Proposal and research on using tungsten carbonyl-CVD process for making W-coating PFMs and W-tubes

Abstract It is proposed to use W(CO)6-CVD (chemical vapor deposition) process to make plasma facing materials (PFMs). The advantages of using W(CO)6-CVD process are as follows: low decomposition temperature of about 400 °C, no corrosion for the processing facilities and no reduction process required, etc. Tungsten coatings were deposited on copper substrates at 400, 450, 500 and 550 °C in hydrogen gas flow. The microstructure, thickness and phase analysis were carried out using SEM and XRD. Coatings with the thickness of 12.5 μm have been deposited on copper substrates at 500 °C. The micro-hardness values of the as-prepared β-W coatings are 500–600 HV. After annealing in high purity hydrogen at 900 °C, α-W coatings were obtained. Besides, a thin W tube has also been obtained under the same conditions on copper tube with nitrogen gas flow.