scholarly journals Mechanical Properties of Gelcast Cerium Dioxide From 23 to 1500 °C

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Stephen J. Sedler ◽  
Thomas R. Chase ◽  
Jane H. Davidson
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Cerium Dioxide ◽  
Porous Ceramic ◽  
Specimen Size ◽  
Strength Data ◽  
Lower Porosity ◽  
Solid Area

This work reports the elastic modulus and four-point flexural strength of a gelcast ceramic, cerium dioxide (ceria), with a microporosity of nominally 20% and a grain size of 11 μm from 23 to 1500 °C. The data augment the sparse data published for ceria and extend previous results by 150 °C. The ceria tested is representative of that constituting the ligaments of a reticulated porous ceramic. The elastic modulus decreases from 90 GPa at 23 °C to 16 GPa at 1500 °C. The flexural strength is 78 MPa below 900 °C and then decreases rapidly to 5 MPa at 1500 °C. These trends are consistent with data reported for other ceramics. Comparing the measured elastic modulus to prior data obtained for lower porosity shows the minimum solid area (MSA) model can be used to extend the modulus data to other porosities. Similarly, the flexural strength data agree with prior data when the effects of specimen size, porosity, and grain size are taken into account.

scholarly journals Assessment of the Rheological and Mechanical Properties of Geopolymer Concrete Comprising Fly Ash and Fluid Catalytic Cracking Residue as Aluminosilicate Precursor

2021 ◽  
Vol 11 (7) ◽  
pp. 3032
Author(s):  
Tuan Anh Le ◽  
Sinh Hoang Le ◽  
Thuy Ninh Nguyen ◽  
Khoa Tan Nguyen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Flexural Strength ◽  
Catalytic Cracking ◽  
Fluid Catalytic Cracking ◽  
High Alumina ◽  
Geopolymer Concrete ◽  
Sem Images

The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.

scholarly journals Fabrication of (SiC-AlN)/ZrB2 Composite with Nano-Micron Hybrid Microstructure via PCS-Derived Ceramics Route

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 334
Author(s):  
Aidong Xia ◽  
Jie Yin ◽  
Xiao Chen ◽  
Zhengren Huang ◽  
Xuejian Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Raw Materials ◽  
Secondary Phase ◽  
Pressing Temperature ◽  
Xrd Pattern ◽  
Mean Grain Size ◽  
The Mean

In this work, a (SiC-AlN)/ZrB2 composite with outstanding mechanical properties was prepared by using polymer-derived ceramics (PDCs) and hot-pressing technique. Flexural strength reached up to 460 ± 41 MPa, while AlN and ZrB2 contents were 10 wt%, and 15 wt%, respectively, under a hot-pressing temperature of 2000 °C. XRD pattern-evidenced SiC generated by pyrolysis of polycarbosilane (PCS) was mainly composed by 2H-SiC and 4H-SiC, both belonging to α-SiC. Micron-level ZrB2 secondary phase was observed inside the (SiC-AlN)/ZrB2 composite, while the mean grain size (MGS) of SiC-AlN matrix was approximately 97 nm. This unique nano-micron hybrid microstructure enhanced the mechanical properties. The present investigation provided a feasible tactic for strengthening ceramics from PDCs raw materials.

scholarly journals Influence of Different Concentration and Ratio of a Photoinitiator System on the Properties of Experimental Resin Composites

2017 ◽  
Vol 28 (6) ◽  
pp. 726-730 ◽  
Author(s):  
Caio Vinícius Signorelli Grohmann ◽  
Eveline Freitas Soares ◽  
Eduardo José Carvalho Souza-Junior ◽  
William Cunha Brandt ◽  
Regina Maria Puppin-Rontani ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Tertiary Amine ◽  
Water Sorption ◽  
Water Solubility ◽  
Distilled Water ◽  
Resin Composites ◽  
Amine Concentration ◽  
One Way Anova

Abstract The aim in this study was to evaluate the influence of different ratio of camphorquinone/tertiary amine concentration on the flexural strength (FS), elastic modulus (EM), degree of conversion (DC), yellowing (YL), water sorption (WS) and water solubility (WSL) of experimental composites. Thus, acrylate blends were prepared with different camphorquinone (CQ) and amine (DABE) concentrations and ratios by weight: (CQ/DABE%): 0.4/0.4% (C1), 0.4/0.8% (C2), 0.6/0.6% (C3), 0.6/1.2% (C4), 0.8/0.8% (C5), 0.8/1.6% (C6), 1.0/1.0% (C7), 1.0/2.0% (C8), 1.5/1.5% (C9), 1.5/3.0% (C10). For the FS and EM, rectangular specimens (7x2x1 mm, n=10) were photo-activated by single-peak LED for 20 s and tested at Instron (0.5 mm/min). Then, the same specimens were evaluated by FTIR for DC measurement. For YL, disks (5x2 mm, n=10) were prepared, light-cured for 20 s and evaluated in spectrophotometer using the b aspect of the CIEL*a*b* system. For WS and WSL, the volume of the samples was calculated (mm³). For WS and WSL, composites disks (5x0.5 mm, n=5) were prepared. After desiccation, the specimens were stored in distilled water for 7 days and again desiccated, in order to measure the WS and WSL. Data were submitted to one-way ANOVA and Tukey’s test (5%). The groups C8, C9 and C10 showed higher DC, EM and YL means, compared to other composites. Therefore, the FS and WS values were similar among all groups. Also, C1, C2 and C3 presented higher WSL in 7 days, compared to other composites. In general, higher concentrations of camphorquinone promoted higher physical-mechanical properties; however, inducing higher yellowing effect for the experimental composites

Thermal Conductivity of Si₃N₄ Ceramics Fabricated From Carbothermal-reduction-derived Powder

2021 ◽  
Author(s):  
Yuelong Wang ◽  
Xingyu Li ◽  
Haoyang Wu ◽  
Baorui Jia ◽  
Deyin Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Grain Boundaries ◽  
Carbothermal Reduction ◽  
Secondary Phase ◽  
Gas Pressure ◽  
Gas Pressure Sintering

Abstract Si3N4-based ceramic (Si3N4-5wt%Y2O3-3wt%MgO) was obtained from carbothermal-reduction-derived powder combined with gas pressure sintering. The phase, microstructure, thermal conductivity and mechanical properties of Si3N4 ceramics were comprehensively analyzed. Dense Si3N4 ceramic with uniform grain size was obtained after sintering at 1900°C for 7 h under a N2 pressure of 1.2 MPa. The secondary phase consisted of Y4Si2O7N2 and Y2Si3O3N4 was found to gather around triangular grain boundaries. The thermal conductivity, flexural strength, hardness and fracture toughness of the Si3N4 ceramics were 95.7 W·m-1·k-1, 715 MPa, 17.2 GPa and 7.2 MPa·m1/2, respectively. The results were compared with product derived from commercial powder, the improvement of thermal conductivity (~8.3%) and fracture toughness (~4.3%) demonstrating the superiority of Si3N4 ceramics prepared from carbothermal-reduction-derived powder.

scholarly journals Direct Correlations among the Grain Size, Texture, and Indentation Behavior of Nanocrystalline Nickel Coatings

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 188 ◽  
Author(s):  
Lu Feng ◽  
Yong-Yue Ren ◽  
Yan-heng Zhang ◽  
Shibin Wang ◽  
Linan Li
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Elastic Anisotropy ◽  
Texture Coefficient ◽  
Process Conditions ◽  
Nickel Coatings ◽  
Fundamental Relationship ◽  
Underlying Mechanisms ◽  
First Time

By using nc-Ni coatings as a model system, systematic experiments were designed to evaluate the interaction between the microstructural and mechanical properties tailored by electrodeposition conditions. A direct correlation between grain size and texture was established for the first time. The grain size of the (111) crystalline plane decreases with the texture coefficient (RTC) regardless of the process conditions, and that of the (220) plane has different trends. Then, a peculiar phenomenon is revealed that the dependence of hardness on grain size is accurately described by the Hall-Petch relationship when changing the temperature or pH, but with different slopes, while it deviates from such a relationship with changing current density, denoting more underlying mechanisms related to texture. Finally, a surprising degree of influence of texture on hardness and elastic modulus is also presented, with the overall trend of hardness increasing with texture; and when the RTC of (111) exceeds 40%, the elastic modulus increases with texture, implying a fundamental relationship between modulus and texture. Texture predominates over the other factors on the elastic modulus, revealing the importance of elastic anisotropy. Significantly, the present work suggests a useful tailoring routine to fabricate high quality nc-Ni coatings with the desired structure and mechanical properties.

scholarly journals Effects of Polymerization Mode and Interaction with Hydroxyapatite on the Rate of pH Neutralization, Mechanical Properties, and Depth of Cure in Self-Adhesive Cements

2019 ◽  
Vol 13 (02) ◽  
pp. 178-186
Author(s):  
Fabiana S. A. S. Camargo ◽  
Alejandra H. M. González ◽  
Roberta C. B. Alonso ◽  
Vinicius Di Hipólito ◽  
Paulo H. P. D'Alpino
Keyword(s):  
Mechanical Properties ◽  
Infrared Spectroscopy ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
The Self ◽  
Chemical Bonds ◽  
Resin Cements ◽  
Adhesive Resin ◽  
Depth Of Cure ◽  
Ph Neutralization

Abstract Objective The aim of the study was to evaluate the physicochemical properties of self-adhesive resin cements associated with hydroxyapatite (HAp) according to the polymerization activation. Materials and Methods Specimens of cements (PermaCem 2.0 [DMG]; MaxCem Elite [Kerr], and RelyX U200 [3M ESPE]) were distributed into three groups: activation mode; self-cured and dual-cured modes; and association or not with HAp powder mode. The pH neutralization was evaluated as a function of time. Flexural strength and elastic modulus were also tested (0.5 mm/min.). The depth of cure was also analyzed using the scraping test (ISO 4049). Infrared spectroscopy was also used to collect the spectra of specimens to evaluate the chemical bonds. Statistical comparisons were conducted at 5% of significance. Results The aggressiveness of the self-adhesive resin cements evaluated varied among the materials with a tendency for neutralization. Self-cure groups exhibited lower pH throughout the entire evaluation when compared with that of the dual-cure ones, irrespective of the addition of HAp. MaxCem Elite when photoactivated was the only cement influenced by the addition of the HAp in terms of mechanical properties. The self-adhesive cements tested presented equivalent depth of cure based on the ISO 4049 requirements, regardless of the evaluated factors. Conclusions Based on the parameters evaluated, the results demonstrated that most of the self-adhesive cements remained unaltered or improved when mixed with HAp, regardless of the activation mode.

Effect of SiC Additions on Microstructure Evolution and Mechanical Properties of W-Based Composite Prepared by Arc-Melting

2019 ◽  
Vol 944 ◽  
pp. 531-536
Author(s):  
Ke Jia Kang ◽  
Peng Fan ◽  
Jian Zhang ◽  
Qiang Guo Luo ◽  
Qiang Shen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flexural Strength ◽  
Microstructure Evolution ◽  
Small Angle ◽  
The Self ◽  
Melting Method ◽  
Arc Melting ◽  
Multi Phase ◽  
Strength And Ductility

In this study, the W-Si-C multi-phase composites were fabricated by an arc melting method. With addition of SiC, the grain size of W is obviously reduced, and the small angle misorientation becomes dominate, which is beneficial for the improvement of deformability. The effects of SiC additions (from 0.5 to 3wt%) on the microstructure and mechanical properties are mainly investigated. With 1 wt% SiC addition, the flexural strength reaches the highest value. The self-generation of W5Si3 may enhance the strength and ductility, but too much W5Si3 exists as brittle BP (Brittle to Plastic) microstructure. The highest flexural strength is obtained at approximately 1 vol% W5Si3.

Evaluation of Relations among Basic Mechanical Properties of Concrete with Machine-Made Sand

2011 ◽  
Vol 418-420 ◽  
pp. 441-444 ◽  
Author(s):  
Feng Lan Li ◽  
Yan Zeng ◽  
Chang Yong Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Rough Surface ◽  
Design Code ◽  
Ordinary Concrete ◽  
Axial Compressive Strength ◽  
Different Characteristics

Due to many different characteristics such as irregular polygon particle with pointed edges, rough surface and larger content of stone powder, machine-made sand has ignorable effects on the properties of concrete. As the basis for the design of concrete structures, the relations among the basic mechanical properties of concrete such as compressive strength, tensile strength, flexural strength and elastic modulus should be clearly understood. This paper summarizes the test data from the published references, and discusses the relations among these properties by statistical analyses compared with those of ordinary concrete. The results show that the axial compressive strength and the tensile strength can be prospected by the same formulas of ordinary concrete specified in current Chinese design code, but the prospected tensile strength should multiply a reducing coefficient when the strength grade of concrete is lower than C30. The elastic modulus of concrete with machine-made sand is larger than that of ordinary concrete, which should be prospect by the formula in this paper. Meanwhile, the formula of flexural strength is suggested.

Influence of Annealing on the Microstructure and Mechanical Properties of Electrodeposited Nanocrystalline Nickel

2011 ◽  
Vol 683 ◽  
pp. 103-112 ◽  
Author(s):  
B. Yang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Grain Boundary ◽  
Boundary Structure ◽  
Boundary State ◽  
Microstructure And Mechanical Properties ◽  
Grain Boundary Structure ◽  
Average Grain Size ◽  
Different Grain Size

The evolution of the microstructure and mechanical properties of electrodeposited nanocrystalline Ni with different annealing procedures was studied systematically. For the annealed specimens hardness decreases with increasing average grain size but the dependence changes at different grain size ranges. The specimens annealed at a low temperature show higher hardness compared to the as-deposited nanocrystalline Ni, despite an increased measured average grain size. In association with this hardening an increase in elastic modulus and a decrease in microstrain was observed after annealing. With increasing annealing temperature both the tensile strength and the fracture strain were observed to decrease, this is companied with a transition from ductile to brittle in the fracture surfaces. These results indicated that the mechanical behaviour of nanocrystalline Ni depends not only on the average grain size but also on the grain boundary structure. A change in the grain boundary state arising from annealing may be responsible for the observed increase in hardness and elastic modulus as well as the deterioration of tensile properties.

Effect of Microstructure on Mechanical Properties and Wear Characteristics of Cemented Tungsten Carbides

2009 ◽  
Vol 76-78 ◽  
pp. 609-612 ◽  
Author(s):  
H.Q. Sun ◽  
Rudy Irwan ◽  
Han Huang ◽  
Gwidon W. Stachowiak
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Friction Coefficient ◽  
Tungsten Carbide ◽  
Removal Rate ◽  
Tungsten Carbides ◽  
Removal Rates ◽  
Wear Characteristics ◽  
Effect Of Microstructure

The effect of microstructure of cemented tungsten carbide materials on their mechanical properties and wear characteristics was investigated using nanoindentation and nanoscratch methods. The results indicated that the variation in grain size insignificantly affected the hardness, elastic modulus and friction coefficient of the work materials, but considerably influenced their removal rates. The carbide with coarser grains exhibited a much higher removal rate was obtained during scratching.

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