Improvement of mechanical property of air plasma sprayed tungsten film using pulsed electric current treatment

• A pulsed electric current treatment (PECT) was applied to improve the mechanical property of air plasma sprayed tungsten (APS-W).
• SEM/EBSD images showed that PECT greatly decreased the amount of splat boundaries in comparison to a press-annealing.
• Misorientation angle and grain size distribution profiles revealed that electric current may enhance atomic diffusion.
• The applied electric current may cause recrystallization and grain growth below recrystallization temperature of tungsten.
• Microhardness test revealed that the mechanical property of APS-W was greatly improved by PECT.

The air plasma spraying method has a problem in the formation of many splat boundaries throughout the plasma sprayed layer, which seriously degrades mechanical properties of the metal layer. In order to improve the mechanical properties of air plasma sprayed tungsten (APS-W) by reducing the splat boundaries, a pulsed electric current is applied on as-sprayed specimens. Through microstructure observations and microhardness measurements, it was confirmed that the reduction of splat boundaries and the increase of hardness were obtained. The results are compared with those of APS-W annealed using induction heating under the same temperature, time and pressure.

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