Journal Published Online: 25 August 2017
Volume 6, Issue 4

Characterization of Niobium Carbide Layers Produced in Ductile Cast Iron Using Thermo-Reactive Treatments

CODEN: MPCACD

Abstract

Ductile cast irons are materials with good ductility and toughness, but they are susceptible to high wear rates since they have low hardness. One way to increase their wear resistance is through thermo-reactive diffusion treatments (TRD), in which carbide layers are produced on the surface of the material. In this study, two ductile cast irons (with and without the addition of copper) were treated in a salt bath composed of borax, ferroniobium (16 wt.%) and aluminum (3 wt.%) at 1000°C for 4 h. The XRD and micro-hardness analysis indicated that NbC layers were produced with hardness values higher than 2000 HV. Two methods were used to examine the adherence of the layer to the substrate. In the first method, indentations were performed using Rockwell C scale (VDI 3198). The second method used Vickers micro-hardness indentations (loads 100, 200, and 300 gf) at the interface layer/substrate. In both tests, the layers showed good adhesion to substrates. The 3198 VDI test also showed that the NbC layer produced good toughness. The results of micro-adhesive and micro-abrasive wear tests showed that the layer was very effective in increasing wear resistance.

Author Information

Soares, C.
Dept. de Engenharia de Materiais, Univ. de São Paulo / Escola de Engenharia de São Carlos, São Carlos, São Paulo, Brazil
Mariani, F. E.
Dept. de Engenharia de Materiais, Univ. de São Paulo / Escola de Engenharia de São Carlos, São Carlos, São Paulo, Brazil
Casteletti, L. C.
Dept. de Engenharia de Materiais, Univ. de São Paulo / Escola de Engenharia de São Carlos, São Carlos, São Paulo, Brazil
Lombardi, A. N.
Dept. de Engenharia Mecânica, Univ. Tecnológica Federal do Paraná, Londrina, Paraná, Brazil
Totten, G. E.
Dept. of Materials, Portland State Univ., Portland, OR
Pages: 10
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Stock #: MPC20160093
ISSN: 2379-1365
DOI: 10.1520/MPC20160093