Materials

Research

12 pages, 2311 KiB

Open AccessFeature PaperArticle

Functionalization of Gold Nanoparticles with Ru-Porphyrin and Their Selectivity in the Oligomerization of Alkynes

by Francesca Limosani, Hynd Remita, Pietro Tagliatesta, Elvira Maria Bauer, Alessandro Leoni and Marilena Carbone

Materials 2022, 15(3), 1207; https://doi.org/10.3390/ma15031207 - 5 Feb 2022

Cited by 7 | Viewed by 1821

Abstract

Gold nanoparticles (AuNPs) were functionalized by ruthenium porphyrins through a sulfur/gold covalent bond using a three-steps reaction. The catalyst was characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) in order to control the binding of ruthenium porphyrin on AuNPs’ surface. The [...] Read more.

Gold nanoparticles (AuNPs) were functionalized by ruthenium porphyrins through a sulfur/gold covalent bond using a three-steps reaction. The catalyst was characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) in order to control the binding of ruthenium porphyrin on AuNPs’ surface. The catalyst was tested and compared with an analog system not bound to AuNPs in the oligomerization reaction using 1-phenylacetylene as the substrate. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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16 pages, 3897 KiB

Open AccessArticle

Effect of Sago Starch Modifications on Polystyrene/Thermoplastic Starch Blends

by Mohamad Kahar Ab Wahab, Halimatul Syahirah Mohamad, Elammaran Jayamani, Hanafi Ismail, Izabela Wnuk, Anna Przybył, Tomasz Stachowiak and Przemysław Postawa

Materials 2021, 14(11), 2867; https://doi.org/10.3390/ma14112867 - 27 May 2021

Cited by 8 | Viewed by 2412

Abstract

The preparation of polystyrene/thermoplastic starch (PS/TPS) blends was divided into three stages. The first stage involved the preparation of TPS from sago starch. Then, for the second stage, PS was blended with TPS to produce a TPS/PS blend. The ratios of the TPS/PS [...] Read more.

The preparation of polystyrene/thermoplastic starch (PS/TPS) blends was divided into three stages. The first stage involved the preparation of TPS from sago starch. Then, for the second stage, PS was blended with TPS to produce a TPS/PS blend. The ratios of the TPS/PS blend were 20:80, 40:60, 60:40, and 80:20. The final stage was a modification of the composition of TPS/PS blends with succinic anhydride and ascorbic acid treatment. Both untreated and treated blends were characterized by their physical, thermal, and surface morphology properties. The obtained results indicate that modified blends have better tensile strength as the adhesion between TPS and PS was improved. This can be observed from SEM micrographs, as modified blends with succinic anhydride and ascorbic acid had smaller TPS dispersion in PS/TPS blends. The micrograph showed that there was no agglomeration and void formation in the TPS/PS blending process. Furthermore, modified blends show better thermal stability, as proved by thermogravimetric analysis. Water uptake into the TPS/PS blends also decreased after the modifications, and the structural analysis showed the formation of a new peak after the modification process. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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20 pages, 6082 KiB

Open AccessArticle

Elevated-Temperature Performance, Combustibility and Fire Propagation Index of Fly Ash-Metakaolin Blend Geopolymers with Addition of Monoaluminium Phosphate (MAP) and Aluminum Dihydrogen Triphosphate (ATP)

by Khairunnisa Zulkifly, Heah Cheng-Yong, Liew Yun-Ming, Ridho Bayuaji, Mohd Mustafa Al Bakri Abdullah, Shamsul Bin Ahmad, Tomasz Stachowiak, Janusz Szmidla, Joanna Gondro, Bartłomiej Jeż, Mohd Suhaimi Bin Khalid, Sebastian Garus, Ong Shee-Ween, Ooi Wan-En and Ng Hui-Teng

Materials 2021, 14(8), 1973; https://doi.org/10.3390/ma14081973 - 15 Apr 2021

Cited by 10 | Viewed by 2759

Abstract

Thermal performance, combustibility, and fire propagation of fly ash-metakaolin (FA-MK) blended geopolymer with the addition of aluminum triphosphate, ATP (Al(H₂PO₄)₃), and monoaluminium phosphate, MAP (AlPO₄) were evaluated in this paper. To prepare the geopolymer mix, [...] Read more.

Thermal performance, combustibility, and fire propagation of fly ash-metakaolin (FA-MK) blended geopolymer with the addition of aluminum triphosphate, ATP (Al(H₂PO₄)₃), and monoaluminium phosphate, MAP (AlPO₄) were evaluated in this paper. To prepare the geopolymer mix, fly ash and metakaolin with a ratio of 1:1 were added with ATP and MAP in a range of 0–3% by weight. The fire/heat resistance was evaluated by comparing the residual compressive strengths after the elevated temperature exposure. Besides, combustibility and fire propagation tests were conducted to examine the thermal performance and the applicability of the geopolymers as passive fire protection. Experimental results revealed that the blended geopolymers with 1 wt.% of ATP and MAP exhibited higher compressive strength and denser geopolymer matrix than control geopolymers. The effect of ATP and MAP addition was more obvious in unheated geopolymer and little improvement was observed for geopolymer subjected to elevated temperature. ATP and MAP at 3 wt.% did not help in enhancing the elevated-temperature performance of blended geopolymers. Even so, all blended geopolymers, regardless of the addition of ATP and MAP, were regarded as the noncombustible materials with negligible (0–0.1) fire propagation index. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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17 pages, 1562 KiB

Open AccessArticle

Design of Experiment on Concrete Mechanical Properties Prediction: A Critical Review

by Beng Wei Chong, Rokiah Othman, Ramadhansyah Putra Jaya, Mohd Rosli Mohd Hasan, Andrei Victor Sandu, Marcin Nabiałek, Bartłomiej Jeż, Paweł Pietrusiewicz, Dariusz Kwiatkowski, Przemysław Postawa and Mohd Mustafa Al Bakri Abdullah

Materials 2021, 14(8), 1866; https://doi.org/10.3390/ma14081866 - 9 Apr 2021

Cited by 44 | Viewed by 4938

Abstract

Concrete mix design and the determination of concrete performance are not merely engineering studies, but also mathematical and statistical endeavors. The study of concrete mechanical properties involves a myriad of factors, including, but not limited to, the amount of each constituent material and [...] Read more.

Concrete mix design and the determination of concrete performance are not merely engineering studies, but also mathematical and statistical endeavors. The study of concrete mechanical properties involves a myriad of factors, including, but not limited to, the amount of each constituent material and its proportion, the type and dosage of chemical additives, and the inclusion of different waste materials. The number of factors and combinations make it difficult, or outright impossible, to formulate an expression of concrete performance through sheer experimentation. Hence, design of experiment has become a part of studies, involving concrete with material addition or replacement. This paper reviewed common design of experimental methods, implemented by past studies, which looked into the analysis of concrete performance. Several analysis methods were employed to optimize data collection and data analysis, such as analysis of variance (ANOVA), regression, Taguchi method, Response Surface Methodology, and Artificial Neural Network. It can be concluded that the use of statistical analysis is helpful for concrete material research, and all the reviewed designs of experimental methods are helpful in simplifying the work and saving time, while providing accurate prediction of concrete mechanical performance. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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16 pages, 1677 KiB

Open AccessArticle

Optimisation of Shrinkage and Strength on Thick Plate Part Using Recycled LDPE Materials

by Norshahira Roslan, Shayfull Zamree Abd Rahim, Abdellah El-hadj Abdellah, Mohd Mustafa Al Bakri Abdullah, Katarzyna Błoch, Paweł Pietrusiewicz, Marcin Nabiałek, Janusz Szmidla, Dariusz Kwiatkowski, Joel Oliveira Correia Vasco, Mohd Nasir Mat Saad and Mohd Fathullah Ghazali

Materials 2021, 14(7), 1795; https://doi.org/10.3390/ma14071795 - 5 Apr 2021

Cited by 9 | Viewed by 3080

Abstract

Achieving good quality of products from plastic injection moulding processes is very challenging, since the process comprises many affecting parameters. Common defects such as warpage are hard to avoid, and the defective parts will eventually go to waste, leading to unnecessary costs to [...] Read more.

Achieving good quality of products from plastic injection moulding processes is very challenging, since the process comprises many affecting parameters. Common defects such as warpage are hard to avoid, and the defective parts will eventually go to waste, leading to unnecessary costs to the manufacturer. The use of recycled material from postindustrial waste has been studied by a few researchers. However, the application of an optimisation method by which to optimise processing parameters to mould parts using recycled materials remains lacking. In this study, Response Surface Methodology (RSM) and Particle Swarm Optimisation (PSO) methods were conducted on thick plate parts moulded using virgin and recycled low-density polyethylene (LDPE) materials (100:0, 70:30, 60:40 and 50:50; virgin to recycle material ratios) to find the optimal input parameters for each of the material ratios. Shrinkage in the x and y directions increased in correlation with the recycled ratio, compared to virgin material. Meanwhile, the tensile strength of the thick plate part continued to decrease when the recycled ratio increased. R30 (70:30) had the optimum shrinkage in the x direction with respect to R0 (100:0) material where the shrinkage increased by 24.49% (RSM) and 33.20% (PSO). On the other hand, the shrinkage in the y direction for R30 material increased by 4.48% (RSM) and decreased by 2.67% (PSO), while the tensile strength of R30 (70:30) material decreased by 0.51% (RSM) and 2.68% (PSO) as compared to R0 (100:0) material. Validation tests indicated that the optimal setting of processing parameter suggested by PSO and RSM for R0 (100:0), R30 (70:30), R40 (60:40) and R50 (50:50) was less than 10%. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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16 pages, 4788 KiB

Open AccessArticle

Image Analysis of Surface Porosity Mortar Containing Processed Spent Bleaching Earth

by Beng Wei Chong, Rokiah Othman, Ramadhansyah Putra Jaya, Doh Shu Ing, Xiaofeng Li, Mohd Haziman Wan Ibrahim, Mohd Mustafa Al Bakri Abdullah, Andrei Victor Sandu, Bartosz Płoszaj, Janusz Szmidla and Tomasz Stachowiak

Materials 2021, 14(7), 1658; https://doi.org/10.3390/ma14071658 - 28 Mar 2021

Cited by 12 | Viewed by 2869

Abstract

Image analysis techniques are gaining popularity in the studies of civil engineering materials. However, the current established image analysis methods often require advanced machinery and strict image acquisition procedures which may be challenging in actual construction practices. In this study, we develop a [...] Read more.

Image analysis techniques are gaining popularity in the studies of civil engineering materials. However, the current established image analysis methods often require advanced machinery and strict image acquisition procedures which may be challenging in actual construction practices. In this study, we develop a simplified image analysis technique that uses images with only a digital camera and does not have a strict image acquisition regime. Mortar with 10%, 20%, 30%, and 40% pozzolanic material as cement replacement are prepared for the study. The properties of mortar are evaluated with flow table test, compressive strength test, water absorption test, and surface porosity based on the proposed image analysis technique. The experimental results show that mortar specimens with 20% processed spent bleaching earth (PSBE) achieve the highest 28-day compressive strength and lowest water absorption. The quantified image analysis results show accurate representation of mortar quality with 20% PSBE mortar having the lowest porosity. The regression analysis found strong correlations between all experimental data and the compressive strength. Hence, the developed technique is verified to be feasible as supplementary mortar properties for the study of mortar with pozzolanic material. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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14 pages, 14146 KiB

Open AccessFeature PaperArticle

Tool Wear and Surface Evaluation in Drilling Fly Ash Geopolymer Using HSS, HSS-Co, and HSS-TiN Cutting Tools

by Mohd Fathullah Ghazali, Mohd Mustafa Al Bakri Abdullah, Shayfull Zamree Abd Rahim, Joanna Gondro, Paweł Pietrusiewicz, Sebastian Garus, Tomasz Stachowiak, Andrei Victor Sandu, Muhammad Faheem Mohd Tahir, Mehmet Erdi Korkmaz and Mohamed Syazwan Osman

Materials 2021, 14(7), 1628; https://doi.org/10.3390/ma14071628 - 26 Mar 2021

Cited by 17 | Viewed by 2713

Abstract

This paper reports on the potential use of geopolymer in the drilling process, with respect to tool wear and surface roughness. The objectives of this research are to analyze the tool life of three different economy-grade drill bit uncoated; high-speed steel (HSS), HSS [...] Read more.

This paper reports on the potential use of geopolymer in the drilling process, with respect to tool wear and surface roughness. The objectives of this research are to analyze the tool life of three different economy-grade drill bit uncoated; high-speed steel (HSS), HSS coated with TiN (HSS-TiN), and HSS-cobalt (HSS-Co) in the drilling of geopolymer and to investigate the effect of spindle speed towards the tool life and surface roughness. It was found that, based on the range of parameters set in this experiment, the spindle speed is directly proportional to the tool wear and inversely proportional to surface roughness. It was also observed that HSS-Co produced the lowest value of surface roughness compared to HSS-TiN and uncoated HSS and therefore is the most favorable tool to be used for drilling the material. For HSS, HSS coated with TiN, and HSS-Co, only the drilling with the spindle speed of 100 rpm was able to drill 15 holes without surpassing the maximum tool wear of 0.10 mm. HSS-Co exhibits the greatest tool life by showing the lowest value of flank wear and produce a better surface finish to the sample by a low value of surface roughness value (Ra). This finding explains that geopolymer is possible to be drilled, and therefore, ranges of cutting tools and parameters suggested can be a guideline for researchers and manufacturers to drill geopolymer for further applications. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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18 pages, 2456 KiB

Open AccessArticle

Warpage Optimisation Using Recycled Polycar-bonates (PC) on Front Panel Housing

by Nur Aisyah Miza Ahmad Tamizi, Shayfull Zamree Abd Rahim, Abdellah El-hadj Abdellah, Mohd Mustafa Al Bakri Abdullah, Marcin Nabiałek, Jerzy J. Wysłocki, Bartłomiej Jeż, Paweł Palutkiewicz, Rozyanty Abdul Rahman, Mohd Nasir Mat Saad and Mohd Fathullah Ghazli

Materials 2021, 14(6), 1416; https://doi.org/10.3390/ma14061416 - 15 Mar 2021

Cited by 4 | Viewed by 1976

Abstract

Many studies have been done using recycled waste materials to minimise environmental problems. It is a great opportunity to explore mechanical recycling and the use of recycled and virgin blend as a material to produce new products with minimum defects. In this study, [...] Read more.

Many studies have been done using recycled waste materials to minimise environmental problems. It is a great opportunity to explore mechanical recycling and the use of recycled and virgin blend as a material to produce new products with minimum defects. In this study, appropriate processing parameters were considered to mould the front panel housing part using R0% (virgin), R30% (30% virgin: 70% recycled), R40% (40% virgin: 60% recycled) and R50% (50% virgin: 50% recycled) of Polycarbonate (PC). The manufacturing ability and quality during preliminary stage can be predicted through simulation analysis using Autodesk Moldflow Insight 2012 software. The recommended processing parameters and values of warpage in x and y directions can also be obtained using this software. No value of warpage was obtained from simulation studies for x direction on the front panel housing. Therefore, this study only focused on reducing the warpage in the y direction. Response Surface Methodology (RSM) and Genetic Algorithm (GA) optimisation methods were used to find the optimal processing parameters. As the results, the optimal ratio of recycled PC material was found to be R30%, followed by R40% and R50% materials using RSM and GA methods as compared to the average value of warpage on the moulded part using R0%. The most influential processing parameter that contributed to warpage defect was packing pressure for all materials used in this study. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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19 pages, 4167 KiB

Open AccessArticle

Warpage Optimisation on the Moulded Part with Straight Drilled and Conformal Cooling Channels Using Response Surface Methodology (RSM), Glowworm Swarm Optimisation (GSO) and Genetic Algorithm (GA) Optimisation Approaches

by Mohd Hazwan Mohd Hanid, Shayfull Zamree Abd Rahim, Joanna Gondro, Safian Sharif, Mohd Mustafa Al Bakri Abdullah, Azlan Mohd Zain, Abdellah El-hadj Abdellah, Mohd Nasir Mat Saad, Jerzy J. Wysłocki and Marcin Nabiałek

Materials 2021, 14(6), 1326; https://doi.org/10.3390/ma14061326 - 10 Mar 2021

Cited by 18 | Viewed by 2512

Abstract

It is quite challenging to control both quality and productivity of products produced using injection molding process. Although many previous researchers have used different types of optimisation approaches to obtain the best configuration of parameters setting to control the quality of the molded [...] Read more.

It is quite challenging to control both quality and productivity of products produced using injection molding process. Although many previous researchers have used different types of optimisation approaches to obtain the best configuration of parameters setting to control the quality of the molded part, optimisation approaches in maximising the performance of cooling channels to enhance the process productivity by decreasing the mould cycle time remain lacking. In this study, optimisation approaches namely Response Surface Methodology (RSM), Genetic Algorithm (GA) and Glowworm Swarm Optimisation (GSO) were employed on front panel housing moulded using Acrylonitrile Butadiene Styrene (ABS). Each optimisation method was analysed for both straight drilled and Milled Groove Square Shape (MGSS) conformal cooling channel moulds. Results from experimental works showed that, the performance of MGSS conformal cooling channels could be enhanced by employing the optimisation approach. Therefore, this research provides useful scientific knowledge and an alternative solution for the plastic injection moulding industry to improve the quality of moulded parts in terms of deformation using the proposed optimisation approaches in the used of conformal cooling channels mould. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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12 pages, 2319 KiB

Open AccessArticle

Self-Fluxing Mechanism in Geopolymerization for Low-Sintering Temperature of Ceramic

by Noorina Hidayu Jamil, Mohd. Mustafa Al Bakri Abdullah, Faizul Che Pa, Hasmaliza Mohamad, Wan Mohd Arif W. Ibrahim, Penphitcha Amonpattaratkit, Joanna Gondro, Wojciech Sochacki and Norfadhilah Ibrahim

Materials 2021, 14(6), 1325; https://doi.org/10.3390/ma14061325 - 10 Mar 2021

Cited by 10 | Viewed by 2479

Abstract

Kaolin, theoretically known as having low reactivity during geopolymerization, was used as a source of aluminosilicate materials in this study. Due to this concern, it is challenging to directly produce kaolin geopolymers without pre-treatment. The addition of ground granulated blast furnace slag (GGBS) [...] Read more.

Kaolin, theoretically known as having low reactivity during geopolymerization, was used as a source of aluminosilicate materials in this study. Due to this concern, it is challenging to directly produce kaolin geopolymers without pre-treatment. The addition of ground granulated blast furnace slag (GGBS) accelerated the geopolymerization process. Kaolin–GGBS geopolymer ceramic was prepared at a low sintering temperature due to the reaction of the chemical composition during the initial stage of geopolymerization. The objective of this work was to study the influence of the chemical composition towards sintering temperature of sintered kaolin–GGBS geopolymer. Kaolin–GGBS geopolymer was prepared with a ratio of solid to liquid 2:1 and cured at 60 °C for 14 days. The cured geopolymer was sintered at different temperatures: 800, 900, 1000, and 1100 °C. Sintering at 900 °C resulted in the highest compressive strength due to the formation of densified microstructure, while higher sintering temperature led to the formation of interconnected pores. The difference in the X-ray absorption near edge structure (XANES) spectra was related to the phases obtained from the X-ray diffraction analysis, such as akermanite and anothite. Thermal analysis indicated the stability of sintered kaolin–GGBS geopolymer when exposed to 1100 °C, proving that kaolin can be directly used without heat treatment in geopolymers. The geopolymerization process facilitates the stability of cured samples when directly sintered, as well as plays a significant role as a self-fluxing agent to reduce the sintering temperature when producing sintered kaolin–GGBS geopolymers. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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11 pages, 19943 KiB

Open AccessArticle

Comparison of Hook and Straight Steel Fibers Addition on Malaysian Fly Ash-Based Geopolymer Concrete on the Slump, Density, Water Absorption and Mechanical Properties

by Meor Ahmad Faris, Mohd Mustafa Al Bakri Abdullah, Ratnasamy Muniandy, Mohammad Firdaus Abu Hashim, Katarzyna Błoch, Bartłomiej Jeż, Sebastian Garus, Paweł Palutkiewicz, Nurul Aida Mohd Mortar and Mohd Fathullah Ghazali

Materials 2021, 14(5), 1310; https://doi.org/10.3390/ma14051310 - 9 Mar 2021

Cited by 41 | Viewed by 3826

Abstract

Geopolymer concrete has the potential to replace ordinary Portland cement which can reduce carbon dioxide emission to the environment. The addition of different amounts of steel fibers, as well as different types of end-shape fibers, could alter the performance of geopolymer concrete. The [...] Read more.

Geopolymer concrete has the potential to replace ordinary Portland cement which can reduce carbon dioxide emission to the environment. The addition of different amounts of steel fibers, as well as different types of end-shape fibers, could alter the performance of geopolymer concrete. The source of aluminosilicate (fly ash) used in the production of geopolymer concrete may lead to a different result. This study focuses on the comparison between Malaysian fly ash geopolymer concrete with the addition of hooked steel fibers and geopolymer concrete with the addition of straight-end steel fibers to the physical and mechanical properties. Malaysian fly ash was first characterized by X-ray fluorescence (XRF) to identify the chemical composition. The sample of steel fiber reinforced geopolymer concrete was produced by mixing fly ash, alkali activators, aggregates, and specific amounts of hook or straight steel fibers. The steel fibers addition for both types of fibers are 0%, 0.5%, 1.0%, 1.5%, and 2.0% by volume percentage. The samples were cured at room temperature. The physical properties (slump, density, and water absorption) of reinforced geopolymer concrete were studied. Meanwhile, a mechanical performance which is compressive, as well as the flexural strength was studied. The results show that the pattern in physical properties of geopolymer concrete for both types of fibers addition is almost similar where the slump is decreased with density and water absorption is increased with the increasing amount of fibers addition. However, the addition of hook steel fiber to the geopolymer concrete produced a lower slump than the addition of straight steel fibers. Meanwhile, the addition of hook steel fiber to the geopolymer concrete shows a higher density and water absorption compared to the sample with the addition of straight steel fibers. However, the difference is not significant. Besides, samples with the addition of hook steel fibers give better performance for compressive and flexural strength compared to the samples with the addition of straight steel fibers where the highest is at 1.0% of fibers addition. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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11 pages, 2625 KiB

Open AccessArticle

The Effects of Various Concentrations of NaOH on the Inter-Particle Gelation of a Fly Ash Geopolymer Aggregate

by Alida Abdullah, Kamarudin Hussin, Mohd Mustafa Al Bakri Abdullah, Zarina Yahya, Wojciech Sochacki, Rafiza Abdul Razak, Katarzyna Błoch and Hamzah Fansuri

Materials 2021, 14(5), 1111; https://doi.org/10.3390/ma14051111 - 27 Feb 2021

Cited by 38 | Viewed by 4306

Abstract

Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. [...] Read more.

Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na₂SiO₃ used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m³. The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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14 pages, 6545 KiB

Open AccessArticle

Optimizing of the Cementitious Composite Matrix by Addition of Steel Wool Fibers (Chopped) Based on Physical and Mechanical Analysis

by Akrm A Rmdan Amer, Mohd Mustafa Al Bakri Abdullah, Yun Ming Liew, Ikmal Hakem A Aziz, Jerzy J. Wysłocki, Muhammad Faheem Mohd Tahir, Wojciech Sochacki, Sebastian Garus, Joanna Gondro and Hetham A. R. Amer

Materials 2021, 14(5), 1094; https://doi.org/10.3390/ma14051094 - 26 Feb 2021

Cited by 8 | Viewed by 2574

Abstract

The demand for durable, resistant, and high-strength structural material has led to the use of fibers as reinforcing elements. This paper presents an investigation into the inclusion of chopped steel wool fibers (CSWFs) in cement to form a high-flexural strength cementitious composite matrix [...] Read more.

The demand for durable, resistant, and high-strength structural material has led to the use of fibers as reinforcing elements. This paper presents an investigation into the inclusion of chopped steel wool fibers (CSWFs) in cement to form a high-flexural strength cementitious composite matrix (CCM). CSWFs were used as the primary reinforcement in CCM at increments of 0.5 wt%, from 0.5–6 wt%, with ratios of cement to sand of 1:1.5 and water to cement of 0.45. The inclusion of CSWFs resulted in an excellent optimization of the physicomechanical properties of the CCM, such as its density (2.302 g/cm³), compressive strength (61.452 MPa), and maximum flexural strength (10.64 MPa), all of which exceeded the performances of other reinforcement elements reported in the literature. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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17 pages, 4046 KiB

Open AccessArticle

Properties of a New Insulation Material Glass Bubble in Geopolymer Concrete

by Noor Fifinatasha Shahedan, Mohd Mustafa Al Bakri Abdullah, Norsuria Mahmed, Andri Kusbiantoro, Sam Tammas-Williams, Long-Yuan Li, Ikmal Hakem Aziz, Petrică Vizureanu, Jerzy J. Wysłocki, Katarzyna Błoch and Marcin Nabiałek

Materials 2021, 14(4), 809; https://doi.org/10.3390/ma14040809 - 8 Feb 2021

Cited by 36 | Viewed by 4482

Abstract

This paper details analytical research results into a novel geopolymer concrete embedded with glass bubble as its thermal insulating material, fly ash as its precursor material, and a combination of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) as its [...] Read more.

This paper details analytical research results into a novel geopolymer concrete embedded with glass bubble as its thermal insulating material, fly ash as its precursor material, and a combination of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) as its alkaline activator to form a geopolymer system. The workability, density, compressive strength (per curing days), and water absorption of the sample loaded at 10% glass bubble (loading level determined to satisfy the minimum strength requirement of a load-bearing structure) were 70 mm, 2165 kg/m³, 52.58 MPa (28 days), 54.92 MPa (60 days), and 65.25 MPa (90 days), and 3.73 %, respectively. The thermal conductivity for geopolymer concrete decreased from 1.47 to 1.19 W/mK, while the thermal diffusivity decreased from 1.88 to 1.02 mm²/s due to increased specific heat from 0.96 to 1.73 MJ/m³K. The improved physicomechanical and thermal (insulating) properties resulting from embedding a glass bubble as an insulating material into geopolymer concrete resulted in a viable composite for use in the construction industry. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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14 pages, 4385 KiB

Open AccessArticle

Characterisation at the Bonding Zone between Fly Ash Based Geopolymer Repair Materials (GRM) and Ordinary Portland Cement Concrete (OPCC)

by Warid Wazien Ahmad Zailani, Mohd Mustafa Al Bakri Abdullah, Mohd Fadzil Arshad, Rafiza Abd Razak, Muhammad Faheem Mohd Tahir, Remy Rozainy Mohd Arif Zainol, Marcin Nabialek, Andrei Victor Sandu, Jerzy J. Wysłocki and Katarzyna Błoch

Materials 2021, 14(1), 56; https://doi.org/10.3390/ma14010056 - 24 Dec 2020

Cited by 39 | Viewed by 3125

Abstract

In recent years, research and development of geopolymers has gained significant interest in the fields of repairs and restoration. This paper investigates the application of a geopolymer as a repair material by implementation of high-calcium fly ash (FA) as a main precursor, activated [...] Read more.

In recent years, research and development of geopolymers has gained significant interest in the fields of repairs and restoration. This paper investigates the application of a geopolymer as a repair material by implementation of high-calcium fly ash (FA) as a main precursor, activated by a sodium hydroxide and sodium silicate solution. Three methods of concrete substrate surface preparation were cast and patched: as-cast against ordinary Portland cement concrete (OPCC), with drilled holes, wire-brushed, and left as-cast against the OPCC grade 30. This study indicated that FA-based geopolymer repair materials (GRMs) possessed very high bonding strength at early stages and that the behavior was not affected significantly by high surface treatment roughness. In addition, the investigations using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy have revealed that the geopolymer repair material became chemically bonded to the OPC concrete substrate, due to the formation of a C–A–S–H gel. Fundamentally, the geopolymer network is composed of tetrahedral anions (SiO₄)⁴⁻ and (AlO₄)⁵⁻ sharing the oxygen, which requires positive ions such as Na⁺, K⁺, Li⁺, Ca²⁺, Na⁺, Ba²⁺, NH⁴⁺, and H₃O⁺. The availability of calcium hydroxide (Ca(OH)₂) at the surface of the OPCC substrate, which was rich in calcium ions (Ca²⁺), reacted with the geopolymer; this compensated the electron vacancies of the framework cavities at the bonding zone between the GRM and the OPCC substrate. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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17 pages, 7976 KiB

Open AccessArticle

Evolution of the Structural and Magnetic Properties of Bulk Fe₆₁Co₁₀B₂₀W₁Y_8−XPt_x Alloys through the Partial Substitution of Pt for Y

by Pawel Pietrusiewicz, Marcin Nabiałek and Bartłomiej Jeż

Materials 2020, 13(21), 4962; https://doi.org/10.3390/ma13214962 - 4 Nov 2020

Cited by 3 | Viewed by 1675

Abstract

This paper presents the results of an investigation into rapidly quenched Fe-based alloys with the chemical formula: Fe₆₁Co₁₀B₂₀W₁Y_8−xPt_x (where x = 3, 4, 5). In these alloys, a small quantity of Pt [...] Read more.

This paper presents the results of an investigation into rapidly quenched Fe-based alloys with the chemical formula: Fe₆₁Co₁₀B₂₀W₁Y_8−xPt_x (where x = 3, 4, 5). In these alloys, a small quantity of Pt was added, and the Y content was reduced concurrently. Samples of the aforementioned alloys were injection-cast in the form of plates with the dimensions: 0.5 mm × 10 mm × 10 mm. The resulting structure was examined using X-ray diffractometry (XRD), Mössbauer spectroscopy and scanning electron microscopy (SEM). The results of the structural research reveal that, with a small addition of Pt, areas rich in Pt and Y are created—in which Fe-Pt and Pt-Y compounds, with different crystallographic systems, are formed. It has also been shown that an increase in Pt content, at the expense of Y, contributed to the formation of fewer crystalline phases, i.e., it allowed a material with a more homogeneous structure to be obtained. Magnetic properties of the Fe₆₁Co₁₀B₂₀W₁Y_8−xPt_x (where x = 3, 4, 5) alloy samples were tested using a vibrating sample magnetometer (VSM). The magnetic properties of the investigated materials revealed that the saturation magnetisation increased with increasing Pt content, at the expense of Y. This effect is due to the occurrence of different proportions of crystalline magnetic phases within the volume of each alloy. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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14 pages, 6354 KiB

Open AccessArticle

Microstructure and Porosity Evolution of the Ti–35Zr Biomedical Alloy Produced by Elemental Powder Metallurgy

by Izabela Matuła, Grzegorz Dercz, Maciej Zubko, Joanna Maszybrocka, Justyna Jurek-Suliga, Sylwia Golba and Izabela Jendrzejewska

Materials 2020, 13(20), 4539; https://doi.org/10.3390/ma13204539 - 13 Oct 2020

Cited by 13 | Viewed by 2116

Abstract

In the present study, the structure and porosity of binary Ti–35Zr (wt.%) alloy were investigated, allowing to consider powder metallurgy as a production method for new metallic materials for potential medical applications. The porous Ti–Zr alloys were obtained by milling, cold isostatic pressing [...] Read more.

In the present study, the structure and porosity of binary Ti–35Zr (wt.%) alloy were investigated, allowing to consider powder metallurgy as a production method for new metallic materials for potential medical applications. The porous Ti–Zr alloys were obtained by milling, cold isostatic pressing and sintering. The pressure during cold isostatic pressing was a changing parameter and was respectively 250, 500, 750 and 1000 MPa. The X-ray diffraction study revealed only the α phase, which corresponds to the Ti–Zr phase diagram. The microstructure of the Ti–35Zr was observed by optical microscopy and scanning electron microscopy. These observations revealed that the volume fraction of the pores decreased from over 20% to about 7% with increasing pressure during the cold isostatic pressing. The microhardness measurements showed changes from 137 HV0.5 to 225 HV0.5. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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18 pages, 3426 KiB

Open AccessArticle

Isokinetic Analysis of Fe₄₁Co₇Cr₁₅Mo₁₄Y₂C₁₅B₆ Bulk Metallic Glass: Effect of Minor Copper Addition

by Parisa Rezaei-Shahreza, Amir Seifoddini, Saeed Hasani, Zahra Jaafari, Agata Śliwa and Marcin Nabiałek

Materials 2020, 13(17), 3704; https://doi.org/10.3390/ma13173704 - 21 Aug 2020

Cited by 11 | Viewed by 2316

Abstract

In the present study, (Fe₄₁Co₇Cr₁₅Mo₁₄Y₂C₁₅B₆)_100−xCu_x (x = 0, 0.25 and 0.5 at.%) amorphous alloys were prepared by copper-mold casting. To clarify the effect of the minor [...] Read more.

In the present study, (Fe₄₁Co₇Cr₁₅Mo₁₄Y₂C₁₅B₆)_100−xCu_x (x = 0, 0.25 and 0.5 at.%) amorphous alloys were prepared by copper-mold casting. To clarify the effect of the minor addition of copper on the mechanism of nucleation and growth during the crystallization process, an isokinetic analysis was performed. The activation energies (E) of the various crystallization stages were calculated by using theoretical models including Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), Augis–Bennett and Gao–Wang methods. In addition, Augis–Bennett, Gao–Wang and Matusita methods were used to investigate the nucleation and growth mechanisms and to determine other kinetic parameters including Avrami exponent (n), the rate constant (K_p) and dimensionality of growth (m). The obtained results revealed that the activation energy—as well as thermal stability—was changed with minor addition of copper. In addition, the obtained Avrami exponent values were confirmed by Johnson–Mehl–Avrami–Kolmogorov (JMAK) method. The research findings demonstrated that the value of Avrami exponent is changed with minor addition of copper, so that the Avrami exponents of all crystallization stages, except the second peak for copper-free amorphous alloy, were equal to integer values ranging from two to four, indicating that the growth mechanisms were controlled by interface. Moreover, the kinetic parameters of n and b for all peaks were increased by an increase in crystallization temperature, which can be attributed to the increase in the nucleation rate. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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15 pages, 5454 KiB

Open AccessArticle

Influence of W Addition on Phase Constitution, Microstructure and Magnetic Properties of the Nanocrystalline Pr₉Fe₆₅W_xB_26-x (Where: x = 2, 4, 6, 8) Alloy Ribbons

by Katarzyna Filipecka, Piotr Pawlik, Andrzej Kozdraś, Waldemar Kaszuwara, Jarosław Ferenc and Jacek Filipecki

Materials 2020, 13(10), 2229; https://doi.org/10.3390/ma13102229 - 13 May 2020

Viewed by 1922

Abstract

The aim of the present work was to investigate an influence of W addition on the phase constitution, microstructure and magnetic properties of the Pr₉Fe₆₅W_xB_26-x (where: x = 2, 4, 6, 8) alloy ribbons. Ribbons were [...] Read more.

The aim of the present work was to investigate an influence of W addition on the phase constitution, microstructure and magnetic properties of the Pr₉Fe₆₅W_xB_26-x (where: x = 2, 4, 6, 8) alloy ribbons. Ribbons were obtained using the melt-spinning technique under low pressure of Ar. The as-cast samples were fully amorphous and revealed soft magnetic properties. These facts were confirmed by X-ray diffractometry, Mössbauer spectroscopy and magnetic measurements. Differential scanning calorimetry and differential thermal analysis allowed us to determine the thermal stability parameters of the amorphous phase. The Kissinger plots were constructed in order to calculate the activation energies for crystallization. Heat treatment carried out at various temperatures caused changes in the phase constitution and magnetic properties of the alloys. The phase analysis has shown the presence of the hard magnetic Pr₂Fe₁₄B and paramagnetic Pr_1+xFe₄B₄ phases. Additionally, for the x = 2 and x = 6 alloys, a crystallization of soft magnetic Fe₂B and α-Fe phases was observed. The Mössbauer spectroscopy allowed us to determine the volume fractions of constituent phases formed during annealing. The microstructure of annealed ribbons was observed using transmission electron microscopy. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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16 pages, 7703 KiB

Open AccessArticle

Structural and Magnetic Studies of Bulk Nanocomposite Magnets Derived from Rapidly Solidified Pr-(Fe,Co)-(Zr,Nb)-B Alloy

by Katarzyna Pawlik, Piotr Pawlik, Jerzy J. Wysłocki and Waldemar Kaszuwara

Materials 2020, 13(7), 1515; https://doi.org/10.3390/ma13071515 - 26 Mar 2020

Cited by 3 | Viewed by 2014

Abstract

In the present study, the phase constitution, microstructure and magnetic properties of the nanocrystalline magnets, derived from fully amorphous or partially crystalline samples by annealing, were analyzed and compared. The melt-spun ribbons (with a thickness of ~30 µm) and suction-cast 0.5 mm and [...] Read more.

In the present study, the phase constitution, microstructure and magnetic properties of the nanocrystalline magnets, derived from fully amorphous or partially crystalline samples by annealing, were analyzed and compared. The melt-spun ribbons (with a thickness of ~30 µm) and suction-cast 0.5 mm and 1 mm thick plates of the Pr₉Fe₅₀Co₁₃Zr₁Nb₄B₂₃ alloy were soft magnetic in the as-cast state. In order to modify their magnetic properties, the annealing process was carried out at various temperatures from 923K to 1033K for 5 min. The Rietveld refinement of X-ray diffraction patterns combined with the partial or no known crystal structures (PONKCS) method allowed one to quantify the component phases and calculate their crystalline grain sizes. It was shown that the volume fraction of constituent phases and their crystallite sizes for the samples annealed at a particular temperature, dependent on the rapid solidification conditions, and thus a presence or absence of the crystallization nuclei in the as-cast state. Additionally, a thermomagnetic analysis was used as a complementary method to confirm the phase constitution. The hysteresis loops have shown that most of the samples exhibit a remanence enhancement typical for the soft/hard magnetic nanocomposite. Moreover, for the plates annealed at the lowest temperatures, the highest coercivities up to ~1150 kA/m were measured. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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14 pages, 3011 KiB

Open AccessArticle

Melting and Recrystallization of Copper Nanoparticles Prepared by Microwave-Assisted Reduction in the Presence of Triethylenetetramine

by Li-Cheng Jheng, Yen-Zen Wang, Wen-Yao Huang, Ko-Shan Ho, Cheng-Hsien Tsai, Ching-Tang Huang and Huang-Shian Tsai

Materials 2020, 13(7), 1507; https://doi.org/10.3390/ma13071507 - 26 Mar 2020

Cited by 6 | Viewed by 2673

Abstract

The small sized copper nanoparticles (Cu-NPs), prepared in the presence of triethylene tetramine (TETA) and assisted with microwave irradiation, have an extremely low melting temperature. Melting of the small sizezd Cu-NPs can be triggered by the heat generated from the e-beam irradiation during [...] Read more.

The small sized copper nanoparticles (Cu-NPs), prepared in the presence of triethylene tetramine (TETA) and assisted with microwave irradiation, have an extremely low melting temperature. Melting of the small sizezd Cu-NPs can be triggered by the heat generated from the e-beam irradiation during SEM and TEM image construction. The dispersed Cu atoms around the agglomerated big Cu particles can undergo recrystallization immediately due to the strong driving force of the huge temperature difference to normal melting temperature (T_m = 1085 °C). Some of the Cu-NPs with bigger sizes also recrystallize and agglomerate into dense, big particles. According to X-ray diffraction patterns, these particles can agglomerate into compact, ordered Cu crystals in less than five minutes at 60 °C. The melting and recrystallization related endothermic and exothermic phase transitions of Cu-NPs can be found from differential scanning calorimeter (DSC) thermograms and optical microscopic pictures. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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14 pages, 5651 KiB

Open AccessArticle

The Process of Magnetizing FeNbYHfB Bulk Amorphous Alloys in Strong Magnetic Fields

by Bartłomiej Jeż, Jerzy Wysłocki, Simon Walters, Przemysław Postawa and Marcin Nabiałek

Materials 2020, 13(6), 1367; https://doi.org/10.3390/ma13061367 - 18 Mar 2020

Cited by 10 | Viewed by 1932

Abstract

The structure of amorphous alloys still has not been described satisfactorily due to the lack of direct methods for observing structural defects. The magnetizing process of amorphous alloys is closely related to its disordered structure. The sensitivity of the magnetization vector to any [...] Read more.

The structure of amorphous alloys still has not been described satisfactorily due to the lack of direct methods for observing structural defects. The magnetizing process of amorphous alloys is closely related to its disordered structure. The sensitivity of the magnetization vector to any heterogeneity allows indirect assessment of the structure of amorphous ferromagnetic alloys. In strong magnetic fields, the magnetization process involves the rotation of a magnetization vector around point and line defects. Based on analysis of primary magnetization curves, it is possible to identify the type of these defects. This paper presents the results of research into the magnetization process of amorphous alloys that are based on iron, in the areas called the approach to ferromagnetic saturation and the Holstein–Primakoff para-process. The structure of a range of specially produced materials was examined using X-ray diffraction. Primary magnetization curves were measured over the range of 0 to 2 T. The process of magnetizing all of the tested alloys was associated with the presence of linear defects, satisfying the relationship D_{di p} < 1_H. It was found that the addition of yttrium, at the expense of hafnium, impedes the magnetization process. The alloy with an atomic content of Y = 10% was characterized by the highest saturation magnetization value and the lowest value of the D_spf parameter, which may indicate the occurrence of antiferromagnetic ordering in certain regions of this alloy sample. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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13 pages, 3258 KiB

Open AccessArticle

Study of Si and Ge Atoms Termination Using H-Dilution in SiGe:H Alloys Deposited by Radio Frequency (13.56 MHz) Plasma Discharge at Low Temperature

by Ismael Cosme, Andrey Kosarev, Saraí Zarate-Galvez, Hiram E. Martinez, Svetlana Mansurova and Yuri Kudriavtsev

Materials 2020, 13(5), 1045; https://doi.org/10.3390/ma13051045 - 26 Feb 2020

Cited by 2 | Viewed by 2579

Abstract

In this work, we present the study of the atomic composition in amorphous Si_XGe_Y:H_Z films deposited by radio frequency (RF—13.56 MHz) plasma discharge at low deposition temperature. A study and control of Si and Ge atoms termination using [...] Read more.

In this work, we present the study of the atomic composition in amorphous Si_XGe_Y:H_Z films deposited by radio frequency (RF—13.56 MHz) plasma discharge at low deposition temperature. A study and control of Si and Ge atoms termination using H-dilution in SiGe:H alloys deposited by RF plasma discharge was conducted and we made a comparison with low-frequency plasma discharge studies. Solid contents of the main elements and contaminants were determined by SIMS technique. It was found that for low dilution rates from R_H = 9 to 30, the germanium content in the solid phase strongly depends on the hydrogen dilution and varies from Y = 0.49 to 0.68. On the other hand, with a higher presence of hydrogen in the mixture, the germanium content does not change and remains close to the value of Y = 0.69. The coefficient of Ge preferential incorporation depended on R_H and varied from P_Ge = 0.8 to 4.3. Also, the termination of Si and Ge atoms with hydrogen was studied using FTIR spectroscopy. Preferential termination of Si atoms was observed in the films deposited with low R_H < 20, while preferential termination of Ge atoms was found in the films deposited with high R_H > 40. In the range of 20 < R_H < 40, hydrogen created chemical bonds with both Si and Ge atoms without preference. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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10 pages, 3724 KiB

Open AccessArticle

Effect of Graphene Oxide Modified with Organic Amine on the Aging Resistance, Rolling Loss and Wet-Skid Resistance of Solution Polymerized Styrene-Butadiene Rubber

by Songhan Wan, Xiaobin Lu, Hongguo Zhao, Songbo Chen, Shuwei Cai, Xianru He and Rui Zhang

Materials 2020, 13(5), 1025; https://doi.org/10.3390/ma13051025 - 25 Feb 2020

Cited by 5 | Viewed by 2393

Abstract

Graphene oxide (GO) was modified by p-phenylenediamine (PPD), aiming at improving the wet-skid resistance and reduce the rolling loss of solution polymerized styrene-butadiene rubber (SSBR). PPD with amino groups enabled GO to obtain anti-aging function. The structure of modified GO (PPD-GO) was characterized [...] Read more.

Graphene oxide (GO) was modified by p-phenylenediamine (PPD), aiming at improving the wet-skid resistance and reduce the rolling loss of solution polymerized styrene-butadiene rubber (SSBR). PPD with amino groups enabled GO to obtain anti-aging function. The structure of modified GO (PPD-GO) was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy. Mechanical tests showed that the mechanical properties of SSBR before and after aging were improved by adding PPD-GO. The results of thermogravimetric-differential scanning calorimeter synchronization analysis (TGA-DSC) indicated that SSBR/PPD-GO obtained good thermo-oxidative stability. The dynamic mechanical analysis (DMA) of SSBR composites showed that the mechanical loss factor (tanδ) peak moved to high temperature with the content of PPD-GO. The tanδ values of SSBR composites showed that it had a good effect on improving the wet-skid resistance and reducing the rolling loss of SSBR by adjusting the content of PPD-GO. In particular, with the addition of 4 phr GO, SSBR was effectively improved in mechanical properties, aging resistance, wet-skid resistance and low rolling loss. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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11 pages, 7158 KiB

Open AccessArticle

The Magnetisation Process of Bulk Amorphous Alloys: Fe_36+xCo_36−xY₈B₂₀, Where: x = 0, 3, 7, or 12

by Katarzyna Błoch, Marcin Nabiałek, Przemysław Postawa, Andrei Victor Sandu, Agata Śliwa and Bartłomiej Jeż

Materials 2020, 13(4), 846; https://doi.org/10.3390/ma13040846 - 13 Feb 2020

Cited by 12 | Viewed by 2138

Abstract

Amorphous Fe- and Co-based alloys possess so-called soft magnetic properties. Due to the high sensitivity of the magnetisation vector to any inhomogeneities occurring in these alloys, it is possible to assess indirectly structural defects. This paper presents the results of research on the [...] Read more.

Amorphous Fe- and Co-based alloys possess so-called soft magnetic properties. Due to the high sensitivity of the magnetisation vector to any inhomogeneities occurring in these alloys, it is possible to assess indirectly structural defects. This paper presents the results of research on the structure and magnetic properties of bulk amorphous alloys with a high content of Fe and Co. The magnetic properties of the produced alloys were tested using a Faraday magnetic balance and a vibrating sample magnetometer (VSM). Analysis of the magnetisation process in the region known as the approach to ferromagnetic saturation was carried out in accordance with Kronmüller’s theorem. Magnetisation in magnetic fields of greater than the effective anisotropy field (Holstein-Primakoff para-process) was also studied. For the studied alloys, it was found that an increase in Fe content causesan increase in saturation magnetisation, and decreases in the values of the coercive field and thespin-wave stiffness parameter, Dspf. A relationship was observed between the width of the amorphous halo and the value of the coercive field. However, no significant links were found between either the presence of structural defects and the properties of these materials, or between the Co content and the value of the coercive field. Full article

(This article belongs to the Special Issue Properties of Amorphous Materials and Nanomaterials)

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