Formation of ANFO Analogues under Fire Conditions in the Presence of Common Plastics

This article is a continuation of a case study in which we presented the results of research on processes generated under fire conditions by mixing molten ammonium nitrate (AN) with selected polymers. Here, we present an analysis of how certain materials, which may frequently appear in farm buildings and are commonly used in the immediate vicinity of humans, can potentially form explosives. The chosen materials include polyamides (PA) from which the wear-resistant machine elements are made (e.g., high-performance gears, wheels of transport trolleys); polyvinyl chloride (PVC) used, i.e., in construction carpentry, electrical insulation, and hydraulic pipes; polystyrene (PS) used, i.e., in insulation and containers; and poly(methyl methacrylate) (PMMA), i.e., so-called organic glass and plexiglass. The research results showed that these seemingly harmless and safe materials, mixed with AN and heated under fire conditions, may turn into explosives and stimulate stored AN. This creates significant risks of an uncontrolled fire progress.

Influence of Heat Treatment on Structure and Durometric Properties of Coatings Obtained by Surfacing with CSR-04СR27NI7MO3CU2Т Cast Rods

The effect of heat treatment modes on the structure and durometric properties of coatings obtained by surfacing with CSR-04СR27NI7MO3CU2Т cast rods, is considered. It is found that the temperature of 800°С and soaking time of 5 hours are optimal to increase the deposited metal hardness. It is shown that such a phenomenon results from the formation of the austenitic structure hardened by the precipitates of the σ-phase (FeCr), chromium carbides (Cr3C2) and titanium carbides (TiC). The heat treatment modes proposed can be applied in the wear-resistant surfacing technology of chemical equipment parts.

Development of a Method for Obtaining a Wear-Resistant Coating for a Cutting Tool

The article presents a method for producing a nanostructured wear-resistant high-hard coating with high physicomechanical and strength characteristics, resistance to shock and vibration loads. The result is an increase in adhesion between the substrate and the coating, as well as an increase in microhardness. One of the common methods of metal cutting is band-cutting machines that use closed band saws as cutting tools. Since materials with high physicomechanical characteristics (hardness, strength, etc.) are increasingly being used in modern production, which significantly complicates the cutting process and makes increased demands on the cutting tool. To expand the range of processed materials for which the productive use of band-cutting machines is possible, it became necessary to create a band saw with higher cutting characteristics. At the same time, the specificity of the working conditions of the band saw shows that the blade should have such characteristics as increased vibration resistance, resistance to alternating and dynamic loads, and the cutting part of the saw should have increased resistance to shock, dynamic, alternating loads, have high hardness, as well as increased wear resistance.

The Effect of Vanadium Content Coupling with Heat Treatment Process on the Properties of Low-Vanadium Wear-Resistant Alloy

The development of wear-resistant materials with excellent properties is of great research value in the manufacturing industry. In this paper, a new kind of low-vanadium wear-resistant alloy was designed and characterized to unveil the influence of vanadium content coupling with heat treatment on the microstructure, hardness, and abrasive wear property. The performances of commercial high chromium cast iron (HCCI) and the new low-vanadium wear-resistant alloy are compared. The alloy with 3 wt.% vanadium quenched at 900 °C and tempered at 250 °C, possessing VC, Mo2C, and M7C3 distributed in the martensite matrix, displayed a wear resistance two times better than the HCCI. The results showed that the increase of vanadium content from 0.98 wt.% to 3.00 wt.% resulted in a decrease in the size of M7C3 and a more homogeneous distribution of M7C3. VC with a bimodal distribution is effective for impeding grooving or indenting by abrasives because of their high hardness, which plays a vital role in improving the wear resistance of low-vanadium wear-resistant alloy.

Features of Machining Rotor Shafts of Diesel Engine Turbochargers with a Multilayer-Coated Tool

Introduction. The paper presents the results of experimental studies of power parameters when hard alloy steels are machined with tools, the cutting units of which have multilayer hard, heat-resistant and wear-resistant coatings. The obtained data will make it possible to optimize machining hard-to-machine materials. Materials and Methods. The aim of the study is to measure the power parameters of turning products and to create experimental formulas of power parameters for different technological modes. For this purpose, a special measuring multicomponent complex was used to estimate the influence of the mode parameters on the change in the cutting force components. Results. The numerically controlled machine tool was retooled by combining it with a three-component dynamometer and tooling. The cutting unit of the tool was coated with a multi-layer hard, heat-resistant and wear-resistant coating. The tool was equipped with instruments connected to a personal computer for measuring and processing experimental data. According to the results of the study, there have been obtained graphical dependences and empirical formulas, which take into account the influence of the mode parameters on the cutting force components when machining the units of alloy steels of high hardness, heat resistance and wear resistance. Discussion and Conclusion.The study allowed us to obtain experimental formulas of cutting force components for different mode parameters when machining parts by the tool equipped with cutting plates. The plates are coated with multilayer hard and wear-resistant coatings of titanium carbonitride, aluminum oxide and nickel nitride. The coating increases significantly the hardness, heat and wears resistance of the tool cutting unit and provides quality machining.