Alumina Zirconia Research Articles

Influence of Cleaning Procedures and Aging on Shear-Bond- Strength of 3Y, 4Y, and 5Y Zirconia to Titanium.

Lab-side-fabricated abutments and hybrid zirconia crowns, which are bonded to titanium bases with resin-based composites, require disinfection before insertion. This study investigated the effect of cleaning procedures (ultrasonic, autoclaving) and aging methods (24h, 90d, thermocycling) on the shear bond strength between alumina particle air-abraded titanium and zirconia (3Y-, 4Y- and 5Y-TZP) specimens luted with phosphate monomer containing adhesive systems and resin-based composite. Autoclaving significantly improved SBS (F (27,231) &#61; 17.265, p < .001) compared to no cleaning and three-stage disinfection. No differences were identified with regard to zirconia or aging methods. Bond strength initially benefits from autoclaving but continuously approaches the comparative values over longer periods.

Thermal cycle behaviour of plasma sprayed thermal barrier coatings on cast iron substrate for the application of liner of internal combustion engine

In the present scenario, research on Thermal Barrier Coatings (TBCs) is attracting significant attention in high-temperature applications due to the rising demand in industrial applications, such as gas turbine blades and internal combustion engine components. To meet these demands, it is essential to enhance the mechanical and oxidation properties of thermal barrier coatings. The atmospheric plasma spray methodology for producing these coatings has become a central focus in recent times. In this work, TBCs were prepared by blending pure alumina and Yttria-Stabilized Zirconia (YSZ) in equal proportions. Extensive study of TBCs carried out under high-temperature conditions through thermal cycle tests at elevated temperatures, around 850 °C. A total of 350 thermal cycles were conducted, and microstructures of the coating surface were examined at 150, 250, and 350 cycles. High-temperature stress, generated due to the sintering of the coating, also influences the life of the coatings. Specimen with a topcoat thickness of 300 μm, exhibited good thermal shock resistance compared to the specimens with topcoats of thickness of 100 μm and 200 μm. The effects of process parameters, porosity, and thermal shock resistance are presented in detail. The topcoat with a thickness of 300 μm demonstrated excellent thermal shock resistance and reduced formation of thermally grown oxide (TGO). The porosity of the coating, found to be between 2% and 3%, contributed to its dense nature, effectively reducing oxidation rates and enhancing the coating's lifespan under cyclic high-temperature conditions.

Mechanochemical dehydration and crystallization of supersaturated zirconia–alumina composite nano powders

Mechanochemical dehydration and crystallization of supersaturated zirconia–alumina composite nano powders

Phase evolution of Al–Al2O3–ZrO2 refractories at 1300 °C under N2 flowing

In order to obtain Al–Al2O3–ZrO2 composite refractories with excellent oxidation resistance, erosion resistance and thermal shock stability, metallic aluminium and fused Al2O3–ZrO2 were used as the raw materials, while phenolic resin was used as the binding agent. The microstructure was characterised by means of X-ray diffraction and scanning electron microscopy tests. Based on the reaction between zirconia and metallic aluminium under N2 flowing at 1300 °C, the reaction mechanism of zirconia and metallic aluminium in-situ reaction at 1300 °C to generate (Al2OC) x(AlN)1− x solid solution, zirconium nitride, and aluminium–zirconium alloy was revealed, and a model for the evolution of the phases in the aluminium-added Al–Al2O3–ZrO2 specimen was constructed to realise the Al–Al2O3–ZrO2 composite refractories phase controlling. Based on the good corrosion resistance of ZrO2 to CaO and the excellent results of the in-situ reaction of metallic aluminium to generate a large number of non-oxide reinforcing phases capable of replacing elemental C, this work is of great significance for the study of refractory in erosion-heavy environments, such as calcium-treated steel.

22‐3: Negative Capacitance ZAO/ZnO Ferroelectric Thin‐Film Transistor for Neuromorphic Computing

We report complementary metal‐oxide semiconductor (CMOS)‐compatible, negative capacitance (NC) ferroelectric (FE) zirconium‐aluminum oxide (ZAO)/ZnO thin‐film transistors (TFTs) at a low thermal budget of 360 °C. The NC‐FE‐TFTs demonstrate uniform device‐to‐device performances, featuring a high memory window of 6.7 ± 0.1 V and steep subthreshold swing of 43 ± 4 mV dec–1 . The observation of negative differential resistance at room temperature confirms the NC effect in FE‐ZAO/ZnO TFTs. In addition, a learning accuracy of ≈92% is achieved, highlighting the potential for high precision neuromorphic computing application.

Understanding the Individual Role of Composition and Spark Plasma Sintering Temperature on the Microstructure and Hardness of Alumina–Zirconia Composites

Understanding the Individual Role of Composition and Spark Plasma Sintering Temperature on the Microstructure and Hardness of Alumina–Zirconia Composites

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Effect of Hydroxyapatite on Sinterability, Mechanical Properties, and Bioactivity of Chemically Synthesized Alumina–Zirconia Composites

Effect of Hydroxyapatite on Sinterability, Mechanical Properties, and Bioactivity of Chemically Synthesized Alumina–Zirconia Composites

Biomass-derived polycarboxylate–aluminum–zirconium complex tanning system: A sustainable and practical approach for chrome-free eco-leather manufacturing

Biomass-derived polycarboxylate–aluminum–zirconium complex tanning system: A sustainable and practical approach for chrome-free eco-leather manufacturing

Ni decorated three-dimension hierarchical pyramidal ZrO2–Al2O3 nanoporous sheets for methane production

ZrO2–Al2O3 nanocomposites were synthesized by a modified co-precipitation method and loaded with 5%Ni as catalysts for methane production via n-heptane cracking. The as-synthesized nanocomposites were characterized by several techniques such as XRD, N2 adsorption-desorption, XPS, TEM, SEM, AFM, TGA, DTG, NH3 -TPD and Raman analysis. The XRD results confirmed the synthesis of amorphous γ alumina and hexagonal phase of zirconium alumina oxide (Zr5Al3O0.5) solid solution. XRD and SEM analyses showed additional small size Related to monoclinic phase of ZrO2 particles loaded on the Al2O3 surface. BET analyses confirmed the ZrO2–Al2O3 formation in mesoporous sheets structure. TEM images of the neat alumina, 10 ZA and their corresponding Ni loaded samples (Ni@10 ZA) revealed well-defined 3D hierarchical pyramidal structures with a height about 200 nm. All catalysts under this study exhibited high tendency to favor methane production via n-heptane cracking. At higher reaction temperatures, Ni@10 ZA catalyst exhibited higher cracking activity compared to the other prepared catalysts under this investigation which confirmed by NH3 -TPD analysis. A promising yield of methane was achieved at about 88 % coupled with 94.71 % selectivity at reaction temperature of 400 °C. Herein, the data collected through this research work revealed that Ni@10 ZA is a promising candidate for methane production via n-heptane cracking.

Prediction of thermal shock induced cracking in multi-material ceramics using a stress-energy criterion

Impact of residual stresses on the thermal shock resistance of alumina–zirconia multi-layer ceramics is investigated within the framework of finite fracture mechanics, using astress-energy criterion. The critical temperature difference (ΔTc) for crack formation is strongly dependent on the magnitude of residual stress and the material’s strength. The predicted minimal spacing between cracks, critical time for crack initiation, and initial depth of the induced cracks are compared and discussed for different designs. An increase of up to ∼40 % in ΔTc is predicted for multi-material ceramics with athin alumina surface layer with compressive stresses, compared to bulk reference alumina.

Development of ZTA (80% Al2O3/20% ZrO2) pre-sintered blocks for milling in CAD/CAM systems

The present work aims to develop a production method of pre-sintered zirconia-toughened-alumina (ZTA) composite blocks for machining in a computer-aided design and computer-aided manufacturing (CAD-CAM) system. The ZTA composite comprised of 80% Al2O3 and 20% ZrO2 was synthesized, uniaxially and isostatically pressed to generate machinable CAD-CAM blocks. Fourteen green-body blocks were prepared and pre-sintered at 1000 °C. After cooling and holder gluing, a stereolithography (STL) file was designed and uploaded to manufacture disk-shaped specimens projected to comply with ISO 6872:2015. Seventy specimens were produced through machining of the blocks, samples were sintered at 1600 °C and two-sided polished. Half of the samples were subjected to accelerated autoclave hydrothermal aging (20h at 134 °C and 2.2 bar). Immediate and aged samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Optical and mechanical properties were assessed by reflectance tests and by biaxial flexural strength test, Vickers indentation and fracture toughness, respectively. Samples produced by machining presented high density and smooth surfaces at SEM evaluation with few microstructural defects. XRD evaluation depicted characteristic peaks of alpha alumina and tetragonal zirconia and autoclave aging had no effect on the crystalline spectra of the composite. Optical and mechanical evaluations demonstrated a high masking ability for the composite and a characteristic strength of 464 MPa and Weibull modulus of 17, with no significant alterations after aging. The milled composite exhibited a hardness of 17.61 GPa and fracture toughness of 5.63 MPa m1/2, which remained unaltered after aging. The synthesis of ZTA blocks for CAD-CAM was successful and allowed for the milling of disk-shaped specimens using the grinding method of the CAD-CAM system. ZTA composite properties were unaffected by hydrothermal autoclave aging and present a promising alternative for the manufacture of infrastructures of fixed dental prostheses.

In‐Situ Fabrication Process of Bacterial Cellulose compositesfor Soft Robots

Bacterial cellulose (BC) produced by acetic acid bacteria is a promising biomaterial that exhibits exceptional mechanical strength, biocompatibility, and biodegradability. In this study, we have successfully fabricated BC composites with various materials such as alumina fibers, zirconia particles, carbon nanotubes, and magnetic particles by adding each material to the culture medium. We also demonstrate the actuation of BC‐magnetic particle composites by a magnetic field. Furthermore, we have achieved the patterning of arbitrarily shaped patterns onto BC pellicles by placing templates in the culture medium. These findings suggest that BC composites have the potential to be applied in various fields such as tissue engineering and drug delivery. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Oxidized sodium lignosulfonate: A biobased chrome-free tanning agent for sustainable eco-leather manufacture

Chrome-free eco-leather manufacture is inevitable in sustainable development of the leather industry. Herein, oxidized sodium lignosulfonate (OSL) was prepared using H2O2 and CuSO4 catalyst as a biomass-derived tanning agent. H2O2 oxidation of OSL breaks the aliphatic side-chain β-O-4′, β-5′, and β-β’ linkages, transforms the adjacent phenolic hydroxyl group and methoxy group on the benzene ring into carboxyl groups and reduces the colority. OSL120 (120% H2O2, Mw 1498) containing moderate carboxyl (6.27 mmol/g) and phenolic hydroxyl (0.18 mmo/g) appropriately coordinates with aluminum–zirconium salts (AZ), thereby promoting the uniform penetration of OSL–AZ complexes into the leather matrix. Moreover, OSL120 provides essential hydrophobic and hydrogen bonds interactions with collagen to form a rigid multi-point crosslinking network among collagen fibers. Thus, chrome-free tanned leather shows natural flesh color and shrinkage temperature up to 89.5 ℃, and crust leather with satisfactory physical properties are achieved. This work gives new insights into the low-carbon leather manufacture with lignin-based tanning system and provides a novel approach for the resource utilization of sodium lignosulfonate.

Bioinert ceramics scaffolds for bone tissue engineering by laser-based powder bed fusion: a preliminary review

The implementation of laser powder bed fusion (PBF-LB) on ceramics is far more demanding than their metallic and polymeric counterparts for bone tissue engineering (BTE). The review will shed light on bioinert ceramics-based biomaterials manufacturing through PBF-LB incorporating alumina and yttria-stabilized zirconia as oxide-based ceramics and nitride-based ceramics as non-oxide-based ceramics with particular prominence on their properties and requirements for biomedical devices and BTE. The review paper will also classify bioinert scaffolds processed through PBF-LB as a medium to manufacture drug delivery systems (DDS) and to ameliorate critical-sized bone defects based on the fracture site length of the bone with the various modes of functionalization through the incorporation of drugs, stem cells, and growth factors for personalized medicine.

Preparation and Characterization of Alumina Zirconia Composite Ceramics

The composite ceramics between Al2O3 (6 mol%MgO) and ZrO2 (4 mol%Y2O3) were prepared in the Al2O3 (6 mol%MgO added: ZrO2 (4 mol%Y2O3 added) ratios of 20:80, 35:65, 50:50, 65:35 and 80:20. All of samples were sintered using two stage sintering routes with the first temperature (T1) at 1600 °C for 30 min and the second temperature (T2) at 1450 °C for 5 h. The physical properties were characterized from percentage of shrinkage and bulk density. It can be found their tend to decrease with Al2O3 (6 mol%MgO) content increase. XRD patterns were showed combination main phase of rhombohedral of Al2O3 and monoclinic, cubic, tetragonal of ZrO2. Rietveld refinement were used to calculate the percentage of phase composition. All of samples were revealed weight percentage of main composition as m-ZrO2 c-ZrO2 t-ZrO2 and r- Al2O3 in different ratios. It can be found, sample with more content of ZrO2 was showed higher weight percentage of c-ZrO2. The high intensity of Al2O3 peak was appeared from sample with high Al2O3 concentration. SEM micrographs reveal morphology of grain such as grain shape and size of grains. The average grain size value is between 0.81 and 1.07 µm and the size of grain tend to increase with high Al2O3 content. EDX technique were analyzed element compositions of Al2O3 (6 mol%MgO): ZrO2 (4 mol%Y2O3) and EDX spectra were showed wt.% element of Al, Zr, O Y and Mg which is confirmed molecular formular. Moreover, EDX method is identified square shape of Al2O3 (6 mol%MgO) and round shape of ZrO2 (4 mol%Y2O3). The mechanical properties were measured by Vickers and Knoop hardness that were used for calculating the fracture toughness value. It can be found that the optimum mechanical properties were obtained from composite ceramic of 0.35Al2O3 (6 mol%MgO): 0.65ZrO2 (4 mol%Y2O3) which is showed the highest of fracture toughness value about 0.38 GPa.m1/2.

YSZ–Al2O3 thermal barrier nanocomposites coatings: Electrophoretic deposition and characterization

AbstractThis paper presents the development of yttria‐stabilized zirconia–alumina (YSZ–Al2O3) nanocomposite coatings deposited on Inconel 738LC superalloy substrates using the electrophoretic deposition technique. To prepare stable suspensions of YSZ and Al2O3 nanoparticles, a mixture of 75 mL acetone and 25 mL ethanol was used as a medium with .4 g/L iodine as a dispersant. The effects of Al2O3 concentration on suspension stability, electrical conductivity, and pH were studied in detail to optimize the suspension chemistry. The deposition kinetics were systematically investigated as a function of suspension concentration, deposition voltage, deposition time, and iodine concentration () to optimize the process parameters. The as‐dried coatings deposited at Vd = 10 V for 90 s were uniform, crack‐free, and sintered at 1150°C for 4 h. The microstructure, phase composition, hardness, and adhesion strength of the coatings were analyzed using scanning electron microscopy, X‐ray diffraction, Vickers microhardness measurements, and conducting shear loading tests, respectively. The results showed that adding Al2O3 to YSZ reduces porosity, crack density, and sintering temperature while stabilizing the tetragonal phase and retarding the martensitic transformation and crack formation. Among the studied coatings, the YSZ–20 wt.% Al2O3 nanocomposite coating deposited at Vd = 10 V for 90 s exhibited the most improved microstructural features, hardness, and adhesion strength.

A Molecular Dynamics Simulation to Shed Light on the Mechanical Alloying of an Al-Zr Alloy Induced by Severe Plastic Deformation

In a recent experimental work, as a result of severe plastic deformation, a non-equilibrium solid solution was obtained despite the very limited solubility of zirconium (Zr) in aluminum (Al). This opens up a new path in the development of heat-treatable alloys with improved electrical and mechanical properties, where mechanically dissolved elements can form intermetallic particles that contribute to precipitation strengthening. In the present study, molecular dynamics simulations were performed to better understand the process of mechanical dissolution of Zr within an Al model, with Zr atoms segregated along its grain boundaries. Stress–strain curves, radial distribution functions, and mechanisms of plastic deformation and dissolution of Zr in Al were analyzed. It is revealed that orientation of the grain boundary with segregation normal to the shear direction promotes more efficient mixing of alloy components compared to its parallel arrangement. This happens because in the second case, grain boundary sliding is the main deformation mechanism, and Zr tends to remain within the interfaces. In contrast, the involvement of dislocations in the case of normal orientation of grain boundaries with Zr segregation significantly contributes to deformation and facilitates better dissolution of Zr in the Al matrix. The findings obtained can provide new insights considering the role of texture during mechanical alloying of strongly dissimilar metals.

The Effect of Zirconia Content on Physical and Mechanical Properties of Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;/ZrO&lt;sub&gt;2&lt;/sub&gt; Composites

The structural, physical and mechanical properties of alumina composites reinforced with various zirconia contents were studied. Zirconia with specific stress-induced toughness mechanisms (from tetragonal to monoclinic) can improve its mechanical properties. The raw materials were commercial products of alumina (Al2O3) and zirconia (ZrO2) with gamma alumina (γ-Al2O3) and monoclinic zirconia (m-ZrO2) phases, respectively. In this study, alumina and zirconia powders containing 0, 10, 20, 30, and 40 wt% were mechanically activated and sintered at 1400°C for 3 h. Fourier transform infrared spectroscopy (FTIR) characterization was used to confirm the functional groups in the sample. Phase analysis of the sintered samples was carried out via X-ray diffraction (XRD). Composite characterization includes diameter shrinkage, density, and Vickers hardness. Corundum (α-Al2O3), monoclinic zirconia (m-ZrO2) and tetragonal zirconia (t-ZrO2) phases were the observed phases in the sintered sample. The Al2O3/ZrO2 60:40 sample had the largest shrinkage in pellet diameter, apparent density, and Vickers hardness, at 8%, 4.35 g/cm3, and 1.33 HVN, respectively.

Nanoelectromechanical resonators for gigahertz frequency control based on hafnia–zirconia–alumina superlattices

Nanoelectromechanical resonators for gigahertz frequency control based on hafnia–zirconia–alumina superlattices