High-temperature properties of joint interface of VPS-tungsten coated CFC

Behavior of actively cooled mock-ups with plasma sprayed tungsten coating under high heat flux conditions

“…This shows that disk-like tungsten is accumulated in the coating layer. Compared with the previous ones where spherical particles were melted or partially melted and joined to each other and pores were formed in the coatings [3], it can be seen that the VPS-W increases in density. VPS-W coated TZM (Mo-0.5Ti-0.07Zr alloys) were also prepared.…”

“…They are simply denoted as W/CX-2002U and W/IG-430U, respectively. The carbon or the graphite substrates had received PVD multilayer diffusion barrier layers of rhenium and tungsten prior to the coating in order to inhibit uncontrolled brittle carbide formation [3]. Heat treatments at 1173 K for 5 h were performed to stabilize the microstructure of the samples.…”

“…From the viewpoints of thermal conductivity and mechanical strength, it seems that carbon/carbon fiber composites (CFC) and molybdenum alloys are preferable as a substrate material for high heat flux loading. Thick tungsten coatings on CFC and isotropic fine grain graphite were successfully produced by vacuum plasma spray (VPS) technique and their good thermal and adhesion properties have been confirmed by high heat flux tests [3]. Furthermore, VPS-W (tungsten) coated CX-2002U and IG-430U were brazed on the OFHC with a cooling tube.…”

Effect of heat treatment at 1300°C on W coating prepared by double-glow plasma on carbon/carbon composite

“…[2][3][4][5] Thick W coatings on carbon/carbon (C/C) composite and isotropic fine grain graphite were successfully produced by vacuum plasma spray and physical vapor deposition, and their good thermal and adhesion properties have been confirmed by high heat flux tests. 6,7 In these experiments, W concentration in the main plasma remained below 2 · 10 -5 , which was below the maximum impurities concentration tolerable in ITER ignited plasma. 4 However, the main impurity was still carbon due to the interactions between the first wall and other plasma facing components made of graphite or carbon-based materials.…”

Development of W coatings for fusion applications

“…A multilayer Re/W was deposited by PVD prior to the VPS coating with the aim to prevent the carbon diffusion from the substrate and formation of brittle tungsten carbides. As the experiments have shown the rhenium, as non-carbide former, is efficient up to 1600 • C. For higher temperature the Re/W multilayer structure disappeared and tungsten carbides were formed [2]. Tungsten coatings of 0.5-1.0 mm applied by VPS on small samples (20 mm × 20 mm × 10 mm) of CFC (type CX-2002U) and FGG (type IG-430U) were successfully tested up to 18.6 MW/m 2 (T max ≤ 2200 • C) [3] and at 100 cycles of heat loads at 10 MW/m 2 -steady state [4].…”