Torsion Tests on AV119 Epoxy – Joined SiC

Abstract

The results of an experimental investigation on epoxy-joined silicon carbide tested in shear mode by four different configurations of torsion test are presented and compared to results obtained by asymmetric four-point bending and four different lap tests in compression. All samples have been joined by an epoxy adhesive (Araldite AV119) which is to be considered as a model brittle joining material chosen to obtain several joined samples in a reasonable time. Advantages and disadvantages of each configuration are discussed and compared to results previously obtained with epoxy-joined Carbon/Carbon composites and ceramics tested with the same methods. *monica.ferraris@polito.it

Shear Strength Measurement of AV119 Epoxy‐Joined SiC by Different Torsion Tests

“…However, the shear strength for TT was 38.7 ± 4.0 MPa and 22.4 ± 9.1 MPa for TRC, both much lower than what previously measured and reported for TC (63.8 ± 7.8 MPa) and THG‐5 (66.4 ± 10.7 MPa, measured both on AV119‐joined SiC and AV119 joined steel) …”

“…AV119‐joined SiC samples in the shape of tubes (TT) were the most difficult to test. Most of them crushed inside the torsion machine fixtures, as reported in . A careful clamping made it possible to obtain the fracture of some samples in the joined area, but the test efficiency was quite low (20%) thus making the use of this configuration unlikely.…”

“…The torsion tests were performed in a universal testing machine (ZWICK 100, Zwick/Roell, Herefordshire, U.K.), where the load was applied until fracture occurred. The torsion load was applied using a rotating disk fixture with a wire equipped in the mechanical test frame . The cross‐head speed was 0.5 mm/min with an estimated rotation speed of about 0.010 rad/min.…”

“…However, a suspect overestimation of shear strength has been found and reported in for AV119 epoxy–joined SiC when tested in torsion and compared with the same samples tested by asymmetrical four‐point bending test, giving a factor of three between results.…”

“…As for previous works on this subject, an epoxy adhesive (Araldite AV119, Huntsman, Salt Lake City, UT) was chosen to obtain several joined samples in a reasonable time. SiC is a well‐known useful material for harsh environment applications, which is still lacking of a reliable testing method when joined to build complex components.…”