Abrasive wear resistance of spheroidal vanadium carbide cast irons

The effect of the chemical composition and heat treatment on the microstructure and abrasive wear resistance of V-Mn, V-Ni-Cr, and V-Mo spheroidal vanadium carbide cast irons (18–23 vol %) has been studied. The wear resistance has been determined under conditions of wear by abrasives with various hardnesses, i.e., corundum and quartz and compared to that of high-chromium cast iron with 13% Cr. It has been found that the advisability of using high-vanadium cast irons is governed by the hardness of the abrasive. When a hard abrasive, i.e., corundum was used, V-Mo cast iron with the maximum concentration of spheroidal VC carbides, which were uniformly distributed in the martensitic matrix, had the highest wear resistance. When a soft abrasive, i.e., quartz, was applied, high-chromium cast iron with a hardness of 68 HRC, which contained the largest amount of M₇C₃ carbides, was more wear-resistant. In the course of isothermal exposure at 300–1000°C, V-Ni-Cr and V-Mo cast irons with an austenitic structure had high resistance to phase and structural transformations. However, the properties and microstructure of V-Mo cast irons with a martensitic matrix depended strongly on the temperature of exposure during heat treatment.     

Effect of bulk heat treatment and plasma surface hardening on the microstructure and erosion wear resistance of complex-alloyed cast irons with spheroidal vanadium carbides

The results of an investigation of the effect of bulk quenching from temperature in the range of 760–1050°C, cryogenic treatment (–196°C) and surface plasma hardening on the abrasive-erosion wear of frugally alloyed V–Cr–Mn–Ni cast irons with spheroidal vanadium carbides have been presented in this article. It has been found that cast irons containing 5.0–7.5% V, 4.5–9.0% Cr, and 5.5–5.7% (total) of Mn and Ni after heat treatment have a 2–3-fold advantage in wear resistance compared to the prototype high-vanadium cast iron (11.9% V, 12.9% Mn). The maximum wear resistance of cast irons studied is achieved by quenching at 760°C followed by plasma surface hardening, as well as quenching at 840°C, followed by cryogenic treatment. These treatments result in the formation of an optimum microstructure that consists of spheroidal vanadium carbides, eutectic carbides M₇C₃, and a martensite-austenite matrix reinforced by secondary carbides. The increase in quenching temperature leads to an increase in the amount of residual austenite and decrease in the erosive wear resistance of cast irons.     

Storage of cryo-compressed hydrogen in flexible glass capillaries

We present the results of the theoretical calculations and the corresponding experiments with compressed hydrogen storage in flexible glass capillaries both at room and liquid nitrogen temperatures. It was demonstrated that the strength of produced quartz capillaries can be high enough to withstand the internal hydrogen pressure up to 233 MPa and capillary vessels can have relatively high volumetric and gravimetric capacity.