Plasma Chromium Oxide-Silica

A&A Coatings Chromium Oxide-Silica material is a fine grade of Chromium Oxide- Silicon Dioxide composite designed to produce coatings which are hard, dense and extremely wear resistant.

The material is designed to produce the most durable plasma sprayed chromium oxide coatings currently known to industry. In addition, coatings of this material exhibit some degree of impact resistance not normally associated with sprayed ceramic coatings. The silicon dioxide acts as a dampening medium that absorbs impact loading, and prevents grain loosening which enhances the wear resistance.

Chromium Oxide-Silica coatings are recommended for resistance to wear by abrasive grains, hard surfaces, particle erosion and cavitation, at all temperatures below 540°C (1000°F). These coatings also have excellent self-mating and anti-galling properties. Coatings of this material are insoluble in acids, alkalis and alcohol. When properly sealed, they are recommended for use in corrosive chemical environments in temperatures up to 175-200°C (350-400°F).

These coatings are being successfully used in petrochemical industry applications such as pump impellers, reciprocating pump compressor rods, I.D.’s of air and gas cylinders, centrifugal pump seals, wear and casing rings and down hole plungers. These coatings can also be useful for mechanical seal applications, and in the textile industry on machine elements which come in contact with fibers and threads where a fine, hard wear and corrosion resistant ceramic coating is required.

Typical Composition: Silicon Dioxide 5%
Titanium Dioxide 3%
Chromium Oxide Balance
Typical Size Range: -53 +15 microns
Melting Point: 2435°C (4415°F)

Physical Properties of Coating

Coating Weight (lb/ft2/.001″):.026

Texture, as sprayed, (microinches aa): 250 – 350
Finish, ground (microinches aa): 15 – 20
Finish, Lapped (microinches aa): 2 – 4
Macrohardness: Rc65
Cross-Sectional Hardness (DPH300): 900
Density (g/cc): 4.8
Bonding: 4,000psi (without bond coat)

Thickness Limitation

Plasma sprayed coatings of Chromium Oxide-Silica can be applied 0.6 mm (.025 inch) thick onto outside diameters without cracking or delaminating.

For inside diameter work plasma sprayed coatings .5 mm (.020 inch) thick can be deposited without cracking or delaminating.

Surface Preparation

A&A Coatings Plasma Sprayed Chromium Oxide-Silica can be applied to most substrates which have been cleaned to remove surface oxides. This cleaning is accomplished with a light grit blast. Additionally, a “Bond coat” is required in some cases. Please contact us for substrate specific requirements

Finishing

A&A Coatings Plasma Sprayed Chromium Oxide-Silica can be ground to required finish size and polished to a 2 – 4 surface finish.

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