Science of materials and mechanical Engineering

Mathematical Model of Arc Welding with Short Circuits for Development of Quality Monitoring System

The paper analyzes the influence of basic parameters of electric arc MAG welding – welding current, arc voltage, electrode diameter and outlet – on electrical processes in welding circuit. Also, we determine basic time parameters of electrode metal transfer for different transfer modes as well as their relationship with basic welding parameters. Furthermore, we develop the stochastic dynamical mathematical model of the welding process. The model includes electrical, physical and welding characteristics of equipment, preset values of welding parameters and electrode metal transfer mode.

The Choice of the Operation Mode of Wear-Resistant Details by Analyzing Friction Films

The bushing bearings based on wastes of АК12ММгН alloy are produced by powder metallurgy method. We analyze friction films formed on the surface of investigated bushing bearings samples ased on wastes of АК12ММгН alloy in the pair with counterface of teel 45 (45–48 HRCe) obtained as a result of tests on friction and wear. We utilize AVMT-1 friction machine to analyze tribotechnical properties of wear-resistant parts based on wastes of АК12ММгН alloy. We demonstrate that this brand new material based on wastes of АК12ММгН alloy has better antifriction properties than the cast material.

The Influence of Magnetic Treatment on Strength Properties of WC–Co and Fe–Al Detonation Coatings

The paper investigates the influence of magnetic treatment on the destruction mechanism of detonation coatings of WC–Co and Fe–Al systems on the steel substrate at bend test. We establish that magnetic treatment enhances mechanical properties of the system “coating–substrate”. The plastic deformation of the system raises from 0,15 to 0, 35 % in the cracking moment. Tensions developed at the destruction moment increases from 700 to 1300 MРa for VK-15 hard-alloy, while for Fe3Al alloy deformation increases from 0,06 to 0,2 % and tensions raises from 214 to 582.

Implementing the Concept of Framework Arrangements of Machine-Tools with Mechanisms of Parallel Structure

This paper presents study samples of operating machines with the mechanisms of parallel structures built on the principles of the concept of machine frame layouts. We bring into light our basic ideas of implementing technical solutions according to the requirements of new metal-working equipment in light of modern trends in machine tools, such as multivariate, frame structure of the carrier system, hybridity, symmetrical layout, modular structure of the layout, and visual computer modeling of create layouts creation.

Structural Compaction of Iron-Based Powder Materials with Self-Fluxing Alloys

We study the influence of compacting pressure, sintering temperature and composition of iron-based composite materials doped by self-fluxing alloys in the quantity of 10–30 % vol. on the structure, density and hardness. We employ the optical microscope МIM-8M and scanning electron microscope REM-106 to study the structure of materials. Specifically, the hardness testing machine TK-2M is used to conduct hardness testing. We uncover that pressing and sintering conditions, as well as the composition impact density and hardness of materials.

Zirconium Nitring in a Closed Reaction Space

Currently there are methods for zirconium nitriding at high temperatures (1300-2000 C) and long-term exposure (up to 24 hours). This paper aims at developing a novel method of zirconium nitriding at lower temperature and exposure time, while maintaining such satisfactory mechanical properties as coating and matrix. Nitriding was conducted at 900 C for about 2 hours in an atmosphere of technically pure nitrogen. Samples were placed in the reaction chamber, which could provide the necessary degree of tightness and vacuum.

The Effect of Plastic Deformation on the Structure of Powder Quasicrystalline Al–Fe–Cr Alloy

The present paper is aimed at studying the effect of compaction by extrusion on the structural features of powder quasicrystalline Al–Fe–Cr alloy. Specifically, we use the powder alluminium alloy Al94Fe3Cr3 with fine-dispersed quasicrystalline particles reinforced by extrusion. We obtain the alloy by applying the water-atomization technique.

The Influence of Annealing Conditions on Structure and Magnetic Properties of Nanodimensional Fe50Pt50 Film on Planar SiO2(100 nm)/Si(100) Substrates

It is studied the influence of annealing conditions in temperature range of 300– 900 °С on formation of magnetic-ordered L10(FePt) phase in nanodimensional Fe50Pt50(15 nm) /Ag(3 nm)/Fe50Pt50(15 nm) film composition (NFC) on planar SiO2(100 nm)/Si(100) substrate. It is investigated its structure, morphology and magnetic properties. It is shown that the formation of L10(FePt) phase occurs at annealing 700 °С for 30 s and heating rate of 5 °С/s. Amount of L10(FePt) phase increases with increase of annealing temperature.

Specificity of Polycarbide Sintering Based on Hard Alloys with Fine- and Nanodisperse Binder

In this paper, we investigate the kinetic patterns and mass transfer mechanisms at different sintering stages of the polycarbide based on hard alloys TiC-5NbC-5WC with NiCr binder (the ratio of Ni:Cr  3:1) composed of fine- and nanodisperse nickel of 7,5, 13,5 and 18 % (mass.). We show that adding 18 % of (mass.) nanodisperse nickel into the alloys activates sintering allowing to reduce the sintering temperature to 1350 С and the isothermal soaking time to 20 minutes. The grain boundary diffusion mechanism for all alloys is implemented at the stage of solid phase sintering.

Nanotechnologic Bases of ZrF4 Application to Increase the Strength of Cast Aluminum Alloy AK12M2

In this paper, we demonstrate that B.B. Gulyaev’s quasi-static representations of macroprocesses in cast aluminum alloys should be further elaborated. We theoretically justify and experimentally confirm the quantitative influence of ZrF4 nanoparticles on determining its optimal entry and strength of the alloy AK12M2. We propose physical and chemical foundation for the salvation model of ZrF4 nanodistribution, notably particles of ZrF4 modifier in a state of statistical lattice of cast aluminium alloy.