Experimental analysis and modeling of the Knoop hardness of lithium disilicate glass-ceramics containing lithium tantalate as a secondary phase

Machine learning predictions of Knoop hardness in lithium disilicate glass‐ceramics

“…As reported in previous work on XRD, 4,31 the chemical composition of the parent glass (in wt.%) was the following: 62.7% SiO 2 , 11.9% Li 2 O, 3.4% Al 2 O 3 , 3.2% K 2 O, 16.8% Ta 2 O 5 , and 2.1% P 2 O 5 . The data set included eight series of eight samples each, where each series had a unique nucleation temperature ( T n ) and each sample contained within had a unique growth temperature ( T gr ).…”

“…A further in‐depth discussion of CNNs can be found in numerous sources 25–27,29 . As far as the authors are aware, this is the first application of CNNs to glass‐ceramics; however, we have previously presented other machine learning applications to GC 4,30,31 …”

“…Understanding the mechanical properties of glass‐ceramics (GCs) is crucial for their use in a number of industries, including dental materials, anti‐ballistic armors, and alternatives to glass containers 1–7 . This processing–microstructure–property relationship is more complex in GCs than in glass, because the mechanical properties are dictated not only by the glass structure but also by the phase assemblage and morphology of the crystalline grains that form in the glassy matrix.…”

“…Additionally, the glass will also undergo compositional changes as a result of the crystalline phases preferentially leaching ions from the glass. One way to extend the predictive capabilities of this type of model would be to consider that every crystalline phase would have a unique contribution to the H K , and the overall H K would simply be a volumetric average, which was done in our previous work where we used X‐ray diffraction (XRD) spectra to parameterize a linear model 4 . This model had an error of 0.07 GPa, implying that considering the linear contributions of each crystalline component is an imperfect method for describing the origin of H K in GCs.…”

“…In addition to the systems previously mentioned, hardness values have been acquired on lithium disilicate (LD) systems using either the nanoindentation 23 or Vickers microindentation 24 . To our knowledge, our previous work 4 was the first to measure H K on an LD system, and our system contained lithium tantalate (LT) as a secondary phase. Those results showed that H K increased as lithium metasilicate decomposed and as LD and LT became the primary phases in the material.…”