The role of advanced coatings in protecting metal components in harsh environments

Hard metal components, made from materials such as Inconel, Monel and Stainless Steel,
that are used in applications within demanding operational environments face a combination of challenges. These include; erosion, abrasion, corrosion, extreme chemical exposure as well
as swings in thermal and mechanical loads and pressures. All of these have the potential to
rapidly degrade materials over prolonged periods of use, leading to increased downtime and
costly maintenance.

Advanced coatings, especially those applied using chemical vapour deposition (CVD), play a
crucial role in extending the lifespan of these components. This article delves into how CVD
coatings enhance the performance of critical metal parts exposed to these conditions.

The impact of harsh conditions on metal components

Components used in Oil and Gas, Power Generation, Aerospace and Industrial applications
undergo constant exposure to elements such as friction, high-speed impacts and exposure
to corrosive substances that challenge their integrity and performance under high stress use.
Traditional materials like steel, although strong, can struggle to withstand these forces over
extended periods. Without protective layers, abrasive wear and chemical interactions can
compromise the dimensional stability and mechanical performance of these components,
leading to efficiency losses and an unnecessary amount of maintenance/component
replacement.

Revolutionising durability with game-changing coatings

To combat these issues, coatings offer a barrier that enhances surface durability and
resilience. While there are various methods to apply hard coatings, CVD stands out for its
ability to uniformly coat complex geometries and internal surfaces, providing a seamless
protective layer that conforms to intricate shapes.

Wear resistance

Abrasion from particulates, mechanical friction and impacts are common challenges in high-
stress applications. For instance, in extrusion tooling, abrasive wear degrades metal
surfaces, requiring frequent replacements. CVD coatings, composed of tungsten carbide
particles embedded in a tough tungsten matrix, provide exceptional wear resistance. These
coatings combine hardness with impact toughness, preventing common wear mechanisms
such as micro-cracking and surface fatigue. In abrasive environments, the hard tungsten
carbide layer resists surface degradation, reducing volume loss and maintaining precision in
equipment performance​​.

Erosion protection

Components in power generation like turbine blades face erosion from high-speed impacts
with water droplets and solid particles. Water droplet erosion (WDE) in steam turbines, for
instance, can roughen blade surfaces, increasing drag and reducing efficiency. CVD
coatings counter this by providing a dense, pore-free structure with high hardness and
ductility. This ensures that the coating absorbs impacts without cracking or chipping,
maintaining a smooth surface and protecting against erosion-induced surface defects.
Rigorous testing has shown that CVD coatings on turbine blades extend service life
significantly, outperforming many alternative processes​.

Corrosion resistance 

Corrosion is a critical issue in environments where metal parts are exposed to chemical
agents or moisture, especially in oil and gas applications. CVD coatings offer corrosion
resistance by creating a uniform, non-porous (<0.5% porosity) barrier that protects the
substrate from chemical infiltration. This is particularly advantageous in environments where
traditional coatings may struggle, as CVD coatings resist acidic media such as hydrochloric
acid and hydrogen sulphide, preventing pitting and material weakening over time. Unlike
coatings with binder materials (such as cobalt), CVD coatings are free from these potential
weak points, offering more robust, lasting corrosion protection​​.

Chemical resistance 

Chemical attacks can degrade metal surfaces, causing wear and, in some cases,
catastrophic failure. For example, the production of petrochemicals and pharmaceuticals
involves processing abrasive or acidic substances that would quickly wear down untreated
metal. CVD coatings are chemically inert and resistant to a wide range of aggressive agents,
including sulphuric and hydrochloric acids, which frequently compromise unprotected metals. This resistance enables coated components to maintain their integrity, extending their usability in highly corrosive environments​.

How CVD coatings drive efficiency and reduce costs

Across industries, CVD coatings improve the reliability, safety and lifespan of critical
components.

Aerospace: CVD coatings on aircraft actuator parts reduce wear and friction,
extending maintenance intervals and preventing issues like oil leakage.

Oil and gas: Valve components, flow-control devices, and downhole tools benefit
from CVD coatings that withstand abrasive media and gas exposure, enhancing
equipment lifespan and reducing maintenance needs.

Power generation: Turbine blades in steam and gas turbines gain added durability
against erosive forces, maintaining efficiency and extending operational periods
between overhauls​​.

Extend the lifespan of your components and cut unnecessary costs

The application of CVD coatings represents a significant advancement in protecting metal
components in harsh environments. By combining hardness, toughness, and chemical
resistance, these coatings form an impenetrable barrier that withstands wear, erosion,
corrosion, and chemical attack.

This capability enables industries to achieve greater operational efficiency, cost savings, and
environmental compliance. CVD coatings have thus become a valuable solution, offering a
path forward in enhancing the durability of essential industrial components.