Galvanic zinc plating: Functioning, pros and usage
The history of galvanic zinc plating dates back to the 19th century, when electrochemistry was first used to coat metals with a thin layer of zinc to protect against corrosion. Since then, the technology has been refined to lend itself to the precise processes we know today. The evolution of zinc plating was driven by the need to provide long-lasting protection for steel structures, automotive parts, electronic equipment and many other products exposed to external factors.
The method has found its way into virtually every sector, from construction, through automotive, to electronics and telecommunication. Galvanic zinc plating not only protects metal from corrosion, but also increases its lifespan, resulting in lower maintenance and replacement costs.
In the face of modern challenges such as sustainability and environmental protection, zinc plating offers solutions that harmonise with environmental and economic needs. By extending the life of products and reducing the need for frequent replacements, it contributes to reducing waste and the resources needed to produce new parts.
What is galvanic zinc plating?
Galvanic zinc plating, also known as electrochemical zinc plating, is a method of protecting metals from the destructive effects of corrosion. The process involves the electrochemical deposition of a thin layer of zinc on the surface of a metal object, usually steel, by immersing it in a solution containing zinc ions and then conducting an electric current through the solution. The metal object then becomes the cathode in the electrochemical system and the zinc from the solution is reduced and deposited on its surface, forming a solid, protective layer.
Galvanic zinc plating offers advanced, effective protection for metal objects, using electrochemistry to create a durable, protective layer of zinc.
Zinc plating on hangers or on rollers
Galvanic zinc plating can be divided into on rollers (barrels) and hangers:
Galvanic zinc plating on hangers is often used for the production of components that have difficult-to-reach areas, such as lines, rods, structural components, or the automotive and energy industries.
CPP “PREMA” S.A. offers a zinc plating service on hangers, where the size of a tub is 600x400x800 mm and the weight of a component must not exceed 25 kg.
Galvanic zinc plating on rollers is useful when it is necessary to coat small-sized or unusually shaped components accurately and evenly. Such components may include, but are not limited to, bolts, nuts and connecting elements.
CPP “PREMA” S.A. offers a zinc plating service on rollers, where the size of a tub is 600x400x800 mm and the weight if a componet must not exceed 25 kg.
Comparison with other protection methods
Compared to other methods of corrosion protection, such as painting or hot-dip zinc plating, galvanic zinc plating offers several unique advantages:
- Coating quality: An extremely uniform, thin protective layer that adheres perfectly to structural details, even in hard-to-reach areas.
- Cathodic Protection: Not only does it form a physical barrier, it also provides cathodic protection. Zinc, being more electrochemically reactive than steel, preferentially corrodes, thus protecting the base metal.
- Aesthetics and Finish: With the possibility to apply additional finishing layers, such as chromium plating, galvanic zinc plating makes it possible to achieve aesthetically appealing surfaces while keeping corrosion protection.
- Precision and Control: The process allows precise control over the thickness of a zinc layer.
How does galvanic zinc plating work?
The galvanic zinc plating process is carried out as follows:
- Metal Surface Preparation: To begin with, all impurities like grease, oil, rust, non-metallic inclusions or other contaminants are removed by mechanical (sandblasting, grinding) or chemical (degreasing, etching, acid baths) processes.
- Immersion in Electrolyte Solution: The object is then immersed in a specially prepared electrolyte solution containing zinc ions. This solution acts as a medium that allows an electric current to flow.
- Electrolysis and Current Conduction: In an electrochemical system, the object to be zinc plated becomes the cathode and the anodes are usually zinc plates. When an electric current is conducted through the solution, zinc ions are reduced and deposited on the metal surface.
- Formation of a Zinc Layer: The deposition of zinc on the metal leads to forming a durable, uniform protective layer that effectively protects the base metal from corrosion. The thickness of this layer can be controlled by adjusting the electrolysis time and current.
- Finishing and Protection: Once the zinc plating process is complete, the item can be subjected to additional finishing processes such as passivation, chrome plating or painting to provide additional protection and give a sublime appearance.
The role of electrochemistry in galvanic zinc plating
Electrochemistry is the foundation of a galvanic zinc plating process. By using the principles of electrochemistry, it is possible to precisely control the zinc deposition process on a metal object. Redox reactions at the electrodes (cathode – metal object, anode – zinc) enable the transfer of zinc atoms from solution to a metal’s surface, creating an effective protective barrier.
Advantages of galvanic zinc plating
As an integral part of modern manufacturing and maintenance processes, galvanic zinc plating offers a number of advantages that make this method particularly attractive compared to other techniques for protecting metals against corrosion.
The main advantages include:
- Excellent Corrosion Protection: Galvanic zinc plating creates a protective layer on a metal’s surface that effectively insulates the metal from harmful external agents such as water or oxygen, preventing the corrosion process.
- Cathodic Protection: The zinc layer offers additional cathodic protection; in the event of damage to the coating, zinc as a more reactive metal than iron (or steel) is subject to corrosion first, thus protecting the base metal.
- Uniformity of Coating: the electrochemical process enables a uniform, even layer of zinc to be achieved, also in hard-to-reach areas and on complex object geometries.
- Aesthetics and Finish: Galvanic zinc plating produces an aesthetically appealing surface that can be further improved by various finishing processes such as passivation, painting or chrome plating.
- Long Lifespan: A properly applied zinc coating can significantly extend the life of metal objects, minimising the need for frequent replacement or maintenance.
Comparison with other corrosion protection methods
Galvanic zinc plating stands out significantly from other metal protection methods due to its efficiency, durability and flexibility of application:
- Hot-dip zinc plating: although it offers a thicker protective layer, it can lead to thermal distortion of delicate components. Galvanic zinc plating, on the other hand, is a process that occurs at lower temperatures, eliminating the risk of deformation while providing excellent protection against rusting.
- Painting: Despite an aesthetically pleasing finish and a certain level of corrosion protection, painting does not provide cathodic protection or an equally long-lasting and effective shield against external agents.
- Chemical methods (e.g. Phosphatisation): Despite their ability to serve as a good surface preparation for further finishing, chemical methods are not able to provide as comprehensive corrosion protection as galvanic zinc plating.
Uses for zinc plating
The main areas of use for this method include:
- Automotive industry: Corrosion protection and enhancement of vehicle components such as suspension, bolts, nuts, or even body components.
- Electronic Components Manufacturing: Providing connectors, housings and various assembly components with resistance to moisture and oxidation.
- Building and architecture: Protecting balustrades, steel structures or building exteriors from changing weather conditions.
- Machinery industry: Preventing premature deterioration of machine parts such as bearings, springs and screws.
- Outdoor furnishings and furniture: Glossing and maintenance of benches, bicycle racks, traffic light poles and other urban and garden furnishings.
Positive impact on products' lifespan and quality
Applying zinc can affect a coated object in many different ways:
- Protection against Corrosion: Galvanic zinc plating effectively protects metals from corrosion, which translates into maintaining the structural integrity and functionality of objects for a longer time period.
- Improved Durability: An additional layer of zinc significantly improves the surface strength of a metal, making it more resistant to mechanical damage and abrasion.
- Aesthetics and Finish: By being able to control the process precisely, an attractive finish can be achieved, which can be further modified by painting or passivation.
- Long-term Savings: By extending the life of products, galvanic zinc plating helps to reduce maintenance costs.
Modern trends and innovations in zinc plating
Newest achievements
- Eco-friendly Electrolytic Solutions: Technological developments have focused on the use of less environmentally damaging electrolytic solutions that minimise the use of toxic substances such as cyanides. Innovative formulations are composed of biodegradable components that provide efficiency as good as traditional methods, while reducing environmental impact.
- Energy Efficiency: new galvanic zinc plating techniques focus on optimising processes in terms of energy consumption. Systems that reduce the electrical power required for the electrolysis process are constantly being developed, resulting in lower production costs and reduced energy consumption.
- Nanotechnology: The use of nanotechnology in galvanic zinc plating opens up new possibilities in the creation of protective layers. Nanoparticles can be added to electrolytic solutions to increase the abrasion and corrosion resistance of zinc coatings and improve their mechanical properties.
- Smart Coatings: Research is also focusing on developing so-called ‘smart coatings’, which can react and change their properties in response to varying temperature or environmental humidity.
Future and balanced development
In response to growing environmental concerns and the need for a sustainable industry, galvanic zinc plating is evolving to meet these challenges:
- Sustainable Production Processes: The drive to minimise waste, recycle the materials used and reduce emissions of harmful substances will optimise galvanic zinc plating processes from an environmental perspective.
- Innovations in Recycling: The development of techniques for recycling electrolytic solutions and recovering metals from galvanic zinc plating processes will reduce the consumption of raw materials and the amount of waste generated.
- Education and Environmental Standards: Environmental awareness among manufacturers and consumers, together with the introduction of stricter environmental standards, will drive the development and implementation of new sustainable technologies.
How to choose a galvanic zinc plating service?
Tips for selecting service providers
Choosing the right galvanic zinc plating service provider requires consideration of a number of factors that demonstrate the competence of a service provider. Among these, the most important are:
- Experience and Specialisation: Look for suppliers with many years of experience who specialise in an area that suits your needs and are able to meet a variety of technical challenges.
- Quality and Certifications: Ensure that the supplier you choose has the appropriate quality certifications that demonstrate adherence to quality standards and operational procedures.
- Technology and Innovation: Pick companies that invest in the latest technologies and innovations in galvanic zinc plating.
- Sustainability and Ecology: Choose a supplier that adopts green practices and technologies that minimise environmental impact.
- Testimonials and Portfolio: Check reviews from other customers and the potential supplier’s portfolio of deliverables.
- Technical Support and Customer Service: Ensure that the service provider also offers adequate technical support and customer service.
Criteria for grading a zinc plating service's quality
If you decide to use a company that offers galvanic zinc plating, pay attention to the following criteria when reviewing treated objects:
- Smoothness and Quality of Coating: Check that the completed coating has good smoothness and adhesion to its surface.
- Zinc Layer Thickness: The thickness of the zinc layer should be in accordance with the technical specification and the needs of the application to provide the expected corrosion protection.
- Corrosion Resistance: The effectiveness of the corrosion protection can be verified by tests and examinations such as the salt spray test.
- Aesthetic Finish: Inspect the zinc plated object carefully to determine whether the applied coating has the desired aesthetic qualities.
Summary
Galvanic zinc plating is a technique that allows metals to be protected against corrosion. As an electrochemical process of coating metal objects with a layer of zinc, not only does it provide protection, but also increases the durability and improves the aesthetics of metal products.
The use of modern surface preparation methods, precise control of the electrolysis process, and innovative approaches to finishing and protection make it possible to achieve high quality zinc coating.
We encourage you to familiarise yourself with the rich offer of CPP “PREMA” S.A., as well as to contact us and cooperate in the creation of a high quality wide range of products.