resumo
Sintering of WC-stainless steel (SS) composites within a typical binder range from 6 up to 15 wt% SS was investigated through constant heating rate dilatometry, in vacuum conditions, complemented by differential thermal analysis and by the study of the high temperature wetting behavior of SS on WC. The densification starts similar to 900 degrees C with a typical densification curve for all compositions, where three distinct regions are discernible: the first one with a slow densification rate, followed by a second region where a sharp increase in the densification rate up to a maximum value dependent on the binder amount is observed and, finally, a third one with a slowdown of the densification rate until the end of the thermal cycle. The attained final density at 1450 degrees C is dependent on the binder amount, increasing proportionally to its initial content. The final microstructure presents a normal grain size distribution and appreciable amounts of eta-phase, besides the major WC phase and residual iron rich phase. The reactive densification behavior and the role of the liquid phase are interpreted accordingly with structural and kinetic data. (C) 2017 Elsevier B.V. All rights reserved.
palavras-chave
LIQUID-PHASE; WC-CO; ACTIVATION-ENERGIES; STAINLESS-STEEL; COBALT SYSTEM; HEATING RATE; DENSIFICATION; POWDER; TEMPERATURE; COMPOSITES
categoria
Materials Science
autores
Fernandes, CM; Oliveira, FJ; Senos, AMR
nossos autores
Ana Maria de Oliveira e Rocha Senos
Colaborador
Cristina Maria da Silva Fernandes
Colaborador
Filipe José Alves de Oliveira
Investigador PrincipalGrupos
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G3 - Materiais Eletroquímicos, Interfaces e Revestimentos
agradecimentos
The authors wish to thank MSc V.L. Silva for the assistance in the wettability experiments. The author C.M. Fernandes gratefully acknowledge the financial support from the program COMPETE and by national funds through FCT under the grant SFRH/BPD/43402/2008. The authors gratefully acknowledge the financial support from the National Strategic Reference Framework (QREN/I&DT/11428/2009) of the European Regional Development Fund (ERDF). This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.