As we unpack from MRO Americas, going through our flyers, business cards, and tchotchkes allows us time to reflect on the information we gathered and the contacts we met. Here at SIFCO, the resounding theme, that our team noticed, was that of Cadmium Replacements and the need for environmentally friendly maintenance alternatives in the aerospace industry.
It is known that the demanding aerospace industry requires well-engineered solutions, but many fear deviating from the already established applications – although they may pose a risk to the operator and the environment. And even if proven solutions are available.
We recognize that selective plating, and surface finishing, are essential maintenance applications in MRO. That’s why SIFCO has developed and refined its products over the last fifty years to provide the highest quality, adherent deposits that are needed to meet industry’s ever-changing requirements.
Cadmium is a well-known and widely-used deposit for corrosion protection applications on landing gear, bushings, flap tracks, and other structural components of the airplane. But, cadmium is also a known carcinogen. And the risk it poses to the operator and the environment is why SIFCO developed its Cadmium alternatives over 15 years ago.
SIFCO’s Cadmium alternatives are superior quality deposits that are drop-in replacements in the Cadmium plating process. Zinc-Nickel LHE and Tin-Zinc LHE are less toxic alternatives to cadmium that can be used to repair damaged cadmium, zinc-nickel, tin-zinc, and damaged IVD aluminum on high strength steels. Both deposits provide excellent corrosion protection and are Low Hydrogen Embrittling, and do not require a post-plating, hydrogen embrittlement relief bake. When used in conjunction with SIFCO’s Trivalent Chromium Conversion, you can achieve 1,000 hours of salt spray with no base metal corrosion. These Zinc-Nickel and Tin-Zinc deposits are capable of meeting the performance requirements of AMS 2451/9, AMS 2451/10 and BAC 5664.
To learn more about SIFCO’s Cadmium alternatives, click here or contact us at info@sifcoasc.com.
In the electric industry, optimizing power flow is a primary concern for the generation, transmission and distribution processes. The key is providing and maintaining low resistance conductive joints through silver plated deposits.
Field experience and laboratory studies have shown that this is especially true in the case of bus bars and bolted high current connections. Specifically, silver plated bus bars outperform unplated bus bars by providing stable contact resistance and a low maximum operating temperature that increase the service life of the bus joint. More importantly, stable contact resistance joints will reduce the need for frequent maintenance, decrease overall downtime of equipment, and greatly reduce the risk of catastrophic failures.
Good industry practices recommend that all bus contacts be silver plated. Most government, IEEE and insurance provider specifications require that all bolted bus connections be plated in accordance with applicable specifications.
One of the key elements to effective bus bar contact plating is applying a uniform deposit of sufficient thickness to provide corrosion protection and a “leveling effect” to increase the surface area of the bus joint.
Brush plating, using pure silver, provides a simple, cost effective solution for in-place plating of bus systems during routine maintenance and can also be of value in upgrading bus, rather than replacing existing bus, when generator or system capacity increases are desired.
The Early Years
In older power plants, the aluminum or copper bus bars were installed. While the performance of an uncoated bus joint may have been sufficient years ago, today’s increasing demands for power, given the limited capacity and economies of the marketplace, are forcing the producers to improve the efficiency and performance of the entire system.
Many early bus connections have not been unbolted since first being installed as far back as 1910. Bus connections have several factors that limit their lifetime performance, including:
Irregularities in the mating surfaces
Particulate contamination prior to installation
Oxidation
These factors, when combined, have an escalating effect of increasing contact resistance and temperature and thereby decreasing the efficiency of the joint over time, potentially causing catastrophic failures. Even when new, imperfections in the bus bar’s copper surface result in only a fraction of that surface coming into direct contact with its connection. By some estimates, that fraction can be as low as ten percent. Although increasing the contact force may flatten out the high areas, the effects are minimal and may even place undesired stress on the fastening system.
The formation of non-conductive surface films due to harmful ambient atmospheric contaminants is also limiting factor of joint reliability – even in bolted contacts. Fritting will reduce the contact resistance of thin surface films, but thicker, more tenacious films may still present a problem that will be magnified by increasing temperature at the joint due to increased resistance. Fritting is the occurrence of the dielectric breakdown of a contact film. A potential gradient of 100V/μm could be sufficient to cause this dielectric breakdown.
The oxidation of the bus material is an ever-present occurrence unless steps are taken to prevent it with a barrier coating. The formation of oxidation layers on the bus material within joints leads to increased resistance, and thereby increased voltage drops and increased local temperatures. It has been reported that the joint resistance across uncoated bus can increase more than 20% due to oxidation formation. Studies have shown that silver plating bus joints significantly reduces bus material oxidation in service.
The combined effects of irregular surfaces, contamination and the formation of non-conductive surface films, and oxidation can create “hot spots” that will further deteriorate the reliability and performance of the joint.
A Better Joint
Testing and field experience has shown that one simple step can be taken to minimize the effects of irregular mating surfaces and the formation of oxides and other surface films on joint performance. That step is plating the joint area with a soft, conductive and corrosion resistant material. The application of a 0.0002” to 0.0005” thick deposit such as silver, nickel or tin can improve the lifetime performance of the joint by as much as 30% and reduce maintenance substantially.
Coating with a soft material such as silver or tin effectively forms a compressive gasket on the surfaces to be connected. The force applied when bolting the surfaces together squeezes the conductive material into the low areas, effectively increasing the contact area and decreasing the overall joint resistance.
Tests have demonstrated that these materials greatly slow down the formation of copper oxide and other surface films, maximizing conductivity and minimizing heat. A silver plated joint allows operation at a higher temperature without joint degradation over the life of the joint. The end result, over time, is significantly increased performance, efficiency, economy and reduced maintenance.
Because of silver’s softness it can be formed more precisely to the contours and crevices of the original piece increasing the actual contact areas. Silver provides a good electrical connection preventing the formation of copper oxide at the mating faces. A nickel coating has shown some cost advantages, but silver displays greater operating performance and efficiencies, exhibiting less resistance and maintaining lower temperatures while in service.
Tank plating the connection using a cyanide silver bath solves the problem of providing a sufficient thickness, but it is costly and time consuming. In the case of bus bars, they must be completely removed from the system and sent offsite for plating. Therefore, the increased outage time required for this method can be unattractive.
Electroplating, as performed using the SIFCO Process®, can be completed on-site with minimal disassembly, during any planned outage without removing the equipment from its location. To ensure safety for the operators and those in the surrounding areas, SIFCO ASC uses non-cyanide silver in its plating process. This portable plating process accurately applies the non-cyanide silver at a rate of 0.020” per hour, producing a smooth even finish. Two mating faces of a 4” x 4” copper bus joint can very easily be masked and plated with 0.0003” of silver in less than 15 minutes.
The desired thickness for each particular application and/or part is calculated prior to plating. SIFCO ASC uses digital ampere-hour meters to accurately control plating thickness to ensure smooth finishes and uniform plating.
A smooth finish and a uniform deposit of sufficient thickness will significantly enhance the reliability and the performance of the electrical joint.
Upgrading the Bus Duct System at TVA’s Fontana Dam
As part of the TVA’s comprehensive hydro modernization program, electrical bus duct systems are sometimes replaced with new systems sufficiently rated for the new higher unit output capacities. This occurs when a generating unit’s output rating is increased beyond the capabilities of its corresponding bus duct system or when the plant’s physical arrangement must change to accommodate other new equipment. TVA has, however, successfully demonstrated that many older bus systems can be re-rated to higher ampacities by using in-place brush plating to increase the current carrying capabilities of the bus. Success is highly dependent upon the modified bolted joints because they must be stable, reliable, and operate at a reduced contact resistance for a wider operating range. All of this can be accomplished at much less cost than bus replacement.
TVA has realized substantial savings by choosing to plate existing bare connections rather than upgrading to a new bus system. Bolted connections were silver plated in-situ during scheduled outages.
Steps in the operation:
Mechanically clean the contact surfaces to remove heavy oxides.
Solvent clean the contact and adjacent surface to remove any traces of oil or other residue.
Mask to define the area to be plated.
Electrochemical preparation
Plate the part
Remove the masking
Conclusion
The performance of contact joints is dependent on maintaining low resistance. The conductivity of the joint will naturally deteriorate over time due to the rigors of service as well as natural forces such as oxidation and moisture.
Testing has shown that plating bus joints with 0.0003” – 0.0005” thickness of silver greatly improves their lifetime performance. On-site selective plating with non-cyanide silver may be the most economical approach because it eliminates the need for component disassembly and transportation to an off-site plating facility, while quickly providing a superior quality, uniformly thick deposit that will stand the test of time.
For more information for your silver plated bus connections, contact us at 800-765-4131 or at info@sifcoasc.com.
Brush plating is an out-of-tank process used to apply electroplated deposits onto localized areas of worn or damaged shipboard components to resize and repair, or to improve the performance of those areas. This portable plating process provides a unique alternative to repair methods such as flame spray and welding when deposit thicknesses ranging from a few tenths of a thousandth of an inch to thirty thousandths of an inch are required.
The portable brush plating process can be used anywhere in the shop or aboard the ship. Unlike flame spray and welding, brush plating is carried out at room temperature and carries no risk of warping or distorting the component being repaired. The extremely adherent deposits are applied uniformly and accurately, in many cases eliminating the need for machining operations.
Typical applications include the repair of out of tolerance conditions on reduction gear housing and shaft bearing areas; the in-place repair of damage to hydraulic cylinders; resizing pump and motor/generator shafts and bearing housings; repairing steam cuts in the mating faces of turbine casings; and the in-place repair of worn crankshaft bearing seats for diesel engines.
Brush plating has been used by the marine industry for over forty years in very demanding applications. It is approved by the American Bureau of Shipping, Lloyds of London, and the US Navy. This flexible process provides a viable, cost effective alternative to flame spray and welding when lower metal thicknesses are needed for repair of shipboard components.
For more information on how selective plating is used in the marine industry, click here.
Suitable for a comprehensive array of aerospace equipment, including airframes and engines, electronic housings, landing gear, turbine blades, actuators, bearing journals, bushing bores, flap tracks and axles, the SIFCO Process® can be used for a range of applications, including:
• Corrosion Protection. With low hydrogen embrittlement and no baking required, repairs can be made in situ with minimal or no disassembly.
• Pre-Braze. Turbine components and frames are nickel plated to ensure proper wetting of the surfaces to be brazed. Selective plating offers a fast, consistent and cost-effective method of application.
• Surface Enhancement. The application of nickel or a nickel alloy improves the hardness and wear resistance of the component.
• Refurbishment. MRO applications use nickel or sulfamate nickel for dimensional restoration of an inside or outside diameter on the component.
• Anodizing. Repair applications replace worn or damaged hardcoat with a new, anodized hardcoat coating.
• Viable cad alternatives. Above all, the SIFCO Process® offers viable alternatives to applications using cadmium plating.
A safe, high quality cad alternatives
One of the most pressing challenges facing industry today is the question of cadmium. A known carcinogen, cadmium is being replaced in many sectors but remains the plating of choice in aerospace because of its performance.
However, government and environmental concerns are forcing manufacturers to find alternatives. Calling on years of experience and significant investment in R&D, SIFCO ASC has developed a range of well-engineered and proven cad alternatives that deliver excellent performance, while posing minimal risk to either operator or the environment.
While detailed studies show these alternatives do not perform well in tanks or as a thermal spray application, they deliver excellent results via selective plating, offering superior sacrificial corrosion protection for steel by combining the barrier protection of tin, with the galvanic protection of zinc.
A less toxic alternative to repairing cadmium, zinc-nickel, and damaged IVD aluminum on high strength steels, Zinc-Nickel LHE® can be applied in the shop or in the field, and does not require a post-plating, hydrogen embrittlement relief bake.
In addition to delivering a high-quality finish which extends service life, using the SIFCO Process® with Zinc-Nickel LHE® enables immediate and cost‑effective repairs caused by damage, wear, corrosion or mis‑machining. Without the need to remove the part from the aircraft, logistical costs are eliminated, and downtime and production delays are minimized. Essentially a drop-in replacement for cadmium, SIFCO ASC continues to strive to remove the barriers to switch.
The aerospace industry is a demanding market. Requiring advanced deposits which are applied consistently for each repair or OEM application. Many times, a critical area of the component is the inside diameter (ID). During tank anodizing, the inside and outside diameters (OD) do not build at the same rate. Often, the OD will meet thickness requirements while the ID remains significantly undersized. While custom cathodes can be developed for specific tank applications, it is costly and time-consuming.
Selective anodizing with the SIFCO Process® can ensure that the desired build is achieved on all areas for your components. Mostly used for touch-up and repair, selective anodizing allows the solution to reach areas that tank plating can’t or may have missed. These defects can occur from rack marks, rough handling, dirty areas, or errors in masking. Selective anodizing even permits the repair of the anodic layer without the need for stripping.
There are six principal types of anodized coatings: chromic, sulfuric, hard coat, chromic-sulfuric, boric-sulfuric and phosphoric. Depending on the type of anodizing process used, an anodized coating can provide improved wear resistance, corrosion protection, dimensional restoration and/or improved adhesive properties. These types of anodizing differ in the electrolytes used, the typical thickness of the coating formed, and the purpose of the coating.
The SIFCO Process® of selective anodizing can be used for many OEM and repair applications. Areas can range from small and simple, to large and complex. The process is portable and can be used both in the shop and the field. What’s more, the SIFCO Process® already meets the following specifications:
Hard chrome plating has been the go-to solution for manufacturers for more than six decades for the aerospace industry. However, the health and environmental concerns of this commonly-used deposit are well known – and with legislation in Europe bringing the reign of hard chrome plating to an end – engineers and site managers need to consider alternatives.
Danijela Milosevic-Popovich, our Research and Development Manager at SIFCO ASC looks at possible hard chrome plating alternatives.
To manufacturers operating within the aerospace industry, the benefits of hard chrome plating are clear to see. A critical process for both military and aerospace in terms of manufacturing and maintenance, hard chrome plating provides surfaces which are wear and corrosion-resistant for essential equipment, from hydraulic piston rods and propeller hubs to landing gear, gear shafts and gun barrels.
The dangers of hexavalent chrome
However, despite its many advantages, hard chrome plating has one major drawback: the use of hexavalent chrome. One of the notorious four Cs – along with cadmium, cyanide and chlorinated solvents – hexavalent chrome is a known carcinogen which causes damage to key organs, including the heart, lungs and kidneys.
Exposure to hexavalent chrome can occur at any stage of the plating process and demands lengthy preparation and clean-up afterwards. This fact, coupled with the production of toxic waste during the plating process, has led to a major reconsideration of its use.
Legislation is driving this agenda, particularly in the EU (European Union) – where the use of hexavalent chromium in electronic equipment is prohibited by the Restriction of Hazardous Substances Directive and the European Union regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals.
Additionally, the European directive, REACH, has been put in place with the aim to protect human health and the environment from hazardous chemicals. Despite applying only to chemicals which are manufactured or imported into the EU, the directive is having wider ramifications.
As the aerospace industry begins to shift in-line with global trends towards more sustainable products, more and more manufacturers are looking at how they can use an alternative to hard chrome plating.
Challenging the dominance of hard chromium plating
In finding a substitute to hard chrome, the problem lies in the benefits hard chromium plating brings to the aerospace sector. It performs at extremely high temperatures, has excellent corrosion and wear resistance and, together with hardness levels of 700-1,000 HV, delivers an excellent surface finish across a wide range of applications. With all of these attributes, finding an alternative solution which covers all bases is challenging.
Moreover, the dominance of hard chrome plating leads many people to ignore its limitations, including the fact it’s a relatively slow process, while the nature of the coating can lead to internal and residual stresses that may result in poor adhesion or the formation of microcracks. However, chromium plating is a universal ‘one stop shop’ and has become the default option for the aerospace industry. But this doesn’t mean there aren’t other options available.
A wide range of new technologies
Manufacturers are able to choose from a wide range of technologies, none of which use hexavalent chrome. These include various spraying techniques such as thermal spray, PVD and CVD, however, these methods require a high temperature, high vacuum, or high melting point for the substrate. There is also a new breed of super steels. Yet while each has advantages, they also have drawbacks including – in the case of new alloys – the fact they are costly and still unproven over time.
As a result, deciding which to choose can be challenging. Added to this, the aerospace industry is typically cautious. Any change – particularly one of this scale – is perceived to have a high level of risk involved. With particular attention to the components manufactured for the aerospace industry, many are designed to function for several decades without the need for maintenance, so their service longevity must be guaranteed. In the defence sector, where hard chrome plating is heavily utilised to protect mission-critical equipment, the stakes are even greater. Quite simply, none of these alternatives offers the universal appeal of hard chrome plating. However, as the industry shifts to a greener future there is another solution that has been proven to deliver a host of benefits in multiple applications: nickel tungsten, which can provide a viable alternative to the industry’s historic coating of choice.
The benefits of nickel-tungsten deposits
Nickel-tungsten has a variety of comparable characteristics to those of hard chrome including corrosion resistance, wear and hardness, even at high temperatures. It is also non-toxic, making it a truly viable alternative. What’s more, it is already specified in various industry standards, such as AMS2451C, MIL-STD-2197 A (SH) and MIL-STD-865D. It is these unique characteristics which have seen it used in a variety of applications, since manufacturers began to seek a more environmentally-friendly method of protecting components from the demanding conditions of the industry.
Nickel-tungsten in selective plating
The application of nickel-tungsten follows the principle of selective plating – a process developed by SIFCO ASC for electroplating localised areas without the use of an immersion tank. It delivers high hardness levels (660-690 HV, as plated) together with excellent wear performance (ten times lower sliding wear rate than hard chromium). In addition, lower surface roughness means less refinishing is required than with hard chrome deposits.
With the need to implement a solution which is tried and tested while following a familiar application process, nickel-tungsten can be adopted to achieve comparable – and sometimes superior – results to hard chrome plating in many applications.
Finding selective plating solutions for specific applications
There are many alternatives to chromium plating, but none are quite so universal in their application. As a result, the industry is being forced to think a little differently. Rather than striving to find a direct and complete replacement for all applications, it is perhaps better to find solutions which deliver results for specific applications. For example, a part might require the wear properties of chrome plating, but not its hardness or corrosion resistance. Equally, hard chrome plating typically has a higher co-efficient of friction than nickel-tungsten, making it less suitable for certain components. So, instead of it being a case of ‘one for all’, it is time to think about ‘many for specific’.
NiW on notched bar with Cu preplate 4
The development of metal matrix composites
Recently, processes have been developed and processing factors have been determined for chrome alternatives in the form of metal matrix composites (MMC). MMC coatings are defined by material with at least two constituent parts. They are formed in two phases: a ductile metallic matrix deposited from the dissolved ions in the solution, and a dispersed phase made from the co-deposited particles.
MMCs such as Cobalt Chromium Carbide, Nickel Tungsten Carbide and Nickel Chromium Carbide can offer unique and superior characteristics to metal plating solutions including hardness, wear resistance, and oxidation protection at high temperatures. When the right combination of materials is chosen, the properties can be tailored beyond the possibilities offered by pure metals and alloys.
However, there is a need for an alternative to hard chrome plating which offers similarly broad appeal. That solution lies in brush plating with nickel-tungsten. Providing a wide range of deposit properties capable of meeting a variety of application needs, and with excellent cohesion and adhesion to the base material, it is equivalent or superior to hard chrome plating in most respects – and superior in many. Perhaps the biggest advantage however, is the fact it’s safe, available and tried and tested in aerospace applications.
Finding safer, eco-friendly alternatives to hard chrome plating has been a main driver of brush electroplating research for the last decade. Brush plating, or selective plating, is a localized electrodeposition technique that does not require the use of tanks and is characterized by the use of a brush to deliver solution to the cathodes. Alternative to chrome in the form of metal matrix composites (MMC) offer unique and superior characteristics to metal plating solutions including hardness, wear resistance, and oxidation protection at high temperatures. Processes have been developed and processing factors have been determined for chrome alternative MMC of Cobalt Chromium Carbide, Nickel Tungsten Carbide and Nickel Chromium Carbide. These composite coatings were deposited using a range of current densities and brush materials to assess their impact on homogeneity and performance.
Join us at 5pm on Monday, June 4 at the NASF SUR/FIN 2018 Expo where Danijela Milosevic-Popovich will review the advancements and process improvements of Cobalt Chromium Carbide, and demonstrate the research and effectiveness of Nickel Tungsten Carbide and Nickel Chromium Carbide.
Danijela is the R&D Engineer/Project Manager at SIFCO ASC. She graduated from University at Buffalo with a Bachelor of Science and Master of Engineering in chemical engineering, then continued on to earn her Master of Engineering Management from Ohio University. Prior to joining SIFCO in 2005, she worked in the semiconductor and rubber industries.
At SIFCO ASC our engineers are at the heart of what we do, and for them, no single day is ever the same. To really understand what it’s like to be a SIFCO ASC engineer, we caught up with Tom Gregg, Jr. who shared insights about his role and why he’s so passionate about his work.
Having worked at SIFCO ASC for almost two decades, Tom’s knowledge – of the industry, of clients, and of processes – is hard to beat. Besides that, his ability to work flexibly and accommodate demanding shift patterns is complemented by his bespoke training and vast experience. Before getting into the selective plating industry, Tom worked in a steel mill which helped him establish essential skills which have helped him become a true credit to the SIFCO ASC team.
After joining the company in 2002, expert on-the-job training meant Tom was able to quickly transfer his skills to ensure the SIFCO Process® added value to every customer job, as well as keeping pace with the demands of the industries of his customers. Over time, Tom has worked his way up to the position of Class 1 Plater, putting him in charge of the shop floor.
A typical day
“The best way of describing my typical day is to say that no two days are ever the same,” says Tom. “Because of the portable nature of our service, we regularly have overnight trips to customers’ sites, making the process as smooth as possible for them. In practice, that reduces downtime and all the costs associated with that, as well as the hassle of enormous repair or maintenance operations. For me and the team, it can mean travelling to Kentucky, Indiana or Pennsylvania, and probably spending a couple of days on the road for each job. But customers appreciate that, and for us, it makes every job different and more exciting to work on.
“Of course, on-site customer work can introduce a few challenges. For each job we work very closely with the customer to make sure the environment is ready for us to do our work. Without that, it would be almost impossible for us to carry out our work effectively – without first cleaning the immediate area. From there, we can carry out the specific set-up required to effectively apply our process – a delicate task which becomes easier with experience so that the operation goes smoothly.
“Our customers really appreciate all of these services though. Our process and the way in which we carry it out can – and does – save them a lot of money in the long run and helps them get the most out of their critical equipment.”
Developing relationships
“In the time that I’ve been part of the SIFCO ASC team I’ve developed an excellent rapport with customers, and when they require our services, they will often ask for me by name, which is always nice as it means they’re confident in my work and that of the broader team. Naturally, once you’ve worked with customers a few times, you get to know them personally too, and that makes my work even more enjoyable. So even when I’m on the road for a few days, there’s almost always some familiar faces around.”
The enjoyment Tom gets from his day-to-day work when working with customers and visiting their sites has also been positively received by his family.
“Having spent a great deal of my career with SIFCO ASC, my family have seen how much I enjoy my work, so much so that when my son had the opportunity to join, he did. From my perspective, that speaks volumes about the type of company SIFCO ASC is, and I’m proud to see my son getting access to the same opportunities as I did and building a career with a strong company that has an equally proud heritage.”
As Tom’s – and his son’s – role evolves, they become increasingly familiar with the industry’s trends and challenges, from changes in equipment through to automation. Their experience, coupled with the expertise of SIFCO ASC, ensures they can meet many demanding applications, while continuing to provide high levels of service which are at our company’s heart.
Derek Vanek,Technical Manager at SIFCO ASC, explains how shipyards can put key technologies in the dock which offer speed, portability and efficiency.
For those in the shipbuilding industry, salt water and generally harsh operating conditions make repairs a constant and inevitable fact of marine life. Causing corrosion and damage to critical components such as pumps, valves and motors, regular maintenance or replacement is commonplace, resulting in costly downtime and loss of earnings. As a result, surface plating is widely used to repair or salvage critical components.
Typically carried out when in shipyards, the nature of the plating process usually means this work is performed by plating or machine shops off-site. Offering corrosion protection and wear resistance, with numerous coatings (including nickels, copper, silver, and nickel alloys) and methods of application, key components are typically disassembled and sent to nearby service shops. However, driven by a desire to save time, increase revenue and add value to their customers, many shipyards are now looking to bring the plating process in-house. In this respect, one method stands head and shoulders above the others: selective plating.
Leading the way in surface plating technology, selective plating lends itself particularly well to the demands and business models of shipyards. It is hardly surprising, therefore, that many are turning to the SIFCO Process®, the world’s leading portable method of selective plating. There are numerous reasons for this – let’s look at the top 6.
1. Performance
Essentially, the three common surface finishing processes (tank plating, thermal spray and selective plating) deliver the same end result. However, there are small differences in certain mechanical properties including adhesion and thickness of the deposit. Generally speaking, selective plating is equal to tank plating and thermal spray in most cases, and superior in many. Tests run in accordance with ASTM C633-79 on the SIFCO Process® show that two commonly used nickel deposits had a bond strength exceeding that of the bonding cement. In addition, the hardness of finish with selective plating lies within the broad range of performance obtained with tank deposits. Similarly, its adhesion is comparable to tank plating in most applications. Metallurgically dense and free of defects, brush plated deposits meet or exceed the requirements for tank electroplates, and far exceed those of thermal spray. Moreover, selective plating is carried out at room temperature, eliminating the risk of heat distortion or hydrogen embrittlement, both of which can lead to parts failure. Whereas thermal spray provides a mechanical bond, the SIFCO Process® creates a powerful atomic bond which is resistant to cyclical temperature fluctuations and sharp, direct impact. For this reason, the SIFCO Process® has been widely adopted by naval shipyards across the US, UK and Japan, and is used on a wide range of components such as turbine casings, providing a metal-to-metal seal with less risk for thermal distortion than welding.
2. Speed
Clearly, one of the key reasons for bringing surface coatings in-house is to accelerate the process and minimize downtime. In this respect, selective plating scores highly. With tank plating, parts have to be removed and usually shipped to a sub-contract plating company. Extensive masking may also be necessary, adding time to the process. Furthermore, certain parts may be too large for the tank to accommodate. With thermal spray technology, the application of the coating cannot be precisely controlled, so further machining is often needed to achieve the correct specification, adding a step to the process. Selective plating avoids these complications. Compared with a deposition rate of 0.001″ per hour for tank plating, selective plating is up to 60 times faster (0.015” per hour), accelerating the process. It’s also more precise, potentially eliminating the need for post-process machining. Most significantly of all, it can be applied in situ with only minimal disassembly and masking. Rather than the parts coming to the process, the process is able to go to the parts – and this is perhaps the key benefit of selective plating.
3. Portability and Ease of Use
While selective plating can be applied in a dedicated workshop – or by an automated process – it can also be delivered as a truly mobile service. Unlike the relatively complex processes of tank plating and thermal spray, only four core elements are required: a power pack, plating tools, plating solutions and a trained operator. It can literally be carried on site, or on board, and applied in situ, helping enhance or repair OEM components or salvage worn or mis-machined parts. It is a relatively easy process, and certified technicians and engineers can take on the role after training, opening up the ways to upskill ‘tiger teams’ to add value to shipyard services.
4. Safety and Environmental
Following significant investment in R&D, SIFCO ASC has developed a range of well-engineered and proven deposits that deliver excellent performance, while posing minimal risk to either operator or the environment. In addition, selective plating consumes less energy and produces less effluent water waste, adding to its sustainable credentials. The SIFCO Process® is therefore a safe, sustainable and cost-effective technology.
5. Versatility
Suitable for a wide variety of sizes – from inside diameters as small as 1/4″ through to components too large to be tank plated, the SIFCO Process® offers a high degree of versatility and is written into shipbuilding specifications, including the American Bureau of Shipping, Mil-STD 2197(SH) and NAVSEA. First approved by the US Navy over 50 years ago, it remains the market leading product, supported by a global business. This, coupled with ease and portability make it an ideal process for a wide range of components and on-board repairs, including large, hard-to-move components such as propeller shafts, bearing seats and turbine casings. Other components suitable for selective plating include propulsion components, hydraulics, and electrical and structural systems, so it is suitable for many marine applications.
Automation
Although the SIFCO Process® is typically a manual process, it can also be automated to meet the demands of higher volume plating applications, to include data logging and improved traceability. In automated applications, a computer program controls tooling and chemicals, while a robotic arm delivers consistent application during both pre-treatment and plating. Real-time data allows shipyards to monitor quality control while improving traceability and repeatability. Additionally, automation reduces ergonomic risk to the operator, limiting their exposure to chemicals used in the process.
6. Cost
Apellidotely, cost will be the key driver in terms of shipyard investment, and many factors combine to make selective plating the process of choice. Requiring minimal equipment and space, it needs less capital investment in tools and personnel. Its portability means it can be used for large, difficult-to-move components such as propeller shafts, reducing the need for expensive disassembly and shipping of components. It provides a permanent and cost-effective repair, with minimal need for additional machining. It facilitates remanufacturing as an alternative option to replacing equipment, extending its useful life. It consumes less energy and chemicals than other technologies and – most critically – it accelerates turnaround to minimize equipment downtime and production delays.
Quality and Assurance
In addition to providing a superior and more consistent coating quality, the SIFCO Process® is easier and faster to apply, resulting in less downtime. Moreover, by having the process in-house or in situ, traceability is improved and risks inherent in the supply chain are reduced with less dependence on sub-contract plating. The net result is improved production flexibility and efficiency and a reduction in total product cost. Critically, the SIFCO Process® uses lower volumes of materials, minimizing EHS concerns. The process not only exceeds the fundamental requirements of shipbuilding manufacturing, and repair and maintenance processes, it also provides a full circle of benefits, including quality, durability, cost saving, portability and time saving.
Learn more about how the SIFCO Process® brings protection on board at www.sifcoasc.com/marine
For years, cadmium has been the solution of choice for corrosion protection and repairs in the aerospace sector.
However, as the industry knows, it’s damaging to the environment and toxic to humans, and so it is slowly being phased out. But when will it happen, and what will take its place?
We conducted a survey and found that only 23% of aerospace respondents believe they will be cadmium free by 2023. The reason, it seems, is a lack of credible and up-to-date research about what alternatives to use.
Most people don’t believe there’s anything suitable out there – or if there is, they’re not yet aware of it.
To help, we established the Cadmium Knowledge Hub. This resource includes detailed manufacturer reports and academic research papers into the topic of cadmium and cadmium replacements.
Here’s a very quick review of one of these investigations – a review of the suitability of four cadmium replacements to electrodeposited cadmium: IVD aluminum coating as well as alkaline zinc-nickel, acid zinc-nickel and tin-zinc plating.
Using cadmium as the control for some rigorous research activities, each replacement was subjected to seventeen separate tests, ranging from adhesion, lubricity and repairability through to fatigue and corrosion resistance. For the first time ever, the results allowed a direct comparison of the methods.
What conclusions did the report come to?
The cadmium replacements evaluated in the tests can be confidently used without compromising performance
Overall, alkaline zinc-nickel exhibits the best performance of the four cadmium replacements, and in terms of ratings, is very similar to cadmium
IVD aluminum earns the second highest overall ratings compared with cadmium, followed by acid zinc-nickel and tin-zinc
Against criteria which demanded that the coating should be ‘continuous, smooth, adherent, uniform in appearance, free from blisters, pits, nodules, burning, contaminants, excessive powder, and other apparent defects which could reduce serviceability or protection’, all cadmium alternatives were judged to be easily controlled and able to produce a suitable finish
Placed in a neutral salt spray (fog) test cabinet for 3000 hours, none of the cadmium alternatives exhibited red rust or failure, demonstrating effective corrosion resistance
Both alkaline zinc-nickel and IVD aluminium plating are easy to strip off and replate
Alkaline zinc-nickel plating is an effective substitute for low-strength steel applications, while IVD aluminum is suitable for both low and high-strength steel applications
For hazardous plating applications, alkaline zinc-nickel and IVD aluminum are effective alternatives to cadmium
SIFCO ASC Zinc-Nickel LHE® has a pH of 8.8 and could be considered an alkaline Zi-Ni. It is an acceptable substitute for both low and high strength steel applications
When using either a primer or primer and topcoat with brush plating, maximum paint adhesion is achieved with the use of a chromate conversion coating. This is true for all finishes, including cadmium.
SIFCO Applied Surface Concepts uses cookies to give you a more personalized experience on our website. If you continue to use our services, we assume that you accept such use. Learn more about cookies and how you can refuse them on our Privacy Policy page.OkPrivacy policy
Chinese (Simplified) 
English 
French 
German 
Spanish 
Swedish 
