Zirconium coatings are aqueous solutions that contain zirconium compounds, primarily zirconium oxides. They are applied to metal substrates like steel, galvanised steel and aluminium in order to improve their properties.
They are used as part of the conversion coating process – this is where the surface of the metal reacts chemically to form a protective pretreatment layer. This layer boosts adhesion, corrosion resistance and wear resistance of metal parts, typically before further painting or powder coating.
First trialled in the mid-1990s, zirconium technology has advanced quickly – these pretreatments have now been on the global finishing market for almost two decades. For those running a metal coating pretreatment program, zirconium is fast becoming the preferred alternative to conventional phosphate coatings, which are instead based on iron or zinc.
The zirconium conversion coating process
- Cleaning: The metal must be thoroughly cleaned and prepared to remove contaminants like grease and oil. This enables the coating to create a permanent bond with the steel, aluminium or zinc.
- Application: The zirconium-based solution is applied either through a dipping or immersion line, an automated in-line spray washer, or a manual high-pressure spray system. Some products are also suitable for manual application with a brush.
- Reaction: The zirconium solution reacts to create a zirconium layer on the surface of the metal.
- Curing: The coated metal component forms an incredibly durable zirconium oxide layer.
Applications for zirconium treatments
Zirconium coatings can increase performance and lifespan of manufactured components used across several industries, popularly aerospace, automotive and oil and gas. They can be useful in any environment where environmental stressors and challenging conditions may be encountered.
- Aerospace: airframe components, thermal barrier coatings, interior cabin hardware, fasteners and connectors.
- Automotive: underbody coatings, engine components, wheels, door systems, fuel systems.
- Oil and gas: pipelines, drilling, offshore structures.
- Marine: ship hulls, onboard machinery, propellers.
- Electronics and telecoms: connectors, switches, printed circuit boards.
- Energy: nuclear reactors, wind turbines, energy generation equipment
- Construction: structural steel, window frames, architectural fittings
- Water treatment: pipes, valves, filtration systems.
- General manufacture: heavy equipment, fencing, railing, material handling equipment
Benefits of zirconium pretreatment
Zirconium-based pretreatments offer a number of operational, economic and ecological benefits over traditional iron and zinc phosphate coatings – reduced energy consumption, high salt-spray performance, phosphate-free processes and low sludge.
- High performance: Zirconium treatments provide superior levels of corrosion resistance (salt spray resistance) and paint adhesion. Zirconium layers bond to the substrate very quickly and effectively, ensuring a long-lasting, hard-wearing and visually-pleasing finish that’s resistant to knocks, bumps and scratches. Use of these pretreatments can produce intense colours.
- Thinner coatings: This high level of performance can be achieved with a thin layer. Compared to traditional phosphating products, zirconium can also require lower coating product concentration to achieve the same level of performance.
- Lower temperatures: Zirconium coatings can work at an ambient temperature, unlike iron phosphate coatings and zinc phosphate coatings, which require a temperature in the region of 40C. Recent advances in zirconium technology also minimise the need for large pH adjustments, making for easy startup.
- Environmental impact: Unlike conventional coatings, zirconium coatings do not contain phosphates or regulated heavy metals, which are known to contribute to pollution of wastewater. As well as requiring less water, the lower energy requirement also decreases carbon dioxide emissions.
- Wastewater: Because they don’t contain phosphate and produce minimal solids, zirconium pretreatments have a lower wastewater treatment requirement. The baths also have lower acidity, which requires less alkalinity to neutralise.
- Maintenance: Zirconium coatings require fewer bath dumps and minimise scale, sludge and foam formation. This all minimises downtime and maintenance costs.
Airedale Group: innovative surface treatment technology
Pretreatments based on zirconium offer a high-performance, consistent and sustainable coating solution. It’s no surprise that they are fast becoming a preferred choice globally.
We are an official UK distributor of Haug Chemie’s leading range of surface treatment chemicals. This involves four zirconium pretreatment products – eska®phor Z 1200, eska®phor Z 1300-1, eska®phor Z 1400, and eska®phor Z 2000 C.
