Diffusion bonding of transparent ceramics by spark plasma sintering (SPS) complemented by hot isostatic pressing (HIP)

Diffusion bonding is a viable technique for fabricating larger parts or composite transparent ceramics. Spark plasma sintering (SPS) and hot isostatic pressing (HIP) allow for simultaneous application of high temperature and pressure, making them suitable for bonding various materials, including transparent ceramics. In this study, we demonstrated the combined use of SPS followed by HIP for successful diffusion bonding of transparent MgAl2O4 (spinel) and Y3Al5O12 (YAG) ceramics. The YAG samples had superior surface quality and were adequately bonded using SPS alone, while rougher spinel samples showed inadequate bonding initially due to insufficient surface contact. However, subsequent HIP treatment effectively closed the voids at the interface and promoted grain growth across the joint, resulting in a strong seamless bond. The combination of SPS and HIP, as a two-step process, holds promise for diffusion bonding of ceramics and offers a potential solution for compensating surface quality issues in the bonded parts.