A Novel, Low-Cost C-C Composite Heat Sink Material

1996 ◽  
Vol 445 ◽  
Author(s):  
W. Kowbel ◽  
V. Chellappa ◽  
J.C. Withers
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Low Cost ◽  
Mechanical And Thermal Properties ◽  
New Class ◽  
Dielectric Coatings ◽  
Potential Applications ◽  
New Material ◽  
New Type ◽  
Composite Heat

AbstractRapid advances in high power electronics packaging require the development of new heat sink materials. Advanced composites designed to provide thermal expansion control as well as improved thermal conductivity have the potential to provide benefits in the removal of excess heat from electronic devices. Carbon-carbon (C-C) composits are under consideration for several military and space electronic applications including SEM-E electronic boxes. The high cost of C-C composits has greatly hindered their wide spread commercialization. A new manufacturing process has been developed to produce high thermal conductivity (over 400 W/mK) C-C composites at greatly reduced cost (less than $50/lb). This new material has potential applications as both a heat sink and a substrate. Dielectric coatings such as A1N and diamond were applied to this new type of heat sink material. Processing, as well as mechanical and thermal properties of this new class of heat sink material will be presented.

Development of Animal Fibres Composites for Construction Applications

2022 ◽  
Author(s):  
Anna Alfocea-Roig ◽  
Sergio Huete-Hernandez ◽  
Alex Maldonado-Alameda ◽  
Jessica Giro-Paloma ◽  
Josep Maria Chimenos-Ribera ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raw Materials ◽  
Industrial Process ◽  
Economic Cost ◽  
Low Grade ◽  
Environmental Consequences ◽  
Potential Applications ◽  
Competitive Prices ◽  
New Material ◽  
The Cost

Climate change has become one of the world’s leading threats. Currently, the construction industry has a high environmental footprint. For this reason, the scientific and technological sector is looking for new materials to reduce the environmental consequences of this division. It is well known that the valorisation of different by-products can contribute to the reduction of the energy global consumption and CO2 emissions. Magnesium Phosphate Cement (MPC) can be obtained by using Low Grade Magnesium Oxide (LG-MgO) as a by-product from the industrial process of magnesite calcination. In this research, a Sustainable MPC (Sust-MPC) for different construction purposes is developed by using LG-MgO along with monopotassium phosphate KH2PO4 (MKP) as raw materials. The increasing use of synthetic fibres in clothing, as well as China’s competitive prices on Animal Fibres (AF) market, have led to a commercial interest fibre decrease for wool-like AF in Spain. This study aims to formulate a Sust-MPC cement with Animal Fibre (AF) to reduce the cost of the new material (Sust-MPC-AF) and to increase the thermal insulation, allowing the use of Sust-MPC-AF in several potential applications. Besides, it should be emphasized that the final pH of Sust-MPC is neutral, which allows containing natural fibres. To develop Sust-MPC-AF, some properties such as thermal conductivity, density, Modulus of Elasticity (MoE), flexural strength, and economic cost were evaluated using the Design of Experiments (DoE). The DoE studies allowed obtaining a model for further optimization considering minimum thermal conductivity and cost dosages. The formulation 30L-25EW presents the minimum conductivity (λ=0.140 W·m-1·K-1). Therefore, two optimal dosages (36L-25EW and 24L-22EW) are obtained by considering mixing variables such as AF/Cement ratio (AF/C) and AF/Extra Water ratio (AF/EW).

scholarly journals Graphene-Based Films: Fabrication, Interfacial Modification, and Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2539
Author(s):  
Sihua Guo ◽  
Jin Chen ◽  
Yong Zhang ◽  
Johan Liu
Keyword(s):  
Mechanical Properties ◽  
Graphene Film ◽  
Current Status ◽  
Mechanical And Thermal Properties ◽  
Coating Technology ◽  
New Class ◽  
Interfacial Modification ◽  
Challenges And Opportunities ◽  
Potential Applications ◽  
Preparation Strategy

Graphene-based film attracts tremendous interest in many potential applications due to its excellent thermal, electrical, and mechanical properties. This review focused on a critical analysis of fabrication, processing methodology, the interfacial modification approach, and the applications of this novel and new class material. Strong attention was paid to the preparation strategy and interfacial modification approach to improve its mechanical and thermal properties. The overview also discussed the challenges and opportunities regarding its industrial production and the current status of the commercialization. This review showed that blade coating technology is an effective method for industrial mass-produced graphene film with controllable thickness. The synergistic effect of different interface interactions can effectively improve the mechanical properties of graphene-based film. At present, the application of graphene-based film on mobile phones has become an interesting example of the use of graphene. Looking for more application cases is of great significance for the development of graphene-based technology.

Syntactic Closed-cell Foams Based on Silicon Carbide

2004 ◽  
Vol 851 ◽  
Author(s):  
Engin Ozcivici ◽  
Raman P. Singh
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Low Cost ◽  
Processing Technique ◽  
Mechanical And Thermal Properties ◽  
Syntactic Foams ◽  
Compression Tests ◽  
Closed Cell ◽  
Carbide Matrix ◽  
Silicon Carbide Matrix

ABSTRACTClosed cell foams were fabricated by incorporating two different grades of hollow alumino-silicate spheres (cenospheres) into a silicon carbide matrix. The silicon carbide matrix was formed by the pyrolysis of a preceramic polymer, and multiple polymer infiltration and pyrolysis (PIP) cycles were employed to minimize the open voids in the material. The physical, mechanical and thermal properties of the fabricated foams were characterized as functions of the number of reinfiltration cycles. The open- and closed-void volume fractions were determined by measurements of bulk and skeletal densities. Mechanical properties, including strength and modulus, were evaluated using four-point bend and compression tests. Finally, thermophysical (thermal conductivity) values of the material were determined using laser-flash technique. This processing technique results in closed-cell syntactic foams with low density (≤ 1.8g/cm3), reasonable mechanical strength (∼ 30 MPa) and very low thermal conductivity (≤ 1 W/m-K). In this manner, this process can be used for the low-cost and net-shape fabrication of closed-cell silicon carbide syntactic foams for high temperature applications.

scholarly journals On the Path to a New Generation of Cement-Based Composites through the Use of Lignocellulosic Micro/Nanofibers

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1584 ◽  
Author(s):  
Rafel Reixach ◽  
Josep Claramunt ◽  
M. Àngel Chamorro ◽  
Joan Llorens ◽  
M. Mercè Pareta ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Low Cost ◽  
Water Immersion ◽  
Cellulose Nanofibers ◽  
Cement Matrix ◽  
Mechanical And Thermal Properties ◽  
Pine Sawdust ◽  
Potential Applications ◽  
Extended Surface ◽  
New Generation

Due to its high biocompatibility, bio-degradability, and low cost, cellulose finds application in disparate areas of research. Here we focus our attention on the potential applications of cellulose nanofiber in cement-based materials for the building sector. We first describe the chemical/morphological composition of cellulose fibers, their process and treatment, the characterization of cement-based composites, and their flexural strength. In recent research in this field, cellulose has been considered in the form of nano-sized particles, i.e., cellulose nanofibers (CNF) or cellulose nanocrystals (CNC). CNF and CNC are used for several reasons, including their mechanical and thermal properties, their extended surface area and low toxicity. This study presents some potential applications of lignocellulosic micro/nanofibers (LCMNF) in cement-based composites in order to improve flexural strength. Samples were made with 0.5-1.0-1.5-2.0 wt% of LCMNF obtained from pine sawdust, CEM I (Portland) and a 1:3 cement-water ratio. The composites were then tested for flexural strength at 7, 14, and 28 days and the evolution of flexural strength was assessed after water immersion during 72 h. Scanning electron microscopy was employed to visualize the bond between LCMNF and the cement matrix. Results showed that LCMNF improved the flexural strength of the composite in all the dosages used.

Surface effects on optical and electrical properties of ZnO nanostructures

2010 ◽  
Vol 82 (11) ◽  
pp. 2055-2073 ◽  
Author(s):  
Cheng-Ying Chen ◽  
Ming-Wei Chen ◽  
Jr-Jian Ke ◽  
Chin-An Lin ◽  
José R. D. Retamal ◽  
...  
Keyword(s):  
High Efficiency ◽  
Surface Effect ◽  
Low Cost ◽  
Dye Sensitized Solar Cells ◽  
Surface Effects ◽  
Industrial Applications ◽  
Zno Nanostructures ◽  
New Class ◽  
Potential Applications ◽  
Sensitized Solar Cells

This article presents a comprehensive review of the current research addressing the surface effects on physical properties and potential applications of nanostructured ZnO. Studies illustrating the transport, photoluminescence (PL), and photoconductivity properties of ZnO with ultrahigh surface-to-volume (S/V) ratio are reviewed first. Secondly, we examine recent studies of the applications of nanostructured ZnO employing the surface effect on gas/chemical sensing, relying on a change of conductivity via electron trapping and detrapping process at the surfaces of nanostructures. Finally, we comprehensively review the photovoltaic (PV) application of ZnO nanostructures. The ultrahigh S/V ratios of nanostructured devices suggest that studies on the synthesis and PV properties of various nanostructured ZnO for dye-sensitized solar cells (DSSCs) offer great potential for high efficiency and low-cost solar cell solutions. After surveying the current literature on the surface effects on nano-structured ZnO, we conclude this review with personal perspectives on a few surface-related issues that remain to be addressed before nanostructured ZnO devices can reach their ultimate potential as a new class of industrial applications.

Effects of natural hard shell particles on physical, chemical, mechanical and thermal properties of composites

2021 ◽  
pp. 096739112110207
Author(s):  
Yahya Hışman Çelik ◽  
Kadir Serdar Çelik ◽  
Erol Kilickap
Keyword(s):  
Thermal Conductivity ◽  
Compression Strength ◽  
Low Cost ◽  
Matrix Material ◽  
Specific Weight ◽  
Mechanical And Thermal Properties ◽  
Environmental Friendliness ◽  
Pistachio Shell ◽  
Hard Shell ◽  
Powder Particles

Shelled herbal foods are widely consumed. The evaluation of the shells of these foods is important due to their features such as low cost, ease of recycling and environmental friendliness. In this study, hazelnut shell (HS), pistachio shell (PS), and apricot kernel shell (AKS) were brought to powder particles by grinding to dimensions of 300–425 µm. Some of the powder particles were converted into ash at 900°C. The amounts of cellulose, ash, humidity, and metal in these particles via chemical analyses were determined, while their structural properties via X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analyses. Composite materials were produced by adding 15 wt.% to the polyester matrix material from these powder particles and ashes. Compression strength, hardness, specific weight, and thermal conductivity of these composites were analyzed. The lowest and highest humidity, ash, cellulose, hemicellulose, and lignin ratios in powders showed differences depending on the type of powders. The amount of Sn and K in the HS, PS, and AKS powders were close to each other, while the amount of Ca, Na, Mg, Fe, Mn, Cu, Zn and Si was higher in AKS powder. The reinforcement adding to the polyester increased the compression strength, hardness, specific weight and thermal conductivity properties.

Thermal Analysis of Heat Sink Employed on Tunnel Lighting Lamps

2013 ◽  
Vol 303-306 ◽  
pp. 2719-2723 ◽  
Author(s):  
Qiao Bo Feng ◽  
Rui Zhu ◽  
Guoan Tang ◽  
Jia Jie Zhang ◽  
Yun Zhu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Solid State ◽  
Light Source ◽  
Thermal Performance ◽  
Heat Sink ◽  
Cooling Capacity ◽  
High Density ◽  
Average Height ◽  
New Type

As a new type of solid-state light source, LED has many advantages. Its lifetime and lighting effect are related to its thermal performance. In this study the effect of heat sink cooling capacity from factors were researched, and the factors were such as material of heat sink, height of heat sink and the number of fins. It was observed that the cooling capacity of heat sink increases with increasing of thermal conductivity. Copper and silver are not fit for heat sink materials though they have excellent cooling capacity because of their high density and price, while aluminum and its alloy are the better choices. And it was revealed that the cooling capacity of heat sink increases with increasing of the height of fins, but this trend has slowed down when the average height reached 40mm.It was also observed that the cooling capacity of heat sink increases with increasing of the number of fins when fins are less, while the heat sink was higher, the cooling capacity maybe decrease with the increasing of the number of fins.

scholarly journals Preparation, characterization, and thermal conductivity of polyvinyl-formaldehyde/MWCNTs foam: A low cost heat sink substrate

2020 ◽  
Vol 9 (3) ◽  
pp. 2934-2945 ◽  
Author(s):  
Badawi Anis ◽  
Hesham El Fllah ◽  
Tawfik Ismail ◽  
Wael M. Fathallah ◽  
A.S.G. Khalil ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Low Cost

Thermal, Strength and Leachability Characteristics of Cellulose Fibre Reinforced Lime-Soil Brick

2016 ◽  
Vol 703 ◽  
pp. 386-395 ◽  
Author(s):  
Weerapol Namboonruang ◽  
Prayoon Yongam-Nuai
Keyword(s):  
Thermal Conductivity ◽  
Flexural Strength ◽  
Low Cost ◽  
Extraction Procedure ◽  
Cellulose Fibre ◽  
Local Area ◽  
Mechanical And Thermal Properties ◽  
Natural Cellulose ◽  
Mechanical Performances ◽  
Masonry Units

This research studies on the possibility of producing a more sustainable lightweight brick. Natural cellulose fibre produced from leaf and wood aggregates, lime and soil from local area of Thailand were added into the brick with minimizing Portland cement content. Effects of varied amount of cellulose fibre contents typically (10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 %) on mechanical and thermal properties of bricks are studied. Mechanical performances have been investigated with compressive, flexural strength and thermal conductivity of the samples. Also, the Leachate Extraction Procedure is observed. Results showed that adding more cellulose fibre contents can reduce the thermal conductivity, density including the compressive and flexural strength of the brick. On the other hand, the water absorption increases. It is also shown that the composite bricks can add fibre contents up to 55% by weight that can be used as non-load bearing concrete masonry units considered by the compressive strength. By conclusion, this application may be an interesting solution in order to improve sustainability and energy efficiency of the low cost house in local area of Thailand.

scholarly journals Experimental study on the effect of graphene on the thermal conductivity of natural rubber latex

2020 ◽  
Vol 145 ◽  
pp. 02074
Author(s):  
Lin Li ◽  
Wen Huang ◽  
Yingchao Ma ◽  
Chaoping Hou
Keyword(s):  
Thermal Conductivity ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Mechanical And Thermal Properties ◽  
Type I ◽  
Rubber Latex ◽  
Type Iv ◽  
Volatile Organic ◽  
New Type ◽  
Type V

Graphene is a new type of carbon material with excellent performance. It not only has good electrical, mechanical and thermal properties, but also can be used as a filler of natural latex materials to optimize the thermal conductivity of natural latex materials. Therefore, graphene is widely used in aviation, automobile, machinery and other fields. In order to study the influence of the coordination ratio of graphene and rubber materials on the thermal conductivity, the natural rubber latex was first diluted and dissolved with volatile organic solvent toluene; then 0g, 0.5g, 1g, 1.5g, 2g, and graphene were respectively mixed into 20g natural rubber latex to prepare 6 thin samples (type I, type II, type III, type IV, type V, type VI). Finally, the thermal conductivity of 6 samples was measured by fla laser thermal conductivity instrument. The results showed that with the increase of graphene dosage, the thermal conductivity of natural rubber latex sheet increased significantly; when the ratio of graphene dosage to natural rubber latex was about 1:10, the rate of improving thermal conductivity of natural rubber latex decreased.

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