Influence of the additives amount upon SPS-sintering, metal joining, and high temperature oxidation of Si₃N₄-ceramics

Technological developments over the past years have created the need for developing new materials and processes that can better fit the requirements for advanced applications. Silicon nitride (Si₃N₄) is one of the most attractive advanced ceramic materials for structural applications due to its excellent mechanical properties, either at ambient or elevated temperatures. Although several techniques for sintering silicon nitride are now available, most of them still require liquid phase formation to confer the ceramic high-density level. This chapter is focused on the spark plasma sintering of α-Si₃N₄ powder using different amount of additives. Both, the α- to β-phase transformation observed along densification of Si₃N₄ specimens and the interfaces they form during the ceramic to metal joining are discussed as a function of the additives amount. Moreover, the Si₃N₄-ceramics behavior when exposed to high-temperature oxidation is presented. This chapter might be interesting for academic and industrial communities concerned with the sinter processing and use of ceramics for high-temperature engineering applications.