the development of brazing technology for sic/sicf composites for the fusion reactor applications...
TRANSCRIPT
The development of brazing technology for SiC/SiCf composites for the fusion reactor
applications
Collaboration: ENEA Frascati, Italy
Max Planck Institute of Microstructure Physics, Halle, Germany
Preparation of eutectic alloys:
The Si-Ti and Si-Cr eutectic alloys were prepared in an Ar plasma furnaceThe as obtained alloys were remelted several times in an high preasure e-beam
to obtained a fine eutectic microstructure
Microstructure of eutectic alloys
Light regions represent the Si2Ti intermetalic cmpound while the dark regions represent pure Si
SEM micrograph of the Si-Ti eutectic alloy
Manufacture of the SiC/SiCf junctions
The junctions were heated at a rate of 10 0C/min at 20 0C above the eutectictemperature, kept at this temperature for 5 min and than cooled down to room temperature at a rate of 20 0C/min
SEM cross section of the junction brazed with Si-Ti alloy
High magnification cross section
3 µmfibre
Si
Si2Ti
SiC matrix
SiC matrix
Si2TiSi
3 µm
SiC matrix
Si
5 nm
High resolution microscopy of the junction cross-sectionHigh resolution microscopy of the junction cross-section
• The interface between SiC-Si is atomically smooth• No amorphous layer was observed
Interface characterizationInterface characterization
Nanochemistry of the junctionsNanochemistry of the junctions
Si-L23 edge
C-K edge
Ti-L23 edge
50 nm
SiC
Si2Ti
SiC
Si2Ti
interface
SiC+Si2Ti
a)
c)
b)
103 eV 105 eV • No interdiffusion was observed
Mechanical testingMechanical testing
Behaviour at shearing test
• eutectic Si-16Ti and Si-18Cr alloys are suitable for joining SiC/SiCf composites
• the joints investigated did not show any defects in the brazing layer
• no interdiffusion or formation of additional phases was observed
• both Si-16Ti and Si-18Cr joints led to the conclusion that direct chemical bonds
• are responsible for the adhesion with the SiC/SiCf composites
• the shear tests of the joints of SiCf/SiC composites exhibit remarkable values
• of the bonding strength up to 140 MPa)
ConclusionsConclusions
B.Riccardi, C.A.Nannetti, J.Woltersdorf, E.Pippel, T.Petrisor, ”Joining of SiC based ceramics and composites with Si-16Ti and Si-18Cr eutectic alloys”. International Journal of Materials and Product Technology 20 (5-6): 440-451, 2004.
PublicationsPublications
B.Riccardi, C.A.Nannetti ,T.Petrisor, J.Woltersdorf, E.Pippel S.Libera L.Pilloni, “Issues of Low Activation Brazing of SiCf/SiC Composites by Using Alloys Without Free Silicon” Journal of Nuclear Materials, 329-33, 562-566 Part A AUG 1, 2004.
B.Riccardi, C.A.Nannetti, J.Woltersdorf, E.Pippel, T.Petrisor.”Brazing of SiC and SiCf/SiC composites performed with 84Si-16Ti eutectic alloy:microstructure and strength”. Journal of Material Science 37 (2002) 5029-5039.
B.Riccardi, C.A.Nannetti, J.Woltersdorf, E.Pippel, T.Petrisor. “High temperature brazing for SiC and SiCf/SiC Ceramic Matrix Composites”. Advanced SiC/SiC Ceramic Composites: development and Applications in Energy Systems, A.Kohyama, M.Singh, H-T.Lin and Y.Katoh eds, Ceramic Transactions Vol 144, The American Ceramic Society, Westerville (OH), 2002, pp 311-322.
B. Riccardi, C. A. Nanneti. T. Petrisor, M. Sacheti, A. Orsini, Italian Patent AN: RM2001A000101 (2001).