Instytut Podstawowych Problemów Techniki

Rogala M., Ferdynus M., Kopeć M., The effect of multilevel spherical triggers on the crashworthiness capacity of thin-walled structures, Aerospace Science and Technology, ISSN: 1270-9638, DOI: 10.1016/j.ast.2025.110299, Vol.163, No.110299, pp.1-18, 2025

Abstract:
Progressive dynamic crushing remains a significant focus in contemporary research aimed at developing and optimizing energy-absorbing structures. This study investigates thin-walled passive energy absorbers featuring multi-level crush initiators in the form of spherical embossments. The experimental setup involved aluminum columns subjected to an impact energy of 1700 J. These columns were designed with varying numbers of embossment levels. Key parameters of the spherical embossments included diameters ranging from 12 to 36 mm and depths from 1.2 to 4.8 mm. Dynamic impact tests were conducted using an Instron Ceast 9350 HES drop tower, with deformation behavior captured via a Phantom Miro M310 high-speed camera. Complementary finite element analyses were also performed to obtain force-displacement responses and crushing efficiency indicators, enabling a comparative assessment of structural performance based on different crush initiator configurations. The results demonstrate that spherical embossments enhance the stability of the crushing process by reducing the peak crushing force. Furthermore, incorporating additional embossment levels increases the mean crushing force and improves the overall energy absorption efficiency of the passive energy absorber.

Keywords:
Multi-level trigger , Spherical embossment, Crashworthiness

Tytko G., Adamczyk-Habrajska M., Linke Y., Liu Z., Kopeć M., High frequency eddy current method in inspection of aluminide coatings integrity after simulating service loads, MEASUREMENT, ISSN: 0263-2241, DOI: 10.1016/j.measurement.2025.117356, Vol.252, No.117356, pp.1-11, 2025

Abstract:
This study investigates the use of high-frequency eddy current testing (ECT) to assess the structural integrity of aluminide coatings on MAR-M247 nickel superalloy under simulated fatigue conditions. Aluminide coatings, deposited via chemical vapor deposition at thicknesses of 20 µm and 40 µm, were tested using custom-designed probes optimized for defect detection. Results demonstrate that substrate grain structure and coating thickness significantly influence coating durability, with fine-grain substrates exhibiting the least resistance changes and greatest fatigue tolerance. Eddy current signal variations correlated with microstructural changes, enabling detection of damage otherwise invisible to traditional methods. These findings establish ECT as a precise, non-destructive approach for monitoring aluminide coatings in critical applications.

Keywords:
Nickel alloys, Aluminide coating, Non-destructive testing, Eddy current testing

Widomski P., Kaszuba M., Barełkowski A., Smolik J., Garbiec D., Ciemiorek-Bartkowska M., Kulikowski K., Lewandowska-Szumieł M., Mościcki T., Gronostajski Z., WTaB coatings as effective solutions for increasing die durability in lead-free brass alloy flashless hot forging process, WEAR, ISSN: 0043-1648, DOI: 10.1016/j.wear.2025.205849, Vol.571, No.205849, pp.1-10, 2025

Abstract:
The forging of lead-free brass alloys is characterized by low tool durability, presenting a significant challenge in industrial applications. To address this issue, unique magnetron-sputtered coatings based on WB and with the addition of Tantalum, were employed to increase tool life. These coatings were produced from proprietary sintered targets using the SPS-HiPIMS technology. Initially, the coatings underwent laboratory testing, where their microstructure, adhesion to the substrate, and mechanical properties were tested and evaluated. The next phase involved testing these coatings on tools used in hot flashless forging processes. The experiments were conducted on dies that were preliminarily gas-nitrided to provide a suitable substrate for the coating application. The results were compared with those of only nitrided dies.
The study involved the use of nitrided dies, dies with WB2.5 and with W0.76Ta0.24B2.5 coatings. After forging, the tools were observed to assess the wear mechanisms. Surface scans were performed to measure material loss by comparing the surface profiles before and after forging. Scanning Electron Microscopy (SEM) was used to analyze the contribution of various wear mechanisms, such as abrasive wear, thermo-mechanical fatigue, and plastic deformation, to the overall tool wear.
The results confirmed the beneficial impact of these coatings on enhancing tool durability. In certain cases, the service life of the tools was extended by up to 50 %. This study demonstrates that the application of newly developed W0.76Ta0.24B2.5 coating which can significantly improve the durability of tools used in the flashless forging of lead-free brass alloys, offering a promising solution for industrial manufacturing challenges.

Łazarska M., Ranachowski Z., Musiał J., Tański T., Jiang Q., Identification of Phase Transformations in Alloy and Non-Alloy Steel During Austempering Using Acoustic Emission and Neural Network, Materials, ISSN: 1996-1944, DOI: 10.3390/ma18102198, Vol.18, No.2198, pp.1-16, 2025

Abstract:
This research was carried out for selected alloy (bearing) and non-alloy (tool) steel. The steels were subjected to austempering. The hardening temperature range was from 100 °C to 180 °C. The use of acoustic emission in connection with the artificial neural network (ANN) enabled the analysis and identification of phase changes occurring in steels during austempering. Classification of acoustic emission events was carried out with the help of their energy values and with the use of an artificial neural network. On this basis, it was observed that in the process of isothermal hardening of steel at the applied temperatures, complex transformations of austenite into martensite and bainite occur. In addition, it was found that the research methods used enabled the identification of signal components originating from the phase transformation causing the formation of thin-plate martensite midrib. The use of acoustic methods in the field of bainitic transformation creates the possibility of their application in the industry.

Keywords:
bainite, martensite, austempering, acoustic emission (AE), neural networks

Macek W., Sitek R., Podulka P., Lesiuk G., Zhu S., Liu X., Kopeć M., Fractography of Haynes 282 alloy manufactured by DMLS after tensile and HCF, Journal of Constructional Steel Research, ISSN: 1873-5983, DOI: 10.1016/j.jcsr.2025.109623, Vol.232, No.109623, pp.1-12, 2025

Abstract:
In this paper, the fracture surface topography of additively manufactured Haynes 282 alloy subjected to tensile and high-cycle fatigue loading was investigated. Haynes 282 alloy bars were printed in three different directions relative to the base plate (0°, 45°, and 90°) via Direct Metal Laser Sintering (DMLS) under an argon protective atmosphere. The specimens were subjected to monotonic tensile loading and fatigue testing under load control using full tension and compression cyclic loading (R = −1) in the range of stress amplitude from ±550 MPa to ±800 MPa. The entire surface topography was evaluated by using a 3D non-contact confocal technique and post-failure specimens after a fatigue test performed at three stress amplitudes, ±650 MPa, ±700 MPa and ±750 MPa. Such an attempt was proposed to analyse the fatigue response of AM Haynes 282 in the region near its yield strength. It was found that the printing orientation and the stress amplitude have a strong impact on service life and fracture surface characteristics. Finally, a surface topography parameter involving the mass density of furrows, root-mean-square height, and fractal dimension was successfully combined with the stress amplitude to estimate the fatigue life. The findings offer a novel approach to fatigue life prediction based on post-failure surface analysis, providing valuable insights for industrial applications and forensic engineering.

Keywords:
Nickel alloys,Fatigue,Additive manufacturing,Direct Metal Laser Sintering (DMLS),Fracture,Surface topography

Brachaczek A., Tokpatayeva R., Olek J., Jarząbek D.M., Piotrowski P., Jenczyk P., Jóźwiak-Niedźwiedzka D., Impact of formate based deicing agents on ASR products: Microstructural, chemical and mechanical characteristics, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2025.140729, Vol.471, No.140729, pp.1-12, 2025

Abstract:
This study investigates the effects of formate-based deicing agents, specifically potassium formate (HCOOK) and sodium formate (HCOONa), on alkali-silica reaction (ASR) in concrete. By adapting ASTM C1260 standards, mortar bars were subjected to deicing solutions of varying concentrations to evaluate their influence on mortar expansion and ASR product characteristics. Results revealed that high concentrations of formate solutions significantly accelerated ASR, inducing expansions comparable to or greater than those caused by sodium hydroxide, while sodium chloride showed minimal expansion effects. Microstructural and chemical analyses demonstrated that ASR gels formed in formate solutions were predominantly amorphous, with different chemical composition depending on the deicer type. Pore solution analysis indicated a strong correlation between alkali ion concentration and mortar expansion. Furthermore, mechanical testing of ASR products revealed that gels formed in potassium formate exhibited higher hardness and elastic modulus compared to those formed in sodium formate. These findings enhance understanding of the detrimental effects of formate-based deicing agents on ASR and provide a foundation for developing mitigation strategies to preserve concrete infrastructure.

Keywords:
Alkali-silica reaction,Concrete microstructure,Expansion,Nanoindentation,Deicing agents,Pore solution analysis

Brachaczek A., Dąbrowski M., Lisowski P., Dziedzic K., Glinicki M.A., Alkali threshold level in concrete to trigger the alkali-silica reaction at simulated road pavement environments with alkali supply, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2025.142023, Vol.487, No.142023, pp.1-17, 2025

Abstract:
To minimize the potential risk of concrete damage due to alkali-silica reaction (ASR) when using ordinary Portland cement in concrete mixtures, the alkali threshold level must be established for specific aggregate combinations. Since deicing salts used in the winter maintenance of highway structures can serve as an external source of alkalis, their impact on alkali threshold determination should be evaluated. An experimental investigation was conducted on concrete specimens subjected to a 60°C performance test, both with and without an external alkali supply. Concrete mixtures were prepared using Portland cements with alkali contents ranging from 0.45 % to 1.2 % Na2Oeq. Mineral aggregates consisted of blends of potentially reactive coarse granite and natural siliceous sand, characterized by varying degrees of reactivity. The development of concrete expansion over time and associated changes in its dynamic elastic modulus, as well as the characteristics of ASR products in concrete is reported. The chemical reactivity index was determined based on the concentrations of Si, Ca, and Al in test suspensions containing aggregate, CaO, and NaOH. At simulated pavement environmental conditions variations in temperature and relative humidity in concrete were monitored. The effects of exposure conditions on expansion behavior and the composition of ASR products are discussed. The alkali threshold levels derived for such different exposure conditions are compared and analyzed in relation to the varying potential reactivity of fine aggregates.

Keywords:
Alkali-silica reaction,Alkali supply,Concrete durability,Critical alkali content,NaCl deicer,Reactive aggregate,Simulated service exposure conditions

Pawłowski P., Stańczak M., Broniszewska-Wojdat P., Blanc L., Frąś T., Rusinek A., Energy-absorption capacity of additively manufactured AlSi10Mg cellular structures subjected to a blast-induced dynamic compression–experimental and numerical study, INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, ISSN: 0734-743X, DOI: 10.1016/j.ijimpeng.2024.105216, Vol.198, No.10, pp.105216-1-105216-17, 2025

Abstract:
The study investigates the role of the topology of the additively manufactured AlSi10Mg cellular structures in the example of 3D and 2D designs: honeycomb, auxetic, lattice and foam. The samples were subjected to quasistatic and blast-induced dynamic compression. As a result, a relation between the structural geometry and the deformation mode of the compressed structures has been developed, demonstrating its influence on the energy absorption characteristics. The deformation and fracture mechanisms were examined in detail using the finite element simulations in the LS-DYNA code based on the material characterisation over a broad range of strain rates and temperatures. The outcomes show an agreement between the experimental data and the computations. The obtained results prove that by selecting the appropriate topological features, the deformation of compressed structures can be enhanced to improve their energy-absorption capacity.

Keywords:
Additive manufacturing,AlSi10Mg,Direct metal laser sintering (DMLS),Cellular structures,Dynamic compression,Blast-energy absorption,Explosively-driven shock tube

Jóźwiak-Niedźwiedzka D., Rovnanik P., Dąbrowski M., Ośko J., Kuć M., Maciak M., Gamma radiation attenuation, mechanical properties and microstructure of barite-modified cement and geopolymer mortars, Nuclear Engineering and Technology, ISSN: 1738-5733, DOI: 10.1016/j.net.2024.10.057, Vol.57 (4), No.103295, pp.1-11, 2025

Abstract:
The present study contributes to the development of alternative materials for radiation shielding, focusing on environmental sustainability and material cost efficiency. The primary aim was to evaluate the compressive and flexural strength, mineral composition, microstructure, and gamma-ray attenuation properties of cement mortars and geopolymer mortars containing barite powder. Mortars based on ordinary Portland cement (OPC) and fly ash geopolymers with varying amounts of barite powder were assessed for their shielding properties at energy levels associated with the decay of 137Cs. From the results, key parameters such as the linear attenuation coefficient (μ), mass attenuation coefficient (μm), half-value layer (HVL), and tenth-value layer (TVL) were determined. The results showed that while cement-based composites exhibited superior gamma radiation attenuation compared to fly ash geopolymer mortars, the latter had higher mass attenuation efficiency, meaning less material density was required for the same level of shielding. Additionally, cement mortars had 23–25 % higher mechanical strength than geopolymer mortars. Importantly, the inclusion of barite powder improved the radiation shielding performance of both materials by 7–10 %, demonstrating its effectiveness in enhancing the protective properties of these mortars. This research highlights the potential of fly ash geopolymer mortars as viable, eco-friendly alternatives to traditional cement mortars in radiation shielding applications.

Keywords:
Cement mortar, Fly ash geopolymer mortar, Barite, Gamma ray attenuation, Microstructure

Kamiński J., Adamczyk-Cieślak B., Kopeć M., Kosiński A., Sitek R., Cover Picture: Materials and Corrosion. 3/2025: Effects of Reduction-Oxidation Cycles on the Structure, Heat and Corrosion Resistance of Haynes 282 Nickel Alloy Manufactured by using Powder Bed Fusion- Laser Beam Method, materials and corrosion, ISSN: 0947-5117, DOI: 10.1002/maco.202570031, pp.1-1, 2025

Keywords:
corrosion, DMLS, haynes 282, nickel superalloy, hydrogen , oxidation

Nabavian Kalat M., Ziai Y., Dziedzic K., Gradys A. D., Urbański L., Zaszczyńska A., Andrés Díaz L., Kowalewski Z. L., Experimental evaluation of build orientation effects on the microstructure, thermal, mechanical, and shape memory properties of SLA 3D-printed epoxy resin, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2025.113829, Vol.228, pp.113829-1-18, 2025

Abstract:
Additive manufacturing (AM) methods, popularly known as 3D printing technologies, particularly the pioneering laser stereolithography (SLA), have revolutionized the production of complex polymeric components. However, challenges such as anisotropy, resulting from the layer-by-layer construction method, can affect the thermomechanical properties and dimensional stability of 3D-printed objects. Although anisotropy in SLA 3D printing is often overlooked due to the high precision of this technique, its impact on the properties and structural performance of the 3D-printed prototype becomes more significant when printing small devices designed for precise micro-mechanisms. This experimental study investigates the impact of the chosen printing surface – a less explored factor – on the performance of SLA 4D-printed thermo-responsive shape memory epoxy (SMEp) specimens. Two identical dog-bone specimens were printed from two distinct surfaces: edge and flat surface, to examine how variations in surface area and quantity of layers influence the microstructure, thermal behavior, mechanical properties, and shape memory performance. The results of this experimental investigation reveal that specimens printed from the edge, with a higher number of layers and smaller surface area, exhibit superior interlayer bonding, tensile strength, dimensional stability, and shape recovery efficiency compared to those printed from the flat surface. Conversely, specimens with fewer, larger layers demonstrated greater elongation and thermal expansion but reduced structural integrity and shape recovery performance. These results highlight the importance of experimentally investigating how different build orientations affect the properties and performance of SLA 3D-printed materials, especially before designing and employing them in applications demanding high precision and reliability.

Keywords:
Additive manufacturing, Laser stereolithography, Shape memory polymers, Materials processing, Anisotropy, Printing orientation

Kopeć M., Gunputh U., Williams G., Wojcieck M., Kowalewski Z., Wood P., On the Cover: Fatigue Damage Evolution in SS316L Produced by Powder Bed Fusion in Different Orientations with Reused Powder Feedstock, EXPERIMENTAL MECHANICS, ISSN: 0014-4851, DOI: 10.1007/s11340-025-01179-w, pp.1-1, 2025

Abstract:
Background Metal Laser Powder Bed Fusion Melting (LPBF-M) is considered economically viable and environmentally
sustainable because of the possibility of reusing the residual powder feedstock leftover in the build chamber after a part
build is completed. There is however limited information on the fatigue damage development of LPBF-M samples made
from reused feedstock.
Objective In this paper, the stainless steel 316 L (SS316L) powder feedstock was examined and characterised after 25
reuses, following which the fatigue damage development of material samples made from the reused powder was assessed.
Methods The suitability of the powder to LPBF-M technology was evaluated by microstructural observations and measurements of Hall flow, apparent and tapped density as well as Carr’s Index and Hausner ratio. LPBF-M bar samples in three
build orientations (Z – vertical, XY – horizontal, ZX – 45° from the build plate) were built for fatigue testing. They were
then subjected to fatigue testing under load control using full tension and compression cyclic loading and stress asymmetry
coefficient equal to -1 in the range of stress amplitude from ± 300 MPa to ± 500 MPa.
Results Samples made from reused powder (25 times) in the LPBF-M process exhibited similar fatigue performance to fresh
unused powder although a lower ductility for vertical samples was observed during tensile testing. Printing in horizontal
(XY) and diagonal (ZX) directions, with reused powder, improved the service life of the SS316L alloy in comparison to
the vertical (Z).
Conclusions Over the 25 reuses of the powder feedstock there was no measurable difference in the flowability between the
fresh (Hall Flow: 21.4 s/50 g) and reused powder (Hall Flow: 20.6 s/50 g). This confirms a uniform and stable powder feeding
process during LPBF-M for both fresh and reused powder. The analysis of fatigue damage parameter, D, concluded cyclic
plasticity and ratcheting to be the main mechanism of damage.

Keywords:
SS316L ,Stainless steel,Fatigue,Additive manufacturing,Laser Powder Bed Fusion Melting (LPBF-M)

Sitek R., Bochenek K., Maj P., Marczak M., Żaba K., Kopeć M., Kaczmarczyk G., Kamiński J., Hot-Pressing of Ti-Al-N Multiphase Composite: Microstructure and Properties, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app15031341, Vol.15, No.1341, pp.1-15, 2025

Abstract:
This study focuses on the development and characterization of a bulk Ti-Al-N
multiphase composite enriched with BN addition and sintered through hot pressing. The
research aimed to create a material with optimized mechanical and corrosion-resistant
properties suitable for demanding industrial applications. The composite was synthesized using a powder metallurgy approach with a mixture of AlN, TiN, and BN powders, processed under a high temperature and pressure. Comprehensive analyses, including microstructural evaluation, hardness testing, X-ray tomography, and electrochemical corrosion assessments, were conducted. The results confirmed the formation of a multiphase microstructure consisting of TiN, Ti₂AlN and Ti₃AlN phases. The microstructure was uniform with minimal porosity, achieving a hardness within the range of 500–540 HV2. Electrochemical tests revealed the formation of a passive oxide layer that provided moderate corrosion resistance in chloride-rich environment. However, localized pitting corrosion was observed under extreme conditions. The study highlights the potential of a BN admixture to enhance mechanical and corrosion-resistant properties and suggests directions for further optimization in sintering processes and material formulations.

Keywords:
AlN-TiN(BN) composite,hot-pressing,μCT,corrosion resistance

Tytko G., Adamczyk-Habrajska M., Linke Y., Pengpeng S., Kopeć M., Eddy Current Method in Non-Magnetic Aluminide Coating Thickness Assessment, JOURNAL OF NONDESTRUCTIVE EVALUATION, ISSN: 0195-9298, DOI: 10.1007/s10921-025-01211-y, Vol.44, No.65, pp.1-11, 2025

Abstract:
This study investigates the use of eddy current testing (ECT) as a non-destructive technique to evaluate the thickness and structural variations of non-magnetic aluminide coatings on MAR-M247 nickel-based superalloy. Coatings with thicknesses of 20 μm and 40 μm were applied to substrates exhibiting fine, coarse, and columnar grain structures. Using sensors of different geometries, impedance measurements were performed within a frequency range of 11.5 MHz to 12.5 MHz. Results demonstrated the designed sensor’s superior sensitivity, with the highest values of absolute resistance difference significantly exceeding the threshold for reliable distinction due to coating thicknesses or grain structures. The study highlights the impact of eddy current penetration depth and edge effects on the measurement accuracy, emphasizing the need for optimized sensor design and frequency selection. Findings confirm the efficacy of ECT in differentiating coatings of varying thicknesses and substrate structures, offering a reliable tool for quality control in high-temperature applications.

Keywords:
Aluminide coating, Eddy current testing, Non-destructive testing, Nickel alloys

Szczęsny G., Kopeć M., Kowalewski Z. L., Toxicity, Irritation, and Allergy of Metal Implants: Historical Perspective and Modern Solutions, Coatings, ISSN: 2079-6412, DOI: 10.3390/coatings15030361, Vol.15, No.361, pp.1-32, 2025

Abstract:
The widespread adoption of metal implants in orthopaedics and dentistry has revolutionized medical treatments, but concerns remain regarding their biocompatibility, toxicity, and immunogenicity. This study conducts a comprehensive literature review of traditional biomaterials used in orthopaedic surgery and traumatology, with a particular focus on their historical development and biological interactions. Research articles were gathered from PubMed andWeb of Science databases using keyword combinations such as “toxicity, irritation, allergy, biomaterials, corrosion, implants, orthopaedic surgery, biocompatible materials, steel, alloys, material properties, applications, implantology, and surface modification”. An initial pool of 400 articles was screened by independent reviewers based on predefined inclusion and exclusion criteria, resulting in 160 relevant articles covering research from 1950 to 2025. This paper explores the electrochemical processes of metals like iron, titanium, aluminium, cobalt, molybdenum, nickel, and chromium post-implantation, which cause ion release and wear debris formation. These metal ions interact with biological molecules, triggering localized irritation, inflammatory responses, and immune-mediated hypersensitivity. Unlike existing reviews, this paper highlights how metal–protein interactions can form antigenic complexes, contributing to delayed hypersensitivity and complications such as peri-implant osteolysis and implant failure. While titanium is traditionally considered bioinert, emerging evidence suggests that under certain conditions, even inert metals can induce adverse biological effects. Furthermore, this review emphasizes the role of oxidative stress, illustrating how metal ion release and systemic toxicity contribute to long-term health risks. It also uncovers the underappreciated genotoxic and cytotoxic effects of metal ions on cellular metabolism, shedding light on potential long-term repercussions. By integrating a rigorous methodological approach with an in-depth exploration of metal-induced biological responses, this paper offers a more nuanced perspective on the complex interplay between metal implants and human biology, advancing the discourse on implant safety and material innovation.

Keywords:
orthopaedic implants, toxicity, metals, biomaterials

Haponova O., Tarelnyk V., Mościcki T., Tarelnyk N., Hybrid Surface Treatment Technologies Based on the Electrospark Alloying Method: A Review, Coatings, ISSN: 2079-6412, Vol.15, No.6, pp.1-26, 2025

Abstract:
Technologies for functional coatings are evolving rapidly, with electrospark alloying (ESA) emerging as a promising method for surface modification due to its efficiency and localized impact. This review analyzes the fundamental principles of ESA and the effects of process parameters on coating characteristics and highlights its advantages and limitations. Particular attention is given to hybrid ESA-based technologies, including combinations with laser treatment, plastic deformation, vapor deposition, and polymer-metal overlays. These hybrid methods significantly improve coating quality by enhancing hardness, adhesion, and structural integrity and reducing roughness and defects. However, the multi-parameter nature of these processes presents optimization challenges. This review identifies knowledge gaps related to process reproducibility, control of microstructure formation, and long-term performance under service conditions. Recent breakthroughs in combining ESA with high-energy surface treatments are discussed. Future research should focus on systematic parameter optimization, in situ diagnostics, and predictive modeling to enable the design of application-specific hybrid coatings.

Keywords:
electrospark alloying, hybrid technologies, surface plastic deformation, laser treatment, vapor phase deposition, metal–polymer material, coating, structure, properties, roughness, coating quality, sustainable development goals

Kondej A., Kukla D., Wachulak P., Zagórski A., Non-destructive method of characterizing nitrided layers in the 42CrMo4 steel using the amplitude-frequency technique of eddy currents, Open Engineering , ISSN: 2391-5439, DOI: 10.1515/eng-2025-0106, Vol.15, No.1, pp.1-11, 2025

Abstract:
The aim of this work was to investigate the possibility of using the eddy current method, a technique for measuring voltage amplitude and resonant frequency, for non-destructive assessment of the thickness of the near-surface layer of iron nitrides in 42CrMo4 steel after gas nitriding. The scope of the work included preparation of test samples, chemical composition tests, surface roughness measurements, hardness distribution using the Vicker’s method and measurements of the thickness of nitrided layer on cross-sections, X-ray phase composition analysis, testing of nitrided layer using the eddy current method, analysis of the correlation of the results of destructive and non-destructive tests. The main research apparatus was the Wirotest M2 with the 25 kHz measuring head. Differences in electromagnetic parameters between the white layer and the rest of the nitrided material, as well as changes in the surface roughness of the layer, are factors influencing the eddy current signal, which allows indirect measurement of its thickness. The analysis of the voltage amplitude is more accurate, than the resonant frequency, in assessing the thickness of nitrides layer. With the increase in thickness of the nitrides layer, the voltage value of the signal of eddy currents increases. The research results also indicate the possibility of using the same measuring head to assess the roughness parameter Ra of the nitrided layer. The Wirotest M2 can be used in quality control of steel parts after nitriding.

Keywords:
non-destructive testing, eddy currents, gas nitriding, nitrides zone, thickness measurement, voltage amplitude

Kopeć M., Kukla D., Kowalewski Z., Assessment of aluminide coating integrity by using acoustic emission, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, DOI: 10.15632/jtam-pl/203353 , pp.1-6, 2025

Abstract:
Coatings are essential for protecting high-temperature components in aerospace and power generation industries. This study evaluates the integrity of aluminide coatings on MAR-M247, a nickelbased superalloy, under uniaxial tensile loading using acoustic emission (AE). Aluminide coatings, deposited via chemical vapor deposition (CVD), provide oxidation and corrosion resistance but are prone to damage under operational stresses. AE monitoring, a nondestructive evaluation method, detects transient elastic waves associated with damage events such as crack initiation and delamination. By analyzing AE signal characteristics like amplitude and energy, this research identifies acoustic signatures indicative of coating degradation. The findings highlight AE’s potential for real-time damage assessment, enabling early detection and predictive maintenance strategies in high-temperature applications.

Keywords:
coatings,acoustic emission,nickel alloys,non destructive testing