Effect of high thermal expansion glass infiltration on mechanical properties of alumina-zirconia composite (original) (raw)
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Mechanical properties of MgO–Al 2O 3–SiO 2 glass-infiltrated Al 2O 3–ZrO 2 composite
Journal of Materials Processing Technology, 2009
This work attempts to improve the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating a glass (magnesium aluminum silicate glass) of lower thermal expansion on the surface at high temperature. The glass improved the strength of the composite at room temperature as well as at higher temperatures. There was a significant improvement in the Weibull modulus after the glass infiltration. Glass-infiltrated samples showed better thermal shock resistance. The magnitude of strength increment was found to be in the order of the surface residual stress generated by thermo-elastic properties mismatch between the composite and the infiltrated glass.
Various electrolyte materials for solid oxide fuel cells were fabricated by hot pressing 10 mol % yttriastabilized zirconia (10-YSZ) reinforced with two different forms of alumina-particulates and platelets-each containing 0 to 30 mol % alumina. Flexure strength and fracture toughness of platelet composites were determined as a function of alumina content at 1000 °C in air and compared with those of particulate composites determined previously. In general, elevated-temperature strength and fracture toughness of both composite systems increased with increasing alumina content. For a given alumina content, flexure strength of particulate composites was greater than that of platelet composites at higher alumina contents (≥20 mol %), whereas, fracture toughness was greater in platelet composites than in particulate composites, regardless of alumina content. The results of slow crack growth (SCG) testing, determined at 1000 °C via dynamic fatigue testing for three different composites including 0 mol % (10-YSZ matrix), 30 mol % particulate and 30 mol % platelet composites, showed that susceptibility to SCG was greatest with SCG parameter n = 6 to 8 for both 0 mol and 30 mol % particulate composites and was least with n = 33 for the 30 mol % platelet composite.
Materials Sciences and Applications, 2017
Alumina-Zirconia (Al 2 O 3-ZrO 2) composites especially Zirconia Toughened Alumina (ZTA) shows better mechanical properties over alumina. Al 2 O 3-ZrO 2 composites were prepared by powder compaction method varying 3 mol% yttria stabilized zirconia (3Y-ZrO 2) content from 0 to 20 vol% using small amount of MgO as sintering aid. The composites were sintered for two hours in air at 1580˚C. At this temperature maximum density was achieved 99.31% of theoretical density for composite containing 20 vol% 3Y-ZrO 2. Density measurement of sintered composites was carried out using Archimedes's method. Hardness and fracture toughness measurement was carried out using Vickers indentation. Phase content and t-ZrO 2 retention were detected by means of X-ray diffraction (XRD). Microstructure of the composites and grain size of alumina and zirconia was determined by Scanning Electron Microscopic (SEM) analysis. Maximum microhardness (17.46 GPa) was achieved for composite containing 5 vol% ZrO 2 and maximum flexural strength (684.32 MPa) and fracture toughness (10.33 MPam 0.5) was achieved for composite containing 20 vol% of 3Y-ZrO 2. The aim of the present work is to investigate the optimum 3Y-ZrO 2 content for obtaining maximum density, microhardness, flexural strength and fracture toughness of Al 2 O 3-ZrO 2 composites.
IJERT-Structural and Mechanical Properties of Zirconia Toughened Alumina (ZTA) Composites
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/structural-and-mechanical-properties-of-zirconia-toughened-alumina-zta-composites https://www.ijert.org/research/structural-and-mechanical-properties-of-zirconia-toughened-alumina-zta-composites-IJERTV3IS20451.pdf The Zirconia toughened Alumina (ZTA) composites with 0-16 wt % of ZrO 2 were prepared by slurry method and sintered at temperature (T s) 1500°C and 1600°C for 2 hours. The density, porosity, structural properties and mechanical properties of Al 2 O 3-ZrO 2 composites with respect to ZrO 2 content as well as sintering temperature have been explored in the present work. About 2% higher density of 16 wt % ZTA has been achieved and the microstructures are highly homogeneous and finer with less porosity when compared to pure Al 2 O 3. The surface morphology of the samples was studied by using SEM. The effect of zirconia content on hardness and elastic modulus were investigated. At 1500°C, maximum hardness shows 15.79 GPa and at 1600°C, it is 19.76 GPa, which is observed for pure Alumina. However, at same temperatures, minimum hardness shows 11.24 GPa and 12.96 GPa, respectively, that is observed for 16 wt% ZrO 2. Elastic modulus also shows same behaviour as shown for hardness. Flexural strength increases with the increase of both zirconia content and sintering temperature. The approach adopted in the present study may provide an alternative to design Al 2 O 3-ZrO 2 composites with improved mechanical properties.
Materials, 2013
Alumina-zirconia (AZ) composites are attractive structural materials, which combine the high hardness and Young's modulus of the alumina matrix with additional toughening effects, due to the zirconia dispersion. In this study, AZ composites containing different amounts of zirconia (in the range 5-20 vol %) were prepared by a wet chemical method, consisting on the surface coating of alumina powders by mixing them with zirconium salt aqueous solutions. After spray-drying, powders were calcined at 600 °C for 1 h. Green bodies were then prepared by two methods: uniaxial pressing of spray-dried granules and slip casting of slurries, obtained by re-dispersing the spray dried granulates. After pressureless sintering at 1500 °C for 1 h, the slip cast samples gave rise to fully dense materials, characterized by a quite homogeneous distribution of ZrO 2 grains in the alumina matrix. The microstructure, phase composition, tetragonal to monoclinic transformation behavior and mechanical properties were investigated and are here discussed as a function of the ZrO 2 content. The material containing 10 vol % ZrO 2 presented a relevant hardness and exhibited the maximum value of K I0 , mainly imputable to the t → m transformation at the crack tip.
Alumina-Reinforced Zirconia Composites
Handbook of Ceramic Composites, 2005
Alumina-reinforced zirconia composites, used as electrolyte materials for solid oxide fuel cells, were fabricated by hot pressing 10 mol% yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina-particulates and platelets-each containing 0 to 30 mol% alumina. Major mechanical and physical properties of both particulate and platelet composites including flexure strength, fracture toughness, slow crack growth, elastic modulus, density, Vickers microhardness, thermal conductivity, and microstructures were determined as a function of alumina content either at 25 °C or at both 25 and 1000 °C. Flexure strength and fracture toughness at 1000 °C were maximized with 30 mol% particulate and 30 mol% platelet composites, respectively, while resistance to slow crack growth at 1000 °C in air was greater for 30 mol% platelet composite than for 30 mol% particulate composites.
Synthesis and Analysis of Alumina, Zirconia and Alumina- Toughened-Zirconia Composites
2015
Composite materials are being increasingly used in automotive engineering, aerospace development, marine technology, electronic devices, construction industries and medical field. In this paper synthesis and analysis of the properties of alumina, zirconia and alumina-toughened zirconia. Alumina-toughened-zirconia is a ceramic material comprising alumina and zirconia. It is a composite ceramic material with alumina grain in the zirconia matrix (in this project 10% alumina and 90% zirconia is the composition for alumina toughened zirconia). In this project we aim at studying the mechanical properties of alumina-toughened zirconia so that its use as a composite material could be justified in the ongoing researches. Billets of alumina,zirconia and alumina-toughened zirconia are synthesized by the application of powder metallurgy process. The micro-structural ceramic powder is first blended with polyvinyl alcohol and this mixture is cold compressed to form green compact. The compact mate...
Thermomechanical properties and microstructure of aluinina-zirconia
Bulletin of Materials Science, 1992
AI,Os~ZrO= composites were prepared in two compositional ranges, 15 ~t/o' o/ ZrO2 and 29 wt,~ ZrO~ with or without yttria or magnesia stabilizers. While 1.5 wt% Y2Oa. produced tetragonal ZrO 2 and fine grain mierostrueture, the 4.5 wt~ Y20 s developed cubic and tetragonaI Zr02 with similar minrostrueture. AI=O~ with 29.5 wt~ ZrO_,-1.5 wt~ Y2Os composition had the highest strength (3,300 kg./cm 2 I. The beading sf:rength remained more nr less ~he same after tllc 6rs~ thermal shock, and then it decreased gradually, but retained some strength after 20 cycles of quench. The toad vs displacement curve became nonlinear alter thermal shock possibly because of formation of microcracks which could be seen by microstructural Sttld[es. Ke).words~ Alumina-zlreonia composites; thermal shock resistance; microcracks; inelasticity.
Glass alumina composites for functional and structural applications
Ceramics International, 2019
SiO 2-Al 2 O 3-CaO based glass was mixed with Al 2 O 3 at various ratios to fabricate composites for functional and structural applications such as substrate, low temperature co-fired ceramics and radomes, which necessitates a thorough characterization of mechanical, thermal and dielectric properties. The optimum densification temperatures decreased from 1350°C (20 wt% glass) to 1200°C (40 wt% glass), and to 850°C (50-60 wt% glass) due to liquid phase sintering for the samples with 20 and 40 wt% glass, and viscous sintering for the samples with 50-60 wt% glass. Main phase was Al 2 O 3 as well as anorthite crystallized after 825°C. Glass addition decreased the mechanical properties such as Young's modulus from 231 GPa (20 wt% glass) to 105 GPa (60 wt% glass), flexural strength from 387 MPa (20 wt% glass) and 213 MPa (60 wt% glass). Dielectric constant and dielectric loss of the composites with 20-60 wt% glass were 8.76-7.32 and 0.0022-0.0081 at 5 MHz, respectively. Thermal expansion coefficient also decreased with increasing glass content from 7.72 ppm/°C (20 wt% glass) to 6.66 ppm/°C (60 wt % glass). The composites with 50-60 wt% glass were suitable for substrate and low temperature co-fired ceramic applications due to lower densification temperatures (< 950°C), lower dielectric properties together with optimized mechanical and thermal properties. The composite with 55 wt% glass was then successfully fabricated by tape casting and co-fired with silver electrode, without any additional phase formation and shape distortion. In addition, the composites with 20 and 40 wt% glass were promising candidates for structural radome applications to be used at high temperatures due to their low thermal expansion coefficient and Young's modulus together with low dielectric properties.
Cerâmica, 2013
This work reports on the characterization of ZrSiO 4 particulate-reinforced Li 2 O-ZrO 2 -SiO 2 -Al 2 O 3 (LZSA) glass-ceramic matrix composites. The typical physical/mechanical and chemical properties of the glass batches and the composites were measured. A composition with 60 wt.% ZrSiO 4 was preliminarily selected because it demonstrated the highest values of bending strength (190 MPa) and deep abrasion resistance (51 mm 3 ). To this same composition was given a 7 wt.% bentonite addition in order to obtain plasticity behavior suitable for extrusion. The sintered samples (1150 °C for 10 min) presented a thermal linear shrinkage of 14% and bending strength values of 220 MPa.