Technical Consulting

Technical consulting in protective coatings focuses on selecting the optimal material–process combination to protect components against extreme wear, corrosion, high temperatures, and erosion.

The engineering matrix below covers solutions based on composite powders—cermets—and pure ceramics, together with the principal application methods.

Material Selection: Composites or Ceramics

Composite Powders — Cermets

Cermets consist of hard ceramic particles embedded in a ductile metallic matrix.

Common compositions: WC–Co (tungsten carbide–cobalt), WC–Co–Cr, and Cr₃C₂–NiCr (chromium carbide–nickel chromium).
Properties: Exceptional resistance to abrasive and adhesive wear, combined with high impact toughness.
Applications: Rotors for positive-displacement downhole motors, industrial valves, pump shafts, and drilling tools.

Technical Ceramics

Technical ceramics consist of metal oxides without a metallic binder.

Common compositions: Al₂O₃ (aluminium oxide), Cr₂O₃ (chromium oxide), and ZrO₂–Y₂O₃ (yttria-stabilised zirconia, or YSZ).
Properties: Chemical inertness, electrical insulation, heat resistance up to 1,500°C and above, and low thermal conductivity.
Applications: Thermal barrier protection for turbine blades, chemical-pump plungers, and anilox printing rollers.

Principal Coating Methods

The application method is selected according to the required coating density, bond strength, and component geometry.

A. High-Velocity Thermal Spraying — HVOF / HVAF

The powder is accelerated by a supersonic gas jet to velocities of 600–1,000 m/s.

Best suited for: Cermets such as WC–Co–Cr and Cr₃C₂–NiCr.
Advantages: Minimal porosity below 1%, bond strength exceeding 70 MPa, and limited overheating or degradation of carbide phases.
Limitations: Unsuitable for pure high-melting-point ceramics because of the relatively low flame temperature.

B. Plasma Spraying — APS / Reactive Plasma Spraying

The powder is injected into a high-temperature plasma jet reaching up to 15,000°C.

Best suited for: High-melting-point ceramics such as Al₂O₃, Cr₂O₃, and ZrO₂.
Advantages: Capable of melting virtually any material while providing excellent thermal and corrosion resistance.
Limitations: Higher porosity than HVOF—typically 2–5%—and lower bond strength of approximately 30–50 MPa. Strict control of component cooling is required.

C. Laser Cladding — An Alternative to Thermal Spraying

Powder is injected into the laser interaction zone, where the laser beam melts a thin layer of the substrate.

Best suited for: Metallic alloys and metal-matrix composites containing coarse carbide particles.
Advantages: A metallurgical bond with the substrate and virtually zero porosity.
Limitations: Higher heat input than thermal spraying, which may cause distortion in thin components.

Engineering Consulting Process

When designing a protective solution, our specialists evaluate three key factors:

Operating conditions → Material selection → Application method

Abrasive wear and friction at temperatures up to 500°C:
Solution: WC–Co–Cr coating applied by HVOF.
Aggressive acids or alkalis combined with friction:
Solution: Cr₂O₃ ceramic applied by plasma spraying, followed by mandatory pore sealing with silane-based compounds.
High-temperature gas environments up to 1,250°C, such as turbines:
Solution: A two-layer system consisting of an oxidation-resistant MCrAlY bond coat applied by HVOF and a YSZ ceramic thermal barrier coating applied by plasma spraying.