Vol 2017, No 1 (2017)

The corrosion resistance of an Ni–Co–Cr–Al–Si–Y + SPh (SPh is silicophosphate impregnation) alloy coating on 30Kh13, 38Kh2MYuA, VKS5, and VKS7 structural steels with low tempering temperatures has been studied. The steel–coating compositions have been tested to determine the accelerated cyclic corrosion resistance, the corrosion resistance under tropic climate chamber conditions and in salt fog, the stress corrosion resistance, and the corrosion resistance in an industrial atmosphere. The heat stability of coated samples is studied, metallographic studies of the samples before and after the tests are performed, and the influence of the coating on the strength characteristics of the structural steels is studied.

The structure of commercial-purity titanium additionally doped with hydrogen and the structural charge during heating to 550–600°C are studied. It is established that phases strongly differentiated by atomic volumes (to 23%) take part during forward and reverse eutectoid transformations. However, the volume effect of the transformation is weak and becomes less pronounced when the hydrogen content is increased in titanium. The α ⇄ β transformation is accompanied by 10% volume effect and results in interphase hardening. It is shown that the structure of commercial-purity titanium can be controlled by changing hydrogenation and heat-treatment conditions.

The eutectic silumin modified by SiO₂ nanoparticles is fabricated and studied. The sizes of particles and their concentration in the melt are varied. The strength of the silumin is found to complexly depend on the SiO₂ nanopowder particle size. The noticeable increase in the hardness during heat treatment of the nanomodified silumin is mainly related to Guinier–Preston zones, and the contribution of grain refinement (precipitation hardening) is insignificant.

A technology is developed to produce highly thermoresistant ceramic monoxide corundum molds using investment casting and an aluminum-organic binder. This technology is a promising trend in creating ceramic molds for precision complex-shape casting of important ingots made of high-alloy steels, high-temperature and titanium alloys, and refractory metals. The use of the casting molds that have a high thermal and chemical resistance to chemically active metals and alloys under high-temperature casting minimizes the physicochemical interaction and substantially decreases the depth of the hard-to-remove metal oxide layer on important products, which increases their service properties.

Ingots of palladium alloys with 5, 8, 12, 16, and 20 wt % Pb, which correspond to the Pd-based solid solution region, are prepared by arc melting in a protective atmosphere. Foils 50 μm thick are prepared from the ingots subjected to cold rolling and intermediate vacuum annealing. The membrane characteristics of the foils, which include the strength, the hydrogen permeability, the corrosion resistance, the α ⇄ β hydride transition temperature, and the crystal lattice parameters, have been studied. The Pd–8 wt % Pb alloy is shown to exhibit the maximum specific hydrogen permeability (2.6 N m³ mm/(m² h MPa^0.5)) at 500°C, an adequate plasticity (δ = 12%), a high strength (\({\sigma _{{u_{hard}}}}\) = 550 MPa, \({\sigma _{{u_{ann}}}}\) = 230 MPa), and corrosion resistance against one of the hydrocarbon-conversion products (CO₂), which allow us to recommend this alloy for application as the membranes in filtration membrane elements.

Casting with the use of low-frequency vibrations is applied to fabricate copper-based materials containing graphite and chromium. The conditions of formation of core (graphite)–shell (chromium carbide) complexes and the influence of low-frequency mechanical activation of molten copper on them are studied.