A domestic research team has successfully developed a technology to manufacture high-hardness, high-density ceramic microparticles for manufacturing ultra-small beads.

The Korea Institute of Materials Science (KIMS, President Lee Jung-hwan), a government-funded research institute under the Ministry of Science and ICT, has successfully developed a nanoscale zirconia superparticle assembly control technology through joint research with Cenotech Co., Ltd., led by Dr. Min Yu-ho and Dr. Choi Jong-jin of the Functional Ceramics Laboratory of the Ceramic Materials Research Division. The research team also developed a technology to convert this into ultra-small ceramic microparticles with high hardness, high density, and high elastic modulus.

The newly developed superparticle assembly control technology simultaneously controls the dispersion stability and assembly speed of nanoparticle colloidal suspensions, enabling the production of ultra-small ceramic spherical assemblies with extremely high sphericity and density. By controlling the sintering process, it maintains sphericity while improving the hardness, density, and elastic modulus of the ceramic material.

The ultra-small ceramic microparticles developed using this technology exhibited the highest hardness compared to yttria-stabilized zirconia ceramic bulk and film materials manufactured by various processes to date. The sphericity and theoretical relative density are over 99% and 98%, respectively. If commercialization technology for manufacturing ultra-small ceramic beads is developed in the future, it is expected that the technology for manufacturing ultra-small, high-hardness ceramic beads measuring 30 micrometers (㎛) or less, currently monopolized by Japanese companies, will be domestically produced.

Recently, demand for ultra-small (30 micrometers or less) beads, smaller than conventional ceramic beads, is rapidly increasing in various cutting-edge industries, including electrical and electronics, energy, and environmental industries, due to the nano-refining of key raw material powders and the integration of components. In particular, for multilayer ceramic capacitors (MLCCs) for automotive applications, nano-refining and high-purity raw material powders are essential for high performance. Consequently, the required bead size is gradually decreasing, while at the same time, higher hardness is required to withstand strong impacts.

Conventional ceramic bead manufacturing processes have technical limitations in producing ultra-small ceramic beads measuring 30 micrometers (㎛) or less. Beyond simply reducing the size, the ceramic beads themselves must possess high hardness and high density to ensure high purity and refinement of the pulverized material. Furthermore, precise size control and high sphericity are crucial.

The research team utilized a spray-drying method, which facilitates mass production, to fabricate ultra-small ceramic assemblies with high sphericity and density. Furthermore, by controlling the sintering process, they successfully transformed the microparticles into ceramic microparticles with enhanced hardness and elastic modulus. The hardness of the developed microparticles was approximately 27 gigapascals (GPa), demonstrating the highest value compared to materials developed using other processes with the same composition. The elastic modulus also showed an excellent value of 210 gigapascals (GPa).

The global market for ceramic beads, a core technology in nanoceramic powder manufacturing and processing, is rapidly growing at an average annual rate of 8.0% from 380 ($USD Million) in 2016, and is expected to reach approximately 636.3 ($USD Million) by 2023. While the ceramic bead market itself is not large, a disruption in bead supply, as seen in Japan's recent export restrictions on Korea, would have a significant economic impact, as it would make it impossible to produce multilayer ceramic capacitors (MLCCs) and secondary battery-related components that require them.

Min Yu-ho, a senior researcher at the Korea Institute of Materials Science and Engineering who led the research and development, said, “The results of this study secure a manufacturing technology for ceramic microparticles with high density, hardness, and sphericity, and can be seen as one step closer to commercializing the manufacturing of ultra-small ceramic beads, which is currently monopolized by Japanese companies.” He added, “It is expected to have even greater value in the future as it can be used in various industrial fields as well as breaking away from our dependence on Japan.”

This research was supported by the Ministry of Trade, Industry and Energy's Materials and Components Technology Development Project (led by Cenotec Co., Ltd.) and was promoted as a project of the Materials and Components Manager Department under the Ceramic PD Planning Department of the Korea Evaluation Institute of Industrial Technology (KEIT). Furthermore, the research results were published online on May 26th in the world-renowned academic journal ACS Nano (first author: Dr. Taewon Lee, researcher Youngrok Kim). The research team plans to further develop the core technology for manufacturing high-density, high-hardness ceramic microparticles through ongoing joint research with Cenotec Co., Ltd. and to develop commercialization technology for the domestic production of ultra-small ceramic beads.