Evolution of interfacial microstructures between tungsten wires/flakes or graphite flakes and Al2O3/ZrO2 eutectic ceramics via a novel combustion synthesis centrifugal casting

Abstract

Abstract The Al2O3/ZrO2 eutectic ceramics with adding tungsten wires/flakes and graphite flakes were successfully prepared via a novel Al/Zr(NO3)4 combustion synthesis centrifugal casting under low-pressure, and the interfacial bonding between them and the Al2O3/ZrO2 eutectic was studied via using the characterization methods of Energy Dispersive Spectrometry (EDS), X-ray diffraction (XRD), Hardness and Raman. The results show that there was a thin chemical reaction layer at the interface between the tungsten wires or flakes and the Al2O3/ZrO2 eutectic system, which increased slightly with the increase of the reaction temperature from 3000 K to 3600 K, indicating that the interface was well combined. When the adiabatic temperature was 3600 K, the reaction layer thickness can reach ∼9.2 μm with the composition of WO3/Al2Zr. However, when graphite flakes were added to the combustion system, they can be oxidized by Al2O3 or ZrO2 to form CO or CO2, and the gas generation leaded to poor interface bonding between them and Al2O3/ZrO2 eutectic system. These studies provided some theoretical guidance for the future addition of tungsten fibers and carbon fibers to Al2O3/ZrO2 eutectic ceramics to improve the fracture toughness and strength of the materials. Moreover, it has guiding significance for preparing various fibers or woven fibers reinforced composite materials with large size, high density and excellent mechanical properties under ultra-high temperature.