Flash Sintering of Composite Ceramic Materials and Structures

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Ceramic materials are used in a wide range of applications including motion sensors, for energy storage in electric vehicles, dental replacement, hip and knee implants, cutting blades, and body and vehicle armour. They are exceptionally durable, even at high temperatures and in corrosive environments, and can be reused or recycled at the end of their life. However the high cost of manufacturing is a major barrier to the use of ceramic materials. Producing a dense strong ceramic material with minimal porosity requires heating to very high temperatures well over 1000 deg.C typically for many hours. Recently scientists have discovered that the temperature and duration of the ceramic densification process (sintering) can be significantly reduced by passing an electric field through the ceramic during the heating process. This "flash sintering" process, so-called because the material densifies extremely rapidly within a few seconds and often with the simultaneous emission of light, has potential to significantly reduce energy use in industrial-scale ceramic manufacturing and reduce emissions of greenhouse gases from the process by up to 40%. The flash sintering technique may revolutionise the ceramic manufacturing industry by reducing the cost and environmental impact of producing ceramic materials.In this research project a detailed investigation of the flash sintering method will be undertaken to establish the viability of this technique for use with a wide range of ceramic materials and particularly to understand the underlying mechanisms which cause the flash sintering effect. A flexible flash sintering facility will be established which can be used to flash sinter a wide range of ceramic materials. Composite materials with varying electrical conductivity will be flash sintered under different conditions. The results will used to understand the effect of both the material properties and the variables involved in the process (e.g. electric field strength, current, voltage, and temperature) on the observed flash sintering behaviour. Materials will be characterised by measuring their density, imaging using scanning electron microscopy and mapping the chemical composition, and using X-ray diffraction to determine any changes to the phase composition of the materials caused by the flash sintering process. New insights will be gained by flash sintering for the first time a structure made of layers of ceramic composite materials graded by composition and examining how the flash sintering behaviour changes compared to samples containing each individual composition. The results of this project will be used by our industrial project partners Lucideon and Morgan Advanced Materials in the industrial development and application of flash sintering technology.