Impact of grain configuration and doping modulation on the thermal electron emission properties and mechanical properties of hafnium cathode

• The effects of different preparation processes and REO doping compositions on the microstructure and properties of Hf cathodes were investigated, and it was ultimately determined that the cathode reached optimal performance at a doping level of 3 wt%. • HCO cathode exhibits over 300% of the thermal current emission density and a significantly longer cathode lifespan compared to conventional Hf cathode. • HCO cathode shows a hardness approaching 12 GPa, which is about 6–7 times of that of traditional Hf. As an indispensable cathode material for plasma torches, hafnium (Hf) materials frequently exhibit inadequate hot cathode emission current density and operational lifespan, severely restricting their use in applications. Governing principles of thermal emission characteristics of Hf cathodes are not yet fully elucidated, especially in the mechanism of the influence of micro-grain configuration and doping element modulation on their thermal electron emission properties and mechanical properties. Herein, the impact of rare earth oxide (REO) doping ratios on the emission current, lifespan, and mechanical strength of Hf cathodes using a distinctive powder metallurgy process was investigated. It was ultimately determined that the cathode reached optimal performance at a doping level of 3 wt%, exhibiting a thermal current emission density of more than 300 % and a much longer cathode lifetime, with a hardness approaching 12 GPa. The origins of the enhanced performance were systematically analyzed through comprehensive microscopic characterizations.