The Microstructures and Mechanical Properties of Molybdenum Disilicide Preforms Infiltrated by Aluminum

2006 ◽  
Vol 317-318 ◽  
pp. 331-334 ◽  
Author(s):  
Xiao Li Zhang ◽  
Zhi Hao Jin ◽  
Zhen Lin Lu
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Bending Strength ◽  
Molybdenum Disilicide ◽  
Experimental Results ◽  
Reactive Infiltration ◽  
Infiltration Temperature ◽  
N2 Atmosphere ◽  
Different Temperatures ◽  
High Infiltration

Infiltrant aluminum was infiltrated into molybdenum disilicide preforms in N2 atmosphere at different temperatures by liquid reactive infiltration processing. The mechanical properties and phase composition of these materials were analyzed and discussed. The experimental results showed that the samples were corresponding to 10 at.% Al averagely after sintered, and consisted of Mo(Al,Si)2 phase and Al-Si alloy phase. High infiltration temperature would lead to Al deficiency mainly in Al-Si alloy phase. The highest bending strength of 737 MPa was reached at infiltration temperature of 1350 °C because the sample had fine and integrated grains, and the strong combination between particles. When the infiltration temperature was higher than 1350 °C, the bending strength of material prepared would decrease because of the phase fragmentation.

Preparation and Properties of SiC/Phenolic Resin for the Heat of LED

2016 ◽  
Vol 848 ◽  
pp. 454-459
Author(s):  
Cong Wu ◽  
Kang Zhao ◽  
Yu Fei Tang ◽  
Ji Yuan Ma
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Powder Metallurgy ◽  
Phenolic Resin ◽  
Bending Strength ◽  
Experimental Results ◽  
Low Thermal Conductivity ◽  
Industry Standard ◽  
Insulation Performance

In order to solve the problem that low thermal conductivity of the plastics for the heat of LED, SiC/Phenolic resin for the heat of LED were fabricated combining powder metallurgy. The effects of particles diameters, content and adding nanoparticles on thermal conductivity of the fabricated composites were investigated, the mechanical properties were also characterized. The experimental results showed that the materials were obtained, and the insulation performance of the fabricated SiC/Phenolic resin was higher than the industry standard one, the thermal conductivity reached 4.1W/(m·k)-1. And the bending strength of the fabricated composites was up to 68.11MPa. The problem of low thermal conductivity of the material is expected to be solved. In addition, it is meaningful for improving LED life.

Synthesis of SiC Ceramics from Coal Gangue

2005 ◽  
Vol 486-487 ◽  
pp. 378-381 ◽  
Author(s):  
Shu Hai Jia
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Carbon Black ◽  
Bending Strength ◽  
Coal Gangue ◽  
Holding Time ◽  
Crystal Phase ◽  
Sic Ceramics ◽  
N2 Atmosphere

The synthesis and the sintering of SiC from coal gangue by carbothermal synthesized in N2 atmosphere are studied. The material, 5 percent carbon black added and sintered at 1400°C for 2 hours, had good properties and a bending strength of 137.8MPa. Too high temperature or too long holding time made the properties of the material to decrease. β-SiC found by observing the microstructure is a major crystal phase in the synthesized ceramics, which would lead to fine mechanical properties.

Fabrication and mechanical properties of Al/Al2O3 composite bodies by reactive infiltration of molten Al into SiO2 preform

2000 ◽  
Vol 15 (11) ◽  
pp. 2314-2321 ◽  
Author(s):  
Noboru Yoshikawa ◽  
Singo Funahashi ◽  
Shoji Taniguchi ◽  
Atsushi Kikuchi
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Sintering Temperature ◽  
Pore Space ◽  
Pressure Infiltration ◽  
X Ray ◽  
Reactive Infiltration ◽  
Pore Size Distributions ◽  
Different Temperatures ◽  
Si Content

Al/Al2O3 composites were fabricated by a displacement reaction between SiO2 and molten Al. In this study, fabrication of Al/Al2O3 composites was attempted by means of reactive infiltration to provide variation of their mechanical properties. SiO2 preforms having various porosities and pore size distributions were prepared by sintering the powder at different temperatures between 1273 and 1723 K. Molten Al was infiltrated at 1373 K without application of pressure. Infiltration kinetics were studied and the microstructures of the composite bodies were observed by means of scanning electron microscopy (with energy dispersive x-ray microanalysis), wave dispersive x-ray microanalysis, and x-ray diffractions. The infiltrated specimens were mainly composed of Al and α–Al2O3 phases, and the Si content was less than 5 at.%. Volume fraction of Al phase in the composite bodies was not altered very much with the porosities of the SiO2 preforms because of the difficulty in filling out the entire pore space. Properties and microstructures of Al/Al2O3 composites, however, were dependent on the sintering temperature of the SiO2 preforms. In the case of low sintering temperature, a thick Al channel existed, which deformed upon compression. In the case of high sintering temperature, the microstructure became homogeneous and had thinner Al channels. The composite bodies became brittle. The deformation behavior was shown to be changed from ductile to brittle as an increase of the sintering temperature of the preforms.

Some Experiences of Tribological, Microstructural and Mechanical Investigation of Post Heat Treated SiAlON Ceramics

2005 ◽  
Vol 473-474 ◽  
pp. 135-140
Author(s):  
Maria Maros Berkes ◽  
Judit Babcsán Kiss ◽  
László Kuzsella ◽  
Péter Arató
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Bending Strength ◽  
Mechanical Tests ◽  
Point Of View ◽  
Post Heat Treatment ◽  
Technical Ceramics ◽  
Different Temperatures ◽  
Pin On Disc ◽  
Damage Process

Tribological performance of technical ceramics is influenced by various factors. Among the others the material properties, loading conditions, residual stresses as well as chemical reactions and interaction between contacting parts effect the damage process. The current paper focuses on the material features, investigating the possibility of modifying the wearing characteristics of a Si3N4 based technical ceramics by post-heat treatment. The microstructure, the mechanical properties and the wearing characteristics were studied on HIP-sintered SiAlON samples, post heattreated in oxidizing atmosphere at different temperatures. Wearing performance was characterized by pin-on disc tests. The wear rate varied with the temperature of heat treatment. From tribological point of view especially treatment at 1200°C proved to be advantageous Microstructural investigations by TEM and X-ray diffraction studies revealed some explanations of these changes. The above studies were completed by mechanical tests. Microhardness, E-modulus, four point bending strength and indentation fracture toughness have been determined in order to study the correlation between the tribological and mechanical properties. Based on our results, the post heat treatment may be useful to improve the wearing performance of SiAlON ceramics.

scholarly journals Environment-Friendly Preparation of Reaction-Bonded Silicon Carbide by Addition of Boron in the Silicon Melt

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1090
Author(s):  
Maoqiang Rui ◽  
Yaxiang Zhang ◽  
Jing Ye
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Argon Atmosphere ◽  
Environment Friendly ◽  
Silicon Melt ◽  
Different Temperatures ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

Reaction-bonded silicon carbide ceramics were sintered by infiltration of Si and B–Si alloy under an argon atmosphere at different temperatures. The element boron was added to the silicon melt to form a B–Si alloy first. The mechanical properties of samples were improved by infiltration of the B–Si melt. The samples infiltrated with the Si-only melt were found to be very sensitive to experimental temperature. The bending strengths of 58.6 and 317.0 MPa were achieved at 1530 and 1570 °C, respectively. The sample made by infiltration of B–Si alloy was successfully sintered at 1530 °C. The relative density of the sample was more than 90%. The infiltration of B–Si alloy reduced the sintering temperature and the bending strength reached 326.9 MPa. The infiltration mechanism of B–Si alloy is discussed herein.

Effect of Z Values on the Microstructure and Mechanical Properties of Post-sintered Reaction Bonded β-SiAlON

2017 ◽  
Vol 36 (5) ◽  
pp. 453-458 ◽  
Author(s):  
Yanjun Li ◽  
Donghua Liu ◽  
Han Jin ◽  
Donghai Ding ◽  
Guoqing Xiao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Bulk Density ◽  
Grain Growth ◽  
Bending Strength ◽  
Raw Materials ◽  
Apparent Porosity ◽  
Reaction Bonding ◽  
Microstructure And Mechanical Properties ◽  
Before And After

Abstractβ-SiAlON materials with different Z values (Z=0.5–3) were fabricated by a reaction bonding combining post-sintering route using raw materials of Si, Al2O3, AlN, etc. The reaction bonded β-SiAlON (RB-β-SiAlON) were post-sintered at 1,750 °C for 6 h. Apparent porosity, bulk density, bending strength and Vicker’s hardness of the samples before and after post-sintering were tested. XRD results showed that the phase composition of both RB-β-SiAlON and post-sintered RB-β-SiAlON (PSRB-β-SiAlON) were β-SiAlON. For RB-β-SiAlON, the apparent porosity was decreased with the increase of Z values, while the strength and hardness was increased accordingly. After the post-sintering procedure, nearly full densified PSRB-β-SiAlON was obtained and the mechanical properties were significantly improved. The bending strength and Vicker’s hardness of the PSRB-β-SiAlON (Z=0.5) achieved 510 MPa and 16.5 GPa, respectively, which were as 2.7 and 6.7 times high as those of the corresponding RB-β-SiAlON. However, the strength and hardness of PSRB-β-SiAlON decreased with the increase of Z value due to the grain growth.

Effect of Nano-Al2O3 on Mechanical Properties and Microstructure of Al2O3/Si3N4 Compound Ceramics

2010 ◽  
Vol 168-170 ◽  
pp. 1846-1849 ◽  
Author(s):  
Shi Ming Hao ◽  
Hui Fang Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Bending Strength ◽  
Nitrogen Atmosphere ◽  
Pressureless Sintering ◽  
X Ray ◽  
Ceramics Matrix

The specimens of Al2O3/Si3N4 compound ceramics which contain 3%, 6%, 9%, 12%, 15%, and 18% nano-Al2O3 additions respectively were obtained by pressureless sintering at 1650 in the nitrogen atmosphere. The bending strength and fracture toughness (KIC) were detected. The microstructure and phase composition of the specimens were analyzed by the means of SEM and X-ray. The results show that Al2O3/Si3N4 compound ceramics can be made only using pressureless sintering. With 9-12% nano-Al2O3addition, the specimens have the top mechanical properties. The bending strength reach 710.86MPa, KIC reach 8.61MPa•M1/2. These excellent properties come from many interwoven nitride distributed uniformly in the Al2O3/Si3N4 compound ceramics matrix, which composed of big and firmly plate-like β- Si3N4, hexagonal Sialon and sheet Si2N2O.

scholarly journals Mechanical properties of concrete with substitution of coated styrofoam balls on coarse aggregate

2019 ◽  
Vol 276 ◽  
pp. 01028
Author(s):  
Bernardinus Herbudiman ◽  
Erma Desmaliana ◽  
Andhi Muhammad Irawan
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Lightweight Concrete ◽  
Density Ratio ◽  
Experimental Results ◽  
Ratio Method ◽  
Coating Materials ◽  
Air Content ◽  
Coarse Aggregates ◽  
Pozzolanic Material

Substitution of Styrofoam balls on coarse aggregates reduced concrete self-weight. Coating on Styrofoam ball surface makes ball has shell on its surface and could increase the adhesive strength between ball surfaces and cement paste. The coating materials made by mixing of Portland cement and RCC-15 (Residual Catalytic Cracker-15) as pozzolanic material. 20 mm diameter Styrofoam balls are used. Coarse aggregates substituted by 5%, 15%, and 20% Styrofoam balls. The test specimens used three 10x20cm cylinders for each variant. Beam specimens of 15x15x60cm used for bending strength test by third point loading method. The testing of mechanical properties were 7, 14, and 28 days compressive strengths, 28 days split-tensile strengths and 28 days flexural strengths. The experimental results of concrete with various Styrofoam ball substitutions of 5%, 15%, and 20% at 28 days show the average compressive strengths are 27.6 MPa, 24.3 MPa, and 20.3 MPa, the splittensile strengths are 2.5 MPa, 2.2 MPa, and 1.7 MPa, and the flexural strengths are 5 MPa, 4.5 MPa, and 3.8 MPa, respectively. The compression strength could be predicted by density ratio method and air content method. The experimental results show that all of the variants of Styrofoam ball coarse aggregates concrete are adequate to achieve structural strength, and have nearly compressive strengths compared with the prediction by density ratio method and air content method. Styrofoam balls substitution content could be increased to make the concrete density below 1,900 kg/m3 and compressive strength above 17.5 MPa to reach structural lightweight concrete performance.

Study on bending and tensile properties of a T-shaped hook-connected structure made of two-and-a-half-dimensional woven composites and laminated composites

2019 ◽  
Vol 89 (19-20) ◽  
pp. 4046-4059 ◽  
Author(s):  
Hongjian Zhang ◽  
Junhua Guo ◽  
Weidong Wen ◽  
Haitao Cui ◽  
Shu He
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Bending Strength ◽  
Laminated Composites ◽  
Prediction Method ◽  
Experimental Results ◽  
Bending Test ◽  
Woven Composites ◽  
Root Edge ◽  
Connected Structure

In this paper, a kind of T-shaped hook-connected structure, which consists of a T-shaped plate made of two-and-a-half-dimensional woven composites and a groove structure made of T300/BMP316 laminated composites, was designed as the simulator specimen of the connection structure between the vane and the case in an aero-engine. As the bending strength and tensile strength are important mechanical properties, bending tests and tensile tests, respectively, of the T-shaped hook-connected structure were conducted to study the mechanical properties and failure modes under bending and tensile loads on web. Experimental results showed that the initial damages both occur at the root-edge, and then the damages extend to the root-middle during the bending test or extend perpendicular to the root-edge to the margin of the flange during the tensile test. Then, a strength prediction method based on the progressive damage theory was developed to simulate the mechanical properties and damage processes of the T-shaped hook-connected structure under bending and tensile loads, respectively. Compared with experimental results, the maximum error is less than 10%, and the damage modes are similar.

scholarly journals Mechanical properties of porous concrete with variations of coarse aggregate gradation

2019 ◽  
Vol 276 ◽  
pp. 01027
Author(s):  
Hazairin ◽  
Erma Desmaliana ◽  
Bernardinus Herbudiman ◽  
Wira Yudha Saputra
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Bending Strength ◽  
Coarse Aggregate ◽  
Experimental Results ◽  
Fine Aggregate ◽  
High Porosity ◽  
Aggregate Gradation ◽  
Porous Concrete ◽  
Air Content

Porous concrete is an innovation in sustainable concrete technology, which has high porosity concrete without fine aggregate. Porous concrete used in rain gardens, planter boxes, permeable pavements at urban open spaces could absorb rainwater so it can reduce run-off. This experimental study purposes to determine the compressive, split-tensile, flexural strengths, and permeability of porous concrete with various gradation of coarse aggregates. This study used a concrete mixture with coarse aggregate gradation variations of gap, continuous, and uniform on the water cement ratio of 0.4. The test specimens used three cylinders of 15x30cm for compressive and split-tensile strengths, except for uniform gradations used three cylinders of 10x20cm. Beam specimens of 15x15x60cm used for bending strength test by third point loading method. The tested mechanical properties are 7, 14, and 28 days-compressive strengths, 28 days split-tensile strength, and 28 days bending strength. The experimental results also show the average compressive strengths of porous concrete with variation of gradations of gap, continuous, and uniform for 28 days is 14.6 MPa, 13.0 MPa, and 10.6 MPa, respectively. Volumetric flow rate of porous concrete with gap, continuous, and uniform aggregate gradations is 28.4 ml/s, 32.1 ml/s, and 39.3 ml/s, respectively. The experimental results show that gap gradation is recommended due to its better compressive and flexural strengths. In porous concrete, aggregate gradations influence the air content. The highest air content results the lowest compressive strength of concrete. The designed air content should be controlled to maintain the expexted compressive strength of porous concrete.

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