title: Nano-mechanical behaviour of lithium metasilicate glass-ceramic.
abstract: This paper reports the first study on the mechanical behavior of lithium metasilicate glass-ceramic using nanoindentation and in situ scanning probe imaging techniques. Indentation contact hardness, Hc, and Young's modulus, E, were measured at 10 mN peak load and 0.1-2 mN/s loading rates to understand the loading rate effect on its properties. Indentation imprints were analysed with the in situ scanning probe imaging to understand indentation mechanisms. The average contact hardness increased by 112% with the loading rate (ANOVA, p<0.05) while the Young's modulus showed the loading rate independence (ANOVA, p>0.05). A strain rate sensitivity model was applied to determine the intrinsic contact hardness. Extensive discontinuities and largest maximum, contact and final depths were also observed at the lowest loading rate. These phenomena corresponded to inhomogeneous shear-band flow and densification leading to the material strain softening. The in situ scanning probe images of indentation imprints showed plastic deformation at all loading rates and shear band-induced pileups at the lowest loading rate. With the increase in loading rate, the induced pile-ups decreased. The continuum model predicted the largest densified shear zone at the lowest loading rate. Finally, these results provide scientific insights into the abrasive machining responses of lithium metasilicate glass-ceramic during dental CAD/CAM processes using sharp diamond abrasives.
authors.affiliation: Matter and Materials, College of Science, Technology and Engineering, James Cook University, Townsville 4811, QLD, Australia.
authors.forename: Abdur-Rasheed
authors.initials: AR
authors.lastname: Alao
authors.affiliation: Matter and Materials, College of Science, Technology and Engineering, James Cook University, Townsville 4811, QLD, Australia. Electronic address: ling.yin@jcu.edu.au.
authors.forename: Ling
authors.initials: L
authors.lastname: Yin
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003764:Dental Materials / Q000737:chemistry*; D055119:Elastic Modulus; D008094:Lithium / Q000737:chemistry*; D008422:Materials Testing; D055595:Mechanical Phenomena; D036103:Nanotechnology; D017640:Silicates / Q000737:chemistry*; D016474:Weight-Bearing
chemical_list: D003764:Dental Materials; D017640:Silicates; C023506:Glass ceramics; D008094:Lithium
keywords: In situ scanning probe imaging; Lithium metasilicate glass ceramic (LMGC); Loading rate; Mechanical behavior; Nanoindentation