This study investigates plasma electrolytic oxidation (PEO) of Nitinol and its effect on surface characteristics and corrosion resistance. Two electrolytes were employed: concentrated phosphoric acid (V) and phosphoric acid (V) modified with ethylene glycol. Oxide layers were produced at applied voltages ranging from 60 to 90 V and characterized in terms of morphology, composition, wettability, and corrosion behavior. The influence of the applied voltage was examined to identify processing conditions leading to oxide layers with favorable characteristics, and the mechanism of oxide layer formation was also analyzed. Scanning electron microscopy (SEM) and 3D surface mapping revealed porous coatings with good homogeneity. Higher voltages promoted increased porosity, while the addition of ethylene glycol resulted in smaller and more uniform pores. Energy-dispersive Xray spectroscopy confirmed a reduction in surface nickel content and the incorporation of phosphorus into the oxide layers. All PEO-treated surfaces exhibited enhanced hydrophilicity, particularly for coatings formed in ethylene glycol-containing electrolytes. Raman and X-ray photoelectron spectroscopy identified TiO2 and Ti2O3 as the dominant phases, with minor amounts of nickel phosphates and organic species. Electrochemical and immersion corrosion tests demonstrated a significant improvement in corrosion resistance, accompanied by low nickel release and detectable phosphorus release, which may be beneficial for osseointegration. Process conducted in a concentrated phosphoric acid bath yielded coatings characterized by gradual biodegradation in 0.9 wt% NaCl, releasing modest amounts phosphorus species into the corrosion medium. The ethylene glycolmodified bath produced more stable coatings. The process voltage was found to determine the coating thickness (SEM) and barrier properties (electrochemical impedance spectroscopy and potentiodynamic polarization). Among the investigated conditions, samples treated at 90 V in phosphoric acid and at 60 V in phosphoric acid with ethylene glycol exhibited the most favorable overall properties.

In this study, the feasibility of electrospraying as an alternative processing technique for the preparation of composite solid rocket propellants (SRPs) was investigated. The main objective was to improve microstructural homogeneity and interfacial contact between the oxidizer, energetic additive, and metallic fuel without altering the chemical composition of the formulation. Additionally, porous electrosprayed SRP formulations were prepared to examine the influence of controlled porosity on thermal decomposition behavior. The prepared materials were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDS) to assess microstructural features and component distribution. Thermal decomposition behavior and kinetic parameters were evaluated using simultaneous DSC/TG analysis conducted at multiple heating rates. Safety-related properties were assessed through friction sensitivity testing, while post-decomposition solid residues were analyzed using SEM/EDS and X-ray diffraction. The results show that electrospraying improves structural homogeneity, reduces solid residue formation after thermal decomposition, and decreases apparent activation energy, while maintaining unchanged friction sensitivity. These findings demonstrate the potential of electrospraying as a physical processing route for tailoring the microstructure and thermal behavior of composite solid rocket propellants.

Explosives are a group of special purpose materials, which are important in various branches of industry, such as mining, civil engineering and military. Interest in this type of materials has increased recently, especially due to the current geopolitical situation. Thus, it is important to assess the properties of the explosive as well as evaluate the effects of their use. This paper presents results of research on the analysis of the pressure distribution and characterization of the blast wave produced by two explosives: Ammonal and Heksoflen (95 wt.% RDX / 5 wt.% Viton A). During the research velocity of detonation was measured by four probes placed inside of the prepared charges. The pressure distribution of the blast waves was measured with use of the three pressure probes, placed at various distances from the detonation point. The obtained data were used to determine the explosive constants related to the overpressure, based on which the overpressure prediction was made at various distances for both tested explosives. Moreover, the detonation of the explosives have been recorded with use of Phantom v9.1 high-speed camera. Performed research indicates that, the pressure of the blast wave highly depends on the type of explosive used. Blast wave caused by Heksoflen is characterized by higher maximum pressure and impulse in comparison to Ammonal. After burning of intermediate detonation products differs significantly for the two explosives. After burning of the Heksoflen intermediate products is characterized with wider zone and longer times.

A series of catalytic oxides (Fe2O3, CuO, ZnO, and Cu2O) were investigated as prospective additives shaping the thermal features of a model solid rocket propellant (SRP) formulation utilising ammonium nitrate as the oxidising agent. An extensive investigation of the thermal behaviour (DSC and ignition/explosion temperature studies) of the model and catalyst-bearing SRP formulations was conducted, providing insights into both the thermodynamics and mechanism of combustion of these systems. XRD analysis of post-combustion residues was used to validate the mechanistic claims, as well as to provide information about the behaviour of copper oxides in the SRP system. In addition, the linear combustion velocity was experimentally determined, and the power output was estimated from density, linear combustion velocity and DSC data, in order to assess the potential motor performance of the tested formulations. The obtained results show that the utilisation of metal oxides significantly improves the combustion performance of ammonium nitrate-based SRP formulations relative to the unmodified ammonium nitrate-based propellants.

This study investigates how porous structure formation influences the properties and safety characteristics of composite rocket propellants. Particular attention was given to approaches that may support more sustainable propellant formulations and processing methods. The work compares the efficiency of different sample-structuring and foaming methods, including a chemical foaming strategy based on two ammonium salts. Additionally, it evaluates the feasibility of generating porosity in propellants containing glycidyl azide polymer through the retention of a low-boiling solvent, remaining from synthesis. This approach is expected to reduce the number of processing steps and simplify them, translating into lessened environmental impact. Propellants incorporating this polymer were found to exhibit consistent low-level porosity and improved performance compared to other ammonium nitrate-based propellants, constituting a potential sustainable alternative to perchlorate-based propellants. The investigation encompassed decomposition kinetics (including decomposition activation energy), combustion product analysis, and exploratory nitrogen porosimetry. From a sustainability perspective, the investigated approach addresses key limitations of perchlorate-based propellants by eliminating chlorine-containing oxidising agents and reducing the need for auxiliary chemicals. In particular, the physical foaming strategy enables pore formation using residual solvent, which is already present in the system, supporting waste minimisation and inherently safer processing. These aspects are discussed in the context of selected principles of Green Chemistry and fundamental properties-sustainability trade-offs. Overall, the results highlight how foaming method selection affects not only propellant behaviour but also opportunities for more resource-efficient and environmentally conscious manufacturing routes.

The research describes the continuous precipitation of hydroxyapatite nanoparticles from aqueous solutions of (NH4)2HPO4 and Ca(NO3)2, carried out in the Koflo static mixer. The role of a specific turbulence distribution and its intensity, solutions' concentrations, and the addition of polyvinyl alcohol (PVA) on both the chemical and phase compositions, and final product features have been investigated. The driving force of the process, nucleation sources, and mechanisms controlling particles' growth have also been determined. It was shown that the shape of HAp particles is primarily influenced by the unit power input epsilon mix and may be changed within petals, whiskers/needles, or spheres. The mean size of single particles varied from 390 to 94 nm, however, agglomeration was observed. Its share was reduced to some extent by i) an increase of epsilon mix and/or ii) the use of a small amount of PVA (up to 2 % w/v). The conditions limiting the formation of other than hydroxyapatite CaP phases (i.e. monetite, brushite), allowing to obtain high purity HAp (>= 99 %) were defined. As the sources of nuclei, primary heterogeneous nucleation and secondary one were indicated. It was also recognized that the particle growth in the system was controlled by bulk diffusion.

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 research focused on studying the issue of coating ammonium nitrate (AN) with nitrocellulose (NC) and its microcrystalline form (MNC), using two esterification methods: traditional (HNO3/H2SO4) and in situ synthesis (KNO3/H2SO4). This study employed Raman and IR spectroscopy, SEM, as well as thermokinetic and mechanical analyses. The results showed that the addition of NC-KNO3 significantly increased the pseudo-energy of activation (EA ≈ 268 kJ/mol for pure NC), improving thermal stability. MNC modifications, however, yielded inconclusive results. Despite the confirmed presence of NC on the AN surface (Raman band at 1128 cm−1), SEM analysis did not show formation of a core–shell structure—a reversed-layer formation was observed, where AN deposited onto NC instead of the expected coating. The addition of diesel oil reduced the sensitivity of the mixtures (e.g., ANNC-D showed 35 J for impact and 288 N for friction) due to improved homogeneity. The esterification method affected the mechanical properties of the material: NC synthesised from HNO3 was less sensitive than that obtained from KNO3. This paper highlights the key role of nitrocellulose in modifying the properties of energetic materials, but further research is needed to control the coating process and optimise the synthesis conditions.

Hybrid organic/inorganic composites are a frequent material used in chemoresistive sensors. These composites typically contain components that exhibit p-and n-type electrical conductivity, so as to enable the formation of p-n junctions and increase the sensitivity of the sensors. The specific mechanism behind the operation of such junctions appears to be well-understood and is rarely examined on a case-by-case basis. The interactions between p-and n-type conductors, however, need not be beneficial to the performance of the sensor. In this work, we provide evidence of the competition between p-and n-type conductivities of a hybrid nanocomposite activated by UV light, subjected to ageing and provide a mechanistic description of the underlying processes, as well as indicate potential for such phenomena to be harnessed in development of future sensor generations. By using nanocomposite consist of nanostructured ZnO and poly(3-hexylthiophene) based graft-comb-copolymers we obtained sensor material that can achieve sub-ppb detection limit of NO2 (as low as 50 ppt) capabilities at room temperature. It is experimentally demonstrated that proper choice of polymer material used in the nanocomposite provide stabilisation of baseline drift and lowers limit of the detection while ensuring good adhesion of the receptor layer to the substrate.

The presented study is an extension of research work on the efficient production of TiO2-ZnO films by plasma electrolytic oxidation (PEO). The focus is on the selection of an appropriate electrolyte for the PEO process under direct current (DC) conditions to provide excellent operating characteristics for in-situ incorporation of ZnO into the oxide coating. Several TiO2-ZnO coatings were obtained using different electrolytes based on phosphoric acid (H3PO4), sodium phosphate (Na3PO4), sodium hypophosphite (NaH2PO2), and sodium metasilicate (Na2SiO3). The comparison of PEO parameters and chemical composition of the electrolytes was based on the assessment of the properties and microstructure of the coatings obtained in individual PEO processes, and the following research techniques were used: scanning electron microscopy (SEM)/ energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. We showed that under direct current (DC) conditions, in 0.05 M Na3PO4 electrolyte, the incorporation efficiency of ZnO nanoparticles (NPs) was as much as seven times higher than that of the previously used NaH2PO2. Moreover, the obtained coatings were characterized by a low degree of surface defects, high adhesion to the substrate, and distinct surface development, which may create excellent surface conditions for photocatalysis purposes.

The aims of this study were to investigate the potential of utilising molecularly imprinted polycarbazole layers to detect highly toxic picric acid (PA) and to provide information about their performance. Quantum chemical calculations showed that strong interactions occur between PA and carbazole (bond energy of approximately 31 kJ/mol), consistent with the theoretical requirements for effective molecular imprinting. The performance of the sensors, however, was found to be highly limited, with the observed imprinting factor values for polycarbazole (PCz) layers being 1.77 and 0.95 for layers deposited on Pt and glassy carbon (GC) electrodes, respectively. Moreover, the molecularly imprinted polymer (MIP) layers showed worse performance than unmodified Pt or GC electrodes, for which the lowest limit of detection (LOD) values were determined (LOD values of 0.09 mM and 0.26 mM, respectively, for bare Pt and MIP PCz/Pt, as well as values of 0.11 mM and 0.57 mM for bare GC and MIP PCz/GC). The MIP layers also showed limited selectivity and susceptibility to interfering agents. An initial hypothesis on the reasons for such performance was postulated based on the common properties of conjugated polymers.

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.

Biomaterials, like hydroxyapatite (HAp), are the subject of many scientific investigations. Their specific application, however, is determined by the form and some characteristic features of the resulting material. Synthesis methods and optimization procedures leading to a product of predetermined characteristics are therefore of great interest. To broaden the existing knowledge, sonoprecipitation was investigated as a potential method for the production of nanosized HAp particles. The research was carried out in a static mixer (STM) immersed in the ultrasonic bath. The influence of operating conditions, e.g., ultrasonic power PUS (εUS), ultrasonic frequency (fUS), and unit mixing power (εmix), was investigated in terms of nucleation intensity, product quality, and characteristics (particle size distribution (PSD), mean size, shape, etc.). As a result, the optimal conditions for the HAp nanoparticles synthesis (mean size: d~150 nm; length: L1~250 nm; width: L2~80 nm) in the form of needles/whiskers/rods—similar to the shape of the HAp present in natural human bones, free from agglomerates, with negligible signs of particle destruction—were determined. The formation of HAp of smaller sizes (d ≤ 100 nm) and more compact shapes (L1~155 nm, L2~90 nm), useful in bone regeneration processes, was also discussed.

In the present paper the humidity sensing properties of regioregular rr-P3HT (poly-3-hexylthiophene) polymer films is investigated by means of surface acoustic wave (SAW) based sensors implemented on LiNbO3 (1280 Y-X) and ST-quartz piezoelectric substrates. The polymeric layers were deposited along the SAW propagation path by spray coating method and the layers thickness was measured by atomic force microscopy (AFM) technique. The response of the SAW devices to relative humidity (rh) changes in the range ~5–60% has been investigated by measuring the SAW phase and frequency changes induced by the (rh) absorption in the rr-P3HT layer. The SAW sensor implemented onto LiNbO3 showed improved performance as the thickness of the membrane increases (from 40 to 240 nm): for 240 nm thick polymeric membrane a phase shift of about −1.2 deg and −8.2 deg was measured for the fundamental (~78 MHz operating frequency) and 3rd (~234 MHz) harmonic wave at (rh) = 60%. A thick rr-P3HT film (~600 nm) was deposited onto the quartz-based SAW sensor: the sensor showed a linear frequency shift of ~−20.5 Hz per unit (rh) changes in the ~5–~50% rh range, and a quite fast response (~5 s) even at low humidity level (~5% rh). The LiNbO3 and quartz-based sensors response was assessed by using a dual delay line system to reduce unwanted common mode signals. The simple and cheap spray coating technology for the rr-P3HT polymer films deposition, complemented with fast low level humidity detection of the tested SAW sensors (much faster than the commercially available Michell SF-52 device), highlight their potential in a low-medium range humidity sensing application.

Nanothermites are promising energetic materials (EMs) which can replace current primary EMs, due to their high linear combustion velocities, short ignition times and high energy density. In this work, Al/CuO compositions were prepared and tested in terms of sensitivity to friction, impact and electromagnetic radiation, as well as in terms of its selected properties, such as specific impulse, combustion velocity and bulk density. The results of these investigations show the necessity of refining the method of preparing nanothermites, thereby provide a foundation for further research.

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.

Identification of the mechanism of changes taking place in energetic materials (EMs) is one of the most important issues in the rational design and use of EMs. Due to the extremely rapid nature of these changes, reliable monitoring and real-time analysis are extremely difficult. Hence, analysis of the mechanism of such processes often has to rely on adaptation of classical methods or on comparison of the initial and final states of the EM. In this critical review, we focus on current approaches to the methodology of investigating the mechanisms of processes taking place in EMs, showcasing viable experimental strategies, points of uncertainty, and adaptations of classical instrumental methods.

In this work, we have investigated the thermal features of hydrogen peroxide-based energetic materials formulations. Initial research has shown that both the auxiliary oxidiser (sodium nitrate, potassium nitrate or calcium nitrate) and sensitising agent (glass microspheres) have significant influence on the rate of hydrogen peroxide decay in such formulations. In terms of the thermal features of the tested energetic materials, a similar and significant influence of the auxiliary oxidising agent and sensitising agent choice was observed. We have established that the use of calcium nitrate as an auxiliary oxidising agent (at ambient temperature of approx 20 °C), which allows the formulations to maintain capacity to undergo detonation for longer under storage conditions, negatively impacts the qualitative characteristics of the mixture as an energetic material. The thermal effects accompanying chemical interaction are much smaller than mixtures containing potassium and sodium nitrates as additional oxidising agents. Another important conclusion is that glass microspheres as sensitising agents significantly impact the thermal decomposition processes of the investigated on-site mixed (OSM) energetic material (EM) samples, except for the mixture using calcium nitrate.

Long-term corrosion studies (six weeks) of aluminium alloy 6061 treated by plasma electrolytic oxidation (PEO) with or without the addition of a corrosion inhibitor (acrylic acid) in oxygenated 3.5 wt% NaCl are reported. A two-step sequential procedure (PEO + enrichment with acrylic acid) was compared with PEO carried out in the presence of the inhibitor. EIS backed by ICP-OES and SEM data showed that the sequential method offers the best long-term protection. A new approach for testing weight loss due to corrosion underneath the PEO coatings is proposed. The obtained results are consistent with other methods used in the study.

In this work, energetic coordination compounds (ECCs) of transition metals (Fe, Ni, Cu, Zn) containing aliphatic amines as ligands were synthesized: ethylenediamine; 1,3-diaminopropane; tris(2-aminoethyl)amine; tris(3-aminopropyl)amine. The compounds were investigated in terms of ignition/explosion temperature, friction and impact sensitivity. For selected compounds, structural characterisation was presented (IR-ATR spectroscopy, Raman spectroscopy) and their morphology was determined (SEM, powder XRD). They were also investigated by differential scanning calorimetry (DSC). In order to assess the potential application of selected ECCs in detonators, underwater explosion tests were carried out, determining energetic performance. The results achieved for detonators containing ECCs were compared with those for reference detonators (containing pentaerythritol tetranitrate, PETN), indicating their potential use as a “green” alternative to nitric acid esters.