E. G. Zelenkova

Diffusion bonding through interlayers

Studies of the application of interlayers in diffusion bonding (DB) are reviewed. A method for the classification of these layers for DB of dissimilar materials is proposed. The role of the interlayers and their contribution to the formation of the joint in all stages of bonding are investigated.

Microstructure and properties of a copper electrocontact material with a nanodispersed titanium dioxide additive

The influence of TiO2 nanopowder additive on the microstructure, physicomechanical properties, and performance characteristics of a copper-based composite is studied. The properties of the composites are compared with those of pure copper compacts. The microstructure and state of the composite’s working surface after performance tests are examined. It is shown that, when the amount of TiO2 grows, the hardness of the material rises and the arc quenching effect is enhanced.

Microstructure and properties of an electrocontact Cu–(ZnO/TiO2) material

A copper-based electrical-contact composite material hardened by disperse zinc oxide and zinc titanate is studied by scanning electron microscopy and energy dispersive X-ray microanalysis. The distribution of oxide phases in the samples containing 2.5 wt % oxide nanopowder mixture in an initial charge is found to be uniform. An increase in the amount of oxides leads to an increase in their sized in sintering. A relation between the sample wear and the sample composition is obtained during laboratory tests. It is shown that the introduction of more than 2.5 wt % oxide mixture results in intense wear of the working surface of the sample and an increase in the running-in period of contacts.

Formation of Phases and Microstructure of ZnO and TiO2 Based Ceramic

Nanopowders of zinc and titanium oxides were used to obtain samples of Zn2TiO4–ZnO ceramic. Phase formation as well as the microstructure and elemental composition of the phases formed were studied by means of electron microscopy. The density and porosity were calculated, and the sizes of grains and pores in the ceramic were determined. The temperature at the zinc titanate forms was determined. It was shown that it corresponds to the sintering temperature of electrocontact materials with this composition. It is proposed that zinc titanate and oxide be used as arc-suppressing and dispersion-hardening additional additives in copper-based electrocontact materials.

Microstructure and the elemental and phase compositions of the diffusion joint of grade 45 steel through a powder layer

The microstructures of the transition zone and the powder layer, the concentration distribution of chemical elements across a diffusion joint, and the microhardness of the grade 45 steel-Ni powder layer-grade 45 steel layered composite materials fabricated by diffusion welding at various temperatures are studied. It is shown that the deposition of a nickel sublayer on steel and the application of a submicron nickel powder as an activating layer make it possible to form a high-quality diffusion joint at a temperature of 850°C, which is ~0.6 of the melting temperature of nickel (which has the lowest melting temperature in the given composite material). The sintering of a nickel powder and the formation of a transition zone between the nickel layer and steel occur simultaneously in a solid phase during diffusion joining. The transition zone consists of an α-Fe solid solution and the FeNi3 compound.

Study of Diffusion Bonding of 45 Steel through the Compacted Nickel Powder Layer

The microstructure of the transition zone and powder spacer, the concentration distribution of chemical elements over the width of the diffusion-bonded joint, and microhardness of 45 steel–compacted Ni powder spacer–45 steel layered composites formed by diffusion bonding have been investigated. It has been shown that the relative spacer thickness χ < 0.06 is optimal for obtaining a high-quality joint has been formed under a compacting pressure of 500 MPa. The solid-state diffusion bonding is accompanied by sintering the nickel powder spacer and the formation of the transition zone between the spacer and steel. The transition zone consists of solid solution of nickel in the α-Fe phase and ordered solid solution of iron in nickel (FeNi3).

Electrocontact material based on silver dispersion-strengthened by nickel, titanium, and zinc oxides

Samples of a composite electrocontact material based on silver strengthened by the dispersed phases of zinc and titanium oxides have been investigated by the electron microscopy and energy dispersive X-ray spectroscopy. A uniform distribution of the oxide phases containing 2 wt % zinc oxide in the initial charge has been revealed. The increase in the amount of zinc oxide leads to an increase of the size of the oxide phases. It has been shown that at the zinc oxide content of 2 wt %, the minimum wear is observed in the process of electroerosion tests; at 3 wt %, an overheating and welding of the contacts are observed.

Formation of the microstructure and transition zone in diffusion welding of steel 45 through a powder layer

Abstract Investigations were carried out into the microstructure and properties of diffusion-welded joints produced through a submicron nickel powder layer deposited on the metallic coating at welding temperatures of (0.4–0.7) Tm. The results show that using the submicron powder as an activating layer produces high quality diffusion-welded joints at 850 °C, which is equal to 0.6Tm.

Prospects of nanoparticle application in contact materials of urban electric transport

Investigation results for electrocontact materials based on silver and copper and modified by nanoparticles are presented. Their optimum compositions; technological production features; and physical, mechanical, and operational properties are determined and the microstructure is studied. It is shown possible to replace the standard, widely applied electrocontact materials and Ag-containing products with copperbased pseudoalloys with nanoparticle additives. Prospects of innovation for the investigative results are considered.