Silica glass, indented

V. Le Houerou, J C. Sangleboeuf, S. Deriano, T. Rouxel, G. Duisit, Surface damage of soda lime silica glasses indentation and scratch behavior, J. Non cryst. Sol., 316 54 63 (2003). 

Mechanisms of phase transformations in ceramics can be different from those in semiconductors, but pressure- or deformation-induced amorphization has been observed for both classes of materials. Even the hardest material known— diamond—experiences a phase transformation under contact load. Changes in structure and density have also been reported for amorphous materials, such as silica glass. Recent studies suggest indentation-induced phase transformations in intermetallic compounds and thus other classes of materials may show a similar behavior as well. 

Figure 8.84 Fracture surface marking shows outline of median crack front at a Vickers indentation in soda-lime-silica glass. (Optical micrograph courtesy of Vincenzo Sglavo.)...

In equation (6.8) C is a constant giving the ratio of the stress to the resistance to deformation at the time the indentation ceases a is the ratio of average single bond strength to Si-0 bond strength. G and K are shear and bulk moduli, respectively, with G = E/2 + p) and K = E/3 1 - 2v). The Poisson ratio is estimated from the ionic oxide volume fraction compared to the Si02 volume fraction. For silica glass with no added modifier, a must equal 1 and C = 0.19. 

ELASTO-PLASTIC BEHAVIOR OF GLASSY CARBON AND SILICA GLASS BY NANO-INDENTATION WITH SPHERICAL TIPPED INDENTER... 

Field and Swain found that the indentation force-displacement behavior for GC exhibited almost complete recovery with a significant hysteresis between loading and unloading when indented with 3 and 10 pm radius spherical tipped indenters. And also we have studied on elasto-plastic deformation of silica glass and glassy carbons with different type of indenters ... 

In the present work, indentation of GCs heat-treated at different temperatures was carried out using a spherical tipped indenter. For comparison, fused silica glass was also used. Quantitative evaluation of elasticity and plasticity of elasto-plastic deformation by the spherical tipped indentation on GC and silica was also attempted. The dependence of hysteresis and elasto-plastic deformation of GCs on their crystal structure are discussed from stress-strain curve. 

Load cycle indentation was performed using a commercial ultra microindentation system (UMlS-2000) with a spheroconical diamond indenter with 3 pm radius. The radius of the indenter was calibrated using silica glass, of which the elastic modulus and Poisson s ratio were known. The initial contact force was 0.1 mN, and load controlled tests are performed. Each test was repeated ten times at different positions on the polished surface of the specimen. 

Figure 1. Load penetration curve of fused silica glass with 3 pm radius spherical tipped indenter.

Table 2. Elastic modulus, yield stress, yield strain, constants of power law fitting and indentation elasticity index obtained from stress strain curves with 3 xm radius spherical tipped indenter on GCs and silica glass.

Indentation and Scratching of Glass FUSED SILICA GLASS. ... 

C. R. Kurkjian, G.W. Kammlott, M.M. Chaudhri, Indentation behavior of soda lime silica glass, fused silica, and single crystal quartz at hquid nitrogen temperature , J. Am. Ceram. Soc., 78 3 737 744(1995). 

Figure 8.3 Calculated load-penetration curve of a spherical diamond indenter into a standard soda-lime-silica glass surface ( = 72GPa, fi = 1 or 0.1 mm).

Figure 8.19 Mean fracture toughness (error bar = +SD) as a function of temperature for soda-lime-silica glass and GeAsSe glass (Tg = 550 and 280 °C respectively)- Ihe indentation values for soda-lime-silica glass are compared to values obtained on chevron-notched bars (Rouxel and Sangleboeuf, 2000)...

Indentation 10 °- to 10 Cylindrical 7 mm diameter, 3 mm deep Typically, Nimonic 105 alloy cylindrical indenter of 1 mm diameter placed between silica glass probe and sample [32]... 

Surface hardness of coatings and molded objects is also measured by scratch and abrasion resistance. In one simple test for painted surfaces, the hardness can be quantified in terms of the pencil hardness (HB, 4H, etc.) that leaves an indentation. As a rule, polymer systems cannot approach the surface hardness of silica glass, which is itself a highly cross-linked structure. Some highly cross-linked laminates do have scratch resistance nearly like that of glass. 

The susceptibility of hardness measurements of silica and silicate glasses to environmental factors is consistent with the effects of water on the deformation of quartz. The load effect and indentation size effect appear to be a result of the frictional forces at the indenter-specimen interfaces. 

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