The microstructure and mechanical characteristics of the samples of medium-grained (WC‒8Co), submicron (WC–8Co–1Cr3C2), and ultrafine (WC–8Co–0.4VC–0.4Cr3C2) hard alloys formed by...

Based on the research of actual submicron WC-Co hard alloy structure, a simple model of this structure was offered. Cracking of the structure occurs in two stages: cracking of WC-WC and cracking of Co interlayer. Stress distribution in the model structure was calculated with 2D Finite Element Method (FEM). This sample with fracture criteria of the elements allows describing the influence of defects on submicron WC-Co hard alloy strength. Submicron WC-8%Co-1%Cr3C2 hard alloy with pores, η-phase (Co3W3C) and free carbon was made by conventional sintering with control of the atmosphere during sintering. Influence of defects on strength and hardness was researched both in actual samples and in the experimental sample. The minimization of defects volume in this hard alloy sample has allowed obtaining a high transverse rupture strength (1.641±0.108 GPa) and hardness (90.5±0.1 HRA)

This paper studies the composition and properties of shells of bivalve mollusks (Crenomytilus grayanus, Callista brevisiphonata, and Mizuhopecten yessoensis) from coastal discharges with a view to the possibility of their use in photocatalytic water treatment systems. The clam shells are considered in terms of application in the form of a powder material as a precursor for creating photocatalysts, and also as a carrier of photocatalytic coatings. It was shown that the main phase composing the shell material was calcium carbonate in two crystallographic modifications—calcite and aragonite. The presence of inorganic impurities in all studied clam shells did not exceed one mass percent. The main share was made up of elements included in the composition of calcium carbonate, which confirmed the high bio-indifference of the materials under study. Depending on the physiological and environmental features of the structure of clam shells, different contents of the organic component in their composition were observed. The granulometric characteristics of crushed clam shells (average diameter, specific surface area, and distribution modality) were studied. It was shown that the maximum values of bending strength of 5 MPa and compressive strength of 2 MPa are characterized by Mizuhopecten yessoensis shells with the lowest porosity of 2.91%. The features of sorption and photosorption processes of both whole and crushed shells in relation to four organic dyes at different temperatures and degrees of illumination were studied. Based on crushed shells of Mizuhopecten Yessoensis and titanium dioxide, functional materials (Ca_xTi_yO_z) were obtained, and their morphology and photocatalytic properties were studied. An example of the practical use of clam shells as a carrier of a photocatalytic coating is given.

Investigations of composition, structure, and hardness of ultrafine-grained solid alloy WC–8Co–0.4VC–0.4Cr3C2 after treatment in a gaseous mixture of CO + CO2of compacts with a lack of...