scholarly journals Microstructure and Mechanical Properties of Si3N4-Fe3Si Composites Prepared by Gas-Pressure Sintering

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1206
Author(s):  
Jiasuo Guan ◽  
Laifei Cheng ◽  
Mingxing Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Crack Deflection ◽  
Gas Pressure ◽  
Interface Debonding ◽  
Abnormal Growth ◽  
Pull Out ◽  
Uniform Microstructure ◽  
Microstructure And Mechanical Properties ◽  
Gas Pressure Sintering

Si3N4-Fe3Si composites were prepared using Fe-Si3N4 as the source of Fe3Si by gas-pressure sintering. By adding different amounts of Fe-Si3N4 into the starting powders, Si3N4-Fe3Si composites with various Fe3Si phase contents were obtained. The microstructure and mechanical properties of the composites were investigated. With the increase of Fe-Si3N4 contents, the content and particle size of Fe3Si both increased. When more than 60 wt. % Fe-Si3N4 were added, the abnormal growth of Fe3Si particles occurred and oversized Fe3Si particles appeared, leading to non-uniform microstructures and worse mechanical properties of the composites. It has been found that Fe3Si particles could toughen the composites through particle pull-out, interface debonding, crack deflection, and particle bridging. Uniform microstructure and improved mechanical properties (flexural strength of 354 MPa and fracture toughness of 8.4 MPa·m1/2) can be achieved for FSN40.

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 Study on Microstructure and Mechanical Properties of WC-10Ni3Al Cemented Carbide Prepared by Different Ball-Milling Suspension

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2224 ◽  
Author(s):  
Minai Zhang ◽  
Zhun Cheng ◽  
Jingmao Li ◽  
Shengguan Qu ◽  
Xiaoqiang Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Ball Milling ◽  
Grain Growth ◽  
Organic Solvents ◽  
Crack Deflection ◽  
Cemented Carbides ◽  
Powder Metallurgy Method ◽  
Microstructure And Mechanical Properties ◽  
Α Al2o3

In this paper, WC-10Ni3Al cemented carbides were prepared by the powder metallurgy method, and the effects of ball-milling powders with two different organic solvents on the microstructure and mechanical properties of cemented carbides were studied. We show that the oxygen in the organic solvent can be absorbed into the mixed powders by ball-milling when ethanol (CH3CH2OH) is used as a ball-milling suspension. This oxygen leads to the formation of α-Al2O3 during sintering, which improves the fracture toughness, due to crack deflection and bridging, while the formation of η-phase (Ni3W3C) inhibits the grain growth and increases the hardness. Alternatively, samples milled using cyclohexane (C6H12) showed grain growth during processing, which led to a decrease in hardness. Therefore, the increase of oxygen content from using organic solvents during milling improves the properties of WC-Ni3Al composites. The growth of WC grains can be inhibited and the hardness can be improved without loss of toughness by self-generating α-Al2O3 and η-phase (Ni3W3C).

Microstructures and Mechanical Properties of B4C-TiB2 Composite Prepared by Hot Pressure Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 50-53 ◽  
Author(s):  
Xin Yan Yue ◽  
Shu Mao Zhao ◽  
Liang Yu ◽  
Hong Qiang Ru
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Microstructural Analysis ◽  
Crack Deflection ◽  
Second Phase ◽  
Fine Grain ◽  
Pull Out ◽  
Microstructures And Mechanical Properties

B4C-TiB2 composite was prepared using hot pressure sintering. The microstructures and mechanical properties of the B4C-TiB2 composite were investigated. The B4C-TiB2 composite with 43 mass % TiB2 showed the optimized properties. The relative density, hardness, flexural strength and fracture toughness of that were 98.2 %, 25.9 GPa, 458 MPa and 8.7 MPa•m1/2, respectively. A number of toughening mechanisms, including fine grain, crack deflection and grain pull-out, were observed during microstructural analysis of the composite. The fracture mode of the B4C-TiB2 composite was greatly affected by the existence of the second phase of TiB2.

scholarly journals Microstructure and mechanical properties of Zr3Al3C5-based ceramics synthesized by Al-Si melt infiltration

2021 ◽  
Vol 10 (3) ◽  
pp. 529-536
Author(s):  
Xiaomeng Fan ◽  
Yuzhao Ma ◽  
Yangfang Deng ◽  
Jinxue Ding ◽  
Laifei Cheng
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Flexural Strength ◽  
Boundary Energy ◽  
Zirconium Carbide ◽  
Formation Temperature ◽  
Abnormal Growth ◽  
Microstructure And Mechanical Properties ◽  
Melt Infiltration

AbstractIn this work, bulk Zr3Al3C5-based ceramics were synthesized by the infiltration of Al-Si melt into zirconium carbide (ZrC) perform. The phase composition, microstructure, and mechanical properties of as-fabricated ceramics were studied. The results demonstrate that Si is more effective to reduce the twin boundary energy of ZrC than Al, and thus promotes the decrease of formation temperature of Zr3Al3C5. With the infiltration temperatures increasing from 1200 to 1500 °C, the Zr3Al3C5 content increases from 10 to 49 vol%, which is contributed to the increase of flexural strength from 62±9 to 222±10 MPa, and fracture toughness (KIC) from 2.8±0.2 to 4.1±0.3 MPa·m1/2. The decrease of mechanical properties for the samples fabricated at 1600 °C is ascribed to the abnormal growth of Zr3Al3C5 grains.

Comparison of Ti(C, N)-based cermets by vacuum and gas-pressure sintering: Microstructure and mechanical properties

2018 ◽  
Vol 44 (1) ◽  
pp. 805-813 ◽  
Author(s):  
Huiwen Xiong ◽  
Yuxue Wu ◽  
Zhiyou Li ◽  
Xueping Gan ◽  
Kechao Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gas Pressure ◽  
Microstructure And Mechanical Properties ◽  
Gas Pressure Sintering

Microstructure and Mechanical Properties of Laminated Buckypaper/SiC Composite

2015 ◽  
Vol 816 ◽  
pp. 147-151
Author(s):  
Xing Li ◽  
Peng Xiao Huang ◽  
Hui Peng ◽  
Ying Zhou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Magnetron Sputtering ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Rf Magnetron Sputtering ◽  
Crack Deflection ◽  
Nanoindentation Testing ◽  
Microstructure And Mechanical Properties

The laminated Buckypaper/SiC composite was prepared by RF magnetron sputtering. For comparison, the monolithic SiC was also prepared in the present study. The microstructure and morphology of the prepared samples were characterized by SEM and XRD. The Young’s modulus, hardness and stiffness of the samples were investigated by nanoindentation testing. The results showed that the Buckypaper/SiC composite had an obviously multilayered microstructure at the nanoscale. Furthermore, the fracture toughness of the laminated Buckypaper/SiC composite could be improved by crack deflection and platelet pullout mechanisms. The laminated Buckypaper/SiC composite had higher Young’s modulus and stiffness than that of the monolithic SiC. However, its hardness was lower than that of monolithic SiC.

Phase assemblage and properties of a nonoxide composite fabricated by a two-step gas-pressure sintering

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040046
Author(s):  
Li Yin ◽  
Yuxin Wang ◽  
Songtao Jiang ◽  
Zhen He ◽  
Saifang Huang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Mass Loss ◽  
Applied Pressure ◽  
Gas Pressure ◽  
Phase Assemblage ◽  
Intermediate Phases ◽  
Phase Behaviors ◽  
Gas Pressure Sintering ◽  
Sintering Method

In this work, a composite composed of [Formula: see text]-Sialon (Z[Formula: see text]=[Formula: see text]4) and ZrN has been fabricated by a two-step gas-pressure sintering method, and the effects of ZrN content and applied pressure on the phase behavior, densification and mechanical properties have been investigated. The phase behaviors were mainly dependent on the ZrN content and the applied pressure. The composites composed of [Formula: see text]-Sialon (Z[Formula: see text]=[Formula: see text]4), ZrN, 15R-Sialon (0.4 MPa) and 12H-Sialon (0.7 MPa) as major phases, with different intermediate phases depending on the ZrN content. It is revealed that with the two-step sintering technique, a higher applied gas pressure has a positive effect on mass loss, and significantly improved the mechanical properties. The addition of ZrN particles greatly helped the densification behavior, reduced the mass loss, and increased fracture toughness of the composites, but decreased hardness due to formation of intermediate phases and grain coarsening. The addition of ZrN increased the fracture toughness due to the toughening mechanisms of crack branching, crack deflection and crack bridging.

Microstructure, chemical aspects, and mechanical properties of TiB2/Si3N4 and TiN/Si3N4 composites

1994 ◽  
Vol 9 (9) ◽  
pp. 2349-2354 ◽  
Author(s):  
Jow-Lay Huang ◽  
Shih-Yih Chen ◽  
Ming-Tung Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Chemical Stability ◽  
Large Deflection ◽  
Crack Deflection ◽  
Toughening Mechanism ◽  
Β Phase ◽  
Microstructure And Mechanical Properties

The chemical stability of TiB2 and TiN in a silicon nitride matrix under various conditions of temperature and gaseous environments was investigated. The addition of TiB2 and TiN on the microstructure and mechanical properties was also studied. No trace of interactions between TiN and Si3N4 was noticed. The addition of TiB2 to Si3N4 enhanced conversion of the α to β phase of the Si3N4 matrix. Observations of BN and TiN indicated a possible reaction between TiB2 and Si3N4. The fracture toughness of Si3N4 was substantially enhanced with the addition of TiB2 or TiN, while the strength was decreased. Crack deflection was the major toughening mechanism in a Si3N4/TiB2 composite. Most of the microcracks passed through TiN particles and cleavaged along preferred orientations with large deflection angles.

scholarly journals Reinforcing Mechanisms of Graphene and Nano-TiC in Al2O3-Based Ceramic-Tool Materials

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1815 ◽  
Author(s):  
Zhefei Sun ◽  
Jun Zhao ◽  
Xuchao Wang ◽  
Enzhao Cui ◽  
Hao Yu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Crack Deflection ◽  
Crack Branching ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Pull Out ◽  
Quantitative Studies ◽  
Reinforcing Effects

Graphene and nano-TiC, which have good reinforcing effects on Al2O3-based ceramic-tool materials, are generally used as additive phases for ceramics. In this study, nine kinds of samples were sintered, to investigate the effects of graphene and nano-TiC on the reinforcing mechanisms of Al2O3-based ceramics. The experimental results indicated that adding 0.5 vol% graphene and 10 vol% nano-TiC can obtain the optimum flexural strength, fracture toughness, and Vickers hardness, which were 705 ± 44 MPa, 7.4 ± 0.4 MPa m1/2, and 20.5 ± 0.8 GPa, respectively. Furthermore, the reinforcing mechanisms of crack bridging, pull-out of graphene, and pull-out of nano-TiC are identified, which are contributed to improving the mechanical properties of ceramics. Meanwhile, other reinforcing mechanisms induced by graphene (graphene break, crack guiding, and 3D propagation) and nano-TiC (crack branching, crack deflection, and peeling) are discussed. These reinforcing mechanisms are coupled together, while decoupling is hard to work out. Thus, further quantitative studies of reinforcing effects of graphene and nano-TiC on Al2O3-based ceramic-tool materials are necessary to be carried out.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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