TPi March 2014

Smal l diameter tubes

A precise approach to intricate tube coating Hardide Coatings, a specialist in advanced surface coating technology, has developed a new surface engineering technology that can be applied to complex geometries and internal surfaces. Advanced tungsten carbide-based coatings can be used to protect both internal and external surfaces of small diameter, high-precision tubes from wear, erosion and acidic corrosion to increase critical component lifetime. Using low temperature chemical vapour deposition (CVD), the coatings can be applied to a wide range of metallic substrates. CVD coatings are crystallised from the gas phase atom-by-atom, producing a conformal coating that can coat internal and external surfaces and complex shapes. CVD takes place in a vacuum chamber reactor at a temperature of approximately 500°C. The coatings are a metallic tungsten matrix with dispersed nano-particles of tungsten carbide typically between one and ten nanometres in size. Dispersed tungsten carbide nano-particles give the material enhanced hardness that can be controlled and tailored to give

Hardide coating reactor being loaded

control and shut-off valves, centrifugal, rotary and axial pump components, to the internal surfaces of very small diameter nozzles and tubes as well as bends, liners, elbow joints and flanges. The coatings can also be used in severe conditions such as in fracking and oil drilling tools including mud driven hydraulic parts. Other successful applications include ejector pumps and combustion tubes for bio-fuel applications. In these applications, the coatings are able to withstand extremely abrasive, erosive and corrosive operating environments, such as sour well applications with H 2 S and acidic fluids. In the past, hard chromium electroplating has been used successfully in many applications, but this process is being severely restricted or phased out under REACH and OSHA environmental and health and safety regulations, as carcinogenic hexavalent chromium salts are used in its production. The patented coatings reduce operational costs by saving downtime, increasing productivity and improving performance. With wear and corrosion resistance combined with toughness and ductility, Hardide technology is an effective option for small diameter high- precision tubes.

a typical range of hardness of between 1,100 and 1,600Hv and, with some types of Hardide coating, up to 3,500Hv. Abrasion resistance is claimed to be up to 12 times better than hard chrome or 500 times better than Inconel. Nano-structured materials are known to possess toughness, and crack and impact resistant features. For example, Hardide-T has proven this by withstanding 3,000 microstrain deformation without any damage; this deformation will crack or chip most other thick hard coatings. A number of Hardide coating variants are offered to solve problems such as severe wear, corrosion or galling. Applications range from metering,

Hardide coats internal surfaces

Hardide Coatings – UK info@hardide.com www.hardide.com

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Tube Products International March 2014

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