Synthesis of cubic boron nitride diffused-D2 steel surface composite by thermo-chemical diffusion process to enhance the wear resistance

Abstract

The diffusion of cubic boron nitride (c-BN) on the D2 tool steel surface was investigated using a thermo-chemical process in order to enhance the tribological properties of tool steel surfaces. The c-BN was diffused on the tool steel surface applying the thermochemical diffusion process using argon controlled furnace. The effect of temperature and soaking time on the diffusion process, micro-hardness, and wear resistance were the main parameters evaluated. The field-emission scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) was used to analyze the morphology and elemental composition of the as-synthesized c-BN-D2 surface composite. Here, the micro-hardness of manufactured coatings was investigated using a Vickers hardness tester. The wear resistance of surface composite was studied using a pin-on-disk apparatus. The morphological investigation revealed that c-BN was successfully diffused in the surface of tool steel in the form of white globular precipitates. The best surface hardness produced has a values of 1570 GPa. The diffused layer thickness varies between 50-90 μm and is very dense. It has mechanical interlocking properties suitable against delamination process and wear formation. The superior performances of novel c-BN-D2 tool steel surface composite permits to extend the machine tool life, especially when is applied on the single-point cutting tools.