Bending Strength, Fracture Toughness and Crack Propagation Characteristics of Si3N4 Ceramic at High Temperature.

Fracture toughness KIc and four-point bending strength σc at high temperature (up to 1500 °C) of Y2O3 ceramics of various grain size were measured. The ceramics were prepared by pressureless air sintering and next hot isostatic pressing of high purity (99.99%) Y2O3 powder. Relative density of about 99 % was achieved. Photos of microstructures revealed small pores distributed mainly inside grains. For smallest grain size (2 - 9 μm) ceramics KIc and σc are almost constant from 20 ° to 1200 °C and next they decrease. For biggest grain size (about 44 μm) they increase up to 800 °C and next they keep constant up to 1200 °C. The micrographs analyses of fracture surfaces indicated that transgranular mode of fracture at room temperature changes to almost intergranular at higher temperatures.

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Study of the Comparative Effect of Sintering Methods and Sintering Additives on the Microstructure and Performance of Si3N4 Ceramic

Materials ◽

10.3390/ma12132142 ◽

2019 ◽

Vol 12 (13) ◽

pp. 2142 ◽

Cited By ~ 3

Author(s):

Liangliang Yang ◽

Allah Ditta ◽

Bo Feng ◽

Yue Zhang ◽

Zhipeng Xie

Keyword(s):

Phase Transition ◽

Thermal Conductivity ◽

Fracture Toughness ◽

Relative Density ◽

Transition Rate ◽

Bending Strength ◽

Si3n4 Ceramic ◽

Sintering Additives ◽

The Difference ◽

And Performance

The Si3N4 ceramics were prepared in this study by gas pressure sintering (GPS) and spark plasma sintering (SPS) techniques, using 5 wt.% Yb2O3–2 wt.% Al2O3 and 5 wt.% CeO2–2 wt.% Al2O3 as sintering additives. Based on the difference in sintering methods and sintering additive systems, the relative density, phase composition, phase transition rate, microstructure, mechanical properties, and thermal conductivity were comparatively investigated and analyzed. SPS proved to be more efficient than GPS, producing higher relative density, bending strength, hardness, and thermal conductivity of Si3N4 ceramic with both additive systems; however, the phase transition rate and fracture toughness were lower. Similarly, higher bending strength, hardness, and thermal conductivity were achieved with Yb2O3–Al2O3 than CeO2–Al2O3 in the case of GPS and SPS, and only the relative density, fracture toughness, and phase transition rate were lower.

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Microstructure and Mechanical Properties of Sintered Fibrous Monolith Cemented Carbide

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.815.233 ◽

2013 ◽

Vol 815 ◽

pp. 233-239

Author(s):

Xue Quan Liu ◽

Cun Guang Ding ◽

Chang Hai Li ◽

Yi Li ◽

Li Xin Li ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Crack Propagation ◽

Fracture Energy ◽

Bending Strength ◽

Extrusion Process ◽

Cemented Carbide ◽

Cemented Carbides ◽

Microstructure And Mechanical Properties

A fibrous monolith cemented carbide with WC-6Co as cell and WC-20Co as cell boundaries was produced through hot co-extrusion process in this paper. The density, hardness, bending strength and fracture toughness of the fibrous monolith cemented carbide were tested, and the fracture and crack propagation were observed by metalloscope and SEM. The results showed that the bending strength and fracture toughness of the fibrous monolith cemented carbides was remarkably improved 71.91% and 45.7% respectively, while the hardness was slightly decreased 1% compared with WC-6Co composites. It is the reason that the tougher shell WC-20Co with higher bending strength and fracture toughness can absorb more fracture energy, which can slow down and prevent the crack propagating from brittle core WC-6Co.

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Failure Behaviour of High Toughness Multi-Layer Si3N4 and Si3N4-TiN Based Laminates

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.290.175 ◽

2005 ◽

Vol 290 ◽

pp. 175-182 ◽

Cited By ~ 5

Author(s):

Gurdial Blugan ◽

Richard Dobedoe ◽

I. Gee ◽

Nina Orlovskaya ◽

Jakob Kübler

Keyword(s):

Fracture Toughness ◽

High Temperature ◽

Residual Stresses ◽

Crack Propagation ◽

Failure Mechanisms ◽

High Strength ◽

Crack Deflection ◽

High Toughness ◽

Energy Absorbing ◽

Crack Bifurcation

Multi-layer laminates were produced using alternating layers of Si3N4 and Si3N4+TiN. The differences in the coefficient of thermal expansions between the alternating layers lead to residual stresses after cooling. These are compressive in the Si3N4 layers and tensile in the Si3N4+TiN layers. The existence of these stresses in the laminates effect the crack propagation behaviour during failure. Different designs of laminates were produced with external layers under compression and tension exhibiting different failure mechanisms. Facture toughness was measured by SEVNB method. In systems with external layers under compression the measured fracture toughness was up to three times that of Si3N4, i.e. up to 17 MPa m1/2. In systems with external layers under tension during failure the energy absorbing effects of crack deflection and crack bifurcation were obtained. High temperature tests were performed to determine the onset temperature for residual stresses in these laminates. Micro-laminates with compressive layers of only 30 µm thickness with high strength and fracture toughness and were manufactured.

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Effects of HfC Particles on Crack Initiation and Propagation Behavior of WC/Co Composites

Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University ◽

10.1051/jnwpu/20193730628 ◽

2019 ◽

Vol 37 (3) ◽

pp. 628-635

Author(s):

Xinyu Yan ◽

Shouren Wang ◽

Daosheng Wen ◽

Gaoqi Wang ◽

Wentao Liu

Keyword(s):

Fracture Toughness ◽

Crack Propagation ◽

Bending Strength ◽

Crack Tip ◽

Crack Deflection ◽

Simulation Software ◽

Homogeneous Distribution ◽

The Matrix ◽

Crack Pinning ◽

Crack Bifurcation

Tungsten carbide composites were prepared by cold-pressing and hot-pressing sintering; fracture toughness and bending strength of the specimens were tested. The microstructures of HfC/WC/Co composites were observed with the SEM. The mathematical models were established to investigate the relationship between stress intensity factors of crack straight-through, crack deflection, and crack bifurcation with crack length, based on the crack propagation energy release rate. The simulation software ABAQUS was used to verify the four crack propagation methods of crack straight-through, crack deflection, crack bifurcation and crack pinning. The simulation results show that adding appropriate amount of HfC can effectively improve the fracture toughness and bending strength of the composites. The homogeneous distribution of HfC and Co in the matrix has a significant effect on the improvement of the strength and toughness of the composites, and the improvement mechanism is to disperse or transfer the stress at the crack tip to HfC by crack deflection, crack bifurcation, crack pinning, transcrystalline fracture, etc. As a result, the stress concentration at the crack tip in the matrix is reduced, and the toughness of the composites is improved.

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SILICON CARBIDE SC-221

Alloy Digest ◽

10.31399/asm.ad.cer0005 ◽

1991 ◽

Vol 40 (7) ◽

Keyword(s):

Fracture Toughness ◽

Silicon Carbide ◽

High Temperature ◽

Mechanical Strength ◽

Physical Properties ◽

Bending Strength ◽

Beta Phase ◽

Pressureless Sintering ◽

Bend Strength ◽

Sintering Method

Abstract SILICON CARBIDE SC-221 is a beta-phase silicon carbide made from the pressureless sintering method. It possesses excellent mechanical strength at high temperature (4-point bending strength of 71ksi [490 MPa] at 1400 C [2552 F]). This datasheet provides information on physical properties, hardness, elasticity, and bend strength as well as fracture toughness. Filing Code: Cer-5. Producer or source: Kyocera America Inc..

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Understanding the thermal durability of wood-based composites (WBCs) using crack propagation fracture toughness

Holzforschung ◽

10.1515/hf-2021-0007 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Sweta Mahapatra ◽

Arijit Sinha ◽

John A. Nairn

Keyword(s):

Fracture Toughness ◽

Crack Propagation ◽

Bending Strength ◽

Oriented Strand Board ◽

Medium Density Fiberboard ◽

Strength Properties ◽

Wood Products ◽

Trilinear Model ◽

Different Temperatures

Abstract Wood-based composites (WBCs) are engineered wood products that are commonly used in the building and furniture industries. Most research on their durability has relied on internal bond testing, bending strength properties, or damage observations. An alternative property with potentially more information is fracture toughness. Here, fracture toughness was continuously measured during crack propagation for three different composites—oriented strand board (OSB), medium density fiberboard (MDF), and particleboard (PB). The resulting plots for fracture toughness as a function of crack growth are known as the material’s R curve. To assess the role of temperature on WBC durability, R curve experiments were repeated at 10 different temperatures from 20 to 200 °C. Trends in experimental results could be described by a trilinear model. OSB and MDF toughness initially increased with temperature and then decreased above 80 °C. The toughness of PB, which was made with a different resin, remained constant or decreased slightly until decreasing faster above 140 °C. Both the resin type and composite structure affected the results.

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High Temperature Fatigue Crack Propagation Characteristics of Pressureless Sintered Silver Nanoparticles

2019 6th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D) ◽

10.23919/ltb-3d.2019.8735315 ◽

2019 ◽

Cited By ~ 1

Author(s):

Koji Osaki ◽

Yoshiharu Kariya ◽

Noritsuka Mizumura ◽

Koji Sasaki

Keyword(s):

Silver Nanoparticles ◽

Fatigue Crack ◽

High Temperature ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Propagation Characteristics ◽

High Temperature Fatigue ◽

Sintered Silver

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Influence of toughness on Weibull modulus of ceramic bending strength

Journal of Materials Research ◽

10.1557/jmr.1986.0120 ◽

1986 ◽

Vol 1 (1) ◽

pp. 120-123 ◽

Cited By ~ 90

Author(s):

K. Kendall ◽

N. McN. Alford ◽

S. R. Tan ◽

J. D. Birchall

Keyword(s):

Fracture Toughness ◽

Crack Propagation ◽

Crack Length ◽

Weibull Modulus ◽

Bending Strength ◽

Griffith Criterion

It is demonstrated both theoretically and experimentally that fracture toughness does not directly influence the Weibull modulus of ceramic bending strength for materials that obey the Griffith criterion for crack propagation. Weibull modulus remains unchanged as toughness is increased. However, toughness variations with crack length do affect the Weibull modulus. Thus materials that display R-curve behavior or Dugdale character give an increased Weibull modulus and appear more reliable.

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