Conductivity, electrical thermal

Electrical—Thermal Conductivities. Electrical conductivities of alloys (Table 5) are often expressed as a percentage relative to an International Annealed Copper Standard (lACS), ie, units of % lACS, where the value of 100 % lACS is assigned to pure copper having a measured resistivity value of 0.017241 Q mm /m. The measurement of resistivity and its conversion to % lACS is covered under ASTM B193 (8). 

Carbon-fiber based porous materials, namely non-woven carbon paper and woven carbon cloth, shown in Fig. 5, have received wide acceptance as materials of choice for the PEFC GDL owing to high porosity ( 70% or higher) and good electrical/thermal conductivity. Mathias et al.32 provided a comprehensive overview of the GDL structure and functions. In this work, the reconstruction of non-woven carbon paper GDL is presented. 

Element Electrical/thermal conductivity Malleable/ductile as solids Lustrous Melting point of oxides, hydrides, and halides... 

By definition, refractory metals exhibit low thermal and electrical conductivities and have equally low thermal expansion properties (Table 3.6). As a relative benchmark, common metals such as iron and copper have coefficients of linear thermal expansion on the order of 12.1 and 17.7 p,m m K , respectively. Also for comparative purposes, the electrical/thermal conductivities for Fe and Cu are 9.71 j,Qcm V78-2 Wm and 1.67p,Q cm V397W m K , respectively. 

Diffusion, Electric/Thermal Conductivity, and Radiation in Plasma... 

Polymer clay nanocomposites are already used in many applications to enhance existing properties of a particular material, and development should be focused on the true multifunctional materials. Certainly, clay nanocomposites will continue to be used for enhanced mechanical, flammability, and gas barrier properties, but fundamental limits in clay chemistry prevent them from being used easily in applications requiring electrical/ thermal conductivity or optical properties. Similarly, combinations of... 

Electrical/thermal conductive fillers Metalhc powders, carbon fiber, graphite, graphene Improves electrical and thermal conductivity... 

The GDL of PEM fuel cells connects between the bipolar plate/flow channel and catalyst layer. It provides the pathways for mass, heat, and electron transport, and also acts as the physical support of CL and membrane. The present state-of-the-art GDL consists of both a macroporous substrate and a micropo-rous layer (MPL). The macroporous substrate is a porous network of graphite fibers, which is usually carbon paper, carbon felt or carbon cloth. The substrate is often coated with hydrophobic materials such as PTFE for better liquid water removal. The MPL is coated on one side of the substrate which faces the catalyst layer. A typical MPL is a composite layer mixed by carbon particles and PTFE. The MPL usually has lower porosity and permeability but higher hydrophobicity and electrical/thermal conductivity than its substrate layer. The MPL enhances the water management and thermal/electricity connection between the substrate layer and CL to better cell performance. Unlike the membrane and catalyst layer, researches focusing on developing new materials and/or revolutionary design are scarce. Therefore, this subsection only focuses on the macroporous substrate/MPL GDL. 

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