Nanomaterials | cladding The PComP coatings were tested by MesoCoat’s
development partners at the US Department of Defense. However, the application technology available at that time could not apply PComP nanocomposite coatings at the high speeds required to cover large areas such as ship decks, says Ghildyal. A better solution was required. “Conventional thermal spray coating systems can
deposit around 5lbs (2.27kg) of coating material per hour, meaning that it would take months to spray an entire ship deck. Consequently, we began a search for a high speed, large area coating technology. After reviewing several promising technologies, MesoCoat chose to licence a High Density InfraRed (HDIR) fusion cladding technology developed by Oak Ridge National Laboratory (ORNL). Now known as CermaClad, this system had the greatest prospect for success and could be customised to apply 500lbs (227kg) of coatings per hour,” he says.
The seeds of the technology were sown in 1996.
Scientists at ORNL began using an HDIR arc lamp made by Canadian fi rm Vortek for thermal processing of functional materials, initially for the semiconductor processing industry. ORNL continued to develop the technology for applying a variety of corrosion and wear resistant materials, as well as expanding its under- standing of the process, fl ow, metallurgy, temperature control and chemistry. MesoCoat licenced it in 2010. “Since then we have developed and demonstrated the technology and qualifi ed a variety of materials with cladding thicknesses ranging from 100 microns to 15 mm for a range of applications,” says Ghildyal.
Developing potential Over the past three years, Ghildyal says the company has been working to develop the CermaClad process control, metallurgy, material science and scalability, as well as reducing the footprint of the system. This has been reduced from a volume of 4ft3
(0.11m3 ) to a size
that can now be used in pipes as small as 8-inches (20.32 cm) in internal diameter. “This technology has unlimited potential because there are no limits on the materials that can be fused. Any metal can be fused on
the substrate for corrosion protection, wear, erosion, insulation, conduction or any other application. Research and development activities are now focusing on applications where MesoCoat has a competitive advantage over other processes,” he says. MesoCoat uses conventional cladding materials such
as Alloy 625, 825, stainless steel, tungsten carbide and chrome carbide in the CermaClad process, combining them with its proprietary nanomaterials and binders. The fi rst step in the process is material preparation, in which the base substrate is cleaned. In the second step, the clad material is applied in solid or powder form to the substrate. Cladding materials are selected accord- ing to the corrosion or wear resistance required for the end use of the substrate being clad. The third step involves fusing the two dissimilar materials together. The fi nal step is to cool the product. According to MesoCoat, CermClad builds the required
layer thickness in one step. “The key to the CermaClad process is the fusion stage,” says Ghildyal. “The HDIR heating lamp technology uses a very high wattage rate that is scalable from 50 KW to more than 1 MW. This can heat a spot up to 1,000,000˚C/s and there is no limitation in terms of the material or thickness that can be clad to the substrate without causing any damage. The metallurgical bonding achieved by this system results in a strong bond, with a strength in excess of 30,000 psi. This offers better metallurgical properties with minimal dilution to the base material. The scalability of the power source allows uniform coverage of different clad thicknesses over a range of surface sizes.”
Testing and certifi cation
MesoCoat recently completed tests at the international certifi cation body and classifi cation society DNV in relation to API 5LD standards and DNV-OS-F101 specifi cations for underwater pipeline systems. According to the Offshore Standards, DNV conducted ASTM G28 tests for corrosion, ASTM A264 for mechani- cal testing and EDAX analysis for composition and metallurgy. The company says CermaClad products exceeded each of these standards for corrosion rate, dilution and bond strength by 50-100%. The tests were
Schematic showing the four steps in the CermaClad internal pipe coating process
www.pipeline-coating.com
September 2015 | PIPELINE COATING 21
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