Joining of SiC, alumina, and mullite by the Refractory Metal—Wrap pressure‐less process. Issue 3 (4th February 2020)

• Record Type: Journal Article
• Authors: Gianchandani, Pardeep Kumar; Casalegno, Valentina; De la Pierre des Ambrois, Stefano; Salvo, Milena; De Aloysio, Giulia; Laghi, Luca; Ferraris, Monica
• Is Part Of: International journal of applied ceramic technology. Volume 17:Issue 3(2020)
• Page Start: 980
• Page End: 989
• Publication Date: 2020-02-04
• Subjects: alumina -- mullite -- pressure‐less joining -- RM‐wrap -- shear tests -- SiC -- thermal properties; Ceramics -- Periodicals; Ceramics -- Technological innovations -- Periodicals; 620.1405
• DOI: 10.1111/ijac.13477
• Languages: English
• ISSNs: 1546-542X

Abstract

Abstract: 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 (3Al2 O3 .2SiO2 ). 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 (MoSi2, NbSi2, TaSi2, or ZrSi2 ) 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 (MoSi2 /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).