Next-Generation Diffusion Coatings
A thin coating — yet indestructible, even under the most extreme operating conditions.
What Are Diffusion Coatings?
Diffusion coatings are advanced protective layers produced through surface engineering methods. Unlike thermally sprayed coatings, they form a durable, inseparable metallurgical bond with the substrate. Controlled diffusion of coating-forming atoms — silicon, aluminium, chromium, or platinum — into the crystal structure of nickel and cobalt superalloys, high-alloy steels, and refractory metals (Mo, Nb, Ta, W with alloying additions such as Zr, Ti, Hf), together with the accompanying chemical reactions, forms a dense, well-adhered, heat-resistant layer based on intermetallic phases offering the highest attainable environmental protection.
There is no distinct phase boundary — the coating becomes an integral part of the component. The high quality of the bond with the substrate eliminates the risk of delamination under stresses and deformations — both technological and operational — and ensures complete imperviousness to oxygen and corrosive elements. An appropriate choice of chemical composition guarantees stability of the phase composition and service properties across a wide temperature range, close to the melting point of the base metal.
What Do They Protect Against?
In sectors with the highest operational safety requirements, diffusion coatings act as a critical barrier separating the working component from an extremely aggressive environment. Structural components — including those of aero and stationary gas turbines, rocket engines, and chemical and power installations — need protection from:
- High-temperature corrosion and oxidation — oxide coatings (e.g. Al₂O₃) form a dense layer arresting further degradation, while self-healing silicide coatings (MoSi₂, NbSi₂, or their composites) protect against high-temperature oxidation
- Sulphidation in aggressive exhaust gas and process gas environments
- Thermal and mechanical fatigue — enduring thousands of heating and cooling cycles without cracking
- Erosion and abrasion
- Many other wear and degradation processes
Our Coating Methods
Activated Powder Method (Pack Cementation, PC)
Cost-effective high-temperature protection of working surfaces. The components being treated are placed in a chamber with a source coating-forming material (silicon or aluminium), inert fillers, and active salts. The whole is heated to high temperature under a protective gas atmosphere — the molten salt reacts with the coating-forming material, creating a uniform, dense coating with high heat resistance.
Vapour-Phase Deposition (VPA)
Precision in every cooling channel. A non-line-of-sight method enabling uniform coating of internal cooling channels with diameters below 1 mm. Parts suspended in a chamber rather than packed — superior control of thickness and microstructure, ideal for turbine blades with complex internal geometry.
Air Plasma Spray (APS)
Ceramic shield for extreme temperatures. The key method for applying ceramic thermal barrier coatings (TBC) that reduce metal temperature by hundreds of degrees Celsius.
Air Plasma Spray in Detail
How It Works
An inert gas — argon or nitrogen — is pressurised and driven rapidly between two electrodes. The ionised gas forms a plasma flame that heats and propels alloy or ceramic particles onto the target surface at velocities of hundreds of metres per second.
Coating Materials
Plasma spray applies metallic, composite, and ceramic coatings. Extremely high temperatures (up to 15,000 °C in the plasma core) make it ideal for ceramic coatings: aluminium oxide, yttria-stabilised zirconium (YSZ), tungsten carbide, wear-resistant cobalt alloys, nickel-matrix chromium carbides, and self-fluxing coatings.
Ceramic Thermal Barrier Coatings (TBC)
TBC is a multi-layer protection system enabling components to operate at temperatures beyond the capability of the metal alone. An MCrAlY metal bond coat provides adhesion and corrosion protection, while the ceramic topcoat (YSZ) with controlled porosity provides thermal insulation reducing substrate temperature by 100–300 °C — and, combined with internal cooling, by as much as 300–400 °C. Related environmental barrier coatings (EBC) additionally protect against corrosion in water-vapour atmospheres.
Applications
Most aerospace coating specifications indicate plasma spraying as the reference method. It effectively protects jet engine hot section components, extending time between overhauls (TBO) and reducing operating costs.
Industry Context
Space Industry
- Protecting rocket nozzles, thrust chambers, and combustion chambers from oxidation, corrosion, erosion, and ablation in supersonic flows
- Barrier against high-temperature oxidation
- Thermal protection of components against exposure to high temperature
Aerospace & Energy
- Protecting turbine blades from aggressive exhaust gases — dense Al₂O₃ layer arrests degradation
- Resistance to thousands of heating and cooling cycles without cracking
- Extending component life (TBO) — higher combustion temperatures at lower operating costs
Nuclear Industry
- Protection against corrosion in liquid metals — Gen IV reactors cooled by lead or sodium
- Tritium barriers reducing hydrogen isotope permeation through piping walls
- Safeguarding components operating for decades under high temperature and radiation
Common Applications
- Rocket nozzles and thrust chambers
- Gas and steam turbine blades
- Jet engine hot section components
- Heat shields and atmospheric re-entry shields
- Rotors, compressor seals, and labyrinth seals
- Afterburner parts and reheat chambers
- Refractory alloy components in nuclear reactors
Key Advantages
Structural Integration
Forms a solid solution with the substrate — cannot spall, peel, or blister. Supreme thermal shock resistance.
100% Density
Impervious, self-healing silicide barrier to oxygen and corrosive elements. Zero open porosity attacking the base metal.
Life Extension
Significantly extends time between overhauls (TBO). In aerospace and energy, this directly reduces operating costs.
Thermal Fatigue Resistance
Integral bonding withstands thousands of heating and cooling cycles — where mechanical coatings crack after hundreds.
Tailored Properties
Thickness, microstructure, and phase composition matched to specific operating conditions without compromising substrate mechanical properties.
Aerospace-Grade Quality
Meeting the most demanding specifications for turbine engines, rocket motors, and reactor components.
What We Offer
We solve engineering problems — we select the coating type and deposition method in the context of your operating requirements and the wear and degradation processes involved.
- We perform metallographic analyses and identify the failure mechanisms of your equipment and structures.
- We deliver materials-science and technological assessments.
- We select the appropriate coating or protective layer according to operating conditions and the durability requirements of the working components.
- We provide oversight of the technological process and operation, and evaluate the effectiveness of the proposed solutions.
- Our solutions increase the durability of your installations, equipment, machinery, and structures — and that is your direct gain.