Vol 41, No 4 (2019)

A metal-ceramic composite Cu-(LaB₆-TiB₂) has been produced by the spark plasma sintering. The microstructure, phase composition, mechanical properties and resistivity of the composite are studied. An effective method for reinforcing the interface between the copper matrix and reinforced ceramic particles LaB₆-TiB₂ has been proposed and implemented. It is demonstrated that consolidation of the metal-ceramic composite by using LaB₆-TiB₂ particles with naked fibers almost doubles the material's strength. Furthermore, the use of reinforced ceramic particles provides the electrical conductivity on a level with the best materials for resistance-welding electrodes (88% IACS).

For WC-6 wt % Co and WC-6 wt % Ni composites, and by using five parameter analysis method as a new approach, the geometric and crystallographic features of carbide/carbide boundaries have been characterized. Two most frequently occurring WC/WC boundaries are 90° twist boundaries about [10–10] (Σ2 boundaries) and 27.8° twist boundaries about [0001] (Σ13a boundaries), the Σ2 boundary populations vary with binder phase types, and carbide crystals are most frequently terminated by (0001) and (10–10) surfaces, such preference does not significantly alter if Σ2 boundaries are partitioned.

For higher tool life of cutting inserts cryogenic treatment is considered as the most prominent method but no substantial researches have been found concerning the impact of cryogenic treatment on cermet inserts especially in hard turning. Therefore, in the present experimental investigation, the comparative assessment of various responses such as cutting force, flank wear, crater wear, chip morphology and surface roughness were carried out during machining of hardened steel with both untreated and cryo treated cermet inserts hard turning under dry cutting condition. Lastly, the input variables were optimized using Response surface methodology (RSM) to evaluate the tool life for the economic analysis. The experimental result demonstrated that the uncoated deep cryo treated with tempered cermet insert delivered better results in comparison to other cermet inserts. According to cost analysis, uncoated and deep cryo treated with tempered cermet insert was found to be the most economical among other cermet inserts at the optimum cutting condition.

Theoretical and experimental investigations have provided a deep insight into the process of diamond dressing of vitrified grinding wheels under the mechanisms of micro- or macrofracture of abrasive grits. This permits determining the process parameters dressing in coarse and finish grinding operations. The authors propose equations for finding the depth of dressing for various types of have been proposed for different wheel working layer states.

The authors investigate the potential of damping down the undulating change of form of a diamond wheel working surface by dressing it with a single-point diamond tool. This is shown to alter the machined surface roughness parameters, namely: the height parameters decrease, the spacing of the profile irregularities and the parameters of the reference length of the profile grow.

The effect of the addition of n-layer graphene on the thermal conductivity of copper samples sintered at high pressure and temperature was studied. It was shown that the addition of graphene Gn (4) to copper powder in an amount of 0.2–0.4 wt % allows an increase in the value of thermal conductivity of samples by 14–37%.