COBEM99

S18 Processos Mecânico-Metalúrgicos

Title:

PROCESS TIME INFLUENCE ON THE COMPOSITION AND SURFACE FINISHING IN IRON SAMPLES SINTERED IN HOLLOW CATHODE DISCHARGE

Summary :

ABSTRACT: THIS PAPER RESULTS FROM NA ATTEMPT TO STUDY THE INFLUENCE OF THE SINTERING TIME ON THE SINTERING IRON PROCESS, WITH SURFACE ENHANCEMENT OF ALLOY ELEMENTS, IN HOLLOW CATHODE DISCHARGE. THE CYLINDRICAL SAMPLE OF IRON POWDER, BEING A CENTRAL CATHODE, WAS PLACED CONCENTRICALLY IN THE INTERIOR OF AN OUTER CATHODE, MACHINE-MADE FROM AN AISI 310 STEEL TUBE. THE SINTERING WAS CARRIED OUT AT 1150O C, USING TIMES OF ½, 1, 2 AND 4 HOURS, IN GAS MIXTURES OF 80% AR + 20% H2, FLOW OF 5 CM3/S, 3 TORR PRESSURE AND INTER-CATHODE RADIAL SPACE OF 5.8 MM. THE DISCHARGE WAS GENERATED USING A PULSED VOLTAGE POWER SOURCE, WITH A 200 MS PERIOD. IT HAS BEEN OBSERVED THAT SINTERING TIME PLAYS AN IMPORTANT ROLE BOTH IN SURFACE FINISHING, WHICH IS REFLECTED IN THE SURFACE ROUGHNESS, AND IN THE QUANTITY OF ATOMS DEPOSITED AND DIFUSED ON THE SAMPLE SURFACE. THE MICROPROBE CHARACTERISATION SHOWED THE PRESENCE OF UNTIL 3.5% CR AND 3.0% NI (ATOM %). THIS SURFACE ENHANCEMENT IS ATTRIBUTED TO THE SPUTTERING MECHANISM OF METALLIC ATOMS FROM THE OUTER CATHODE, DEPOSITING AND CONSEQUENT DIFFUSION OF THESE ELEMENTS IN THE SAMPLE. KEY-WORDS: HOLLOW CATHODE DISCHARGE, PLASMA SINTERING, SURFACE DEPOSITION, IRON SINTERING WITH ALLOY ELEMENTS SURFACE ENRICHMENT, SPUTTERING

Author :

Brunatto, Silvio Francisco
Kühn, Ingeborg 0
Muzart, Joel Louis Rene

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