Choosing the right metal coating to extend equipment lifespan

Industrial equipment operates under extreme conditions, facing significant challenges such as wear, corrosion and erosion. These factors contribute to equipment degradation, leading to increased maintenance costs, unplanned downtime and shorter service life. To mitigate these issues, engineers rely on protective coatings to enhance durability and performance.

However, selecting the right coating can be difficult with the number of options available, including traditional methods like hard chrome plating (HCP) and thermal spray coatings, alongside advanced solutions such as Chemical Vapour Deposition (CVD). To make the right choice, engineers need to have a clear understanding of each and their appropriate applications.

The challenges of wear in industrial equipment

Wear-related failures account for a significant proportion of equipment maintenance and replacement costs. The primary types of wear that coatings aim to mitigate include:

• Abrasive wear: Occurs when hard particles or surfaces slide across a component, leading to material loss.
• Erosive wear: Caused by high-velocity impacts of solid particles or liquid droplets, common in turbines and pumps.
• Adhesive wear: Happens when two surfaces come into contact under high pressure, leading to material transfer or galling.
• Corrosive wear: Results from chemical reactions with the environment, leading to material degradation.

The right metal coating should address these wear mechanisms effectively while maintaining its integrity under operational stresses.

Comparing the key metal coating options

1. Hard chrome plating (HCP)

Hard Chrome Plating has been widely used for decades due to its hardness and moderate wear resistance. However, it has significant limitations that are slowly leading to it being replaced in almost every industry.

• Contains hexavalent chromium, a known carcinogen, making it environmentally hazardous and subject to strict regulations like REACH.
• Develops micro-cracks that allow corrosive elements to penetrate, reducing its effectiveness.
• Requires post-coating grinding to achieve the desired finish, adding to processing costs.

2. Thermal spray coating (HVOF, Plasma Spray, D-Gun)

Thermal spray coatings, such as High-Velocity Oxy-Fuel (HVOF), provide good wear resistance and can be applied in thick layers. That said, they have drawbacks that make them unsuitable for certain components.

• They are line-of-sight coatings, meaning they struggle to coat internal surfaces and complex geometries.
• Coatings are typically porous, necessitating sealing treatments to prevent corrosion.
• Require post-coating grinding, which limits their applicability on intricate parts.

3. Physical Vapour Deposition (PVD)

PVD coatings offer excellent surface hardness and are widely used for precision applications. However, their thin nature (typically under 5 µm) limits their durability in highly abrasive environments. This makes them best suited for applications where high wear resistance is not the primary concern.

• PVD coatings are commonly used for cutting tools and decorative applications where a smooth, thin finish is required.
• The process is limited to line-of-sight deposition, making it unsuitable for coating internal surfaces and complex geometries.
• Due to their thin nature, PVD coatings wear out faster in high-impact or high-friction environments, reducing their longevity.

4. Chemical Vapour Deposition (CVD)

CVD coatings, particularly tungsten carbide-based coatings, offer a superior alternative due to their unique properties.

• Non-line-of-sight application: Can coat internal surfaces, complex geometries, and tight tolerances.
• High hardness and toughness: Hardness up to 1600 Hv (77 HRc) with exceptional toughness, resisting cracking and spalling.
• Pore-free structure: Unlike HCP and thermal spray coatings, CVD coatings are fully dense and do not allow corrosion to penetrate.
• Excellent adhesion: Bonded at the atomic level, providing stronger adhesion than mechanically bonded coatings like HVOF.
• Environmentally friendly: REACH-compliant and free from hazardous substances like hexavalent chromium.
• Minimal post-processing required: Achieves a smooth finish without the need for extensive grinding.

Selecting the right metal coating for your application

Choose the metal coating that is the best in all respects

Choosing the right metal coating is critical for extending the lifespan of industrial equipment, reducing downtime, and optimising performance. While traditional coatings like hard chrome plating and thermal spray offer some benefits, they fall short in addressing modern industry demands for durability, environmental compliance, and coating of complex geometries.

CVD coatings outperform these alternatives by providing exceptional wear resistance, superior corrosion protection, and the ability to coat intricate shapes and internal surfaces. For engineers seeking the best long-term solution, CVD technology represents the future of industrial coating protection.

For industries such as aerospace, oil & gas, power generation and manufacturing, Hardide tungsten carbine CVD coatings provide the most durable and cost-effective solution. Their ability to protect complex and high-wear components ensures longer equipment lifespan, reduced maintenance costs and higher operational efficiency.