"Toughening Al2O3 based Ceramics by Introducing a Second Phase via Flash Sintering" 

Shiyu Zhou, MSE PhD Candidate 

Advisor: Professor Haiyan Wang

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ABSTRACT

Alumina materials have always attracted widespread attention because of their optimal hardness, wear resistance, high thermal resistance, and chemical stability. However, alumina's lack of good toughness limits its application in many fields. The addition of a second phase during sintering is considered an effective toughening mechanism because it can lead to crack deflection, bridging, microcracks, and phase transitions in alumina ceramics. To obtain alumina-based dual-phase ceramics with high toughness and high hardness, it is crucial to have a general understanding of different sintering methods and select appropriate additives. This report summarizes how crack deflection, bridging, microcracks, and phase transitions influence the toughness of ceramic materials by adding a second phase. To demonstrate how sintering may affect mechanical test results of ceramic materials, five methods of sintering ceramics are explained and compared, namely UHP, HIP, SPS, microwave sintering and flash sintering. Additionally, this report briefly summarizes the research on the toughening of alumina ceramics by these methods, and puts forward the problems and challenges of these methods in improving the toughness of alumina ceramics, and ultimately highlights the potential of flash sintering as the method and titanium dioxide as the additive to achieve the toughening goals of alumina ceramics.