The Science and Versatility of Hot Zinc Spray for Galvanising Large, Unconventional Items

Introduction

Corrosion is more than just a cosmetic issue; it’s a destructive force that can undermine the structural integrity of metal components, leading to failure and increased maintenance costs. To combat this widespread problem, galvanization is often employed. It involves coating metal surfaces with zinc, a material renowned for its corrosion-resistant properties. But why zinc? From a scientific standpoint, zinc acts as a sacrificial anode, offering cathodic protection. It corrodes in preference to the base metal, thereby protecting it from the elements. While various methods like hot-dip galvanizing exist, hot zinc spray offers distinct advantages, especially when dealing with large or awkwardly shaped items.

Why Zinc?

Zinc has a natural affinity for reacting with oxygen, water, and carbon dioxide to form a stable, corrosion-resistant layer known as zinc carbonate. This layer effectively blocks moisture and other corrosive agents from penetrating and damaging the underlying metal. The electrochemical characteristics of zinc also make it an ideal candidate for galvanizing, as it willingly “sacrifices” itself to protect the metal it covers, a process scientifically referred to as cathodic protection.

What is Hot Zinc Spray?

Hot zinc spray, also known as thermal spraying or metallising, utilises compressed air and high-velocity oxygen fuel (HVOF) or electric arc spray systems to melt zinc wire. The molten zinc is atomised and sprayed onto the metal surface, forming a robust, adherent coating as it cools and solidifies.

Process of Applying Hot Zinc Spray

• Surface Preparation: Before application, the metal surface must be immaculately cleaned to remove impurities like rust and paint, usually through sandblasting.
• Priming: A primer may be applied to improve the coating’s adhesion properties.
• Spraying: Molten zinc is then sprayed onto the surface, providing a durable and uniform coating.
• Sealing: A sealant can be applied to enhance durability and corrosion resistance.
• Quality Check: Finally, the coating is inspected to ensure it meets all quality specifications.

Advantages of Hot Zinc Spray for Large, Awkwardly Shaped Items

Versatility

Hot zinc spray is incredibly versatile and can coat items of almost any size and geometry. Whether it’s a large tank, complex machinery, or a bridge, this method ensures even coverage.

Uniform Coverage

This technique can coat every surface, nook, and cranny, providing uniform coverage that hot-dip galvanising often fails to achieve.

On-Site Application

The process can be carried out on-site, eliminating the logistical and financial burdens of transporting large items to a galvanising facility.

No Heat Distortion

Hot zinc spray is less likely to cause heat distortion compared to hot-dip galvanising, which makes it ideal for items that are delicate or have thin metal sections.

Limitations of Hot-Dip Galvanising

Size and Shape Constraints

The physical dimensions of the galvanising bath dictate what can and cannot be galvanised using this method.

Fettling

Items will need to be fettled in order to achieve a smooth top coat.

Heat Distortion and Drilling

The hot-dip method involves submerging the entire item in molten zinc, this can lead to heat distortion. Additionally, items often need holes drilled into them for hanging during the dipping process, further compromising their structural integrity.

NSP Coatings: Pioneering Excellence in Hot Zinc Spray

When it comes to offering hot zinc spray services, NSP Coatings stands as a leader in the industry. With in-house capabilities, they ensure high-quality, uniform coatings that not only extend the lifespan of your metal items but also deliver a superior finish. NSP Coatings believes in the unparalleled advantages that hot zinc spray offers, especially for large and unconventional items that other methods struggle to protect effectively.