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Joining of SiC, alumina, and mullite by the Refractory Metal—Wrap pressure‐less process
Author(s) -
Gianchandani Pardeep Kumar,
Casalegno Valentina,
De la Pierre des Ambrois Stefano,
Salvo Milena,
De Aloysio Giulia,
Laghi Luca,
Ferraris Monica
Publication year - 2020
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/ijac.13477
Subject(s) - materials science , mullite , refractory metals , thermal conductivity , thermal expansion , composite material , foil method , thermal diffusivity , ceramic , silicon , metal , silicon carbide , atmospheric temperature range , metallurgy , physics , quantum mechanics , meteorology
The aim of this work was to discuss the suitability of the joining process called “RM‐Wrap” (RM = Refractory Metals, ie, Mo, Nb, Ta, Zr) as a pressure‐less and tailorable technique to join several different ceramics such as SiC, alumina, and mullite (3Al 2 O 3 .2SiO 2 ). In the RM‐Wrap joining technique the refractory metal foil is used as a wrap containing one or more silicon foils. It is performed at 1450°C, under flowing argon, and the resulting joining materials are in situ formed composites made of refractory metal disilicides (MoSi 2 , NbSi 2 , TaSi 2 , or ZrSi 2 ) embedded in a silicon‐rich matrix; their coefficient of thermal expansion has been calculated and the Laser Flash Method was used to measure the thermal diffusivity of one of them (MoSi 2 /Si) in 25°C‐1000°C range, then to calculate its thermal conductivity. All the obtained joints are uniform, continuous, and crack free. Some preliminary oxidation tests were carried out on all joints at 1100°C, 6 hours in air, giving unchanged morphology of the interface and the joining materials itself; the joint strength of RM‐Wrap joined SiC was measured at room temperature using three different mechanical tests: (a) single lap (SL), (b) single lap off‐set (SLO) and (c) torsion on hourglass‐shaped samples (THG) (on Mo‐wrap joined SiC).