Abstract
Samples of unalloyed iron powder were compacted and sintered in an abnormal glow discharge, generated in a gas mixture of 80% Ar + 20% H2 by using a pulsed power source. The samples were placed on a holder, acting as the discharge cathode, and were heated by the bombardment of ions, strongly accelerated in the cathode sheath. Sintering was performed at temperatures of 1173, 1273 and 1373 K for 30 min, varying the voltage applied to the cathode from 400 to 700 V and pressure ranging from 470 to 2650 Pa. It is shown that the kinetic energy of ions striking the sample surface increased approximately three times, when the voltage changed from 400 to 700 V, with a corresponding reduction of surface porosity. The surface sealing is related to the ion bombardment, which produced a high mobility of surface atoms and consequent enhanced diffusion as well as sputtering and condensation on the concave surface, resulting in an activation of surface sintering.
Highlights
Glow discharge processes, as plasma assisted chemical vapor deposition (PACVD), plasma assisted physical vapor deposition (PAPVD), etching, nitriding or nitrocarburizing and surface cleaning are exhaustively used in industry[1,2,3,4,5,6,7,8,9,10,11,12]
For the sample plasma-sintered in condition 2, a significant porosity sealing was observed, which is attributed to higher energy of ion bombardment of the sample surface, as compared to the condition 1
Such an effect is associated with the enhanced condensation of atoms resulting from sputtering and the increased surface diffusion of atoms resulting from the highenergy ion bombardment of the sample surface
Summary
As plasma assisted chemical vapor deposition (PACVD), plasma assisted physical vapor deposition (PAPVD), etching, nitriding or nitrocarburizing and surface cleaning are exhaustively used in industry[1,2,3,4,5,6,7,8,9,10,11,12]. In these techniques, the reactive species generated in the plasma produce an activated processing and the ion bombardment of the parts or the target is used for heating or sputtering respectively. In order to study the influence of ion bombardment on the surface porosity, the negative voltage connected to the cathode was varied
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