Influence of Thermal History on the Crystallization Behavior and Hardness of a Glass‐Ceramic

Abstract

The glass system SiOz-A1z03-LizO-Ti02 was examined to determine the dependence of hardness on heat-treatment temperature. In addition to hardness measurements, X-ray diffraction (XRD) was used to determine the type and amount of phases present and to relate this to the hardness results. Hardness increased with heat-treatment temperature. This correlated with the amounts of crystals present, as determined by XRD. For a particular heat-treatment temperature, when hardness was plotted versus load on the indenter, there was a load dependence. There was at first a rapid decrease as the load on the indenter increased, with a constant value being approached at higher loads. [

Theoretical Calculation and Measurement of the Hardness of Diopside

“…2 that Kick's law (with n =1.85) describes the load dependency well. This load dependency is well demonstrated in the literature for other materials 30–33 . Therefore, the hardness of diopside and other materials cannot be described by a single value.…”

Effect of thermal history and chemical composition on hardness of silicate glasses

“…Compared to the glasses studied in this work, the E-glass fibers have significantly higher T f values (i.e., 1166 K) and considerably lower hardness ($6.6 GPa) at a load of 0.3-1.2 mN. The hardness measurements conducted in this work have been performed at a load of 0.49 N. Normally, hardness of glasses decreases with increasing load [25,26], i.e., the hardness of the glass fibers should be lower than 6.6 GPa at a load of 0.49 N. The highest T f of the E-glasses studied in this work is 988 K, which corresponds to a H v value of 7.3 ± 0.2 GPa. Hence, the hardness measurements of the E-glass fibers are in qualitative agreement with those of the glasses studied in this work.…”

Composition–structure–property relationships in boroaluminosilicate glasses

“…9(a) and (b). First, we note that the iron-containing and iron-free glasses display similar composition dependences for both E and G. In the peralkaline regime, the elastic moduli decrease with increasing [ [37,38], all indentations were carried out using identical load and loading time. Furthermore, we note that there was no initiation of radial cracks from the indents at the applied load of 0.49 N. Fig.…”

“…3 shows the composition dependence of fragility for both ironcontaining and iron-free compositions. In the peralkaline compositions regime, the liquid fragility is relatively composition independent and equal to around [35][36][37][38] O 3 ]. We also note that the iron-free compositions are generally more fragile than the ironcontaining compositions.…”