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COATINGS WERE PROCESSED BY ELECTRIC ARC SURFACE ALLOYING OF FE-30CR-4C ELECTRODE ON THE LOW-ALLOYED VCO AND VH13 FERRITIC STEELS. THE OBTAINED SURFACE ALLOY (COATING) SHOWS A HYPEREUTECTIC STRUCTURE FORMED BY PRIMARY (FE,CR)7C3 PLATELETS SURROUNDED BY THE EUTECTIC, AUSTENITIC SOLID SOLUTION AND (FE,CR)7C3 CARBIDES. THIS SURFACE ALLOY PRESENTS A HIGH HARDNESS (850 HV), COMPARED TO THE VCO (400 HV) OR VH13 (450 HV) STEEL, AND A DECREASE IN THE WEAR RATIO BY A FACTOR CLOSE TO TWO. CONTRARY TO THE SUBSTRATES, THE SURFACE ALLOY EXHIBITS AN EXCELLENT HIGH TEMPERATURE OXIDATION RESISTANCE DUE TO A MICROCRYSTALIZED CHROMIUM OXIDE LAYER FORMED AFTER 100 H OF OXIDATION AT 950 OC. OXIDATION KINETICS AND FORMED OXIDES OF THE SURFACE ALLOY AND SUBSTRATES ARE DISCUSSED IN THE LIGHT OF THERMODYNAMICS AND DIFFUSION PROCESSES. |
