Glass hardness modulus ratio

The hardness shear modulus ratio in this case is similar to the one for metallic glasses. This suggests that the structure in the KCl-KBr solid solution is highly disordered i.e., glassy. 

Fig. 6.2.11. Plot showing expanding cavity relation between hardness-to-modulus ratio and the ratio of plastic zone radius to cavity radius. Data points represent experimental measurements of plastic zone dimensions in deft to right) glass, A1203, ZrOj, KC1, ZnS, cold-rolled steel, and hot-rolled brass. (After Lawn et al., 1980b)...

Glass Transition Temperature Tg (DSC, TMA, and DMA). The resin systems used in today s copper-clad laminates are almost all three-dimensionally cross-linked thermoset polymers. This means that the materials are manufactured (in a curing reaction) into a hard final product and cannot be remelted many times the way thermoplastic polymers can. In many cases, different resin systems are blended to create a material with specific properties. The functionality of the individual resins and their ratio in the blend define the properties of the thermoset.The degree of cure of the hardened thermoset resin system can be described by characteristics such as percent of uncured monomer and heat of final cure or by mechanical properties such as hardness, modulus, and yield stress. But one of the most commonly used characteristics to describe the degree of cure and cross-hnk density of a thermoset polymer is the glass transition temperature (Tg). 

We introduced in Chapter 8 the brittleness index as the hardness-toughness ratio to characterize the competition between the plastic and brittle deformations of glass. Here again, a similar approach can be used instructively in order to balance the elastic and plastic deformations. Hence, we introduce hardness-elastic modulus ratios in order to quantify the competition between elastic and plastic responses. An instrumented indentation machine allows for extraction of hardness H and elastic modulus E-, different ratios have been considered, the simplest one being H/E. The higher the ratio, the higher the resistance to plastic deformation and hence the higher the elastic compliance of the film. 

Other penetrometer-indentometers include transducers to sense the position and movement of the probe and microprocessors for temperature control and data collection and reduction. These instruments are used mainly to measure softening points, which are not glass transitions but are usually close to those values. Because a softening point is indicative of behavior under load, it is often more useful for predicting performance than the Tg. Penetrometer-indentometers can also be used to measure indentation hardness, creep, creep recovery, and modulus. Examples of such instruments include the TA Instruments, Mettler, Perkin-Elmer, Seiko, and Shimadzu thermomechanical analyzers (TMAs). They can be used to generate modulus and modulus-temperature data from indentation-time plots by applying the Hertz equation (eq. 36) (170,296), where E is the elastic or Young s modulus, jx the Poisson s ratio, r the radius of the hemispherical indentor, P the force on the indentor (mass load x g), h the indentation, and ifk the indentation hardness. 

Yield and absolute hardness, 72 Y-sialon glass density, 229 Knoop hardness, 229 Modulus, 229 Young s modulus of AljOj, 241, 259-261 anisotropy in /3-AI2O3, 281 of B4C, 228, 241 and bond type, 172 and crack depth, 155 and cracking, 147 of CrjCj, 302 of germanium, 252 of glass, 238 and hardness, 72 hardness ratio, 179 from Knoop indents, 180 mismatch stress, 273 of MgO, 241, 269 and penetration depth, 47, 240 and plasticity parameter, 241 and residual impression parameter, 240... 

The glass density (d) was measured on powdered samples by the pycnometry method with an accuracy of 0.005 g cm Young s modulus ( ) and Poisson s ratio (y) were measured by the pulse-echo technique on 4 mm thick rectangular specimen. Vickers indentations (load of 9.8 N apphed during 15 s), were performed to estimate both Meyer s hardness (H) and the indentation fracture toughness (Kc) by means of the following equations ... 

---