Thermal Spray Applications as an Alternative to Hard Chrome Plating
Thermal spray coatings are increasingly used as an alternative to hard chrome plating in a range of applications.
What is Hard Chrome Plating and Why Move Away from It?
Hard chrome plating involves applying a thin layer of chromium onto a component using an electroplating process. It was widely adopted for its durability, wear resistance and corrosion protection. However, the process uses hexavalent chromium – a substance known to be harmful to both people and the environment. Strict regulations, rising costs and health concerns have driven many plating companies seeking alternatives to the traditional plating process.
Beyond the environmental impact, hard chrome plating also has physical limitations. It can suffer from micro-cracking, uneven thickness, and difficulties when coating large or complex parts. Over time, these weaknesses can lead to premature failure of critical components.
This is where thermal spray comes in.
Thermal Spray Coatings
A range of thermal spray coatings can be applied as an alternative to hard chrome plating with differing costs and quality. At the entry level, twin wire arc spray coatings of Metallisation 103T (FeCrB) will give similar results to traditional chrome plate although a little less dense. For some applications, even a coating of Metallisation 60E (13% Cr steel) would be suitable.
The Benefits
- Wider choice of materials – instead of being limited to chromium, coatings can be tailored from metals, alloys and ceramics to suit specific environments.
- Thicker coatings possible – thermal spray can build up greater thickness than plating, extending component life and protection.
- No micro cracking – coatings avoid the fine cracks seen in chrome layers, reducing the risk of corrosion pathways.
- Suitable for large or complex parts – unlike plating tanks, thermal spray can coat components of almost any size or shape.
Limitations
One limitation of thermal spray coatings is that the process is line-of-sight so you need to be able to see the surface being sprayed. This makes coating of small internal bores impossible although above approximately 75mm diameter, internal bore spray processes are available.
Key Applications
Aerospace and Aviation
Landing gear, actuators and hydraulic rods were traditionally chrome plated. With stricter aerospace regulations and the need for reliable performance, HVOF thermal spray coatings have become the preferred choice. They deliver high hardness, wear resistance and fatigue strength – all vital in flight-critical parts.
Automotive and Transport
From piston rods to engine components, thermal spray is being used to improve efficiency and cut maintenance. Coatings such as tungsten carbide not only resist wear but also provide excellent corrosion protection in harsh conditions.
Oil, Gas and Energy
Drilling equipment, pumps and valves face constant attack from abrasion and corrosion. Thermal spray coatings extend component life and reduce the risk of downtime in environments where reliability is everything.
Industrial Machinery
Rolls, bearings, shafts and other heavy duty parts benefit from coatings that prevent wear and reduce friction. Unlike chrome plating, thermal spray can be applied to very large surfaces, making it ideal for paper mills, steel plants and power stations.
HVOF Coatings
The next level of coating is with High Velocity Oxygen Fuel (HVOF) spraying NiCrBSi materials. These coatings are extremely dense and offer very good corrosion and acid resistance. They have a similar hardness to hard chrome plate and can be finished with conventional SiC grinding wheels.
At the peak of chrome plate alternative coatings is HVOF Tungsten Carbide (WC) based alloys. Various alloys of Tungsten Carbide, Cobalt and Chrome give excellent hardness and performance for sliding wear applications as well as resistance to corrosion. Having wear characteristics up to 10x greater than hard chrome plating, HVOF WC coatings require finishing by diamond grinding or polishing.
Can Thermal Spray Coatings Achieve The Same Finish?
One question that often arises is whether thermal spray can achieve the same smooth finish as hard chrome plating. The answer is yes. Coatings can be ground and polished to a mirror like surface, ideal for hydraulic rods and sealing applications.
Ready to Talk About Hard Chrome Replacement?
If you’re currently using hard chrome plating and want to explore alternatives, thermal spray is a proven solution that combines performance, safety and sustainability. Our team at Metallisation Ltd is here to guide you through the options, explain the processes in plain terms and recommend the right approach for your business.
