Influence of Additives of Nanoparticles on Structure Formation of Fine-Grained Hardmetals

Abstract

This paper introduces a new concept of coated fine carbides modified by nanoparticles Al2O3, ZrO2 (inhibitors) as the starting method for improved hardmetals. The study involved computational and experimental methods to determine functional relationships between the parameters of microstructure, sizes, volume content of additives of nanoparticles and properties (transverse rupture toughness, hardness, fracture toughness) of the heterophase hardmetal composites. Factors having a positive influence on the structure of hardmetals are the decrease in the average size and contiguity of carbide grains due to SPS-consolidation and ultrasonic activation during mixing. The study of microstructural parameters by scanning electron microscopy in a combination with x-ray phase analysis indicates high statistical homogeneity of the relative distribution of nanoparticles (inhibitors) in the cobalt binder between carbide grains and the formation of nanostructured inclusions in hardmetal composites.

Study of the Possibilities of Obtaining Powder Materials by Rotational Turning with Multi-Faceted Cutters

“…Surfaces of the hollow spheres have traces of shear deformations and structural elements in the form of lamellae with dimensions of about 2 μm along the shear surfaces [9], which corresponds to the frequency of formation of these elements υ=120,000 sec -1 . It should be emphasized that the cyclic nature of the loads put on the cutting insert during RTMC required the use of a hard-alloy composite dispersely strengthened with 𝐴𝐴𝐴𝐴 2 𝑂𝑂 3 nanoparticles [10].…”

Combined Application of Composite Powders WC-Co and Additives of Nanoparticles as an Effective Method of Improving the Properties of Hard Metals

“…The carbide composites, which were studied in this work, are complex heterogeneous by their structure materials with at least one phase exhibiting the properties of the nanomaterial. It was shown in the works [4,8] that the efficiency of the modifying hard metals with Al 2 O 3 nanoparticles depends significantly on the sizes, concentration and volume fractions of all WC-Co-Al 2 O 3 composites particles. In the case of random voids filling between carbide grains, various structural fragments can be formed by oxide particles, that have different degrees of contact and internal microporosity can form.…”

“…The hardness and density parameters of the material do not differ significantly from the base material and are at the level: but the values of the microhardness of the interlayer of binder material -cobalt, which was estimated with the help of nanoindentation, are slightly increased, since the known effect of dispersive hardening at the level of structural fragments (Co-Al 2 O 3 ) is realized. On the basis of the experimentally obtained positive results and the revealed features of the structure formation of heterophase carbide composites, the geometric model described in detail [4,8] was refined and corrected, including the known and new density positions packaging of bimodal and polymodal dispersed systems. A new model of heterogeneous carbide structures assumes the use of composite submicron powders (WC-Co), obtained by various methods, which provides the maximum packing density and high homogeneity of the mutual distribution of phase constituents of the composite (Fig.…”

Effect of Production Methods on the Microstructure, Phase Composition, and Properties of Hard Alloy VK8 with Submicron Grain

“…Currently, a mixture of WC-Co fine powders with a particle size of about 1 m is used in order to provide high mechanical performance of the hard alloys. One of the ways to create a fine-grained microstructure consists in the use of nanosize and submicron hard alloy powders [4][5][6]. However, the production of nanosize powders is accomplished by their difficult stabilization and requires energy-consuming grinding in planetary mills or attritors that results in contamination of the mixture, as well as intense deformation that increases absorbed energy and ultimately leads to particle growth.…”