Effect of NbN doping on forming of the structure in diamond-(Fe-Cu-Ni-Sn) system and physico-mechanical properties of this composites

Abstract

In this study the changes in the structure of the transition zone of diamond – metal bond and the metal bond in composites diamond-(Fe-Cu-Ni-Sn-NbN), after sintering in an oven at 800C for 1 hour in dependence of the parameters of the hot mounting pressing and their influence on the mechanical and tribological properties, was investigated. It is shown that an increase in pressure from 100 to 200 MPa and with a duration of the hot mounting pressing from 2 to 3 minutes, the composition diamond-(49,98Fe-31,36Cu-8,82Ni-7,84Sn-2NbN) provides an increase of 4,3 times in the wear resistance of the samples by improving the retention of the diamond grains of the metal bond and increases the strength limits upon compression from 758 to 890 MPa and upon bending from 754 to 880 MPa. This is consistent with a change in the phase composition, the morphology and the structure of the phase components of the composite. It was found that samples of composites diamond-(49,98Fe-31,36Cu-8,82Ni-7,84Sn-2NbN) have higher wear resistance than the composites diamond-(51Fe-32Cu-9Ni-8Sn) of about 3,8 times and 2, 4 times higher regarding the samples diamond-(49,98Fe-31,36Cu-8,82Ni-7,84Sn-2CrB2), obtained under the same conditions. Thus, in the composite metal bond with the addition of powder NbN, grinding of the elements of the structure occurs, which is accompanied by the disappearance of the pores at the interphase boundaries. It was elucidated the mechanism, which provides increase (enhances) the tribological properties of such composites.