Correlation of Thermal Conduction Properties With Mechanical Deformation Characteristics of a Set of SiC–Si3N4 Nanocomposites

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Vikas Tomar ◽  
Vikas Samvedi
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Optimal Control ◽  
High Temperature ◽  
Fracture Strength ◽  
Thermal Conduction ◽  
Volume Fraction ◽  
Ceramic Materials ◽  
Thermal And Mechanical Properties ◽  
Sic Particles

New developments in high temperature ceramic materials technology have focused on obtaining nanocomposite materials with nanoscale features for an optimal control of thermal and mechanical properties. One example is the silicon carbide (SiC)–silicon nitride (Si3N4) nanocomposites with nanosized SiC particles placed either in microsized Si3N4 grains or along Si3N4 grain boundaries (GBs). This work focuses on analyzing the influence of GBs, interfaces, and impurities on thermal and mechanical properties of a set of SiC–Si3N4 nanocomposites at three different temperatures (300 K, 900 K, and 1500 K). Nanocomposite thermal conductivity values predicted in this study are smaller in comparison to the bulk Si3N4 values (∼30 W/m K). Even with the volume fraction of SiC phase being limited to maximum 40%, it is shown that the thermal conductivity values could be reduced to less than those of the bulk SiC phase (∼3 W/m K) by microstructural feature arrangement. Nanocomposite phonon spectral density values show a short rage structural order indicating a high degree of diffused phonon reflection. Visual analyses of the atomistic arrangements did not reveal any loss of crystallinity in the nanocomposites at high temperatures. This indicates that structural arrangement, not the phase change, is a factor controlling thermal conduction as a function of temperature. The nanocomposite deformation mechanism is a trade-off between the stress concentration caused by SiC particles and Si3N4–Si3N4 GB sliding. The temperature increase tends to work in favor of GB sliding leading to softening of structures. However, microstructural strength increases with increase in temperature when GBs are absent. GBs also contribute to reduction in thermal conductivity as well as increase in fracture strength. Replacement of sharp GBs by diffused GBs having C/N impurities, lowered thermal conductivity, and increased fracture strength. Decrease in SiC–Si3N4 interfaces by removal of SiC particles tends to favor an increase in thermal conductivity as well as fracture resistance. Overall, it is shown that for high temperature mechanical strength improvement, judicious placement of SiC particles and optimal control of GB atomic volume fraction are the main controlling factors.

MICROSTRUCTURE AND PROPERTIES OF SiC PARTICLES REINFORCED COPPER BASED ALLOY COMPOSITE

2013 ◽  
Vol 27 (19) ◽  
pp. 1341025 ◽  
Author(s):  
YU HONG ◽  
XIAOLI CHEN ◽  
WENFANG WANG ◽  
YUCHENG WU
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Relative Density ◽  
Volume Fraction ◽  
Copper Matrix ◽  
Matrix Composites ◽  
Wear Properties ◽  
Sic Particles ◽  
Copper Based Alloy

Copper-matrix composites reinforced with SiC particles are prepared by mechanical alloying. The microstructure characteristics, relative density, hardness, tensile strength, electrical conductivity, thermal conductivity and wear properties of the composites are investigated in this paper. The results indicate that the relative density, macro-hardness and mechanical properties of composites are improved by modifying the surface of SiC particles with Cu and Ni . The electrical conductivity and thermal conductivity of composites, however, are not obviously improved. For a given volume fraction of SiC , the Cu / SiC ( Ni ) has higher mechanical properties than Cu / SiC ( Cu ). The wear resistance of the composites are improved by the addition of SiC . The composites with optimized interface have lower wear rate.

scholarly journals Utilization of SiC and Cu Particles to Enhance Thermal and Mechanical Properties of Al Matrix Composites

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2770 ◽  
Author(s):  
Dongxu Wu ◽  
Congliang Huang ◽  
Yukai Wang ◽  
Yi An ◽  
Chuwen Guo
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
High Thermal Conductivity ◽  
Low Density ◽  
Matrix Composites ◽  
Thermal And Mechanical Properties ◽  
Cu Content ◽  
Sic Particles ◽  
Al Matrix Composites ◽  
Al Matrix

In this work, SiC and Cu particles were utilized to enhance the thermal and mechanical properties of Al matrix composites. The ball-milling and cold-compact methods were applied to prepare Al matrix composites, and the uniform distribution of SiC and Cu particles in the composite confirms the validity of our preparation method. After characterizing the thermal conductivity and the compressibility of the prepared composites, results show that small particles have a higher potential to improve compressibility than large particles, which is attributed to the size effect of elastic modulus. The addition of SiC to the Al matrix will improve the compressibility behavior of Al matrix composites, and the compressibility can be enhanced by 100% when SiC content is increased from 0 to 30%. However, the addition of SiC particles has a negative effect on thermal conductivity because of the low thermal conductivity of SiC particles. The addition of Cu particles to Al-SiC MMCs could further slightly improve the compressibility behavior of Al-SiC/Cu MMCs, while the thermal conductivity could be enhanced by about 100% when the Cu content was increased from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure and/or sintering temperature. This work is expected to supply some information for preparing Al matrix composites with low density but high thermal conductivity and high compressibility.

Improved thermal and mechanical properties of carbon fiber filled polyamide 46 composites

2017 ◽  
Vol 37 (4) ◽  
pp. 345-353 ◽  
Author(s):  
Yisha Yang ◽  
Duxin Li ◽  
Gaojie Si ◽  
Qilong Liu ◽  
Yue Chen
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Carbon Fiber ◽  
Thermal Conduction ◽  
Weight Fraction ◽  
Thermal And Mechanical Properties ◽  
Conduction Model ◽  
Pure Matrix ◽  
Crystallization Onset ◽  
Conductive System

Abstract The thermal and mechanical properties of polyamide 46 (PA46) filled with carbon fiber (CF/PA46) composites were studied. CF/PA46 was fabricated by the method of melt blending and injection molding. The results showed that thermal conductivity, tensile strength and impact strength of the composite increased with the increase of weight fraction of CF, however, the elongation at the break decreased as its weight fraction increased. The addition of CF had little effect on the melting temperature of composites, while the crystallization onset (To) and crystallization peak (Tp) temperatures of composites shifted to higher points. The scanning electron microscope images showed that when the weight fraction of CF was increased, the CF was more likely to form thermal chains and a network. When the CF weight fraction was 40%, thermal conductivity was 1.49 W/(m·K), approximately 5.54 times as high as that of the pure PA46, and the thermal diffusivity was 0.9755 mm2/s, 6.5 times higher than that of the pure matrix. Comparing the experimental data with the three expected thermal conduction models data, the Maxwell-Eucken thermal conduction model was considered more suitable for the PA46/CF composite, in which the weight fraction of the filler was <10% in the thermal conductive system.

scholarly journals Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Rui He ◽  
Nan Dai ◽  
Zhenjun Wang
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
High Temperature ◽  
Mass Loss ◽  
Raw Materials ◽  
Expansion Ratio ◽  
Thermal And Mechanical Properties ◽  
Stress Strain

Geopolymers are prepared by alkali solution-activated natural minerals or industrial waste materials, which have been widely used as new sustainable building and construction materials for their excellent thermal and mechanical properties. The thermal and mechanical properties of geopolymers at high temperature have attracted great attention from many researchers. However, there are few systematic works concerning these two issues. Therefore, this work reviewed the thermal and mechanical behaviors of geopolymers at high temperature. Firstly, the thermal properties of geopolymers in terms of mass loss, thermal expansion, and thermal conductivity after high temperature were explained. Secondly, the mechanical properties of residual compressive strength and stress-strain relationship of fly ash geopolymers and metakaolin geopolymers after high temperature were analyzed. Finally, the microstructure and mineralogical characteristics of geopolymers upon heating were interpreted according to the changes of microstructures and compositions. The results show that the thermal properties of geopolymers are superior to cement concrete. The geopolymers possess few mass loss and a low expansion ratio and thermal conductivity at high temperature. The thermal and mechanical properties of the geopolymers are usually closely related to the raw materials and the constituents of the geopolymers. Preparation and testing conditions can affect the mechanical properties of the geopolymers. The stress-strain curves of geopolymer are changed by the composition of geopolymers and the high temperature. The silicon-type fillers not only improve the thermal expansion of the geopolymers but also enhance mechanical properties of the geopolymers. But, they do not contribute to reducing the thermal conductivity. the different raw materials, aluminosilicate precursor and reinforcement materials, result in different geopolymer damage during the heating. However, phase transitions can occur during the process of heating regardless of the raw materials. The additional performance enhancements can be achieved by optimizing the paste formulation, adjusting the inner structure, changing the alkali type, and incorporating reinforcements.

A Study of Some Mechanical and Physical Properties for Palm Fiber/Polyester Composite

2020 ◽  
Vol 38 (3B) ◽  
pp. 104-114
Author(s):  
Samah M. Hussein
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Date Palm ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Dielectric Strength ◽  
Palm Fiber ◽  
Mechanical And Physical Properties ◽  
Polyester Composite

This research has been done by reinforcing the matrix (unsaturated polyester) resin with natural material (date palm fiber (DPF)). The fibers were exposure to alkali treatment before reinforcement. The samples have been prepared by using hand lay-up technique with fiber volume fraction of (10%, 20% and 30%). After preparation of the mechanical and physical properties have been studied such as, compression, flexural, impact strength, thermal conductivity, Dielectric constant and dielectric strength. The polyester composite reinforced with date palm fiber at volume fraction (10% and 20%) has good mechanical properties rather than pure unsaturated polyester material, while the composite reinforced with 30% Vf present poor mechanical properties. Thermal conductivity results indicated insulator composite behavior. The effect of present fiber polar group induces of decreasing in dielectric strength, and increasing dielectric constant. The reinforcement composite 20% Vf showed the best results in mechanical, thermal and electrical properties.

Polyimide Copolymers Containing Various Levels Of The 6F Moiety For High Temperature And Microelectronic Applications

1991 ◽  
Vol 227 ◽  
Author(s):  
M. Haider ◽  
E. Chenevey ◽  
R. H. Vora ◽  
W. Cooper ◽  
M. Glick ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Electrical Properties ◽  
Oxidative Stability ◽  
Trifluoromethyl Group ◽  
Thermal And Mechanical Properties

ABSTRACTTrifluoromethyl group-containing polyimides not only show extraordinary electrical properties, but they also exhibit excellent long-term thermo-oxidative stability. Among the most thermomechanically stable structural polyimides are those from 6F dianhydride (6FDA) and 6F diamines. The effects of substituting non-fluorine containing monomers such as BTDA, mPDA and 4,4′-DADPS for the hexafluoroisopropylidene monomers on the dielectric, thermo-oxidative, thermal and mechanical properties of the copolymers were studied.

scholarly journals Flame-retardant MXene/Polyimide Film with Outstanding Thermal and Mechanical Properties Based on the Secondary Orientation Strategy

2021 ◽  
Author(s):  
Yue Zhu ◽  
Qingyu Peng ◽  
Haowen Zheng ◽  
Fuhua Xue ◽  
Pengyang Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Transition Metal ◽  
Mechanical Performance ◽  
Polyimide Film ◽  
Polymeric Films ◽  
Two Dimensional ◽  
Thermal And Mechanical Properties ◽  
Metal Carbides ◽  
Transition Metal Carbides

With the development of multifunction and miniaturization in modern electronics, polymeric films with strong mechanical performance and high thermal conductivity are urgently needed. Two-dimensional transition metal carbides and nitrides (MXenes)...

Estimation of Effective Thermal and Mechanical Properties of Particulate Thermal Interface Materials (TIMs) by a Random Network Model

2017 ◽  
Author(s):  
Pavan Kumar Vaitheeswaran ◽  
Ganesh Subbarayan
Keyword(s):  
Mechanical Properties ◽  
Network Model ◽  
Thermal Stresses ◽  
Volume Fraction ◽  
Random Network ◽  
Thermal Interface Materials ◽  
Thermal And Mechanical Properties ◽  
Thermal Interface ◽  
Classical Models ◽  
Interface Materials

Particulate thermal interface materials (TIMs) are commonly used to transport heat from chip to heat sink. While high thermal conductance is achieved by large volume loadings of highly conducting particles in a compliant matrix, small volume loadings of stiff particles will ensure reduced thermal stresses in the brittle silicon device. Developing numerical models to estimate effective thermal and mechanical properties of TIM systems would help optimize TIM performance with respect to these conflicting requirements. Classical models, often based on single particle solutions or regular arrangement of particles, are insufficient as real-life TIM systems contain a distriubtion of particles at high volume fractions, where classical models are invalid. In our earlier work, a computationally efficient random network model was developed to estimate the effective thermal conductivity of TIM systems [1,2]. This model is extended in this paper to estimate the effective elastic modulus of TIMs. Realistic microstructures are simulated and analyzed using the proposed method. Factors affecting the modulus (volume fraction and particle size distribution) are also studied.

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.

scholarly journals Influence of the Direction of Mixture Compaction on the Selected Properties of a Hemp-Lime Composite

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4629
Author(s):  
Przemysław Brzyski ◽  
Piotr Gleń ◽  
Mateusz Gładecki ◽  
Monika Rumińska ◽  
Zbigniew Suchorab ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Preparation Method ◽  
Thermal And Mechanical Properties ◽  
Compaction Process ◽  
External Wall ◽  
Capillary Uptake ◽  
Parallel Direction ◽  
The Individual

The aim of the research presented in the article was to check the differences in the hygro-thermal and mechanical properties of hemp-lime composites with different shives fractions, depending on the direction of mixture compaction. The research part of the paper presents the preparation method and investigation on the composites. Thermal conductivity, capillary uptake, as well as flexural and compressive strengths were examined. Additionally, an analysis of the temperature distribution in the external wall insulated with the tested composites was performed. The results confirm that the direction of compaction influences the individual properties of the composites in a similar way, depending on the size of the shives. The differences are more pronounced in the case of the composite containing longer fractions of shives. Both thermal conductivity of the material and the capillary uptake ability are lower in the parallel direction of the compaction process. Composites exhibit greater stiffness, but they fail faster with increasing loads when loaded in the direction perpendicular to compaction.

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