Characterization of VPS-W coating layers on molybdenum after heat exposure

• W powders were successfully coated on molybdenum using VPS coating technique.
• W powders were completely changed into recrystallized grains after heat exposure.
• VPS-W coating layer shows good adhesion to the Mo substrate after heat exposure due to the interdiffusion between W and Mo.
• W-coated Mo material will extend the service life of hot-zone parts for high-temperature furnace applications.

Tungsten (W) coating layers were successfully deposited using a vacuum plasma spraying (VPS) technique on a molybdenum (Mo) substrate. Tungsten powder with a median size of 10 μm was applied to prepare coatings via a plasma spray system. For the VPS process, argon and hydrogen were used as plasma-forming gases, and the coatings were deposited in 35 mbar vacuum pressure. A coating with a thickness of 300 μm was obtained, and some unmelted W powders were observed in the coating layer. This heat exposure experiment was performed in a sapphire crystal growing furnace at 2100 °C up to 110 h. After heat exposure, the VPS-W coating layers were soundly bonded with the Mo substrate due to the interdiffusion between W and Mo.

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