Mechanical Properties Of Alumina Research Articles

Surface Environment Effects on Mechanical Properties of Alumina

Surface Environment Effects on Mechanical Properties of Alumina

The mechanical properties of ceramic matrix composite composed of polysilazane-derived silicon oxycarbonitride ceramic with nano alumina

The primary objective of this study is to develop ceramic-based composite materials by synthesizing silicon oxycarbonitride (SiCNO) ceramic from a liquid polysilazane precursor. The SiCNO ceramic powder is incorporated with nano alumina powder, compressed, and pyrolyzed at varying temperatures to produce ceramic bulks. The experimental findings reveal a substantial enhancement in the mechanical properties of alumina with the incorporation of SiCNO ceramic powder. The addition of 10 wt% SiCNO ceramic powder to the alumina ceramic matrix composite results in a 34.5% increase in compressive strength and 41.3% increase in compressive modulus compared to pure alumina. Notably, the sample containing 20 wt% SiCNO ceramic powder in the alumina ceramic matrix, pyrolyzed at 1100 °C, demonstrates a remarkable 151.1% increase in flexural strength compared to pure alumina. These results underscore the effective enhancement of alumina's mechanical properties by SiCNO ceramic powder as a component, while maintaining a relatively low density.

Effect of Mn doping on the densification and properties of transparent alumina by high-pressure spark plasma sintering

It is common practice to control the densification and microstructure of alumina using additives or dopants. In the present study, the effect of Mn-doping on the sintering behavior, optical properties, microstructure, and mechanical properties of alumina was examined. Addition of 0.5 at.% Mn was shown to significantly reduce densification rate and grain growth during high-pressure spark plasma sintering (HPSPS). The major effects resulted from the formation of MnAl2O4 nano inclusions located at grain boundary triple points. The Mn-doped alumina was highly transparent and had a light-brown tint due to absorption between ∼410 and 580 nm and a cutoff at 300 nm. The MnAl2O4 nano-inclusions caused the Young's modulus to decrease from 400 ± 5 GPa for pure alumina to 370 ± 5 GPa for Mn-doped alumina, while the fracture toughness increased from 2.97 to 3.66 MPa m0.5, and the hardness was the same. Thus, the addition of Mn enables control of the transparent alumina densification process and microstructure development, and it can be used to tailor the optical and mechanical properties for specific applications.

Microstructures and Mechanical Properties of Alumina and/or Yttrium Oxides Strengthened 9Cr Steel Fabricated by Vacuum Casting

The oxides with Al2O3‐containing and/or Y‐containing are introduced into 9Cr ferritic/martensitic steel fabricated by vacuum casting to modify its microstructures and improve its mechanical properties. The results show that the micron nonmetallic particles are refined, and the number of submicron particles is increased after the introduction of Al2O3‐containing oxides, while the number of submicron particles is decreased when both Al2O3‐and Y‐containing oxides are introduced. The average grain size, the width of martensite, and the M23C6 phases in the tempered steel are optimized when the Al2O3‐containing oxides are introduced. However, with the further introduction of Y‐containing oxides, these tempered microstructures do not change much, except for the precipitation of the δ‐Fe phase. Due to the grain refinement and second‐phase particle strengthening after the introduction of Al2O3‐containing particles, the tensile strength is improved not only at room temperature but also at 550 °C, but the impact energy drops significantly, which is caused by a large number of TiN particles promoted by Al2O3 particles through heterogeneous nucleation. At the same time, the further introduction of Y‐containing oxides reduces the tensile strength and increases the elongation at room temperature, which is attributed to the precipitation of soft δ‐Fe promoted by the addition of Y.

Effect of co-doping manganese oxide and titania on sintering behaviour and mechanical properties of alumina

The effect of co-doping of titania and manganese oxide at different weight percentages (0.5–5 wt%) on sintering behaviour and mechanical properties of alumina were evaluated. The undoped and doped alumina were prepared through pressureless sintering which was carried out at different temperatures (1000 °C–1500 °C) and were characterized through XRD and SEM. XRD revealed presence of R–TiO2 and α-alumina at low sintering temperature which further reacted to form Al2TiO5 at sintering temperature above 1350 °C. Manganese oxide (MnO2) was not reactive with alumina due to atomic radii mismatch. SEM indicated abnormal grain growth with increase in sintering temperature and dopant composition. The addition of doping led to reduction in the sintering temperature with high relative density (∼98%) and enhanced mechanical properties (E = 370 GPa and HV = 14.8 GPa) which was only achievable by undoped alumina by sintering at higher temperature regime.

Impacts of inclusion of additives on physical, microstructural, and mechanical properties of Alumina and Zirconia toughened alumina (ZTA) ceramic composite: A review

Zirconia toughened alumina (ZTA) is one of the widely discussed advanced ceramic in recent times. ZTA boasts excellent mechanically properties such as high hardness, high strength. Additionally, the material is chemically inert and possess greater compressive strength. Despite having such versatility, lack of fracture toughness and shock resistance prevent its utilization in broad scale. To improve the fracture toughness and other mechanical properties, metals, metallic oxides additives such as MgO, CaO, CeO2, Cr2O3, strontium hexa-alumina, Ag, Ni, FeO were commonly added to ZTA in the academic research. The purpose of this review paper is to provide a wholistic perspective on the trend of mechanical property alteration upon addition of different additives. Trend of mechanical property alteration such as density, fracture toughness, microhardness, strength provide a comparative analysis to solve this critical research and industrial problems.

Effect of Alumina Contents on the Some Mechanical Properties of Alumina (Al2O3) Reinforced Polymer Composites

Effect of Alumina Contents on the Some Mechanical Properties of Alumina (Al2O3) Reinforced Polymer Composites

A study of mechanical properties of alumina–zirconia composite films prepared by a combination of tape casting and solution impregnation method

Zirconia-toughened alumina (ZTA) ceramics are one of the most important engineering ceramics with high bending strength and fracture toughness. ZTA ceramics have found important applications in catalysts, implants, wear resistance tools, and electric circuit substrate. The near net shape method based on impregnation of porous body with desired solution has been used to prepare composites with improved properties. In this paper alumina–zirconia composite thin film has been prepared by a combination of aqueous tape casting and solution impregnation methods to improve sintering behavior and mechanical properties. At first, porous 3 mol% yttria-stabilized zirconia was prepared using aqueous tape casting, followed by impregnation with aluminum nitrate solution. Then, the rheological behavior was studied. The microstructure and phase content of samples were studied by SEM and XRD. Microhardness, nanohardness, Young’s modulus, and fracture toughness were measured by Vickers microhardness and nanoindentation methods, respectively. It was found that alumina–zirconia composites with homogeneous distribution of phases and high density can be obtained by solution impregnation method. The mechanical properties of composite thin films prepared by solution impregnation method have been improved compared to those of the composite prepared by tape casting of mixture of alumina and 3YSZ powders.

Microstructural and Mechanical Properties of Alumina (Al2O3) Matrix Composites Reinforced with SiC from Rice Husk by Spark Plasma Sintering

Abstract Alumina (Al2O3) suffers from low fracture toughness and low bending strength which restrict its application in the industry for some advanced components. The incorporation of submicron SiC into Al2O3 matrix improves mechanical properties of the matrix. However, the high cost of SiC has delayed the industrial interest of synthesizing Al2O3-SiC composites. Rice husk, an agricultural waste material, is a potential source of low-cost SiC. Therefore, this study presents a simple approach to synthesizing SiC from locally sourced rice husk and using it to reinforce alumina. Rice husk was pyrolysed in a tube furnace under argon atmosphere at different temperatures (1000 °C – 1500 °C) and reaction times (60 – 120 min). Furthermore, Alumina powder was admixed with 5 – 20 vol% SiC derived from rice husk, and then sintered at temperatures between 1300 °C – 1600 °C by spark plasma sintering. Maximum yield of SiC was obtained from rice husk at 1500 °C and 120 min. Materials with theoretical densities higher than 95% were achieved for the sintered composites. The hardness of sintered composites reached a maximum of 20.2±1.4 GPa, while a maximum of 4.7±.7 MPa.m0.5 was obtained for the fracture toughness.

Development and evaluation of Al2O3–ZrO2 composite processed by digital light 3D printing

Digital Light Processing (DLP) is a promising approach to fabricate delicate ceramic components with high-fidelity structural features. In this work, the alumina and zirconia/alumina ceramic suspensions with low viscosity and high solid loading (40 vol%) were prepared specifically for DLP 3D printing. After debinding and sintering, the final parts were obtained without any defects. The surface morphologies and mechanical properties of alumina (Al2O3) and zirconia toughened alumina (ZTA) composites were investigated and the results showed that the final parts exhibited high relative densities and good interlayer combination at the sintering temperature of 1600 °C. Comparing with the Al2O3, the ZTA composites exhibited significantly enhanced density (99.4%), bending strength (516.7 MPa) and indentation fracture toughness (7.76 MPa m1/2).

Structural properties and mechanical behavior of SWCNTs and MWCNTs reinforced Al2O3 fabricated by spark plasma sintering

Abstract Carbon nanotubes due to their structural and mechanical properties are good candidates as the second phase to improve the mechanical properties of alumina-based ceramics. In the present study, the effects of single wall and multi-wall carbon nanotubes on structural and mechanical properties of alumina were investigated. SWCNTs and MWCNTs were dispersed in alumina powder via a conventional method using 1 wt % PVA water solution as media. Sintering process for two different composite powders, alumina-2 wt. % SWCNTs and alumina 2 wt % MWCNTs was performed by spark plasma sintering technique at 1500 °C and 20 MPa for 10 min. Results showed that the presence of CNTs in alumina caused a considerable amount of porosity in final bodies. SEM images of fracture surfaces revealed the agglomeration of SWCNTs which played a dominant role in the deterioration of mechanical properties. MWCNTs reinforced alumina obtained higher Vickers hardness and bending strength values (12.91 GPa and 291 MPa, respectively) compared to that of SWCNTs (9.18 GPa and 276 MPa, respectively), due to sever agglomerate of SWCNTs throughout sintered composites. Typical load-displacement (P/h) curves were obtained from bending strength test and discussed. It was concluded that the addition of MWCNTs to alumina represented better densification and mechanical properties compared to SWCNTs.

Microstructure and Mechanical Properties of Alumina and Titanium Diboride Containing AA2014 Hybrid Composites

This paper presents an experimental analysis on microstructure, hardness, density and mechanical properties of aluminum hybrid metal matrix composites manufactured through powder metallurgy. The present article dealt with the composite-I (90 wt % − AA2014 + 5 wt % − Al2O3 + 5 wt% − TiB2), composite-II (85 wt % − AA2014 + 5 wt % − Al2O3 + 10 wt% − TiB2) and composite-III (85 wt % − AA2014 + 10 wt % − Al2O3 + 5 wt % − TiB2) were developed from the elemental powders mixing, die compaction and sintering. Three composites were compacted at a pressure of 350 ± 10 MPa and sintered at 610 ± 10 °C for 2 h in a vacuum hot press under the nitrogen atmosphere. Three composites were measured for microstructural observation, density analysis, porosity, hardness and mechanical properties investigation. In this experimental investigation, particles of alumina and titanium diboride were homogeneously diffused in the aluminum alloy 2014. Composite-I exhibits the 1.4% of average porosity of the composition and 98.5% of it theoretical density. Addition of reinforced particles of 15 wt % in the composites has increased hardness, porosity and reduced the sintered density.

Sintering behaviour and properties of manganese-doped alumina

The effect of manganese (0.1, 0.5 and 1.0 wt%) on the sintering and mechanical properties of alumina was studied. Sintering was carried out by the conventional heating method in a box furnace and in a hybrid multimode microwave furnace. XRD analysis revealed the precipitation of a spinel second phase (MnAl2O4) in manganese-doped samples as a result of manganese limited solubility in the corundum lattice. The addition of 0.1 wt% manganese was most beneficial in enhancing the densification of alumina (97.5% relative density when compared to 94.2% for the undoped sample), hindered grain growth, and improved the hardness of the ceramic when sintered at 1500 °C. The study also revealed that microwave sintering was effective in suppressing grain growth of alumina. In addition, the hardness was dependent on the sintered bulk density and that grain coarsening ensued as the density of the sintered alumina exceeded 95% of theoretical.

Effect of carbon nanotubes reinforcement on the mechanical properties of alumina and ZTA composites for ballistic application

Abstract Toughened and hardened alumina/carbon nanotubes and zirconia-toughened alumina (ZTA)/carbon nanotubes nanocomposites were developed by conventional ceramics route using pressureless sintering for the ballistic application. The multiwall carbon nanotubes (CNT) were functionalized with nitric acid oxidation reaction. Moreover, the surfactants sodium dodecyl sulphate and gum arabic were used to promote a homogeneous distribution of CNT in the ceramic matrix. Ceramic powders were prepared with pure alumina, alumina with the addition of 20 wt% of tetragonal zirconia/yttria, alumina/CNT and ZTA/CNT with the addition of 0.1 and 0.5 wt% of CNT. The morphology of nanocomposites was characterized by SEM-FEG. The mechanical properties of sintered samples were evaluated by flexural bending, Vickers microhardness and fracture toughness by SEVNB method. The addition of CNT in the ceramic and composite caused a general increase in densification, hardness, flexural strength and fracture toughness. ZTA composite with the addition of 0.1 wt% of CNT yielded the best results.

The influence of spinel and magnesia powder bed on mechanical properties of alumina sintered under air and nitrogen atmosphere

ABSTRACTThe aim of the present work was changing the surface properties of alumina ceramic via sintering of samples in spinel MgAl2O4 and magnesia MgO powder bed. During sintering nitrogen and air atmosphere were used; and the reference material was sintered at the same conditions but in an alumina powder bed. All samples were sintered to a density higher than 99.2% of theoretical density of alumina. In order to examine samples SEM, EDX and XRD (X-ray diffraction from 18 to 70 °2Theta) analysis were performed together with B3B flexural strength measurement. Results revealed that by sintering of alumina samples in a spinel powder bed pore-free surfaces were prepared, which had a favourable effect on B3B flexural strength. This was ascribed to the high solubility of Al3+ in spinel at sintering temperatures, which increases the sintering driving force. A further positive effect on B3B flexural strength was observed when samples were sintered in nitrogen instead of air.

Al2O3-TiB2 nanocomposite coating deposition on Titanium by Air Plasma Spraying

Titanium has low wear and corrosion resistance due to its low hardness. The corrosion and wear resistance of titanium are improved using various surface modification methods such as coating with sufficient materials. Al2O3 based microparticles’coatings have interesting mechanical properties. Mechanical properties of alumina can be improved with several techniques such as applications of alumina nanoparticles instead of microparticles and also adding ceramics such as TiB2. Air Plasma Spraying is a physical method for coating, which is one of the most commercial and economical coating techniques. The aim of this work is to coat TiB2-Al2O3 Nanocomposite on commercially pure titanium by Air Plasma Spraying method. Spraying process was operated at two steps. In this research, the effect of current on melting of TiB2-Al2O3Nanocomposite and microstructure of coatings was investigated. Surface characteristics were evaluated using Field Emission Scanning Electron Microscopy (FESEM(. The microstructure of the coatings consisted of two distinct regions and was completely melted and quenched as splats, and the other one was incompletely melted.

In-situ development of carbon nanotubes network and graphitic carbon by catalytic modification of phenolic resin binder in Al2O3–MgO–C refractories

In-situ formation of cross-linked carbon nanotubes network reinforced the refractory matrix and helps to improve the mechanical properties at elevated temperature. In this paper, the effect of modified phenol-formaldehyde (PF) resin binder on the various mechanical properties of alumina–magnesia–carbon (AMC) refractories was investigated. Initially, PF resin was modified by adding a different proportion of nickel catalyst. The AMC specimens (with the 7% carbon) were prepared by using 5% of modified PF resin. The pressed samples were cured at 180 °C for 24 h and characterized by XRD, Raman spectroscopy, and FE-SEM. The characterisation shows that, in-situ formation of graphitic carbon and carbon nanotubes network in the specimens due to modification of PF resin. In-situ formation of phases leads to enhancement of density and mechanical properties of refractory at elevated temperature due to the reinforcing effect.

Effect of Reinforcement on the Tribological Behavior of CuFe-Based Composites

Two types of CuFe matrix composites with different reinforcements: silica and alumina particulates were developed using powder metallurgy. The mechanical properties were determined from Brinell hardness and flexural strength. The dry sliding friction and wear performance of the composites were investigated by the friction test. The results indicated that mechanical properties of alumina were superior to those of silica. The friction tests of the composites showed that the alumina reinforcement particle provides better braking performance. A wear track examination of composites showed that same abrasive wear. Our results indicated that composites with alumina reinforcement particles of high compatibility are to be preferred for braking performance.

Measuring mechanical properties of plasma-sprayed alumina coatings by nanoindentation technique

AISI 1020 steel substrate is coated with alumina as feedstock material using plasma spraying process in order to correlate the microstructural features with mechanical properties of coating. The present work focuses on the effects of microstructural inhomogeneity on mechanical properties of alumina coating through nanoindentation technique. Young’s modulus and hardness of the alumina coating are analytically evaluated. Indentation stress–strain curves are generated from the experimentally obtained load–displacement curves to characterise the mechanical properties of the coating. The results have shown large variation in hardness and Young’s modulus of alumina due to microstructural inhomogeneity of the coating.

Effect of TiO<sub>2</sub> and MgO on Microstructure of α-Alumina Ceramics and its Sintering Behavior

Observation on the effect of adding titanium oxide (TiO2) and magnesium oxide (MgO) on the sintering of α-alumina (Al2O3) has been performed. In this study, technical alumina used as basic material in which the sample is formed by the pressureless sintering/cold press and sintered at 1500°C which is lower than alumina sintering temperature at 1700°C. Elemental analysis, observation of microstructure, hardness, fracture toughness and density measurements were carried out to determine the physical and mechanical properties of alumina. The results indicate a change in the microstructure where the content of the platelet structure are much more than the equilateral structure. At sintering temperature of 1500°C, neck growth occurs at ceramics grain, supported by the results of the density test which indicate perfect compaction has occurred in this process.