Effect of Al2O3 Addition on Microstructure, Thermal Expansion and Mechanical Properties of Ta2O5 Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 631-634 ◽  
Author(s):  
Jian Er Zhou ◽  
Jing Zhang ◽  
Xiao Zhen Zhang ◽  
Xue Bing Hu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Phase Transformation ◽  
Mechanical Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Minor Phase ◽  
Α Phase ◽  
Dry Pressing

The Ta2O5-based ceramics were prepared by dry pressing/sintering technique using Ta2O5and Al2O3as the starting materials. The present work investigated the effect of alumina (Al2O3) additions on the composition, microstructure, thermal expansion coefficient (TEC) and bending strength of Ta2O5ceramics. The thermal expansion of the samples was measured by the dilatometry method. It was found that Al2O3additions can effectively inhibit the β to α phase transformation in Ta2O5ceramics. Orthorhombic AlTaO4as the minor phase formed when 2.5 and 7.0 wt% Al2O3was added. The addition of Al2O3results in obvious change of TEC and an increase of bending strength. This work demonstrated that the addition of Al2O3is an effective way to modify the TEC and mechanical strength of Ta2O5ceramics.

Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 123-125 ◽  
Author(s):  
Yong Li ◽  
Qi Hong Wei ◽  
Ling Li ◽  
Chong Hai Wang ◽  
Xiao Li Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Heat Treatment Temperature ◽  
Bending Strength ◽  
Sol Gel ◽  
Negative Thermal Expansion ◽  
Treatment Temperature ◽  
Heat Treated

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.

In Situ Formation of Mullite-Al2O3 Refractory Ceramic from Al-Matrix Mixtures

2014 ◽  
Vol 602-603 ◽  
pp. 628-631
Author(s):  
Xing Yong Gu ◽  
Ping Li ◽  
Wei Xia Dong ◽  
Ting Luo
Keyword(s):  
Thermal Expansion ◽  
Bulk Density ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Potential Effect ◽  
Apparent Porosity ◽  
Mullite Phase ◽  
Two Samples

Two types of mullite-Al2O3 composites were designed and sintered in situ from different composition containing Al composites e.g. kaolin, alumina hydroxide and calcined bauxite etc, and auxiliary additives. The phase composition and microstructure were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Bulk density, apparent porosity, thermal expansion coefficient and bending strength were also measured. The two samples exhibited XRD reflections characteristic of alumina and mullite phases. The amount of these phases depended on starting batch compositions, and reaction of starting and auxiliary materials together to form mullite. Because of in-situ formation of mullite fiber, the bulk density and bending strength were improved and apparent porosity was decreased for the composites with uniform microstructure. The presence of high mullite phase was found to decrease the thermal expansion coefficient. The potential effect of these morphologies and phase on properties was discussed. These mullite-Al2O3 composite was expected to have major applications in the areas of refractory material.

Synthesis and Characteristics of Porous Silicon Carbide Ceramic Reinforced by Silicon Carbide Whiskers

2014 ◽  
Vol 602-603 ◽  
pp. 397-402 ◽  
Author(s):  
Xiao Xue Liu ◽  
Hong Sheng Zhao ◽  
Hui Yang ◽  
Kai Hong Zhang ◽  
Zi Qiang Li
Keyword(s):  
Silicon Carbide ◽  
Thermal Expansion ◽  
Porous Silicon ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Silicon Powder ◽  
Fluid Filtration ◽  
Porous Silicon Carbide ◽  
Silicon Carbide Ceramics

Silicon powder and phenolic resin were used as raw materials to produce porous silicon carbide (SiC) ceramics, with SiC whiskers (SiCw) as reinforcement additionally. Starting with the preparation of core-shell structure precursor powder through coat-mix method, and then by carrying out molding, carbonization and sintering processes, SiCw/SiC ceramic examples were produced. The phase composite, fracture surface morphology, pore size and porosity, bending strength and thermal expansion coefficient of the final product were measured. Results show that the addition of SiCw apparently improved the intensive property of the products and the changing pattern were quantitatively analyzed; while little influence was observed on some other properties such as phase composition and thermal expansion coefficient. It means that SiCw can strengthen porous silicon carbide ceramics without weakening their thermal properties, which is particularly important because of its application in the field of high temperature fluid filtration. Incorporated SiCw is supposed to work in accordance with some toughening mechanism such as load transferring and matrix prestressing. Microstructure, pore evaluation and weight loss rate during carbonation and sintering were also noted to describe the procedure better.

scholarly journals Measurement of Mechanical and Thermal Strains by Optical FBG Sensors Embedded in CFRP Rod

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Keunhee Cho ◽  
Sung Tae Kim ◽  
Young-Hwan Park ◽  
Jeong-Rae Cho
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Strain Sensor ◽  
Thermal And Mechanical Properties ◽  
Fbg Sensor ◽  
Thermal Test ◽  
Fbg Sensors ◽  
Thermooptic Coefficient

The present study intends to provide the photoelastic coefficient and thermal expansion coefficient needed to use an FBG-embedded CFRP rod (smart rod) as strain sensor. Due to the monolithic combination of the FBG sensor with a CFRP rod, the smart rod is likely to exhibit thermal and mechanical properties differing from those of the bare FBG sensor. A tensile test showed that the photoelastic coefficient of the smart rod is 0.204, which is about 7.3% lower than the 0.22 value of the bare optical FBG. Moreover, the thermal expansion coefficient of the smart rod obtained through a thermal test appeared to be negative with a low value of −0.190×10−6/°C. Consequently, the temperature dependence of the smart rod is mainly expressed by means of the thermooptic coefficient. Compared to the bare FBG sensor, the smart rod is easier to handle and can measure compressive strains, which make it a convenient sensor for various concrete structures.

scholarly journals Magnesium Reinforced with Inconel 718 Particles Prepared Ex Situ—Microstructure and Properties

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 798
Author(s):  
Zuzanka Trojanová ◽  
Zdeněk Drozd ◽  
Pavel Lukáč ◽  
Peter Minárik ◽  
Gergely Németh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Internal Friction ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Inconel 718 ◽  
Hot Extrusion ◽  
Fiber Texture ◽  
Ex Situ ◽  
Tension And Compression

Magnesium samples reinforced with 0.7, 1.4, and 2.4 vol.% of Inconel 718 particles were prepared using a disintegrated melt deposition technique followed by hot extrusion. Mechanical properties, thermal expansion, and damping were studied with the aim of revealing the particle influence on the microstructure, texture, tensile and compressive behavior, thermal expansion coefficient, and internal friction. The flow stresses are significantly influenced by the test temperature and the vol.% of particles. A substantial asymmetry in the tensile and compressive properties was observed at lower temperatures. This asymmetry is caused by different deformation mechanisms operating in tension and compression. The fiber texture of extruded composite samples, refined grain sizes, and the increased dislocation density improved the mechanical properties. On the other hand, a decrease in the thermal expansion coefficient and internal friction was observed.

Specific Mechanical Properties of New Hybrid Laminates with Thermoplastic Matrix and a Variable Metal Component

2015 ◽  
Vol 825-826 ◽  
pp. 344-352 ◽  
Author(s):  
Daisy Nestler ◽  
Heike Jung ◽  
Sebastian Arnold ◽  
Bernhard Wielage ◽  
Guntram Wagner
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Carbon Fibre ◽  
Aluminium Alloy ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Glass Fibre ◽  
Reinforced Plastics ◽  
Hybrid Laminates ◽  
Reinforced Thermoplastics

Hybrid laminates combine the positive properties of metals and fibre reinforced plastics. Thereby, the relatively free selectable components provide further benefits. Especially thermoplastic matrices offer positive aspects like the possibility of deformation, recyclability as well as the possibility of mass production. To obtain such hybrid laminates the first step is the production of pre-consolidated unidirectional endless fibre reinforced thermoplastic foils. In a second step, these pre-impregnated fibre-foil tapes were alternating thermally pressed with metallic layers in tailored compositions. To use the full capacity of the hybrid laminates an adequate interface between the fibre reinforced thermoplastics and the metallic foil is essential. Different investigations of the authors display the principle possibility to produce hybrid laminates with carbon endless fibre reinforced thermoplastics and aluminium alloy foils. Nevertheless, load free delamination’s occurs. The reason for these delaminations within the interface of the fibre reinforced thermoplastics and the metallic foil are the differences in the thermal expansion coefficient of the components. Caused by the consolidation at elevated temperatures these differences become more significant and reduce the reproducibility of the hybrid laminates. To minimize these thermal induced stresses the graduation of the thermal expansion coefficient is one possibility. This graduation is possible by utilising glass fibre thermoplastic tapes between the aluminium alloy foil and the carbon fibre reinforced thermoplastics. Further investigations are dealing with so called expansion alloys to adapt the thermal expansion coefficient. The latter approach provides the benefit to utilize the full mechanical properties of the carbon fibre reinforced thermoplastics and to economize the glass-fibre tapes. Nevertheless, these expansion alloys are characterized by a high density. Hence, within this contribution the specific mechanical properties as well as the advantages and disadvantages of hybrid laminates with expansion alloys or aluminium alloys with glass-fibre thermoplastics interlayers are discussed and assessed. These specific mechanical properties display the potential of the expansion alloy in spite of the high density by means of comparable values. The sample only consisting of carbon fibre reinforced plastics highlights the great variety and possibilities of different hybrid laminate structures and combinations regarding the thickness and positioning of the component layers.

Use of Natural Hydroxyapatite for Coating of Titanium for Implantation

2000 ◽  
Author(s):  
Subrata Pal ◽  
Santosh N. Shinde ◽  
Sukumar Roy
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Corrosion Resistance ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Natural Hydroxyapatite

Abstract It is welknown that titanium is the best biocompatiable metal available till date. Since commercially pure titanium (cpTi) has satisfactory mechanical properties, including sufficient ductility, together with a thermal expansion coefficient similar to that of hydroxyapatite, corrosion resistance and blood and tissue compatible behavior, it was selected for coating with hydroxyapatite.

Sign in / Sign up

Export Citation Format

Share Document