Influence of additive composition on thermal and mechanical properties of β–Si3N4 ceramics

2004 ◽  
Vol 19 (11) ◽  
pp. 3270-3278 ◽  
Author(s):  
Xinwen Zhu ◽  
Hiroyuki Hayashi ◽  
You Zhou ◽  
Kiyoshi Hirao
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Nitrogen Pressure ◽  
High Fracture Toughness ◽  
Oxygen Impurity ◽  
Thermal And Mechanical Properties ◽  
High Fracture ◽  
Doped Materials ◽  
Gas Pressure Sintering

Dense β–Si3N4 ceramics were fabricated from α–Si3N4 raw powder by gas-pressure sintering at 1900 °C for 12 h under a nitrogen pressure of 1 MPa, using four different kinds of additive compositions: Yb2O3–MgO, Yb2O3–MgSiN2, Y2O3–MgO, and Y2O3–MgSiN2. The effects of additive composition on the microstructure and thermal and mechanical properties of β–Si3N4 ceramics were investigated. It was found that the replacement of Yb2O3 by Y2O3 has no significant effect on the thermal conductivity and fracture toughness, but the replacement of MgO by MgSiN2 leads to an increase in thermal conductivity from 97 to 113 Wm-1K-1and fracture toughness from 8 to 10 MPa m1/2, respectively. The enhanced thermal conductivity of the MgSiN2-doped materials is attributed to the purification of β–Si3N4 grain and increase of Si3N4–Si3N4 contiguity, resulting from the enhanced growth of large elongated grains. The improved fracture toughness of the MgSiN2-doped materials is attributed to the increase of grain size and fraction of large elongated grains. However, the same thermal conductivity between the Yb2O3- and Y2O3-doped materials is related to not only their similar microstructures, but also the similar abilities of removing oxygen impurity in Si3N4 lattice between Yb2O3 and Y2O3. The same fracture toughness between the Yb2O3- and Y2O3-doped materials is consistent with their similar microstructures. This work implies that MgSiN2 is an effective sintering aid for developing not only high thermal conductivity (>110 Wm−1K−1) but also high fracture toughness (>10 MPa m1/2) of Si3N4 ceramics.

KAISER ALUMINUM ALLOY 7050

Alloy Digest ◽  
2000 ◽  
Vol 49 (1) ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Aluminum Alloy ◽  
Heat Treating ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Kaiser Aluminum ◽  
Structural Parts ◽  
Very High

Abstract Kaiser Aluminum Alloy 7050 has very high mechanical properties including tensile strength, high fracture toughness, and a high resistance to exfoliation and stress-corrosion cracking. The alloy is typically used in aircraft structural parts. This datasheet provides information on composition, physical properties, hardness, tensile properties, and shear strength as well as fracture toughness and fatigue. It also includes information on forming, heat treating, machining, and joining. Filing Code: AL-366. Producer or source: Tennalum, A Division of Kaiser Aluminum.

scholarly journals Automatic Evaluation of the Mechanical Properties of Steels Maraging using Digital Image Processing Techniques

2020 ◽  
Author(s):  
Angélica Alves Viana ◽  
Savio Lopes Rabelo ◽  
José Daniel de Alencar Santos ◽  
Venceslau Xavier de Lima Filho ◽  
Douglas De Araújo Rodrigues ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Maraging Steel ◽  
Raw Material ◽  
High Fracture Toughness ◽  
Mechanical Resistance ◽  
High Fracture ◽  
Traditional System ◽  
Transformation Methods ◽  
Processing Techniques

Some strategic sectors of the economy require that the raw material of their machines and equipment have mechanical properties that satisfy their use. Maraging steel is a material of great concern since it is necessary to have a high mechanical resistance associated with high fracture toughness. The traditional tests to determine the fracture toughness of this material before use in applications are the Charpy and KIC tests. However, this process is characterized by being exhaustive and requiring specialized and trained professionals. Thus, to reverse this situation, this work proposes a new approach to determine the mechanical properties of maraging steel. For this, initially, the method removes any artifacts present in the image resulting from the mode of acquisition. In sequence, this works tested the method Extended Minimum Transformation (EMT) and mathematical morphology to find these markers of the regions of the dimples. Then, the Adaptive Thresholding, Optimal Global Thresholdusing the Otsu Method and Watershed transformation methods were used to segment the dimples. In the end, the diameter of the dimples and the toughness of the material were calculated. Tests are carried out and compared with the result obtained by specialists using the traditional system to evaluate the proposed approach. The results obtained were satisfactory for the application because the proposed approach presented speed and precision to the conventional methods.

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.

Preparation of a Novel Poly(Methyl Methacrylate)-Dimethyl Diethoxysilane Nano-Composite

2007 ◽  
Vol 361-363 ◽  
pp. 491-494 ◽  
Author(s):  
Kyu Hyeon Lee ◽  
Yong Keun Lee ◽  
Bum Soon Lim ◽  
Sung Baek Cho ◽  
Sang Hoon Rhee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Methyl Methacrylate ◽  
Bone Cement ◽  
Tetraethyl Orthosilicate ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Nano Composite ◽  
Poly Methyl Methacrylate

The poly(methyl methacrylate)/silica nano-composite made from trimethoxysilyl functionalized poly(methyl methacrylate) and dimethyl diethoxysilane was newly prepared and its apatite-forming ability and mechanical properties were evaluated comparing to poly(methyl methacrylate)/silica nano-composite made from trimethoxysilyl functionalized poly(methyl methacrylate) and tetraethyl orthosilicate. Its apatite-forming ability was similar to that of poly(methyl methacrylate)/silica nano-composite using tetraethyl orthosilicate but its fracture toughness was much improved. Its high fracture toughness might come from the less quantity of siloxane linkages in its structure because dimethyl diethoxysilane had only two ethoxysilane groups while tetraethyl orthosilicate had four ethoxysilane groups. From the results, it can be concluded that it has a possibility to be used as bioactive bone cement.

Correlation between microstructure and mechanical properties in silicon carbide with alumina addition

1993 ◽  
Vol 8 (7) ◽  
pp. 1635-1643 ◽  
Author(s):  
S.S. Shinozaki ◽  
J. Hangas ◽  
K.R. Carduner ◽  
M.J. Rokosz ◽  
K. Suzuki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Analytical Electron Microscopy ◽  
High Strength ◽  
High Fracture Toughness ◽  
Sintered Body ◽  
High Fracture ◽  
High Fatigue ◽  
Alumina Addition

The microstructure of pressureless sintered silicon carbide (SiC) materials with alumina (Al2O3) addition was investigated using analytical electron microscopy and nuclear magnetic resonance. A sintered body with a density of higher than 99% theoretical was obtained with an addition of 5 wt.% Al2O3. The sintered body (SiC–Al2O3) has high strength, high fracture toughness, and high fatigue resistance. Its fracture toughness is approximately 5 MPa-m1/2, which is twice as high as that of pressureless sintered SiC materials with boron and carbon additions (SiC–B–C). The correlation between the microstructure and the mechanical properties is presented here. The starting β–SiC powder is mostly transformed to α–SiC with various polytype distributions during the sintering process. The microstructure has homogeneously distributed, fine, plate-like interlocking gains with a high aspect ratio. Well-developed basal planes form parallel and elongated boundaries, and the crystal structure is mostly the 6H polytype (56%) mixed with thin lamellar 4H.

Microstructural evolution and mechanical properties of gas-pressure-sintered Si3N4 with Yb2O3 as a sintering aid

1999 ◽  
Vol 14 (5) ◽  
pp. 1904-1909 ◽  
Author(s):  
Ki-Min Lee ◽  
Won-Ho Lee ◽  
Young-Hag Koh ◽  
Jong-Jin Choi ◽  
Hyoun-Ee Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Microstructural Evolution ◽  
Outer Region ◽  
Functionally Graded ◽  
Gas Pressure ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Sintering Aid ◽  
Inner Region

Microstructural evolution and mechanical properties of gas-pressure-sintered Si3N4 with 4 wt% Yb2O3 as a sintering aid were investigated. The microstructure was not uniform throughout the specimen. Extremely large elongated grains were formed at the outer region near the surface, while relatively small elongated grains were formed at the inner region of the specimen. The outer region expanded inward with the sintering time. Mechanical properties, such as flexural strength, fracture toughness, and R-curve behavior of the specimens were strongly influenced by these variations in microstructure. The fracture toughness and the R-curve behavior of the outer region were higher than those of the inner region of the same specimen. On the other hand, the strength of the inner region was higher than that of the outer region. By controlling the relative thickness of each region, Si3N4 specimens having functionally graded microstructure were obtained. The Si3N4 with such microstructure exhibited high strength, high fracture toughness, and good flaw tolerance at the same time.

scholarly journals Effect of Additive Ti3SiC2 Content on Mechanical Properties of B4C–TiB2 Composites Ceramics Sintered by Spark Plasma Sintering

2020 ◽  
Author(s):  
Xingheng Yan ◽  
Xingui Zhou ◽  
Honglei Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Spark Plasma Sintering ◽  
Bending Strength ◽  
High Fracture Toughness ◽  
Transgranular Fracture ◽  
Composite Ceramics ◽  
High Fracture ◽  
Plasma Sintering ◽  
Spark Plasma

Abstract B4C-TiB2 composite ceramics with ultra-high fracture toughness were successfully prepared via spark plasma sintering at 1900℃ using B4C and Ti3SiC2 as raw materials. The results show that compared with pure B4C ceramics sintered by SPS, the hardness of B4C-TiB2 composite ceramics is decreased, but the flexural strength and fracture toughness are significantly improved, especially the fracture toughness has been improved by leaps and bounds. When the content of Ti3SiC2 is 30vol.%, the B4C-TiB2 composite ceramic has the best comprehensive mechanical properties: hardness, bending strength and fracture toughness are 27.28 GPa, 405.11 MPa and 18.94 MPa·m1/2, respectively. The fracture mode of the B4C-TiB2 composite ceramics is a mixture of transgranular fracture and intergranular fracture. Two main two reasons for the ultra-high fracture toughness are the existence of lamellar graphite at the grain boundary, and the formation of a three-dimensional interpenetrating network covering the whole composite.

Fracture Energy and Fracture Toughness of In Situ Calcium Hexaluminate (CA6)-Alumina Monolithic Refractory

2018 ◽  
Vol 766 ◽  
pp. 77-82
Author(s):  
Jiraprabha Khajornboon ◽  
Kouichiro Washijima ◽  
Takeshi Shiono
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Energy ◽  
Raw Materials ◽  
Stoichiometric Composition ◽  
Physical And Mechanical Properties ◽  
Apparent Porosity ◽  
High Fracture Toughness ◽  
High Fracture

One of main raw materials for monolithic refractory is calcium aluminate cement which provides CA6 hexagonal plate-like microstructure with self-toughening properties and fracture resistance. In the present study, in-situ CA6 was formed by using sintered alumina mixing with alumina cement in stoichiometric composition to achieve 100 mass% and 50 mass% of CA6 in alumina monolithic refractory with 2 mass% of silica addition. Samples were fired from 1400-1500°C for 5 h and characterized for physical and mechanical properties. The results showed that both samples could not obtain CA6 content as expected and apparent porosity did not exhibit in the same tendency. However, only proper amount of CA6 content could gain proper amount of apparent porosity which is the main effect of mechanical properties. Especially the formation of CA6 lower than 50 mass% with the presence of low melting phase caused low apparent porosity and led to high fracture toughness and effective fracture energy.

Influence of NbC-Addition on Mechanical Properties of WC-Co

2005 ◽  
Vol 498-499 ◽  
pp. 363-368 ◽  
Author(s):  
Wilson Acchar ◽  
Harim Revoredo de Macedo
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Niobium Carbide ◽  
Testing Machine ◽  
High Hardness ◽  
Inert Atmosphere ◽  
High Fracture Toughness ◽  
High Wear Resistance ◽  
High Fracture ◽  
First Results

Cemented carbides have been intensively used as cutting tool through their high hardness, high fracture toughness and high wear resistance. A considerable amount of works has been developed in order to improve the mechanical properties of alternate cemented carbide systems. This work has the purpose to reports the first results obtained to WC-Co reinforced with 5 wt.% NbC. The mixture of powders was hot-pressed at 1250 °C in a inert atmosphere. Hardness and fracture toughness were carried out in a Vickers hardness testing machine. The results have showed that the addition of niobium carbide improves the hardness of tungsten carbide and inhibits the WCgrain growth.

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