A. Romański

New Fe-Ni and Fe-Mn Powders Used in Manufacturing Diamond Tools

The work attempts substitution of very expensive, wear resistant Co-WC powders, that are commonly used in the production of sintered diamond tools, with cheap iron-base counterparts manufactured by ball milling. It has been shown that ball milled Fe-Ni and Fe-Mn powders can be consolidated to a virtually pore-free condition by hot pressing at 900°C. The as-consolidated materials are characterised by high hardness and resistance to 3-body abrasion.

Wear-resistant iron-based Mn–Cu–Sn matrix for sintered diamond tools

ABSTRACT The objective of the present work was to determine the suitability of a new iron-based Mn–Cu–Sn matrix alloy for the manufacture of diamond-impregnated tool components. A number of specimens were consolidated by the hot press route from ball-milled powders. Density, microstructural features, phase composition, bending properties and hardness were evaluated. The results revealed excellent mechanical properties, including σ0.2u2009>u2009850u2005MPa in 3-point bending and HK0.5u2009>u2009300. A commercial Co-WC reference matrix alloy was also produced for comparison purposes. Diamond-impregnated specimens with different matrices were tested for wear rate on abrasive sandstone using a test rig specially designed to simulate tool application conditions. The tests that involved 3- and 2-body abrasion ranked the alloys in different orders. Statistical analysis showed that the wear rate of diamond-impregnated composites was mainly affected by diamond concentration, but statistically significant contribution of the matrix resistance to 3-body abrasion was also found.

Processing and Characterization of Fe-Mn-Cu-Sn-C Alloys Prepared by Ball Milling and Spark Plasma Sintering

In this work, Fe-Mn-Cu-Sn-C alloys were prepared by means of powder metallurgy (PM). Powder mixtures were ball-milled for 8, 30 and 120xa0h and densified to <xa01% porosity using spark plasma sintering (SPS) at 900xa0°C and 35xa0MPa. After consolidation, all samples of the Fe alloys were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), hardness and flexural strength tests. Resistance to abrasive wear was evaluated in both three-body abrasion and two-body abrasion tests. The SEM observations revealed an evident dependence of grain size and microstructural homogeneity on milling time. The XRD analysis showed a marked increase in austenite content in the as-sintered specimens with milling time. Although the proportion of deformation-induced martensite was small, the strengthening effect of abrasion on the subsurface layer of the investigated alloys was clearly indicated by Knoop hardness measurements.

Sinetring of Cobalt - (3-25 wt.%) Iron Materials

The kinetics of sintering of Co-Fe materials was studied. The main objective of the work was to establish the effects of iron content and sintering parameters on the microstructure and phase composition of the as-sintered materials. Specimens containing from 3 to 25 wt.% iron were sintered in a dilatometer for one hour at 900, 1000 and 1150OC in either hydrogen or nitrogen atmosphere. The length of specimens during the heating, hold at the temperature and cooling steps were monitored to establish the sample’s shrinkage. Microstructural observations were carried out on polished and etched transverse sections which were also subjected to the X-ray phase analysis.