Low-temperature joining of boron carbide ceramics

Abstract

Low-temperature joining of boron carbide (B₄C) ceramics using an Al sheet was investigated in the temperature range of 600–1200°C for 2 h in vacuum (10⁻²–10⁻⁴ Pa). Successful joining and high bending strength close to that of the B₄C base were achieved in the samples joined at 700–1100°C. Different techniques including scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) were used to characterize the high-strength B₄C joints. SEM observations suggested the dense interlayer and the crack-free interface as well as the penetration of Al into the surface microcracks of B₄C base. Further TEM examinations revealed that B₄C and Al joined directly. EPMA analysis demonstrated the existence of several reaction products within interlayer, including AlB₂ and Al₃BC, which resulted in the development of high-strength composite interlayer.