PSI - Issue 42

Alla V. Balueva et al. / Procedia Structural Integrity 42 (2022) 9–17 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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(b)

(a)

Fig. 5. (a) Hexagonal closed packed structure; (b) a x-y dimensional cross section of the prism is a hexagon with a side a.

Let us consider one example. Assume Ti(OH) 2 is optimized in the 6-31Gpi basis set. Then, the surface energy accordingly to formula (4.1) is = 0.62 . . (2.66)10 5 2 = (0.62)(4.36)10 −18 (2.66)10 5 2 ~ 1.02 10 2 (4.3) which agrees in order of magnitude with available experimental data, where  ranges from 2 0.5 10 x J m , reported in [Suttin and Gubbi, 2007] till 2 7.5 10 x J m obtained in [Shekhawat and Suttin, 2007]. 5. Conclusions The calculated estimates obtained in this work both for the binding energy of TiO 2 with tricalcium phosphate fragments and for the adhesive strength are reasonable and comparable with the values obtained in experiments [Shekhawat and Suttin, 2007] and calculations using other quantum chemical packages [Grubova, 2019]. It seems that the most significant factor determining the strength of the TiO 2 bond with calcium phosphates is the number of oxygen atoms in the resulting compound and their interaction with the titanium atom. In this case, with an increase in the number of oxygen atoms, there is a parallel increase in the electron density around the Ti (II) atom, the characteristic frequencies of interatomic bonds, adhesive strength, as well as the formation of more favorable geometric shapes of the resulting compounds. The revealed pattern can be useful in regulating the adhesion strength of the coating to the substrate. On the whole, quantum chemical modeling seems to be a useful and effective method for assessing the bond strength of a substrate and a coating, which has the advantage of versatility and does not require complex, expensive, and time-consuming physical experiments. Acknowledgements The research was done with partial support of contract # АААА - А 20-120011690132-4. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562 [Towns et. al., 2014]. We thank consultants for their assistance with porting, optimization and visualization, which was made possible through the XSEDE Extended Collaborative Support Service (ECSS) program [Wilkins-Diehr, 2015].