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Multifunctional Ceramic composites

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The development of ceramic compositesthat are electrical conductors and display good high-temperature structural properties is of great interest for a wide range of applications. Composites made of insulating ceramics (such as alumina, silicon nitride, aluminum nitride, silicon carbide ) and variable amounts of electroconductive phases (metallic, intermetallic or ceramic) can fulfill these requirements.

The following composites are produced and studied at ISTEC:

  • Si3N4-TiN, Si3N4-MoSi2
  • AlN-SiC-MoSi2, AlN-SiC-ZrB2, AlN-SiC-ZrC
  • Al2O3-TiC, Al2O3-TiB2, Al2O3-TiN, Al2O3-Mo, Al2O3-NiAl.

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These composites are currently employed in applications as heaters, igniters. The addition of a “lubricant” secondary phase such as h-BN allows high machinability. Cermet (ceramic-metal composites) based on TiCN-WC-Ni-Co and WC-Co hard metals are also studied as cutting tools.

Characteristics like:

  • sintering behaviour
  • microstructure
  • electrical resistivity
  • thermo-mechanical properties at room and high temperature

are investigated.

PUBBLICATIONS:

 

D. Sciti, S. Guicciardi, C. Melandri, A. Bellosi, “High Temperature resistant composites in the AlN-SiC-MoSi2 System”, Journal of the American Ceramic Society, 86 [10] (2003) 1720-26

D.Sciti, L. Silvestroni, A. Balbo, S. Guicciardi, G. Pezzotti, “High-Strength And Toughness Electroconductive SiC-based Composites”, Advanced Engineering Materials, 8, No 10, (2006) 997-1101

A.Bellosi, V. Medri, F. Monteverde, Processing and properties of Ti(C,N)-WC-Based Materials, Journal of the American Ceramic Society 84 [11] (2001) 2669-76.

S. Guicciardi, R. Calzavarini, V. Medri, S. Bugliosi, A. Bellosi, Effects of different BN grades on the machinability of Si3N4-MoSi2-BN composites, Materials Science & Engineering A445-446 (2007) 579-586

PROCESSES & FACILITIES:

ISTEC is involved in the following activities:

  • design and manufacturing of bulk ceramic composites dense or porous containing various sintering additives starting from commercial powders.
  • powder processing
  • sintering by hot pressing, pressureless sintering, gas pressure sintering
  • microstructural characterization by SEM-EDS, X-ray diffraction
  • mechanical and thermal characterization (4-pt flexural strength up to 1500°C, fracture toughness, hardness, modulus, thermal expansion, etc).

Tests of oxidation resistance and post-oxidation microstructural characterization by SEM-EDS, X-ray diffraction.

MAIN SCIENTIFIC COLLABORATIONS:

2010-2012: European Project E2PHEST2US, “Enhanced Energy Production of Heat and Electricity by a combined solar Thermoionic-Thermoelectric Unit System”, (Grant agreement n. 241270).