TY - JOUR

T1 - Pulsed current-assisted joining of copper to graphite using Ti-Cu brazing layers

AU - Vidyuk, T. M.

AU - Dudina, D. V.

AU - Esikov, M. A.

AU - Mali, V. I.

AU - Anisimov, A. G.

AU - Bokhonov, B. B.

AU - Batraev, I. S.

PY - 2019/10/1

Y1 - 2019/10/1

N2 - Copper-graphite joints are functional elements of many electronic and electromechanical devices. Unique properties of graphite, such as the ability to withstand high temperatures, a low friction coefficient and high thermal and electrical conductivities make it an attractive material for various applications. For enabling efficient heat sink or making sliding electrical contacts, graphite requires joining to metallic copper. Poor wettability between copper and graphite is a problem that needs to be overcome to form a reliable joint. In the present work, we used a Ti25Cu75 alloy to braze graphite to copper in a pulsed current-assisted process. Brazing was carried out in a Spark Plasma Sintering (SPS) apparatus under a uniaxial pressure of 13 MPa. The SPS conditions - a possibility of localized heating under an applied pressure in dynamic vacuum - are beneficial for the joining processes of conductive materials. For joining graphite and copper plates, a die-free configuration was used. The microstructure and the phase composition of the copper-graphite brazed joints were investigated. Strong joints were formed when the upper electrode temperature measured by a thermocouple reached 700 °C. At the graphite-alloy interface, a TiC layer 0.5-1 μm thick was formed; in addition, TiC particles were found in the metallic matrix in a layer 5-10 μm thick adjacent to the graphite plate. The tensile strength of the brazed joint was higher than the tensile strength of graphite (13 MPa).

AB - Copper-graphite joints are functional elements of many electronic and electromechanical devices. Unique properties of graphite, such as the ability to withstand high temperatures, a low friction coefficient and high thermal and electrical conductivities make it an attractive material for various applications. For enabling efficient heat sink or making sliding electrical contacts, graphite requires joining to metallic copper. Poor wettability between copper and graphite is a problem that needs to be overcome to form a reliable joint. In the present work, we used a Ti25Cu75 alloy to braze graphite to copper in a pulsed current-assisted process. Brazing was carried out in a Spark Plasma Sintering (SPS) apparatus under a uniaxial pressure of 13 MPa. The SPS conditions - a possibility of localized heating under an applied pressure in dynamic vacuum - are beneficial for the joining processes of conductive materials. For joining graphite and copper plates, a die-free configuration was used. The microstructure and the phase composition of the copper-graphite brazed joints were investigated. Strong joints were formed when the upper electrode temperature measured by a thermocouple reached 700 °C. At the graphite-alloy interface, a TiC layer 0.5-1 μm thick was formed; in addition, TiC particles were found in the metallic matrix in a layer 5-10 μm thick adjacent to the graphite plate. The tensile strength of the brazed joint was higher than the tensile strength of graphite (13 MPa).

KW - Brazing

KW - Copper

KW - Graphite

KW - Microstructure

KW - Spark plasma sintering

KW - Ti-Cu alloy

KW - Titanium carbide

KW - PLASMA

KW - CFC COMPOSITES

UR - http://www.scopus.com/inward/record.url?scp=85086935690&partnerID=8YFLogxK

U2 - 10.1016/j.matpr.2019.12.095

DO - 10.1016/j.matpr.2019.12.095

M3 - Conference article

AN - SCOPUS:85086935690

VL - 25

SP - 377

EP - 380

JO - Materials Today: Proceedings

JF - Materials Today: Proceedings

SN - 2214-7853

T2 - 3rd All-Russian Conference, with International Participation Hot Topics of Solid State Chemistry : From New Ideas to New Materials, HTSSC 2019

Y2 - 1 October 2019 through 5 October 2019

ER -