Machinability and properties of zirconia ceramics prepared by gelcasting method

ABSTRACT

The machinability of newly developed zirconia ceramics for computer numerically controlled milling (CNC) was investigated. The zirconia blanks were prepared by the gelcasting method and tested in the green and two pre-sintered states. All blanks exhibited uniform sintering shrinkage in all directions. The blanks were investigated from the viewpoint of surface milling roughness, quality of milled edges and sharp tips, and machinability of thin structures. The best milling results were obtained for the blanks pre-sintered at 900°C/1 h. Mechanical properties of zirconia blanks, such as biaxial flexural strength, microhardness, indentation elastic modulus, and fracture toughness were determined in the green and pre-sintered states (900 and 1100°C/1 h) and the correlation with the milling results was discussed. The biaxial strength tests of sintered discs showed the advantage of optimised surface milling over conventional polishing.

KEYWORDS:

• Zirconia
• gelcasting
• pre-sintering
• machinability
• CNC milling
• mechanical properties

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was financially supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project LTACH19034 and CEITEC 2020 (LQ1601). Part of the work was carried out with the support of the CEITEC Nano Research Infrastructure (MEYS CR, 2016–2019). This work was also supported by Ministerstvo Školství, Mládeže a Tělovýchovy.