Bond moduli quartz

Dislocation lines do not move concertedly, that is, all at once. They move, by forming kinks along their lengths, and when the kinks move, the lines move. The open crystal structure of quartz (crystobalite) results in a relatively large amount of volume being associated with a kink on a dislocation line. This relatively large volume lowers the value of quartz s bond modulus, making its hardness consistent with those of other covalently bonded substances. 

The hardness (480kg/mm2) of the quartz version of Ge02 is also consistent with its bond modulus. Unfortunately, Sn02 does not have a quartz like structure so there are only two members of this isoelectronic set (Si02 and Ge02). 

Figures 3 and 4 illustrate a dependency of fatigue life on composition of the filler particles. Materials B and E which contain glass and/or silicate particles exhibit longer fatigue lives than materials which contain only quartz particles. This observation is substantiated by the statistical analysis indicated in Table 3, The higher fatigue properties of the glass/silicate filled materials may be due to a lower modulus mismatch between these softer filler particles and the matrix polymer than exists between the hard quartz particles and the polymer. The improved properties might also reflect more efficient and durable bonding between the particles and the polymer.

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