Kermetico HVAF and HVOF thermal spray equipment

Chromium Carbide Coatings – HVAF Thermal Spraying for Wear Resistance at Elevated Temperatures

Thermal spray chromium carbide coating

Thermal sprayed chromium carbide coatings combat high-temperature wear due to the high wear resistance imparted by the hard carbide particles and the high temperature oxidation resistant nature of the Cr2O3 oxide formed over both phases of CR3C2-NiCr.

While tungsten carbide coatings provide better wear resistance when temperatures are under 510°C (950°F), high velocity sprayed chrome carbide coatings mitigate abrasive and erosive wear at temperatures up to 750°C (1380°F).

The corrosion resistance is provided by the NiCr matrix while the wear resistance is provided mainly by the carbide ceramic phase.

Cr3C2-NiCr Feedstock Properties

Chrome carbide coatings are sprayed with Cr3C2-NiCr agglomerated and sintered powder -30 +5 microns.

Nominal composition

wt.%

Cr3C2

base

Total carbon

9.2-10.8

Nickel

18-22

Chrome

4.5-5.5 in the metal phase

HVAF Chromium Carbide Coating Properties

Cr3C2-NiCr coating properties are influenced significantly by the spray process and spray parameters.

The abrasive wear rate for the chromium carbide coatings is controlled by several factors such as:

  • the morphology of the starting powder
  • the size and distribution of the chrome carbide particles
  • the hardness of the chromium carbide particles relative to the abrasive particles
  • the properties of the matrix and its volume fraction, and
  • the coating process, which determines the coating characteristics such as:
    • Phase composition
    • Density
    • Hardness
    • Bond strength and
    • The residual stresses

Typical Properties of the Kermetico HVAF Chrome Carbide Coating

FeatureS.I. UnitsU.S. Units
 Apparent metallographic porosity

<1.0%

Bond strength to steel70 MPa @500µm10,000 PSI @0.020”
Coating hardness, HV300

950-1,100

Typical as-sprayed roughness Ra, micro-inch

2-3.2 µm

80-120 µinch

Maximum coating thickness

1 mm

0.040”

Maximum working temperature

750°C

1,380oF

Kermetico HVAF applied chrome carbide coatings have excellent resistance to elevated temperature erosion and sliding wear.

  • Impact resistance and fatigue resistance are good.
  • Thermal shock resistance is excellent.
  • General corrosion and elevated temperature corrosion resistance are very good.

Usually, this coating is used at elevated temperatures where tungsten carbide coatings do not work or when faster and a less costly finishing is necessary.

A specific characteristic of a Kermetico HVAF chromium carbide coating is that it remains ductile during the long-term service at high temperatures, in particular, above 600oC (1,100°F) .

The combustion temperature in the Kermetico HVAF process is well below the melting point of Cr3C2, which eliminates the possibility of the carbides dissolution into the nickel-chromium matrix during coating application.

As a result, there is no precipitation of carbides within the nickel-chromium matrix during the service of the HVAF coating and the metal matrix remains ductile.

Such precipitation of carbides is the main reason for the HVOF-sprayed coatings embrittlement and failure during high temperature service.

A Typical Cross-Sectional Micrograph of HVAF CrC-NiCr Coating

Kermetico HVAF Cr3C2-NiCr Chromium Carbide Coating

Kermetico HVAF Cr3C2-NiCr Chromium Carbide Coating

Typical Applications of the High Velocity Air Fuel Chromium Carbide Coatings

Sliding wear, erosion, and fretting at elevated temperatures:

Uniform high hardness and ductility, low stress and porosity lead to a substantial increase of service life of parts protected with Kermetico HVAF Cr3C2-NiCr coatings in comparison with HVOF. Our partner in India deposits chrome carbide coatings as well.

Ground Chrome Carbide Coating Kermetico HVAF Sprayed

Ground Chrome Carbide Coating Kermetico HVAF Sprayed

Please check other HVAF coating properties here.

HVAF & HVOF Equipment to Spray Chrome Carbide Coatings

Most Kermetico guns can spray chrome carbide coatings.

  • Convertible HVOF and HVAF equipment:
    • C7 – an HVAF/HVOF gun for large parts, maximum Chrome Carbide spray rate – 16 kg (35.5 lbs.)/hour
    • C6 – a general purpose HVAF-HVOF gun, maximum Cr3C2-NiCr spray rate – 14 kg (31 lbs.)/hour
    • CID – unique HVAF+ HVOF system to spray coatings onto internal surfaces 100 mm and larger
  • Multi-purpose HVAF AK systems, with a wide range of spray guns:
    • AK7 – a high-power gun for the thermal spray of large parts, maximum Cr3C2-NiCr spray rate – 16 kg (35.5 lbs.)/hour
    • AK6 – a carbide-specific gun to spray a balanced mix of parts in a job shop, maximum Cr3C2-NiCr spray rate – 14 kg (31 lbs.)/hour
    • AK5 – a compact gun to spray smaller parts, thin walls and complex surfaces, maximum Cr3C2-NiCr spray rate – 8 kg (18 lbs.)/hour
    • AK-ID – an 80 mm (3.15”) and larger internal diameters spray gun, maximum Cr3C2-NiCr spray rate – 4 kg (9 lbs.)/hour
    • AK-IDR – a rotating ID gun to spray 4” (100 mm) and larger bores, maximum Cr3C2-NiCr spray rate – 4 kg (9 lbs.)/hour
    • AK-HH – a handheld gun for on-site coating, maximum chromium carbide spray rate – 8 kg (18 lbs.)/hour
  • Additional equipment:

Kermetico, Inc. – Material Science Excellence, HVAF and HVOF Equipment Manufacturing and Thermal Spray Coating Services Since 2006

We create equipment that helps materials scientists, engineers, and businessman achieve their goals.

We have installed more than 60 HVAF systems in the USA, Europe, Japan, and China.

Some of the systems are at work in Universities and National Labs, but most of them are used in production thermal spray shops.

We proudly design and produce our coatings and our HVAF thermal spray equipment in California and install it all over the world.

You can visit our R&D center in Benicia to meet our designers and watch our HVAF equipment in action.

We provide HVAF thermal spray coating services for customers in the San Francisco Bay Area in California, USA.

Chromium Carbide Coatings – HVAF Thermal Spraying for Wear Resistance at Elevated Temperatures
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Chromium Carbide Coatings – HVAF Thermal Spraying for Wear Resistance at Elevated Temperatures