Fabrication and Evaluation of Plasma-Sprayed Functionally Gradient W/Cu Coatings as Plasma Facing Materials in Fusion Devices

Abstract

Tungsten has been decided as the plasma facing material (PFM) for some high heat flux regions of the divertor in the International Thermo-Nuclear Experimental Reactors (ITER). In this paper, our efforts concentrated on the functionally gradient W/Cu coating fabricated on the oxygen free copper by atmosphere plasma spraying under the inert gases protection. The functionally gradient W/Cu coatings were designed to relieve the thermal stress during the spraying processes. For comparison, the tungsten coatings were also deposited directly onto the copper substrates by the same technology. XRD, SEM and EDS were applied to identify the phases, morphologies and compositions of these coatings. Tensile tests were performed to measure the bonding strength between the coatings and the substrates. Furthermore, water quenching and high heat loading experiments using a pulse laser beam were also carried out to estimate the thermal shock properties of these coatings.

Development of advanced high heat flux and plasma-facing materials

“…But when the laser energy density was increased to 198 MW m −2 , cracking, melting, and cratering appeared in all coatings after 240 cycles. Under the same conditions after 1200 cycles, peeling occurred on the surface of one sample and no peeling occurred on the coating surface of the other samples [331].…”

“…Several initial sizes of W powder were investigated for plasma spraying, and the results show that the smaller the size of initial powder, the lower porosity of the coatings will be. The interlayer coating materials of W/Cu were obtained by mixing W and Cu powder with volume ratio of 50:50 and linearly graded [317,331]. W/Cu mixtures and W powders were sprayed layer by layer on an oxygen-free copper substrate by atmosphere plasma spraying (APS) using a PT-A-3000 S plasma-spray facility made in Sweden.…”

“…Argon and nitrogen were used for cooling the substrates and preventing the coatings from oxidation. The detailed spraying parameters are given in [331]. The thickness of the W/Cu graded layer was 300 μm, and the maximum thickness of pure W coating was 3 mm.…”

Polyisobutylene Modified Bisphenol A Diglycidyl Ether Based Epoxy Resins Possessing Improved Mechanical Properties

“…Polyisobutylene (PIBs) based networks possess excellent flexibility and strong adherence to substrate such as wood, fiber glass, metals like aluminum and stainless steel, rubbers, electronic or electro-optic devices, good damping and barrier properties, thermal stability, and excellent chemical and solvent resistance . The above properties can be effectively used for various coating applications . To the best of our knowledge, epoxy resins incorporating end-functional PIBs as reactive liquid rubbers have not been reported in the literature.…”

Syntheses and Characterization of Polyisobutylene Macromonomers with Methacrylate, Acrylate, Glycidyl Ether, or Vinyl Ether End-Functionality

“…Radiation curable coatings based on vinyl ether end-functional PIB exhibited high refractive index, good adhesion, dampening, and barrier properties and could be used for encapsulating electronic devices and as high refractive index coatings for optical fibers . The incorporation of PIB as rubbery segment into epoxy networks greatly reduces the brittleness and moisture sensitivity of conventional epoxy resins . Thus, networks based on epoxy functional PIB find widespread application as chemical resistance coatings, underwater paints, coatings subject to humid environments, and wire insulation…”