Tailoring interfacial bonding states of highly thermal performance diamond/Al composites: Spark plasma sintering vs. vacuum hot pressing

Abstract

Interfacial configurations of the diamond/Al composites fabricated by vacuum hot pressing (VHP) and spark plasma sintering (SPS) have been investigated to evaluate feasibility of both techniques for tailoring interfacial bonding states, namely non-bonded, diffusion-bonded, partially and fully reaction-bonded interfaces. Multiscale interfacial characterization reveals that the unique diffusionbonded interface at the micrometer scale, being very favorable for enhancing global thermal conductivity (TC), has been achieved by conventional VHP technique due to its large processing window and homogenous thermal field. Comparatively, micrometer-scale and, even macroscopic (radial and axial) thermal gradients can be inevitably generated during the SPS process in rapid heating-cooling mode. As a result, the mixed interfacial bonding states have always been introduced in the SPSed samples which reduce the effectiveness of TC enhancement. The formation mechanisms of nanoscale interfacial Al 2 O 3 and Al 4 C 3 at the diamond/Al interface are also discussed.

Enhanced bending strength and thermal conductivity in diamond/Al composites with B4C coating

“…The theoretical density of the composte is determined by. where ρ D (3.52 g/cm 3 27 ) and ρ m (2.70 g/cm 3 27 ) is theoretical density of diamond and aluminum matrix, respectively. V D and V M are the volume fraction of diamond particles and aluminum matrix respectively.…”

“…Meanwhile, SEM images for bending fracture surface show that wider interfacial gap is observed between uncoated diamond and aluminum matrix. The separation between diamond and aluminum is caused during the cooling process by the large difference in expansion coefficients between aluminum (23.0 × 10 −6 K −1 29 ) and carbon materials (1.0 × 10 −6 K −1 27 ). Therefore, the low density for uncoated diamond/Al composites is attributed to large amounts of wide gap around diamond particles.…”

From 1D to 2D arrangements of graphite flakes in an aluminium matrix composite: Impact on thermal properties

“…4c and d) show one example of a 'clean' and tightly-bonded side surface Gf/Al interface (perpendicular to the direction for thermal diffusivity measurements) where no plate-like Al4C3 due to interfacial reaction and no interfacial porosity are observed. As was revealed in [6,21], this so-called diffusion-bonded interface should be the favourable interface structure for minimizing interfacial thermal resistance and, in turn, for overall TC enhancement.…”

Fabrication of Functionally Graded Diamond/Al Composites by Liquid–Solid Separation Technology

“…During the solidification process, the voids and pores of diamond/Al composites reach more than 2 vol.% due to the difference of CTE between Al and diamond particles [26], which also reduces the interface bonding of composites. The interface of partial diffusion bonding is not enough to form the ligament connecting diamond particles and Al, and reduces the properties of the composites [27]. It is noteworthy that no selective bonding of Al on the {100} facets of the diamond is found in Figures 5 and 7.…”