Mechanical Properties of Ceramics

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Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics

Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics

a function of the applied load. Both hardness and Young’s modulus decrease with increasing loads. Fur- thermore, it also indicates that there appears to be a larger decrease in the hardness than in the Young’s modulus with increasing load. These phenomena have been attributed to the well-known indentation size ef- fect. Gong et al. [14] studied an alumina ceramic by nanoindentation testing and found that more cracks were generated at higher loads. However, the absence of cracks in the vicinity of the indented zone (Figure 2) suggests that it should not be reasonable to explain the load-dependent mechanical properties of our nanostruc- tured transparent ceramics only by the indentation size effect. Dislocation activity, as evidenced in Figure 3, compared to HRTEM images of the sample at atmos- pheric pressure [11] should be considered as an import- ant factor that can influence the mechanical properties of nanostructured transparent ceramics. A more detailed study is clearly needed to understand how the disloca- tion activity influences the mechanical properties.
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Densification Behavior and Mechanical Properties of Cerium Oxide and Manganese Oxide doped Yttria Tetragonal Zirconia Polycrystals Ceramics for Dental Applications

Densification Behavior and Mechanical Properties of Cerium Oxide and Manganese Oxide doped Yttria Tetragonal Zirconia Polycrystals Ceramics for Dental Applications

Zirconia is known for excellent mechanical properties; hence it holds a unique place amongst all oxide ceramics. Zirconia impart transformation toughening, because zirconia maintains strength and chemical inertness. Besides, Yttria-stabilised tetragonal zirconia polycrystalline ceramics (Y-TZP) has been a very popular engineering material, as the mechanical properties is outstanding. Y-TZP has been widely used in many applications like engine parts, valves, cutting tools, and moulds. This is due to their good fracture toughness, high strength, elastic modulus, and wear resistance [1-3].
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Physico-Mechanical Properties of TiO2 Doped 45S5 Bioactive Glasses and Glass –Ceramics

Physico-Mechanical Properties of TiO2 Doped 45S5 Bioactive Glasses and Glass –Ceramics

through controlled crystallization of bioactive glasses. Nucleation and crystal Growth temp. Were determined by the parameters obtained from differential thermal analysis (DTA) of bioactive - glasses. The crystalline phases which are formed in bioactive glass - ceramics were recognized by using X - ray diffraction (XRD) study. The density of bioactive glass and glass - ceramic samples was obtained by Archimedes principle using distilled water as buoyant. The Mechanical properties like compressive strength and flexural strength of TiO2 doped bioactive glasses and glass – ceramics were measured. Experimental results show that a increase in glass nucleation and crystallization temperature of bioactive - glass by doping of TiO 2 in it and the formation of
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Investigation of Some Structural and Mechanical Properties of Ba0 5CaxSr0 5 xTiO3 Ceramics

Investigation of Some Structural and Mechanical Properties of Ba0 5CaxSr0 5 xTiO3 Ceramics

bigger than that of BCST ceramics in Figures 3(b)-(e) doped with Ca. This is in agreement with the work of [23] in which BST with x = 0.5 sample sintered at 1260˚C showed a large distribution of grain dimensions between 5 and 25 μm. Sub-micronic grains ≈ 0.90 μm, are located at the boundary of the largest ones as observed by [24]. Also, a less homogeneous microstructure, with an evi- dent bi-modal grain size distribution was pointed out by the SEM images (Figures 3(b)-(e)). Besides, large parti- cles, exaggerated smaller grains resulted by abnormal grain growth, were also noticed. The average values of particle size of studied ceramics, shown in Figure 4, were calculated from the micrographs of Figure 3 ac- cording to the selected intersected lines method [25]. However, the average particle size values which found from ESM micrographs were decreased from 3.81 µm to 1.69 µm with increasing of Ca content in the sample from x = 0.0 to x = 0.4, which are larger than those val- ues obtained for these grains as calculated by using Scherrer’s equation (see Figure 4). The dependence of grain size on Ca content, Figure 4, seems to be de- creased for both values determined from the X-ray and the SEM measurements. In other words, as the calcium content, x, increases in the ceramic from 0 to 0.4, the grain size is decreased in consistent with the A-site cation size effect reported in previous literature [18,19]. 4.3. Mechanical Properties Investigations 4.3.1. Room Temperature Characterization
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Effect of TiO2 on Crystallization and Mechanical Properties of Blast Furnace (BF) Slag Based Glass Ceramics

Effect of TiO2 on Crystallization and Mechanical Properties of Blast Furnace (BF) Slag Based Glass Ceramics

It is conceivable to plan glass ceramic production from metallurgical slag. A few aftereffects of planning glass ceramic from different slags have been presented by different researchers. Francis inquired about on the blast furnace slag derived glass ceramic and found different crystalline phases named diopside pyroxene, gehlenite, and barium aluminum silicate. Khater directed an examination concerning the glass ceramic from Saudi slag and observed the diopside crystalline phase at around 1120°C. Wang and Liang did research on glass ceramic developed from titanium slag and fly ash. Furthermore, it is no doubt understood that glass ceramics developed from different types of slags generally have great mechanical properties and in addition substance properties. Subsequently, the innovation to reuse metallurgical slag is discriminatingly essential to secure the earth as well as to give helpful material [3].
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The Influence of Sintering Temperatures on the Mechanical Properties of Glass Ceramics Made from Coal Fly Ash and Glass Waste

The Influence of Sintering Temperatures on the Mechanical Properties of Glass Ceramics Made from Coal Fly Ash and Glass Waste

In this study, glass ceramics composites made from the mixture between fly ash and glass waste powder. The glass waste powder was varied 0%, 10%, 20%, 30%, and 50%. Each mixture was uni-axially pressed using stainless steel molding with a compacting pressures of 130 MPa to produce green body. The green body was then sintered using pressureless sintering method with a heating rate of 5°C/min at various temperatures of 900, 950, 1000, 1050 and 1100°C for 2h. From the experimental result, it shows that the increase of glass waste powder contents in the composites tends to increase mechanical properties of glass ceramics product. The optimum properties of glass ceramics in this study were obtained from specimen with mixture ratio of 50% fly ash + 50% glass waste with compacting pressure of 130 MPa. The maximum hardness of 2205 MPa and density of 2.03 g/cm³ is obtained in the 50FA-50GL specimen with sintering temperature of 1100°C while the maximum bending strength of 45 MPa is obtained in the specimen with sintering temperature of 1050°C. The presence of crystalline phases in the glass ceramic specimen is highly varied based on the composition of green body before sinter. The major crystalline phases are found in the glass ceramics specimen corresponds to quartz (SiO 2 ), mullite syn. (Al 4.64 Si 1.36 O 9.68 ), Hematite (Fe 2 O 3 ), Albite Ca-rich [(Na,Ca)Al(Si,Al) 3 O 8 ], MAPO-20 syn. (C 8 H 24 Al 4 Mg 2 N 2 O 24 P 6 ), and enstatite (Mg 1.83 Fe 0.17 Si 2 O 6 ).
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Change in Mechanical Properties of Ion Irradiated Ceramics Studied by Nanoindentation

Change in Mechanical Properties of Ion Irradiated Ceramics Studied by Nanoindentation

Changes in hardness of several representative ceramics and semiconductors associated with ion irradiation were systematically studied using a combination of nanoindentation and finite element analysis. We established a new method for obtaining the precise hardness of the embedded damaged layer of ion-irradiated samples. The method was applied to silicon carbide, -quartz, silica glass and silicon, which enabled us to semi-quantitatively discuss changes in their mechanical properties with irradiation-induced structural changes on the basis of experimentally obtained material parameters. Finally, we propose a new atomistic mechanism for plastic deformation of covalent amorphous materials. The present results will provide a standard framework for discussing mechanical property changes in ceramics with energetic particle irradiation.
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Mechanical properties of ceramics tiles by replacement of quartz by RHA and POFA

Mechanical properties of ceramics tiles by replacement of quartz by RHA and POFA

The addition of fly ash and blast furnace slag in a traditional triaxial porcelain composition in the proportion of 1:1 and 1:2 has been studied by Dana and Das (2005). It was found to be beneficial towards improvement in mechanical strength and early vitrification at 1175 °C. Presence of microcrystalline components of quartz and mullite in fly ash and alkaline earth oxides in blast furnace slag were responsible to develop anorthite and mullite phases which ultimately improved the mechanical strength. They stressed that such type of synergistic porcelain composition may find potential applications to manufacture high strength ceramic floor tiles for industrial as well as domestic buildings. Further, part substitution of natural minerals (quartz and feldspar) by overburden industrial by-products (fly ash and blast furnace slag) reduce the cost of raw materials, thermal energy without altering the requisite physico-mechanical properties.
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Effects of Cr3C2 and V8C7 on the Microstructure and Mechanical Properties of WC SiC Whisker Ceramics

Effects of Cr3C2 and V8C7 on the Microstructure and Mechanical Properties of WC SiC Whisker Ceramics

decrease in Young’s modulus. This trend was similar to that observed for the bulk density in Fig. 1. For ceramics with relatively low porosity, the Young’s modulus decreased linearly with increasing porosity. Changes in Young’s moduli with the bulk density are shown in Fig. 6. The slope of the plot in Fig. 6 approximates the calculated slope based on porosity. Consequently, changes in the Young’s modulus as a function of GGI content reflect the effect of the GGI addition on sinterability.

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Mechanical Properties of Dental Zirconia Ceramics Changed with Sandblasting and Heat Treatment

Mechanical Properties of Dental Zirconia Ceramics Changed with Sandblasting and Heat Treatment

As listed in Table 1, two types of TZP ceramics were  used  in  this  study.    CZA  powder  was  processed  by  cold  isostatic  pressing  method  into  a  cylindrical  rod,  19.5  mm  in  diameter  and  100  mm  in  length.    After  peeling  of  the  rod  surface  and  firing  at  1450 ℃   for  two  hours,  disk-shaped  specimens  of  two  sizes,  14  mm  in  diameter/2  mm  in  thickness  and  15  mm  in  diameter/0.5  mm  in  thickness,  were  prepared  by  cutting and grinding with a 400-grit diamond wheel.    Conventional Y-TZP was used for comparison in  this  study.    Its  powder  was  pressed  using  the  same  method.    After  firing  at  1350 ℃   for  six  hours,  disk- shaped  specimens  of  two  sizes  were  prepared  in  the  same manner as CZA.
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Improved Mechanical Properties of Al2O3 Ceramics by Sputtered TiN Coatings

Improved Mechanical Properties of Al2O3 Ceramics by Sputtered TiN Coatings

The growth rate and thickness of TiN film were measured by an α-step profilometer. Surface morphologies of samples can be demonstrated by scanning electron microscopy (SEM). The element distributions on the sample surface were characterized using SEM elemental mapping tech- nique. The compositional analyses of samples were deter- mined by energy dispersive x-ray spectroscopy (EDS). Me- chanical properties of samples were conducted to various experiments such as tribological (friction and wear) and scratch tests. Friction and wear tests both were carried out on a pin-on-disk machine. In this equipment, the tungsten carbide (WC) ball with a diameter of 10 mm was served as the pin. The samples were tested against WC balls at room temperature. In these pin-on-disk tests, normal load, linear sliding speed, sliding distance and relative humidity were kept at 2 N, 2 cm/s, 200 m and 50%, respectively. Through the experiments, the relationship between the friction coeffi- cient of sample and the sliding distance can be investigated. Besides, after the wear tests with the sliding ball, SEM was used to observe the wear tracks. On the other hand, the scratch test is employed to estimate the adhesive characteris- tics of the coated TiN films. During the scratch test, a dia- mond stylus with a tip radius of 0.2 mm was loaded against the coated sample. The loading rate and horizontal displace- ment rate were fixed at 100 N/min and 10 mm/min, respec- tively. The load at which such appreciable failure occurs in the coated sample is defined as the critical load (L c ). The L c
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The sintering, microstructural analysis and mechanical properties of two β' MgSiAlON ceramics

The sintering, microstructural analysis and mechanical properties of two β' MgSiAlON ceramics

University of Warwick institutional repository: http://go.warwick.ac.uk/wrap A Thesis Submitted for the Degree of PhD at the University of Warwick http://go.warwick.ac.uk/wrap/2823 This [r]

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Microstructure and Mechanical Properties of W C B Ceramics Containing VC

Microstructure and Mechanical Properties of W C B Ceramics Containing VC

composite. W-C-B ceramics with good mechanical proper- ties were obtained at an x value of 80, in which the composition in the reaction equation was 95 mol% WC. This ceramic was still more sinterable than WC, and WC grains grew easily during sintering. 7) However, the grain growth reduced hardness considerably. As a result, the appropriate sintering temperature range for obtaining a fine-grain body was very narrow. To widen the temperature range, the grain growth must be suppressed. A candidate grain-growth

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Experimental Investigations of Mechanical Characteristics and Tribological Mechanisms of Nanometric Zirconia Dental Ceramics

Experimental Investigations of Mechanical Characteristics and Tribological Mechanisms of Nanometric Zirconia Dental Ceramics

planting material [5, 6]. Besides, it favors the bond between the soft gum tissue at the cervical margin and the implant, the reduction of dental plaque aggregation and the health of the implant and surrounding soft tissue. As a bone replacing material, zirconia ceramics can form close chemical bond with the bone tissue in the organism and has excellent biocompatibility and biological activity. Ever since it came out as a novel biological material in 1970s, it has become the most promising material for replacing hard tissue. However, its high fragility and low strength restricted its application in the weight-bearing parts in the human body, so the selective addition of second-phase particles and whiskers as well as other methods were adopted to improve its mechanical properties. Xu Shuhua and Huang Chuanyong also made studies on the microstructures and properties of HA-ZrO 2
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Effects of ZnO nanoparticulate addition on the properties of PMNT ceramics

Effects of ZnO nanoparticulate addition on the properties of PMNT ceramics

ZnO is known to have semiconductive properties and is now used in some electronic devices. It was found to improve sensitivity in materials used for sensing devices. Apart from this, the role of ZnO as a sintering aid in the sintering process was previously observed in ferro- electric ceramics such as PZT and PZT-BLT [9,10]. Moreover, addition of a ZnO nanoparticulate into these material systems also enhanced the hardness and frac- ture toughness of the ceramics. In this study, the ZnO nanoparticulate was thus selected as an additive for PMNT ceramics to improve mechanical properties, while dielectric and ferroelectric properties of the cera- mics were expected to be maintained. Effects of the ZnO concentration on the phase, microstructure, and mechanical and electrical properties of PMNT ceramics were investigated and discussed.
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Influence of Additives and Hot Press Sintering on Mechanical and Lipophilic Properties of Silicon Nitride Ceramics

Influence of Additives and Hot Press Sintering on Mechanical and Lipophilic Properties of Silicon Nitride Ceramics

4.1 Microstructure obtained by hot-press sintering The microstructures of each specimen were observed in order to clarify the mechanism of the improvement of mechanical properties (especially strength), the decrease of the contact angle of oil and the reduction of the coefficient of friction by hot-press sintering. Figure 2 shows the typical microstructure of FM and FM HP specimens as observed by

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Microstructure, mechanical and thermal properties of chalcogenide glasses and glass-ceramics based on Se-As-Ge system nucleated by Sn

Microstructure, mechanical and thermal properties of chalcogenide glasses and glass-ceramics based on Se-As-Ge system nucleated by Sn

Chalcogenide glasses are semiconductor materials that are oxygen-free and have been considered by many researchers because of their high transmittance in the IR region and military and civilian applications. They are also a good candidate as an alternative to the thermal cameras. IR transparency of these glasses is generally reported in the wavelength range of 1-12μm [1-5]. High nonlinear refractive index and low phonon energy are the other characteristics of chalcogenides. Refractive index and transparency range of these glasses are dependent on the composition [5]. Due to their unique optical and physical properties, chalcogenide glasses have been considered as promising materials for mid- infrared (IR) optics such as amplifiers, thermal imaging and chemical sensors [6-10]. However, chalcogenide glasses have poor mechanical properties compared to mono or polycrystals that are regularly utilized in the infrared industry so that limit application areas of chalcogenide glasses [11]. Improving mechanical properties of mid and far IR passing glasses is very
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Thermoelectric Properties of Inhomogeneous Ceramics Based on the Layered Calcium Cobaltate

Thermoelectric Properties of Inhomogeneous Ceramics Based on the Layered Calcium Cobaltate

Their crystal structure, microstrucrture, electrical conductivity, thermo-EMF coefficient, and power factor in air within 25−800°C were investigated. It had been found that increase of cobalt oxide content in the samples led to the increasing of their electrical conductivity, the creation of phase inhomogeneity in ceramics (by both varying of their cationic composition and by heat treatment at temperatures above temperature of peritectoid decomposition) improves its thermo-EMF coefficient, which, in the whole, improves thermoelectric properties of ceramics based on the layered calcium cobaltate Ca 3 Co 4 O 9+δ . So, power factor values of phase and
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The electrical properties and structure of halo borate glasses and glass ceramics

The electrical properties and structure of halo borate glasses and glass ceramics

levels sodium ion vacancy production occurs and the resistivity is' drastically reduced, at higher levels halide interstitials occur , and the rate of resistivity reduction is not mainta[r]

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The electrical and other physical properties of haloborate glasses and glass ceramics

The electrical and other physical properties of haloborate glasses and glass ceramics

For many years the understanding o f the polishing mechanism follow ed similar reasoning. The microscopic 'ridges* were thought to Sow into the trou ghs', creating regions o f a n ew material phase, as indicated in Figure 2J2A. This is known as the Beilby layer. A fairly recen t article [166] has examined the polishing mechanism in m ore depth for a selection o f optica l by conducting an investigation o f the variation in removal depth with changes in softening temperature, resistance to chemical attack and micro-hardness. Since the removal rate was not seen to be a strong function o f softening temperature or chemical resistance Izumitani re jected the flow and plastic deformation theories. However, the concept o f the Bcilby layer was ad opted since it explained the reappearance o f surface scratches on a highly polished surface when lightly etched, which would also appear consistent with the plastically-deformed sub-surface idea. The conclusions made from this work indicate the principal material removal mechanism to be the creation o f a ’ soft* surface layer b y the action o f the lubricant employed, which can subsequently be more easily removed by abrasion. T h e author is in little doubt that the ab ove results and conclusions are sound, but feels that the argument may obscure a full description o f the surface after polishing, since this work unfortunately did not examine the surface properties after preparation with the same rigour as the behaviour during polishing.
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