Study on activated W powders by chemical activation pretreatment and its sintering behavior

• A chemical activation was used to activate powders for enhancing the sintering effect.
• The improved densification of W sample is due to its surface defects.
• The density of the activated W sample is up to be 98% of TD sintering at 2200 °C.

In this study, tungsten (W) powders were subjected to chemical activation pretreatment by immersion into an aqueous solution of hydrofluoric acid and ammonium fluoride, and then were reinforced with an ultrasonic wave at room temperature. A field emission electron microscope was utilized to observe the surface topography of the original W and simply pretreated W. The results showed the surface of the as-pretreated was more rough and had more surface defects than original W. Both as-received and pretreated W powders were sintered under identical conditions. Their sinterability was compared and analyzed in terms of their densification, hardness and microstructure. It was concluded that increased surface area and defects which facilitate atomic mobility during the sintering process were responsible for the improved densification.

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