Scientists use nanotubes to boost fracture

Researchers from Iran University of Science and Technology in association with scientists from EPFL University, Switzerland, and Stockholm University, Sweden, tripled the fracture toughness in zirconia-based ceramic structures by using carbon nanotubes. The ceramic, having appropriate distribution of carbon nanotubes on a zirconia base and possessing highly desirable mechanical properties, has various applications in advanced industries, including aerospace, electronics, and medical engineering. Mahdiyar Taheri, M.Sc. in materials engineering and metallurgy in Iran University of Science and Technology, elaborated on different stages of the research, and said, “Carbon nanotubes were firstly distributed in a ceramic bed by using Turbula mixer, and the samples were baked through the new method of spark plasma sintering (SPS). The produced samples were next characterized by using SEM and TEM devices. After the baking process at various temperatures, mechanical properties were evaluated at room temperature (determination of fracture toughness through cone penetration method) and at high temperature (through mechanical spectrometry method).” Results confirmed the appropriate distribution of carbon nanotubes in zirconia matrix at high volume ratio at dry environment. Among other important results obtained by the researchers, mention can be made of significant improvement in fracture toughness due to the simultaneous effect of the presence of carbon nanotubes in the base and increasing the size of particles in the stabilized zirconia bed, modification in high temperature properties of the compound, and appropriate cooking of the bodies. The production of ceramic bodies through the method proposed in this research, which has useful characteristics, including thermal and electrical properties and biocompatibility, may resolve the problems in the use of ceramic implants and thermal devices used in various industries. Results of the research have been published in Ceramics International, vol. 40, issue 2, March 2014, pp. 3347-3352