Geir Grasmo

• Tareq, Foysal Kabir; Nasir, Rakib Bin & Grasmo, Geir (2026). Multiphase and microstructural engineering of DED-LB-fabricated Ni solid solution-nickel silicides with alloying addition and heat-treatment for improved mechanical, oxidation/corrosion performance. Materials & design. ISSN 0264-1275. 267. doi: 10.1016/j.matdes.2026.116362. Full text in Research Archive
• Tareq, Foysal Kabir & Grasmo, Geir (2025). Improved properties of near-eutectic nickel silicide alloyed with vanadium, chromium, and carbon in inductively coupled plasma spheroidization for additive manufacturing. Materials & design. ISSN 0264-1275. 256. doi: 10.1016/j.matdes.2025.114377. Full text in Research Archive Show summary

  Nickel-rich silicides offer excellent hardness, thermal stability, corrosion and wear resistance. However, their application is limited by poor fracture resistance and a propensity for cracking, particularly when processed through conventional thermo-metallurgical methods. To address these limitations, this study explores the enhancement of nickel-silicon alloy properties through alloying with V (5 wt%), Cr (3 wt%), and C (0.3 wt%). The Ni-12Si alloy features a Niss-Ni3Si eutectic with a γ-Ni31Si12 phase. Alloying elements refine the microstructure, are present as soluble constituents in the phases, stabilizing the γ-Ni31Si12, and introducing element-rich phase precipitation. Additionally, plasma spheroidization of these as-crushed powder was performed to improve powder characteristics for additive manufacturing. The spheroidization process, optimized by adjusting plasma power and powder feed rate, yields spherical powders with refined microstructures, and improved flowability, showing suitability for laser-based directed energy deposition (DED-LB). DED-LB deposition of spheroidized powders on S355 steel substrate showed the Ni-12Si bead exhibited solidification microcracks at the grain boundaries, whereas the alloyed variants Ni-11.4Si-5V, Ni-11.1Si-3Cr, and Ni-12Si-0.3C demonstrated flawless deposits with improved properties. These enhancements are attributed to the synergistic effects of alloying on phase evolution, microstructural refinement and transformation, and grain boundary modification through the formation of fine, element-rich precipitates at grain boundaries.

• Tareq, Foysal Kabir; Aune, Ragnhild Elizabeth; Odden, Jan Ove & Grasmo, Geir (2025). Enhancing Characteristics of Hypoeutectic, Congruent, and Eutectic Nickel Silicide Alloys by Optimizing Inductively Coupled Plasma Spheroidization Parameters for Additive Manufacturing. Journal of Alloys and Compounds. ISSN 0925-8388. 1036. doi: 10.1016/j.jallcom.2025.181635. Full text in Research Archive Show summary

  Nickel-silicon (Ni–Si) alloys are known for their excellent physicochemical, thermal, and mechanical properties, making them suitable for high-temperature oxidation-resistant, corrosion-resistant, and wear-resistant applications. However, their inherent brittleness and the processing challenges associated with conventional methods, such as casting, forging, and machining, limit broader industrial applicability. To address these limitations and enhance their suitability for additive manufacturing (AM), this study investigates the spheroidization of Ni–Si alloy powders using inductively coupled plasma spheroidization (ICPS). The work focuses on hypoeutectic Ni-16.1Si, congruent Ni-32.4Si, and eutectic Ni-38Si (weight%) powders, which initially exhibit irregular morphology and consist of γ-Ni31Si12/δ-Ni2Si, Ni3Si2/NiSi/NiSi2, and NiSi/NiSi2 phases, respectively. The ICPS process was optimized by evaluating the effects of plasma power, chamber pressure, and powder feed rate, resulting in the formation of spherical particles with smooth surfaces, narrower particle size distributions, refined microstructures, modified phase compositions, and enhanced flowability, characteristics well-suited for AM requirements. The spheroidized powders were deposited onto S355 steel substrates using a laser-based directed energy deposition process to assess their suitability for surface engineering applications. While higher Si-content alloys exhibited increased susceptibility to microcracking due to residual stress and brittle phase formation, Ni-16.1Si demonstrated the most favorable mechanical performance, including high surface hardness, low abrasion-induced volume loss, and strong resistance to indentation-induced cracking. Overall, this study establishes a strong foundation for the use of spheroidized Ni–Si powders in AM, particularly for applications requiring durable hard surface engineering materials.

• Ibrahim, Mohammad; Hulme, Christopher; Grasmo, Geir & Aune, Ragnhild Elizabeth (2024). Preliminary Evaluation of Nickel Silicide (NiSi12-wt%) Laser Cladding for Enhancing Microhardness and Corrosion Resistance of S355 Steel. Metals. 14(12). doi: 10.3390/met14121389. Full text in Research Archive Show summary

  S355 construction steel, a commonly used mild steel due to its exceptional strength, is prone to environmental degradation, especially pitting corrosion in highly corrosive marine environments. To address this vulnerability, applying a surface layer of nickel silicide (NiSi) cladding on such components could offer a solution, given that NiSi-based alloys are known for their high corrosion resistance and exceptional mechanical properties. Thus, the present study has investigated the corrosion resistance and microhardness of the NiSi12-wt% cladding deposited onto substrates of S355 steel using laser metal deposition. An accelerated ASTM G48 corrosion test and a Vickers microhardness test were conducted in a solution of 6% ferric chloride (FeCl3) solution at room and elevated temperatures to represent marine environments, with uncladded sheet substrates exposed to the same test environments as a reference. All exposed S355 steel samples, with and without cladding, underwent microhardness testing and were characterized using light optical microscopy (LOM) and low-voltage field emission scanning electron microscopy (LVFESEM). The findings indicate that the NiSi12-wt% cladding significantly enhances the corrosion resistance and mechanical properties of the S355 steel samples, showcasing its potential for use in marine and industrial environments where corrosion and mechanical wear are expected.

• Ibrahim, Mohammad; Gobber, Federico Simone; Hulme, Christopher; Grasmo, Geir & Aune, Ragnhild Elizabeth (2024). Influence of Atomizing Gas Pressure on Microstructure and Properties of Nickel Silicide Intended for Additive Manufacturing. Metals. 14(8). doi: 10.3390/met14080930. Full text in Research Archive Show summary

  Nickel silicides are crucial in advanced technology applications ranging from semiconductor devices to high-temperature materials. Gas atomization is a process that involves the formation of fine liquid droplets and their rapid cooling and solidification to make powder particles. The final microstructure and the properties of the particles are highly sensitive to the gas atomization process parameters. In the present study, gas atomization of NiSi12-wt% was performed at three different pressures (35, 40, and 45 bars) to optimize the particle size distribution for additive manufacturing applications. A comprehensive range of characterization techniques, including scanning electron microscopy, X-ray diffraction, particle size distribution measurements, light optical microscopy, and density measurements, was used to evaluate the microstructural features, phase composition, and density of the produced NiSi12-wt% powders. Higher atomizing gas pressures resulted in a finer particle size distribution due to improved molten droplet breakup, increased satellite formation, and a well-suited particle size distribution for additive manufacturing applications.

• Tareq, Foysal Kabir; Hovig, Even Wilberg; Aune, Ragnhild Elizabeth & Grasmo, Geir (2023). Microstructure and Mechanical Properties of Arc-Melted NiSi11Cx Alloys, TMS 2023 152nd Annual Meeting & Exhibition Supplemental Proceedings. Springer. ISSN 9783031225239. p. 216–225. doi: 10.1007/978-3-031-22524-6_21. Full text in Research Archive Show summary

  Functional materials such as nickel silicides (Ni3Si) are considered promising materials for building complex and strong structures. They have proven to have a high melting point, low electronic resistivity, excellent corrosion resistance, and thermally stability, however, their overall performances are still challenging due to their brittleness. Therefore, it is essential to prepare high-strength nickel silicide-based materials to improve their toughness. In the present study, arc melting has been utilized to synthesize nickel silicide (NiSi11, wt%) and carbon (C) alloyed nickel silicide (NiSi11Cx, x = 0.2, 1 wt%) with varying amounts of C aiming to improve the microstructure and mechanical properties of the alloy. The NiSi11 and NiSi11Cx alloys were characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and microhardness tests. Results show that the NiSi11 alloy comprises lamellar-like eutectic Ni3Si and Ni solid solution phases. After alloying with C, the microstructure of the Ni-rich solid solution and Ni3Si phase is changed to a relatively fine-scale morphology, and C is mainly dissolved in the Ni-rich solid solution phase. The microhardness of the alloys is increased with the addition of C, which is mainly attributed to the microstructure refinement and solid solution strengthening obtained through C addition.

• Ibrahim, Mohammad; Du, Qiang; Hovig, Even Wilberg; Grasmo, Geir; Hulme, Christopher & Aune, Ragnhild Elizabeth (2023). Gas-Atomized Nickel Silicide Powders Alloyed with Molybdenum, Cobalt, Titanium, Boron, and Vanadium for Additive Manufacturing. Metals. 13(9). doi: 10.3390/met13091591. Full text in Research Archive Show summary

  Nickel silicides (NiSi) are renowned for their ability to withstand high temperatures and resist oxidation and corrosion in challenging environments. As a result, these alloys have garnered interest for potential applications in turbine blades and underwater settings. However, their high brittleness is a constant obstacle that hinders their use in producing larger parts. A literature review has revealed that incorporating trace amounts of transition metals can enhance the ductility of silicides. Consequently, the present study aims to create NiSi-based powders with the addition of titanium (Ti), boron (B), cobalt (Co), molybdenum (Mo), and vanadium (V) for Additive Manufacturing (AM) through the process of gas atomization. The study comprehensively assesses the microstructure, phase composition, thermal properties, and surface morphology of the produced powder particles, specifically NiSi11.9Co3.4, NiSi10.15V4.85, NiSi11.2Mo1.8, and Ni-Si10.78Ti1.84B0.1. Commonly used analytical techniques (SEM, EDS, XRD, DSC, and laser diffraction) are used to identify the alloy configuration that offers optimal characteristics for AM applications. The results show spherical particles within the size range of 20–63 μm, and only isolated satellites were observed to exist in the produced powders, securing their smooth flow during AM processing.

• Ibrahim, Mohammad; Sætre, Tor Oskar; Grasmo, Geir & Aune, Ragnhild (2022). Characterisation of Nickel Silicide Deposited on Steel and Nickel Substrates, World PM2022 Proceedings. European Powder Metallurgy Association. ISSN 9781899072552. Full text in Research Archive
• Falconer, Shaun; Krause, Peter; Bäck, Thomas; Nordgård-Hansen, Ellen Marie & Grasmo, Geir (2022). Condition Classification of Fibre Ropes during Cyclic Bend over Sheave testing Using Machine Learning. International Journal of Prognostics and Health Management. 13(1). doi: 10.36001/IJPHM.2022.v13i1.3105. Full text in Research Archive Show summary

  Fibre ropes have been shown to be a viable alternative to steel wire rope for offshore lifting operations. Visual inspection remains a common method of fibre rope condition monitoring and has the potential to be further automated by machine learning. This would provide a valuable aid to current inspection frameworks to make more accurate decisions on recertification or retirement of fibre ropes in operational use. Three different machine learning algorithms: decision tree, random forest and support vector machine are compared to classical statistical approaches such as logistic regression, k-nearest neighbours and Naïve-Bayes for condition classification for fibre ropes under cyclic-bend-over-sheave (CBOS) testing. By measuring the rope global elongation throughout the CBOS tests, a binary classification system has been used to label recorded samples as healthy or close to rupture. Predictions are made on one rope through leave-one-out cross validation. The models are then assessed through calculating the accuracy, probability of detection, probability of false alarm and Matthew’s Correlation Coefficient, and ranked based on the results. The results show that both machine learning and classical statistical methods are effective options for condition classification of fibre ropes under CBOS regimes. Typical values for Matthews Correlation Coefficient (MCC) were shown to exceed 0.8 for the best performing methods.

• Tareq, Foysal Kabir; Aune, Ragnhild Elizabeth; Grasmo, Geir; Akhtar, Naureen & Sætre, Tor Oskar (2022). Preparation and Characterization of Spherical Nickel Silicide Powder by Inductively Coupled Plasma Spheroidization for Additive Manufacturing, TMS 2022 151st Annual Meeting & Exhibition Supplemental Proceedings. Springer. ISSN 9783030923815. p. 1488–1496. doi: 10.1007/978-3-030-92381-5_141. Full text in Research Archive Show summary

  Metal alloy powder with spherical-shaped morphology, high flowability, and packing density is the main requirements for metal-based additive manufacturing (AM). Among metal alloys, nickel silicide is considered as a potential candidate due to its unique properties such as high melting point, good electrical conductivity, as well as high corrosion and wear resistance. However, the fabrication of spherical nickel silicide powder has proven to be a challenging task. In the present work, spherical NiSi16 alloy powders were synthesized by inductively coupled plasma spheroidization (ICPS). The influence of the feed rate on the properties of the as-prepared powder was investigated using different analytical techniques to evaluate the particle morphology, particle size distribution, oxygen content, bulk density, fluidity, and spheroidization rate. The results showed some unique advantages of the ICPS technology in the preparation of spherical nickel silicide powder that is believed to be well suited for AM.

• Falconer, Shaun; Nordgård-Hansen, Ellen Marie & Grasmo, Geir (2021). Remaining useful life estimation of HMPE rope during CBOS testing through machine learning. Ocean Engineering. ISSN 0029-8018. 238. doi: 10.1016/j.oceaneng.2021.109617. Full text in Research Archive Show summary

  Fibre rope used in cranes for offshore deployment and recovery has significant potential to perform lifts with smaller cranes and vessels to reach depths limited by weight of steel wire rope. Current condition monitoring methods based on manual inspection and time-based and reactive maintenance have significant potential for improvement coupled with more accurate remaining useful life (RUL) prediction. Machine learning has found use as a condition monitoring approach, coupled with vast improvements in data acquisition methods. This paper details data-driven RUL prediction methods based on machine learning algorithms applied on cyclic-bend-over-sheave (CBOS) tests performed on two fibre rope types until failure. Data extracted through computer vision and thermal monitoring is used to predict RUL through neural networks, support vector machines and random forest. Random forest and neural networks methods are shown to be particularly adept at predicting RUL compared to support vector machines . Additionally, improved RUL predictions can be achieved by combining data from distinct rope types subject to different test conditions.

• Falconer, Shaun; Nordgård-Hansen, Ellen Marie & Grasmo, Geir (2020). Computer vision and thermal monitoring of HMPE fibre rope condition during CBOS testing. Applied Ocean Research. ISSN 0141-1187. 102. doi: 10.1016/j.apor.2020.102248. Full text in Research Archive Show summary

  Fibre rope usage in deep sea lifting operations is gaining more prominence in recent times. With rope minimum break loads (MBL) comparable to that of their steel wire counterparts, the use of high modulus polyethylene (HMPE) ropes is seen as a viable option for use in subsea construction cranes. The ropes are worn out during use and visual inspection remains one of the main methods of determining whether a fibre rope is to be retired from use, therefore a natural extension is condition monitoring through computer vision. Creep and temperature are constraining with HMPE ropes and should be monitored continuously, particularly when the rope is cyclically bent over sheaves. Additionally, interpreting the thermal history of the rope during use could give insight into deterioration. In this paper, a condition monitoring system based on combined computer vision and thermal monitoring is used during cyclic bend over sheave tests performed on 560 kN break load of 12 strand braided HMPE ropes. New monitoring features such as local length and width through computer vision algorithms combined with surface thermal monitoring and global elongation are presented and their effectiveness as condition monitoring features is assessed.

• Falconer, Shaun; Nordgård-Hansen, Ellen Marie & Grasmo, Geir (2020). Temperature Measurements as a Method for Monitoring Ropes. In Liyanage, Jayantha Prasanna; Amadi-Echendu, Joe E. & Mathew, Joseph (Ed.), Engineering assets and public infrastructures in the age of digitalization : Proceedings of the 13th world congress on engineering asset management. Springer. ISSN 9783030480202. p. 772–779. doi: 10.1007/978-3-030-48021-9_85. Full text in Research Archive
• Stave, Daniel Årrestad; Schlanbusch, Rune; Vysochinskiy, Dmitry & Grasmo, Geir (2019). Condition Monitoring of Steel Wire Ropes. In Dohm, M. A. R. (Eds.), Exploring Opportunities - Synthetic/Steel - Proceedings of the OIPEEC Conference 2019. OIPEEC. ISSN 9781733600408. Full text in Research Archive
• Falconer, Shaun; Grasmo, Geir & Nordgård-Hansen, Ellen Marie (2019). Condition monitoring of HMPE fibre rope using computer vision during CBOS testing. In Dohm, M. A. R. (Eds.), Exploring Opportunities - Synthetic/Steel - Proceedings of the OIPEEC Conference 2019. OIPEEC. ISSN 9781733600408. p. 129–147. Full text in Research Archive Show summary

  The paper details the results of recent cyclic-bend-over-sheave (CBOS) experiments performed at the Mechatronics Innovation Lab (MIL) located at the University of Agder, Norway. A method for measuring diameter and elongation of discrete sections of fibre rope using computer vision is detailed. Estimations of the change in roundness of the rope are also explored based on the diameter measurements. These measurements are then assessed for their suitability as condition indicators.

• Falconer, Shaun; Gromsrud, Andreas; Oland, Espen & Grasmo, Geir (2017). Preliminary Results on Condition Monitoring of Fiber Ropes using Automatic Width and Discrete Length Measurements, PHM 2017 Proceedings of the Annual Conference of the Prognostics and Health Management Society 2017. PHM Society. ISSN 9781936263264. doi: 10.36001/phmconf.2017.v9i1.2478. Full text in Research Archive Show summary

  As the offshore sector moves to deeper waters, fiber ropes have the potential to replace more traditional solutions such as steel wire ropes for deep sea lifting and heave-compensated operations. While steel wire ropes must account for their own weight when determining the maximum depth that a payload can be deployed, fiber ropes such as high modulus polyethylene (HMPE), are more buoyant than their steel counterparts, enabling payloads to be deployed at deeper depths using smaller cranes. For this reason, companies are actively developing fiber rope cranes to be used in industry. The inherent issue with these designs is monitoring the condition of the fiber rope due the multitude of damage mechanisms and condition indicators that exist, therefore determining the time to rupture remains an unsolved problem. To this end, this paper considers the use of computer vision to monitor the width at discrete length sections and use that as a potential condition indicator. Furthermore, the paper describes in detail how OpenCV is applied to detect the contour of the rope to find the width, how the experiment has been performed, as well as other practical experiences from testing a 28mm Dyneema R fiber rope. The experimental results show an exponential relationship between the applied tension and the reduction in width (which was reduced by more than 10% before rupture), and it is believed that if the width can be monitored at discrete sections along the rope over time, the width itself will prove to be a good condition indicator.

View all works in NVA

• Knudsen, Atle; Giulianotti, Mark; Håverstad, Thor Arne; Tande, John Olav Giæver; Klausen, Rune & Nesse, Arvid [Show all 7 contributors for this article] (2024). Vi trenger en sektorplan for havvind. Full text in Research Archive
• Falconer, Shaun; Grasmo, Geir & Nordgård-Hansen, Ellen Marie (2019). Condition monitoring of HMPE fibre rope using computer vision during CBOS testing. Full text in Research Archive
• Falconer, Shaun; Nordgård-Hansen, Ellen Marie & Grasmo, Geir (2018). Temperature measurements as a method for monitoring ropes. Full text in Research Archive
• Falconer, Shaun; Gromsrud, Andreas; Oland, Espen & Grasmo, Geir (2017). Preliminary Results on Condition Monitoring of Fiber Ropes using Automatic Width and Discrete Length Measurements. Full text in Research Archive

View all works in NVA