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4 pages, 139 KiB

Open AccessEditorial

Mechanical Properties and Applications of Advanced Ceramics

by Lidija Ćurković and Irena Žmak

Materials 2024, 17(13), 3143; https://doi.org/10.3390/ma17133143 - 27 Jun 2024

Viewed by 819

Abstract

The development of new materials or technologies has created turning points throughout the history of mankind, as the societies that had access to this new knowledge were able to overpower others [...] Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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14 pages, 5726 KiB

Open AccessArticle

Interface Strength, Damage and Fracture between Ceramic Films and Metallic Substrates

by Lihong Liang, Linfeng Chen, Luobing Wu and Huifeng Tan

Materials 2021, 14(2), 353; https://doi.org/10.3390/ma14020353 - 12 Jan 2021

Cited by 6 | Viewed by 2425

Abstract

Interface strength, damage and fracture properties between ceramic films and metallic substrates affect the service reliability of related parts. The films’ thickness, grain size and residual stress affect the interface properties and fracture behavior, thus related studies attract great attention. In this paper, [...] Read more.

Interface strength, damage and fracture properties between ceramic films and metallic substrates affect the service reliability of related parts. The films’ thickness, grain size and residual stress affect the interface properties and fracture behavior, thus related studies attract great attention. In this paper, the interface damage evolution and fracture behavior between ceramic films and metallic substrates were simulated by developing a three dimensional finite element model of alumina films on Ni substrates with cohesive elements in the interfaces. The interface fracture energy as a key parameter in the simulation was firstly determined based on its thermodynamic definition. The simulation results show the Mises stress distribution and damage evolution of the film/substrate structures during uniaxial tensile loading. Specially, when grain size of the films is in nanoscale, the interface strength increases obviously, agreeing with the previous experimental results. The effects of residual stress on interface properties was further simulated. The interface strength was found to decrease with increasing radial residual force and the axial residual pressure increases the interface strength. When the thickness of the films increases, the interface strength keeps a constant but the speed of interface damage becomes faster, that is, the thicker films show catastrophic fracture. The underlying mechanism of damage speed was analyzed. Understanding these size effects and the effects of residual stress is helpful to guide the design of related parts. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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17 pages, 5284 KiB

Open AccessArticle

Titania-Coated Alumina Foam Photocatalyst for Memantine Degradation Derived by Replica Method and Sol-Gel Reaction

by Zrinka Švagelj, Vilko Mandić, Lidija Ćurković, Martina Biošić, Irena Žmak and Mattia Gaborardi

Materials 2020, 13(1), 227; https://doi.org/10.3390/ma13010227 - 4 Jan 2020

Cited by 29 | Viewed by 4527

Abstract

In the present work, alumina (Al₂O₃) foam was prepared by the replica method where a polyurethane (PU) foam (30 pores per inch (ppi)) template was impregnated with a 60 wt.% Al₂O₃ suspension. Sintered Al₂O [...] Read more.

In the present work, alumina (Al₂O₃) foam was prepared by the replica method where a polyurethane (PU) foam (30 pores per inch (ppi)) template was impregnated with a 60 wt.% Al₂O₃ suspension. Sintered Al₂O₃ foam was used as substrate for the deposition of sol-gel derived titania (TiO₂) film using dip coating. For the preparation of TiO₂ sol, titanium(IV) isopropoxide (Ti-iPrOH) was used as the precursor. The common problem of qualification and quantification of a crystalline coating on a highly porous 3D substrate with an uneven surface was addressed using a combination of different structural characterization methods. Using Powder X-ray Diffraction (PXRD) and synchrotron Grazing Incidence X-ray Diffraction (GIXRD) on bulk and powdered Al₂O₃ foam and TiO₂-coated Al₂O₃ foam samples, it was determined Al₂O₃ foam crystallizes to corundum and coating to anatase, which was also confirmed by Fourier Transformed Infrared Spectroscopy (FTIR). Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS) revealed the structural and microstructural properties of the substrate and coating. Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) were used to clarify the evolution of the porous microstructure. The Al₂O₃-TiO₂ composite was evaluated as a photocatalyst candidate for the degradation of the micropollutant medication memantine. The degradation rate was monitored using a light-emitting diode (LED) lamp operating at electromagnetic (EM) wavelength of 365 nm. The photocatalytic activity of sol-gel-derived TiO₂ film immobilized on the Al₂O₃ foam was compared with commercially available TiO₂ nanoparticles, P25-Degussa, in the form of a suspension. The levels of memantine were monitored by High-Performance Liquid Chromatography–Tandem Mass Spectrometry (HPLC–MS/MS). The efficiency and rate of the memantine photodegradation by suspended TiO₂ nanoparticles is higher than the TiO₂-coated Al₂O₃ foam. But, from the practical point of view, TiO₂-coated Al₂O₃ foam is more appropriate as a valuable photocatalytic composite material. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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10 pages, 1549 KiB

Open AccessArticle

On the Room-Temperature Creep Behavior and Its Correlation with Length Scale of a LiTaO₃ Single Crystal by Spherical Nanoindentation

by Wei Hang, Xianwei Huang, Min Liu and Yi Ma

Materials 2019, 12(24), 4213; https://doi.org/10.3390/ma12244213 - 15 Dec 2019

Cited by 7 | Viewed by 2226

Abstract

Relying on nanoindentation technology, the room-temperature creep behavior of a LiTaO₃ single crystal in the typical orientation (01

\bar{1}

2), i.e., Y-42° plane was investigated. Three kinds of spherical tips with the radii of 0.76, 2.95 and 9.8 μm were respectively [...] Read more.

Relying on nanoindentation technology, the room-temperature creep behavior of a LiTaO₃ single crystal in the typical orientation (01

\bar{1}

2), i.e., Y-42° plane was investigated. Three kinds of spherical tips with the radii of 0.76, 2.95 and 9.8 μm were respectively applied to detect nanoindentation length scale effect on creep deformation at both elastic and plastic regions. Superficially, both creep displacement and rate were nearly linearly increased with increasing holding depth and independent of tip size, which could be ascribed to the simultaneously enlarged holding strain and deformation volume beneath the indenter. At a similar holding strain, creep deformation, i.e., creep strain and strain rate were more pronounced under smaller spherical tips. Strain rate sensitivities of creep flows under different spherical tips and holding strains were also estimated. The potential room-temperature creep mechanism of LiTaO₃ under high shear compression stress was discussed. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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11 pages, 4928 KiB

Open AccessArticle

Analysis of the Functionally Step-Variable Graded Plate Under In-Plane Compression

by Leszek Czechowski and Zbigniew Kołakowski

Materials 2019, 12(24), 4090; https://doi.org/10.3390/ma12244090 - 7 Dec 2019

Cited by 8 | Viewed by 2302

Abstract

A study of the pre- and post-buckling state of square plates built from functionally graded materials (FGMs) and pure ceramics is presented. In contrast to the theoretical approach, the structure under consideration contains a finite number of layers with a step-variable change in [...] Read more.

A study of the pre- and post-buckling state of square plates built from functionally graded materials (FGMs) and pure ceramics is presented. In contrast to the theoretical approach, the structure under consideration contains a finite number of layers with a step-variable change in mechanical properties across the thickness. An influence of ceramics content on a wall and a number of finite layers of the step-variable FGM on the buckling and post-critical state was scrutinized. The problem was solved using the finite element method and the asymptotic nonlinear Koiter’s theory. The investigations were conducted for several boundary conditions and material distributions to assess the behavior of the plate and to compare critical forces and post-critical equilibrium paths. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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14 pages, 4147 KiB

Open AccessFeature PaperArticle

TiN-Nanoparticulate-Reinforced ZrO₂ for Electrical Discharge Machining

by Ana Lazar, Tomaž Kosmač, Janez Zavašnik, Anže Abram and Andraž Kocjan

Materials 2019, 12(17), 2789; https://doi.org/10.3390/ma12172789 - 30 Aug 2019

Cited by 11 | Viewed by 3178

Abstract

This study presents a fabrication route for an electrically conductive ZrO₂–TiN ceramic nanocomposite with a nanoscale TiN phase occupying ≤30 vol% to improve the mechanical reinforcement of the zirconia matrix, and at the same time provide electrical conductivity to facilitate electro-discharge [...] Read more.

This study presents a fabrication route for an electrically conductive ZrO₂–TiN ceramic nanocomposite with a nanoscale TiN phase occupying ≤30 vol% to improve the mechanical reinforcement of the zirconia matrix, and at the same time provide electrical conductivity to facilitate electro-discharge machining (EDM). The TiN nanoparticles were incorporated into a 3 mol% yttria-stabilized tetragonal zirconia (Y-TZP) powder, either by admixing a TiN nanopowder (MCP) or by using in-situ synthesis (ISS) via the forced hydrolysis of a titanyl sulphate aqueous solution and the direct nitriding of as-synthesized titania nanoparticles, followed by consolidation and rapid sintering in a spark plasma sintering (SPS) system. The initial phase composition and crystal structure of the as-synthesized powders and the sintered samples were characterized by transmission electron microscopy (TEM) and X-ray difraction (XRD). The influence of the different fabrication routes on the microstructural evolution, electrical and mechanical properties, and affinity for EDM were assessed using TEM, focused ion beam scanning electron microscopy (FIB-SEM, Vickers indentation, electrical conductivity measurements, and profilometry. The MCP synthesis route resulted in finer microstructures that are less prone to microstructural inhomogeneities; however, using the ISS route, it was possible to fabricate electrically conductive Y-TZP nanocomposites containing only 15 vol% of the TiN nanoparticulate phase. Both synthesis routes resulted in an increase of the fracture toughness with an increase of the TiN phase due to the nanoparticulate TiN reinforcement of the Y-TZP ceramic matrix via crack-bridging toughening mechanisms. As both synthesis routes yielded Y-TZP nanocomposites capable of successful EDM machining at a TiN content of ≥30 vol% for the MCP and ≥ 15 vol% TiN for the ISS, a possible mechanism was developed based on the microstructure evolution and grain growth. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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16 pages, 4951 KiB

Open AccessArticle

Effect of Additives on Stability of Alumina—Waste Alumina Suspension for Slip Casting: Optimization Using Box-Behnken Design

by Milan Vukšić, Irena Žmak, Lidija Ćurković and Danko Ćorić

Materials 2019, 12(11), 1738; https://doi.org/10.3390/ma12111738 - 29 May 2019

Cited by 9 | Viewed by 3986

Abstract

The green machining of alumina (Al₂O₃) green bodies generates a certain amount of waste alumina powder. Waste alumina ceramic powder should be disposed of as non-hazardous waste in a legally compliant manner. The influence of additives on the stability [...] Read more.

The green machining of alumina (Al₂O₃) green bodies generates a certain amount of waste alumina powder. Waste alumina ceramic powder should be disposed of as non-hazardous waste in a legally compliant manner. The influence of additives on the stability of 70 wt.% (≈40 vol.%) alumina—waste alumina water-based suspension was investigated in the presented research. A Box-Behnken three-factor response surface design was used for the preparation of stable highly-concentrated suspensions with the addition of three additives. The optimal amount of each additive was selected according to the obtained results of minimal apparent viscosity: 0.05 wt.% Tiron as dispersant, 0.1 wt.% poly (vinyl alcohol) as binder and 0.2 wt.% magnesium aluminate spinel as abnormal grain growth inhibitor. The analysis of variance was used to identify the contribution of each additive. The zeta potential and sedimentations tests were performed to confirm the suspension stability measurements at different pH values. Alumina particles were optimally dispersed at pH values between 8 and 11. According to the results, the investigated composition of 20 wt.% waste alumina powder (weight content, dry alumina powder), with the addition of optimal amounts of additives, shows a possible application in the production of ceramics by slip casting. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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11 pages, 11213 KiB

Open AccessArticle

Cavitation Wear of Basalt-Based Glass Ceramic

by Marko Pavlovic, Marina Dojcinovic, Radica Prokic-Cvetkovic, Ljubisa Andric, Zoran Ceganjac and Ljiljana Trumbulovic

Materials 2019, 12(9), 1552; https://doi.org/10.3390/ma12091552 - 12 May 2019

Cited by 12 | Viewed by 3678

Abstract

This paper examines the possibility of using basalt-based glass ceramics for construction of structural parts of equipment in metallurgy and mining. An ultrasonic vibration method with a stationary sample pursuant to the ASTM G32 standard was used to evaluate the possibility of the [...] Read more.

This paper examines the possibility of using basalt-based glass ceramics for construction of structural parts of equipment in metallurgy and mining. An ultrasonic vibration method with a stationary sample pursuant to the ASTM G32 standard was used to evaluate the possibility of the glass ceramic samples application in such operating conditions. As the starting material for synthesis of samples, olivine–pyroxene basalt from the locality Vrelo–Kopaonik Mountain (Serbia) was used. In order to obtain pre-determined structure and properties of basalt-based glass ceramics, raw material preparation methods through the sample crushing, grinding, and mechanical activation processes have been examined together with sample synthesis by means of melting, casting, and thermal treatment applied for the samples concerned. The mass loss of samples in function of the cavitation time was monitored. Sample surface degradation level was quantified using the image analysis. During the test, changes in sample morphology were monitored by means of the scanning electronic microscopy method. The results showed that basalt-based glass ceramics are highly resistant to cavitation wear and can be used in similar exploitation conditions as a substitute for other metal materials. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Advanced Ceramics)

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