scholarly journals Tetragonal-to-Monoclinic Transformation Influence on the Mechanical Properties of CeO2- ZrO2 Ceramics

2005 ◽  
Vol 498-499 ◽  
pp. 506-511 ◽  
Author(s):  
Maria do Carmo de Andrade Nono
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Performance ◽  
Surface Hardness ◽  
X Rays ◽  
Mechanical Parameters ◽  
Bending Tests ◽  
Structural High

CeO2- ZrO2 ceramics are considered a candidate material for applications as structural high performance ceramics. In this work are presented and discussed the tetragonal-to-monoclinic stress-induced transformation influence on the mechanical properties in these ceramics. Sintered ceramics were fabricated from powders mixtures containing ZrO2 and 8 to 14 CeO2 % mol. SEM observations were used to study de ceramic microstructures and X-rays diffraction to identification and determination of tetragonal and monoclinic phases. It was adopted the 4-point bending tests, Vickers surface hardness and fracture toughness technique to the determination of the mechanical parameters. The results showed that the mechanical properties were strongly dependent of the CeO2 content, the microstructure and the fraction of tetragonal-to-monoclinic stress-induced transformation.

Fracture Toughness and Cracking Behaviour of SCC Compared to VC

2013 ◽  
Vol 577-578 ◽  
pp. 205-208
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Fracture Toughness ◽  
Fracture Process ◽  
Critical Value ◽  
Fracture Parameter ◽  
Self Compacting Concrete ◽  
Bending Tests ◽  
Three Point Bending ◽  
Notched Specimens ◽  
Subsequent Determination

Vibrated concrete (VC) and self-compacting concrete (SCC) have a substantially different composition, resulting in dissimilar mechanical properties regarding cracking behaviour. The critical value of the mode I stress-intensity factor KICis an appropriate fracture parameter for evaluating fracture toughness and can be obtained from three-point bending tests (3PBT) on small, notched specimens. Subsequent determination of the energy release rate thus allows to examine the crack propagation and fracture process of both concrete types. This paper describes the results of such 3PBTs on samples, made from VC and SCC. Evaluation of the cracking behaviour, derived from these results, reveals remarkable differences.

Effect of Graphene Oxide on Interfacial Interactions and Fracture Toughness of Basalt Fiber-Reinforced Epoxy Composites

2020 ◽  
Vol 20 (11) ◽  
pp. 6760-6767
Author(s):  
Seong Hwang Kim ◽  
Soo-Jin Park
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Graphene Oxide ◽  
High Performance ◽  
Basalt Fiber ◽  
Superior Performance ◽  
Microstructured Fibers ◽  
Multi Scale ◽  
Fundamental Understanding ◽  
Interlaminar Shear

Multiscale hierarchy is a promising chemical approach that provides superior performance in syner-gistically integrated microstructured fibers and nanostructured materials in composite applications. The main purpose of this work was to introduce graphene oxide (GO) between an epoxy matrix and basalt fibers to improve mechanical properties by enhancing interfacial adhesion. The composites were reinforced with various concentrations of GO. For all of the fabricated composites, the optimum GO content was found to be 0.5 wt%, which improved the interlaminar shear strength and fracture toughness by 66.2% and 86.1%, respectively, compared with those of neat composites. We observed a direct linear relationship between fracture toughness and certain surface free energy. In addition, the fracture toughness mechanisms were illustrated using a crack theory based on morphology analyses of fracture surfaces. Such an effort could accelerate the conversion of multi-scale composites into high-performance materials and provide rational guidance and fundamental understanding toward realizing the theoretical limits of mechanical properties.

Nickel-Alumina Composites: In Situ Synthesis by a Displacement Reaction, and Mechanical Properties

1994 ◽  
Vol 365 ◽  
Author(s):  
Steven A. Jones ◽  
James M. Burlitch ◽  
Ersan Üstündag ◽  
Jeannie Yoo ◽  
Alan T. Zehnder
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Constants ◽  
High Performance ◽  
In Situ Synthesis ◽  
Displacement Reaction ◽  
Ductile Phase ◽  
Flexure Strength ◽  
Alumina Composites

ABSTRACTNickel-alumina composites have the potential to be high performance materials. Alumina, with its excellent oxidation resistance, combined with a ductile phase such as nickel may provide a tough material with a lower density and higher Young's modulus, overall, a higher specific modulus than typical Superalloys. Dense, interpenetrating Ni-Al2O3 composites were synthesized using a displacement reaction between NiO and aluminum. The resulting composites were characterized in terms of their mechanical properties such as hardness, flexure strength, fracture toughness and elastic constants. The synthesis, characterization, and mechanical properties, as well as the effect of the interpenetrating microstructure on the toughening mechanisms and other properties will be discussed.

EFFECT OF PETROLOGICAL FEATURES ON MECHANICAL PROPERTIES OF ROCK SALT FROM THE LGOM (LEGNICA–GŁOGÓW COPPER DISTRICT)

2016 ◽  
pp. 51-64 ◽  
Author(s):  
Katarzyna CYRAN ◽  
Tomasz TOBOŁA ◽  
Paweł KAMIŃSKI
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Rock Salt ◽  
Fluid Inclusions ◽  
Mechanical Parameters ◽  
Research Results ◽  
Strength Tests ◽  
Crystal Boundaries

The paper presents the attempt to find a correlation between the content of impurities and mechanical parameters of rock salt from the LGOM. Research was carried out in three steps: uniaxial compressive strength tests, determination of the content of insoluble minerals (impurities), and observations under the microscope and Raman microspectroscopy. The research results reveal that the rock salt which is characterized by low content of insoluble minerals (0.13–2.11% wt.) shows no correlation between the mechanical properties and the content of impurities. However, it was found that mechanical properties depend on both the distribution of impurities in halite crystals and the presence of fluid inclusions and hydrocarbons along the crystal boundaries. Moreover, the distribution of anhydrite at the edges of halite crystals may influence an increase of rock salt strength. On the contrary, the presence of fluid inclusions and hydrocarbons along the halite crystal boundaries may reduce the rock salt strength.

Experimental Research and Analysis of Non-alloy Structural Steel Response Exposed to High Temperature Conditions

2013 ◽  
Vol 32 (2) ◽  
pp. 163-169
Author(s):  
Josip Brnic ◽  
Goran Turkalj ◽  
Sanjin Krscanski
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Structural Steel ◽  
Impact Energy ◽  
Charpy Impact ◽  
Experimental Results ◽  
Charpy Impact Energy ◽  
Over Time

AbstractThis paper presents and analyzes the responses of non-alloy structural steel (1.0044) subjected to uniaxial stresses at high temperatures. This research has two important determinants. The first one is determination of stress-strain dependence and the second is monitoring the behavior of materials subjected to a constant stress at constant temperature over time. Experimental results refer to mechanical properties, elastic modulus, total elongations, creep resistance and Charpy V-notch impact energy. Experimental results show that the tensile strength and yield strength of the considered material fall when the temperature rises over 523 K. Significant decrease in value is especially noticeable when the temperature rises over 723 K. In addition, engineering assessment of fracture toughness was made on the basis of Charpy impact energy. It is visible that when temperature raises then impact energy increases very slightly.

scholarly journals Comparative study of the around-Fermi electronic structure of 5d metals and metal-oxides by means of high-resolution X-ray emission and absorption spectroscopies

2020 ◽  
Vol 27 (3) ◽  
pp. 689-694 ◽  
Author(s):  
Anna Wach ◽  
Jacinto Sá ◽  
Jakub Szlachetko
Keyword(s):  
Mechanical Properties ◽  
Working Conditions ◽  
Electronic States ◽  
Theoretical Modelling ◽  
X Rays ◽  
Oxide Materials ◽  
X Ray ◽  
Physical Chemical ◽  
Tungsten Metal

The composition of occupied and unoccupied electronic states in the vicinity of Fermi energies is vital for all materials and relates to their physical, chemical and mechanical properties. This work demonstrates how the combination of resonant and non-resonant X-ray emission spectroscopies supplemented with theoretical modelling allows for quantitative analysis of electronic states in 5d transition metal and metal-oxide materials. Application of X-rays provides element selectivity that, in combination with the penetrating properties of hard X-rays, allows determination of the composition of electronic states under working conditions, i.e. non-vacuum environment. Tungsten metal and tungsten oxide are evaluated to show the capability to simultaneously assess composition of around-band-gap electronic states as well as the character and magnitude of the crystal field splitting.

scholarly journals DETERMINATION OF PHYSICAL-MECHANICAL PARAMETERS OF WALNUTS

2019 ◽  
pp. 12-17
Author(s):  
Yurii Polievoda ◽  
Igor Tverdokhlib
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Walnut Shell ◽  
Mechanical Parameters ◽  
Peeling Process ◽  
Energy Indices

The information about growing and processing of walnut in Europe and Ukraine is given. The actuality of the implementation of peeling, maximally preserved nuts is established. Based on the conducted research, the physical and mechanical properties of walnut shell are determined. The rational energy indices of the peeling process are found at maximum preservation of the fetus. The use of the developed equipment for preliminary peeling of the walnut in order to get microcracks is proposed.

scholarly journals Glulam Mechanical Characterization

2012 ◽  
Vol 730-732 ◽  
pp. 994-999
Author(s):  
Hélder S. Sousa ◽  
Jorge M. Branco ◽  
Paulo B. Lourenço
Keyword(s):  
Mechanical Properties ◽  
Strength Class ◽  
Mechanical Characterization ◽  
Structural Element ◽  
Bending Tests ◽  
Glulam Beam ◽  
Glued Laminated Timber ◽  
Normative Requirements ◽  
Type Of Failure

The glued laminated timber (glulam) mechanical properties may be evaluated through the determination of the key mechanical properties of the lamellae that compose that element. Simple bending and tension parallel to the grain tests were performed in order to assess the strength class of three glulam elements. Regarding the bending tests, 8 samples were taken from a glulam beam and assessed. Values for the resistant bending tension and both local and global modulus of elasticity were obtained. For the tension parallel to the grain tests, a total of 120 samples were assessed. The samples were divided regarding the structural element from where they were extracted as well to the type of failure mode found in the tests. The values of the lamellae properties were then used for determination of the properties of the glulam material. The data gathered from the tests was assessed statistically and concluded that the mechanical properties of the glulam elements did not fulfill the required parameters of the normative requirements.

scholarly journals Mechanical and Heterogeneous Properties of Coal and Rock Quantified and Mapped at the Microscale

2020 ◽  
Vol 10 (1) ◽  
pp. 342 ◽  
Author(s):  
Changlun Sun ◽  
Guichen Li ◽  
Suhui Zhang ◽  
Jiahui Xu ◽  
Houqiang Yang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Convenient Method ◽  
Elastic Moduli ◽  
Averaging Method ◽  
Sample Volume ◽  
Small Sample ◽  
Mechanical Parameters ◽  
Experimental Technology ◽  
Small Sample Volume

Due to the impossibility of obtaining intact standard experimental samples, it is difficult to test the mechanical properties of soft and broken coal and rock obtained from deep coal mines. So, an advanced experimental technology based on a small sample volume, nanoindentation technology, was introduced and used to measure the mechanical parameters of them. By using the averaging method, the hardness of shale, mudstone and coal are 1191.90 MPa, 674.95 MPa and 424.30 MPa, respectively; their elastic moduli are 20.39 GPa, 11.72 GPa and 5.47 GPa; and their fracture toughness were 1.66 MPa·m0.5, 1.28 MPa·m0.5 and 0.77 MPa·m0.5. These three mechanical parameters were used to quantify and map the heterogeneous properties of coal and rock for convenience and accuracy. For example, the inter quartile range (IQR) of the hardness of shale, mudstone, and coal are 1502.10 MPa, 1016.20 MPa and 54.64 MPa, respectively, meaning that coal has the best homogeneity among them. Nanoindentation technology provides researchers with a convenient method to conduct mechanical experiments at the microscale.

Effect of Microstructure and Sintering Temperature on Fabrication of NITE-SiCf/SiC Composite

2007 ◽  
Vol 345-346 ◽  
pp. 1229-1232 ◽  
Author(s):  
Young Ju Lee ◽  
Han Ki Yoon
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
High Performance ◽  
Composite System ◽  
Matrix Composites ◽  
Practical Applications ◽  
Sic Fiber ◽  
Carbide Matrix ◽  
Sic Composites

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiCf/SiC composites) are attractive materials for use in the blankets and divertors of fusion reactors due to their excellent thermo-mechanical properties and inherently low induced radioactivation. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture impose a severe limitation on the practical applications of SiC materials. SiCf/SiC composites can be considered as a promising candidate in various structural materials, because of their good fracture toughness. In this composite system, the direction of SiC fiber will give an effect to the mechanical properties such as fracture toughness and tensile strength. Therefore, it is important to control a proper direction of SiC fiber for the fabrication of high performance SiCf/SiC composites. .

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