Graphitization Behavior of Single Crystal Diamond for the Application in Nano-Metric Cutting

Abstract

Background: Graphitization behavior of diamond has received an increasing interest in nanoscale machining of some hard and brittle materials. Diamond has always been an important and excellent tool material in cutting area. However, the graphitization of the diamond tool is inevitable when it was used in special conditions. It is indicated that the graphitization of diamond crystal has great influence on the wear resistance of diamond cutting tool. The graphitization behavior needs to be investigated extensively in nanoscale with an atomic view. Molecular dynamics simulation provides a useful tool for understanding of the graphitization mechanism of diamond. The investigation on graphi-tization behavior of single crystal diamond can also provide a useful reference for the application of diamond cutting tool.Materials and Methods: In this paper, a molecular dynamics (MD) diamond crystal model is built to examine the graphitization behavior of diamond under various conditions. The sixfold ring method was employed to identify the structural characteristics of graphite and diamond. The effects of temperature and crystal orientation on the graphitization of diamond have been revealed. Considering the effect of temperature, the anisotropy of diamond graphitization against various crystal planes is presented and discussed carefully. The nano-metric cutting model of diamond tool evaluated by the sixfold ring meth-od also proves the graphitization mechanisms in atomic view.Results: Results indicate that the sixfold ring method is a reliable method to evaluate the graphitization behavior of diamond crystal. There exists a critical temperature of the graphitization of diamond. The results also show that {111} plane is more easy to get graphitization as compared with other crystal planes. However, {100} plane of diamond model presents the highest anti-graphitization property.Conclusion: The obtained results have provided the in-depth understanding on the wear of diamond tool in nano-metric machining and underpin the development of diamond cutting tool

Effect of Titanium and Molybdenum Cover on the Surface Restructuration of Diamond Single Crystal during Annealing

“…We assume that such catalytic graphitization could take place near 800 and 500 °C for Mo-coated (100) and (111) diamond surfaces, respectively. The lower temperature required for the graphitization of the Mo-D-111 sample correlates with the theoretical results, which showed preferential exfoliation of the (111) diamond face [ 15 , 16 ]. Additionally, graphitic layers can be formed on top of molybdenum carbide nanoparticles, as shown earlier [ 60 ].…”

“…Diamond can be directly transformed into graphite, but this process is associated with a very high activation energy. The graphitization process can occur upon laser irradiation [ 10 , 11 , 12 ] or high-temperature annealing [ 9 , 13 , 14 , 15 , 16 ]. In the presence of a metal catalyst, the growth of single- and multi-layer graphene on diamond occurs at temperatures substantially lower than those required for the transformation of a bare surface [ 17 , 18 , 19 , 20 , 21 , 22 ].…”

Cubic and hexagonal boron nitride phases and phase boundaries

“…48,49 A consensus is reached that the graphitization of cubic diamond powder on a micron scale is a surface energy-driven transformation, transitioning into polycrystalline graphite as the particle size increases. 43,50,51 Such surface energy-driven graphitization is believed to be a rather general phenomena applicable not only to diamond but also to c-BN structure, as h-BN phase is predominantly observed near the surface and grain-interface of c-BN particles. 43 The HTHP conditions cause the crystal structure of c-BN to undergo a phase transition, where the sp 3 hybridized carbon atoms in c-BN are transformed into a sp 2 hybridized structure similar to graphene in h-BN.…”

The Description of Heat Capacity by the Debye – Mayer – Kelly Hybrid Model<strong> </strong>

“…The presence of impurities can contribute to the catalytic graphitization of diamond. In [39] the kinetics of graphitization of thin diamond-like carbon (DLC) films was studied at 773K coated with Ni metallic nanoparticles [39].…”