Title

SINTERIZAÇÃO POR PLASMA DE AÇOS CARBONO NA CONFIGURAÇÃO ÂNODO-CÁTODO CONFINADO

PLASMA SINTERING OF CARBON STEELS IN CONFINED CATHODE-ANODE CONFIGURATION

Authorship

Bonetti, Alan Neves; Pavanati, Henrique Cezar; Maliska, Ana Maria

Bonetti, Alan Neves

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Pavanati, Henrique Cezar

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Maliska, Ana Maria

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DOI

10.5151/2594-5327-0406

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Abstract

Neste trabalho amostras de Fe-0,8% C foram compactadas em uma matriz uniaxial de duplo efeito, com pressão de compactação de 600 MPa e posteriormente sinterizadas a 1150 oC durante 60 min em forno de aquecimento resistivo e em reator de plasma na configuração ânodo-cátodo confinado. A atmosfera usada no reator de plasma foi de 95% H2 e 5% Ar, e no forno convencional 100% H2. A tensão de pico aplicada ao cátodo na configuração ânodo-cátodo confinado foi de 700 V, tempo de pulso ligado de 180

In this work samples of Fe-0.8%C, compacted to a pressure of 600 MPa using a double action press with moving die body, were sintered at 1150 oC during 60 min in resistive furnace and in a plasma reactor, using a confined anode-cathode configuration. The atmosphere used in plasma was gas mixture of 95% H2 and 5% Ar, and in conventional furnace 100% H2. In plasma reactor the sintering was carried out applying a voltage of 700 V to the cathode and adjusting the pressure in order to reach the desired temperature. In the confined anode-cathode configuration, the samples were positioned on a holder acting as the discharge anode, inside a hollow cathode. The cathode was heated by the bombardment of ions and fast neutrals accelerated in the cathode sheath and, as a consequence of the confined geometry, the sample was efficiently heated by thermal radiation. The sample characterization was carried out by optical microscopy, scanning electron microscopy and microhardness test. The results show an intense decarburization at the surface in samples sintered in the conventional furnace. In the case of the samples sintered in plasma reactor it was also observed a slight decarburization. However, it occurs in the whole sample. In this case no superficial decarburization was observed. This effect can be attributed to the different sintering pressure used in both processing techniques. The sintering pressure in the conventional furnace was two orders of magnitude higher than in the plasma reactor. It is confirmed when hybrid plasma/resistance heating is used to sintering carbon steels. The results of this study show also the viability of sintering carbon steel by plasma in the confined anode-cathode configuration without superficial decarburization.

Keywords

Metalurgia do pó, Sinterização por plasma, Aços ao carbono.

Powder metallurgy; Plasma sintering; Carbon steel.