분말사출성형한 W-15 wt%Cu 나노복합분말의 고상소결에 미치는 잔류불순물의 영향

Abstract

The effects of residual impurities on solid state sintering of the powder injection molded (PIMed) W-15wt%Cu nanocomposite powder were investigated. The W-Cu nanocomposite powder was produced by the mechano-chemical process consisting of high energy ball-milling and hydrogen reduction of W blue powder-CuO mixture. Solid state sintering of the powder compacts was conducted at 1050℃ for 2~10 h in hydrogen atmosphere. The densification of PIM specimen was slightly larger than that of PM(conventional PM specimen), being due to fast coalescence of aggregate in the PIM. The only difference between PIM and PM specimens was the amount of residual impurities. The carbon as a strong reduction agent effectively reduced residual W oxide in the PIM specimen. The H2O formed by H2 reduction of oxide disintegrated W-Cu aggregates during removal process, on the contrary to this, micropore volume rapidly decreased due to coalescence of the disintegrated W-Cu aggregates during evolution of CO. It can be concluded that the higher densification was due to the earlier occurred Cu phase spreading that was induced by effective removal of residual oxides by carbon.