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Sinterization of Niobium Carbide, Tungsten Carbide and functionally graded material containing carbides by means Spark Plasmas Sintering (SPS).

Grant number: 12/12693-8
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): October 01, 2012
Effective date (End): September 30, 2013
Field of knowledge:Engineering - Mechanical Engineering - Manufacturing Processes
Principal Investigator:Izabel Fernanda Machado
Grantee:Nério Vicente Júnior
Home Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Carbides are widely employed materials in cutting tools and forging die inserts owing their very high hardness, excellent corrosion resistance and chemical stability. On the other hand, poor toughness appears as a critical point. Therefore, a small amount of metallic phases (binder phases) are usually employed. In Functionally Graded Materials (FGM) the transition from one to another material consists in layers containing a gradual chemical composition, leading to an internal stress release. This technique has been used to manufacture ceramic-metallic components. The Spark Plasma Sintering (SPS) process is a kind of advanced sintering technique. It does make use of the pulsed DC electric current to generate in situ heating by the Joule effect. This feature allows the application of very high heating rates as well as a minimal thermal losses. On this work three topics will be faced: i) Sintering of niobium carbide (NbC) and tungsten carbide (WC); ii) Sintering of composites formed by those carbides and high resistant metallic alloys; iii) Sintering of two FGM's (one for each carbide) composed by the best carbides and metallic alloys combination. The optimization of the SPS sintering parameters will be performed on the bases of the interdependence between density, microstructure and hardness. Moreover, metallographic and X-ray diffraction analyses will be carried out for the microstructures and the product of reactions assessment. Lastly, hardness, toughness, bending and the measurement of mechanical and thermal requirements during working will be tested as well.