Plasma-Spark Sintering of Oxide–Non-Oxide Components with the Addition of a TiC–ZrC Solid Solution and Various Metal Powder Mixtures

Abstract

The effects of powder mixtures of W–Mo and Zr–Ti combined with sintered solid solution TiC–ZrC during spark plasma sintering of compositions at a pressing load of 60 MPa in the range 1200 – 1600°C on the phase composition, microstructure, grain sizes of crystalline phases, relative density, linear shrinkage, physical-mechanical properties, and linear correlation of elasticity modulus and fracture toughness of mullite–β-Si3N4–c-BN samples are shown in the present work. Synthesized powders of β-Si3N4 and c-BN are characterized by extensive crystallization of β-Si3N4 and c-BN. Solid solution TiC–ZrC sintered by a spark-plasma method at 1800°C shows roughly equal crystallization of (Zr,Ti)C and (Ti, Zr)C and a nonuniform and incompletely sintered crystalline microstructure. Samples with W–Mo and Zr–Ti mixtures sintered in the range 1200 – 1600°C show extensive mullitization; active crystallization of β-Si3N4, (Ti,Zr)C, solid solutions Mo, Wand W, Mo, and β-Zr,Ti; and lower crystallization of c-BN, (Zr,Ti)C, and β-Ti,Zr. The W–Mo mixture in the range 1400 – 1600°C favors the formation of a more uniformly and densely sintered microstructure of the ceramic phase; roughly round-shaped particles of solid solutions Mo, W and W, Mo in the metallic phase; more reinforced boundary areas of ceramic-metallic and metallic phases; and polydisperse grain compositions of crystalline phases. As a result, the composition with the W–Mo mixture sinters more uniformly and gradually in the range 1200 – 1600°C with the corresponding sample showing greater values of physical-mechanical properties, higher cracking resistance, and a greater linear correlation of the elasticity modulus and fracture toughness.