Most nanothermite compositions utilise Al as a fuel, due to its low cost, high reactivity and availability. Nevertheless, aluminothermites exhibit high ignition temperature and low active metal content. In this paper, the combustion behaviour of Ti/CuO and Ti/CuO/NC systems is discussed. The compositions were prepared with a wet-mixing/sonication process followed by an electrospray technique and were examined in terms of their mechanical and radiation sensitivity, energetic parameters and morphology. The results exhibited a strong correlation between equivalence ratio and energetic parameters. The performed tests showed the crucial impact the addiction of the chosen energetic binder on the morphology and performance of the compositions. The results of our experiments indicate the occurrence of a different combustion mechanism than the one observed for Al-based nanothermites. In our case, the combustion mechanism involves a limitation by the diffusion of the oxidising agent and its decomposition products into the reactive fuel core.

Nanothermites have found broad applications; however, due to being systems largely reacting in condensed phases, their performance is somewhat limited by heat and mass transfer. In order to alleviate this issue, nanothermites doped with gas-generating energetic materials have been developed. In this work, we present an investigation of a model Ti/CuO nanothermite doped by four classical energetic materials and investigate their properties and combustion performance. Mechanical and laser irradiation sensitivity, as well as ignition/explosion temperatures have been determined for the studied systems to establish their safety features. In terms of combustion performance, thrust force parameters and linear combustion velocity have been determined and the structure of the evolving flame front was recorded during open-air combustion experiments. The obtained results indicate that the developed doped nanothermite formulations are extremely promising materials for future applications.

Modern energetic materials (EMs), e.g., nanothermite and NSTEX (Nanostructured Thermites and Explosive) compositions are attracting increasing research interest. In this work, we present the results of our investigation on the properties of a novel Ti/CuO nanothermite system doped with cellulose nitrate (NC) and 5-Nitro-1,2-dihydro-3H-1,2,4-triazin-3-one (NTO). In terms of safety parameters, the friction (40–>360 N), impact (40–>50 J) and laser irradiation sensitivity were determined for tested systems, which indicated tunable properties. The combustion velocity (up to 735 m/s), pressure parameters for combustion in closed vessel, thrust parameters and open-air combustion behaviour were measured. Moreover, in order to deeply study the impact of NTO on the combustion mechanism, SEM, DSC/TG and XRD analyses were conducted. The obtained results indicate that the Ti/CuO/NC/NTO system is extremely promising for future applications.

A study of the combustion processes of Ti/CuO and Ti/CuO/NC nanothermites prepared via electrospraying was conducted in this work. For this purpose, the compositions were thermally conditioned at 350, 550 and 750 °C, as selected based on our initial differential scanning calorimetry-thermogravimetry (DSC/TG) investigations. The tested compositions were analysed for chemical composition and morphology using SEM-EDS, Raman spectroscopy and XRD measurements. Additionally, the thermal behaviour and decomposition kinetics of compositions were explored by means of DSC/TG. The Kissinger and Ozawa methods were applied to the DSC curves to calculate the reaction activation energy. SEM-EDS analyses indicated that sintering accelerated with increasing equivalence ratio and there was a strong effect on the sintering process due to cellulose nitrate (NC) addition. The main combustion reaction was found to start at 420–450 °C, as confirmed by XRD and Raman study of samples annealed at 350 °C and 550 °C. Moreover, increasing the fuel content in the composition led to lower E_a, higher reaction heats and a more violent combustion process. Conversely, the addition of NC had an ambiguous effect on E_a. Finally, a multi-step combustion mechanism was proposed and is to some extent in line with the more general reactive sintering (RS) mechanism. However, unusual mass transfer was observed, i.e., to the fuel core, rather than the opposite, which is typically observed for Al-based nanothermites.

Modern energetic materials (EMs) have many different civil applications. One of their most promising applications in civil engineering is explosive hardening, which facilitates the fast and cost-effective improvement of mechanical properties in the treated material. In this work, we present the results of our investigation on the explosive hardening of S235JR Steel with PBX formulations containing silicone binders and 1,3,5-trinitro-1,3,5-triazinane (RDX). In terms of safety, the impact (5–15 J) and friction (240–360 N) sensitivity of the tested plastic-bonded explosives (PBXs) was verified, simultaneously with DSC tests, energy of activation calculations, and critical diameter measurement. The developed material, prepared with techniques similar to the anticipated working conditions, is characterized by a high detonation velocity (up to 7300 m/s), low sensitivity for mechanical factors (10 J, 288 N), and a small critical diameter (3.3 mm). The developed PBX based on a silicone binder demonstrated grain fragmentation, recrystallization, and an increase in the surface hardness of S235JR steel, which was confirmed with SEM, EBSD, microstructure analysis, and microhardness studies.

This article presents the research results on the influence of heat treatment of chromium steel, used in the production of drill bits, on their mechanical properties and operational safety. The analyses revealed that the steel used in manufacturing the studied drill bit underwent hardening and tempering processes, which affected its structure and hardness. The presence of tempered martensite and manganese sulfides was observed, which, although not having a destructive impact on the steel’s properties, may limit the formation of undesirable iron sulfides. Additionally, a layer with reduced hardness was identified on the working surface of the drill bit, suggesting the possibility of tool overheating during operation. During the tool’s use, complex mechanical stresses, such as torsional, compressive, and bending stresses, may accumulate in areas prone to damage, especially at the interface between the tooth and the drill bit shank. The article emphasizes the importance of proper tool usage, including adjusting pressure and drilling angle and maintaining optimal operational conditions to ensure safety and durability. The research findings aim to enhance workplace safety and improve the performance of cutting tools in materials engineering.