Estimation of Fracture Toughness for ε Zirconium Hydride by Vickers Microhardness Indentation Method

JOM ◽  
2021 ◽  
Author(s):  
Changxing Cui ◽  
Feng Wang ◽  
Zhongwu Hu ◽  
Yanchao Li ◽  
Benqi Jiao ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Vickers Microhardness ◽  
Zirconium Hydride ◽  
Indentation Method ◽  
Microhardness Indentation

scholarly journals Fracture toughness of three heat pressed ceramic systems

2018 ◽  
Vol 17 ◽  
pp. 1-9
Author(s):  
Livia Fiorin ◽  
Guilherme Teixeira Theodoro ◽  
Izabela Cristina Maurício Moris ◽  
Renata Cristina Silveira Rodrigues ◽  
Ricardo Faria Ribeiro ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Glass Ceramic ◽  
Vickers Microhardness ◽  
Dental Ceramics ◽  
Test Results ◽  
Indentation Method ◽  
Clinical Prognosis ◽  
Significant Difference ◽  
Impulse Excitation

Aim: The aim of this study was to evaluate fracture toughness by indentation method of three dental ceramics processed by heat pressing. The ceramics evaluated were fluorapatite glass ceramic (ZIR), glass ceramic containing leucite (POM) and leucite-reinforced glass ceramic (EMP). Materials and methods: Ninety disks (13mm of diameter x 4mm of thickness) and nine rectangular specimens (25x4x2mm) were made to evaluate, respectively, microhardness/fracture toughness (n=30) and elastic modulus (n=3). Samples were obtained by pressing ceramic into refractory molds. After polishing, Vickers microhardness was evaluated under 4,904N load for 20s. Elastic modulus was measured by impulse excitation technique. Data from microhardness and elastic modulus were used to calculate fracture toughness, after measuring crack length under 19,6N load applied for 20s. Results were evaluated by ANOVA and Tukey´s test. Results: Microhardness (VHN) of POM (637.9±53.6) was statistically greater (p<0.05) than ZIR (593.0±14.3), followed by EMP (519.1±21.5); no significant difference (p=0.206) was noted for elastic modulus (GPa) (ZIR: 71.5±9.0; POM: 67.3±4.4; EMP: 61.7±2.3). Fracture toughness (MPa/m) of POM (0.873±0.066) was statistically lower (p<0.05) than ZIR (0.977±0.021) and EMP (0.965±0.035). Conclusion: The results suggest that fluorapatite glass ceramic (ZIR) and leucite-reinforced glass ceramic (EMP) processed by heat pressing presented greater fracture toughness, improving clinical prognosis of metal free restorations.

Titanium Effect on Microstructure and Fracture toughness of Al2O3-BASED Composites

2011 ◽  
Vol 691 ◽  
pp. 32-36
Author(s):  
José G. Miranda-Hernández ◽  
Elizabeth Refugio-García ◽  
Eduardo Térres-Rojas ◽  
Enrique Rocha-Rangel
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Scanning Electron Microscopy ◽  
Fine Particles ◽  
Ceramic Matrix ◽  
High Energy ◽  
Titanium Content ◽  
Indentation Method ◽  
Sintered Temperature ◽  
Scanning Electron

The effect of different titanium additions (0.5, 1, 2, 3 and 10 vol. %), milling intensity (4 and 8 h) and sintered temperature (1500 and 1600 °C) on microstructure and fracture toughness of Al2O3-based composites was analyzed in this study. After high energy milling of a titanium and Al2O3mixtures, powder mixture presents fine distribution and good homogenization between ceramic and metal. After milling powders during 8 h they were obtained very fine particles with 200 nm average sizes. Microstructures of the sintered bodies were analyzed with a scanning electron microscopy, where it was observed that the microstructure presents the formation of a small and fine metallic net inside the ceramic matrix. From fracture toughness measurements realized by the fracture indentation method, it had that when titanium content in the composite increases, fracture toughness is enhanced until 83% with respect to the fracture toughness of pure Al2O3. This behavior is due to the formation of metallic bridges by titanium in the Al2O3matrix.

scholarly journals Влияние содержания корунда и температуры спекания на механические свойства керамических композитов CaO-ZrO-=SUB=-2-=/SUB=--Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

2018 ◽  
Vol 44 (4) ◽  
pp. 25 ◽  
Author(s):  
А.А. Дмитриевский ◽  
А.И. Тюрин ◽  
А.О. Жигачев ◽  
Д.Г. Гусева ◽  
П.Н Овчинников
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Mechanical Characteristics ◽  
Vickers Microhardness ◽  
Ceramic Composites ◽  
Optimum Regime ◽  
Two Stage

AbstractWe have studied the mechanical properties (Vickers microhardness H _V and fracture toughness K _C) of nanostructured CaO–ZrO_2–Al_2O_3 ceramic composites as dependent on the content of corundum (0 ≤ $$C_{Al_{2}O_{3}}$$ C A l 2 O 3 ≤ 25%) and the temperature of sintering (1250°C ≤ T _1 ≤ 1500°C). Optimum value of the corundum content ( $$C_{Al_{2}O_{3}}$$ C A l 2 O 3 = 5%) and optimum regime ( T _1 = 1300°C, 5 min; T _2 = 1200°C, 4 h) of two-stage sintering are established, which favor attaining the best mechanical characteristics of ceramic composites ( H _V = 12.25 GPa, K _C = 8.47 MPa m^1/2).

Synthesis of Bulk Quasicrystals by Spark Plasma Sintering

2000 ◽  
Vol 643 ◽  
Author(s):  
E. Fleury ◽  
J.H. Lee ◽  
S.H. Kim ◽  
G.S. Song ◽  
J.S. Kim ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Spark Plasma Sintering ◽  
Vickers Microhardness ◽  
Secondary Phases ◽  
Hot Press ◽  
Plasma Sintering ◽  
Short Period ◽  
Spark Plasma ◽  
Powder Particles ◽  
Sintering Method

AbstractSpark plasma sintering method was applied to Al-Cu-Fe and Al-Si-Cu-Fe gas-atomized powders to prepare almost pore-free cylindrical specimens with icosahedral and 1/1 cubic approximant phases, respectively. This investigation has revealed that a high density could be obtained despite the short period and low temperature imposed during spark plasma sintering. In comparison to hot press technique, these conditions are favorable since they limit the formation of secondary phases and avoid exaggerated grain growth. The Vickers microhardness and fracture toughness of these two alloy systems were found to be larger than those obtained from cast and hot pressed samples, which could be attributed to a strong bonding between powder particles and the small-grained microstructure of the bulk SPS quasicrystalline specimens.

Measuring Residual Stress with the Indentation Method in Struc­tural Ceramics

2005 ◽  
Vol 297-300 ◽  
pp. 515-520
Author(s):  
Tarou Tokuda ◽  
Rong Gang Wang ◽  
Mitsuo Kido ◽  
Gonojo Katayama
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Phase Transformation ◽  
Residual Stresses ◽  
Treatment Method ◽  
Indentation Load ◽  
X Rays ◽  
Ray Method ◽  
Indentation Method ◽  
X Ray

This study deals with the indentation method of measuring residual stress in structural ceramics. First we investigate the appropriate pretreatment for measuring fracture toughness (basis value, KC) while avoiding any influence from residual stress, which is important when estimating residual stress using the indentation method. Based on the fracture toughness value, the residual stresses in Al2O3, Si3N4 and ZrO2 ceramics are estimated using the indentation method. Phase transformation is a problem when estimating residual stress using the indentation method with ZrO2 ceramics. Residual stresses in Al2O3 and Si3N4 can be largely eliminated by annealing the specimen after hand grinding. Consequently, it is thought that this treatment method is effective for determining the basis value KC. The estimated residual stress values in Al2O3 and Si3N4 obtained by the indentation method at 98 N corresponded closely to the values obtained wih X-rays. The residual stress value obtained by the indentation method for ZrO2 was close to the value obtained through the X-ray method, when the indentation load was 294 N. When estimating the residual stress in ZrO2 using the indentation method, the influence of the phase transformation caused by the indentation is added onto the original residual stress, when the indentation is small. The influence becomes smaller when the indentation load is large. If the applied indentation load is between 294 N and 490 N, the indentation method is effective for estimating the residual stresses in Al2O3, Si3N4 and ZrO2 ceramics.

scholarly journals Study of Erosion Behaviour of Conventional and Nanostructured WC-12Co Coatings Sprayed by Atmospheric Plasma

2009 ◽  
Vol 423 ◽  
pp. 35-40 ◽  
Author(s):  
V. Bonache ◽  
M.D. Salvador ◽  
J.C. García ◽  
V. García ◽  
Enrique Sánchez ◽  
...  
Keyword(s):  
Vickers Microhardness ◽  
Optical Microscope ◽  
Impact Angle ◽  
Atmospheric Plasma ◽  
Solid Particle Erosion ◽  
X Ray Diffraction ◽  
Indentation Method ◽  
X Ray ◽  
Erosion Behaviour ◽  
Wide Range

Thermal sprayed WC-Co coatings are used extensively to enhance the wear resistance of a wide range of engineering components. In this paper, erosive resistance of plasma atmospheric sprayed WC-12Co coatings has been evaluated. Solid particle erosion tests were conducted on these coatings at different angles of impact with silica and alumina abrasives of size 250 µm. Coatings have been deposited by using micrometric and nanometric agglomerated powders, employing H2 and He as plasmogen gas. In order to determine the erosion regime (ductile or brittle), the influence of impact angle on the erosion rate has been studied. Optical microscope and FESEM have been used to analyze the eroded surface. The influence of the plasmogen gas and the powder employed on the erosive behaviour of the coating has been evaluated. An attempt to connect the erosive behaviour with mechanical properties and microstructure has been made. Hardness has been determined by means of several measurements of Vickers microhardness; fracture toughness has been estimated through indentation method. Identification of phases has been made by means of X Ray diffraction.

Effect of Grain Size on Vickers Microhardness and Fracture Toughness in Calcium Phosphate Bioceramics

2011 ◽  
Vol 83 ◽  
pp. 237-243 ◽  
Author(s):  
R. Tolouei ◽  
Singh Ramesh ◽  
Chou Yong Tan ◽  
Mahdi Amiriyan ◽  
Wan Dung Teng
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Vickers Microhardness ◽  
Chemical Precipitation ◽  
Cold Isostatic Pressing ◽  
Precipitation Method ◽  
Indentation Fracture ◽  
Average Grain Size ◽  
Indentation Fracture Toughness ◽  
Higher Temperature

Grain size dependences of Vickers microhardness and indentation fracture toughness in fully dense hydroxyapatite bioceramics without additives were studied. The nanostructure and highly pure Hydroxyapatite powders produced by wet chemical precipitation method were used as starting material. After uniaxial and cold isostatic pressing, the green HA samples sintered at temperatures ranging from 1000 °C to 1300 °C with one minute holding time. Dense compacts with grain sizes in the nanometer to micrometer range were processed. The average grain size of HA compact sintered at 1000 °C was around 500 nm. Grain size increased to 3 µm when the compacts were sintered at a higher temperature. The average microhardness value of sintered HA decreased with an increased in grain size. Indentation fracture toughness for HA compacts of 700 nm grain size was 1.41±0.4 MPa.m1/2 which is similar to fracture toughness of human cortical bone.

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