PSI - Issue 20

Yakovleva S.P. et al. / Procedia Structural Integrity 20 (2019) 190–197

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Yakovleva S.P. et al. / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 3.The wear rate of experienced DMC and industrial diamond dressers. 1 – DMC with a matrix of 20% P1+80% P2, pressing at D 1 = 45 mm; 2 – DMC with a matrix of 30% P1 + 70% P2, pressing at D 2 = 50 mm; 3, 4 - diamond dressers.

Depending on strength of the fixing in the matrix, the process of diamond wear manifests itself in various ways. Diamond grains, weakly held by the matrix, are drop out of it under the action of external forces; this type of wear is demonstrated by DMC before heat treatment, when the diamond retention occurs due to mechanical forces (Fig. 4, a).With good diamond retention, the cutting faces and tops of the diamond particles are partially broken off, while the remaining part is retained by the matrix, while maintaining abrasive properties; in this case, the tool working surface is updated (self-sharpening).The high level of diamond retention in the heat-treated composites was manifested in the presence of multiple cleavages from the diamond body, and not on the diamond-matrix interface (Fig. 4, b); this fact is consistent, for example, with the work by Bondarenko et al. (2004), which also observed the develop of transcrystalline cleavage prosesses of diamond in case its good adhesion to the matrix. In general, heat-treated DMC with best diamond retention are characterized by the formation of wear sites with a developed microrelief on diamond crystals, that corresponds to the data of the work by Kuzej et al. (2009). Thus, fractographic analysis showed the important role of heat treatment to improve diamond retention, which was reflected in a favorable change in the mechanism of destruction and removal of diamond particles during wear: the prevalence of chipping along the diamond – matrix interface gave way to transcrystalline cleavage of diamond grains (respectively, their removal by the falling out mechanism is changed by the cleaving mechanism). The increase in the DMC operational characteristics is a result of improving of diamond retention due to the addition of chemical adhesion to mechanical fixing and through the formation of new cutting edges in diamond particles during wear.

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b

Fig. 4.Micromechanisms of diamond particles removal from the DMC wear surface: a – by the falling out (DMC afterexplosive compaction); b – transcrystalline cleavage (DMC obtained by combining explosive compaction and heat treatment at 900 ° C).