you’ll definitely still need a liner for!) Polypropylene tanks are also much more flammable than steel tanks, which can be an issue if you are using electrical heaters to heat up your bath. While steel can hold up to well over +°F, polypropylene melts at around 320°F. Another factor is their size limit - because of polypropylene’s lower tensile strength and modulus, you will likely need supports to prevent bulging and breaks at the seams; but steel tanks have a lot more natural support because of their higher tensile strength. However, steel tanks are vulnerable to other conditions that the polypropylene tanks will almost never encounter: they can rust and they are susceptible to pinholes, which can be very dangerous if not immediately fixed.
At the end of the day, you’re really going to have to take the time and think about what solution works best for your business needs. That’s why you should ask the experts here at Plating International. With over 40+ of working experience, we can help you well above-and-beyond all your plating needs. Contact us today for a quote on plating tanks!
The company is the world’s best chrome plating equipment supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
Comments
All Comments (0)