Thermal conductive polymer composite pipes have been used to replace metal pipes that are easy to be corroded. However, the low thermal conductivity of the matrix is the critical factor limiting their applications. Here, large‐size exfoliation of graphene and carbon nanotube (CNT) are proposed to prepare thermal‐conductive polyethylene nanocomposites with a low filler content. Expanded graphite and CNT are co‐dispersed by high pressure homogenizer in presence of polyvinyl pyrrolidone. Such a dispersion method can maintain the high aspect ratio and reduce generation of defects of graphene and CNTs, which is vital for building a long‐range thermal conductivity pathway in the nanocomposites. In addition, the graphene and CNT fillers can be obtained with high yield and efficiency. When the fillers are dispersed into the polyethylene by optimizing the composition, thermal conductive composites can be obtained with enhanced mechanical properties. The nanocomposite with 5.22 wt.% filler can reach a thermal conductivity of 1.265 W·m−1·K−1, 3.94 times to that of the neat polyethylene, and the mechanical strength can be increased by 42%, supporting improvement of the thermal conductivity and mechanical strength at the same time.
Large-scale distributed thermal storage requires high-energy-density and low-cost thermal storage materials. Here, a concocted composite composed of Al 2 (SO 4 ) 3 •18H 2 O and FeSO 4 •7H 2 O salts, as well as carbon nanotubes (CNTs) as a thermal conductive agent has been proposed for the applications of large-scale distributed thermal storage. The composite was physically mixed but displayed enhanced structural stability due to the use of carbon nanotubes that formed networks in the composite. The use of CNTs could restrain the volume change of the salt mixture in thermal charge/discharge. The detailed thermophysical properties and thermal energy storage performance were studied, including latent heat, thermal conductivity, and thermal cycling stability. A differential scanning calorimeter (DSC) revealed that the largely endothermic temperature and absorbed heat of the composite were 118.43 °C and 422.40 J g −1 , and it also delivered a high stability of ca. almost no capacity fading in exampled 100 cycles. The introduction of the carbon nanotube creates thermal conductivity networks in the composite, endowing the composite material with enhanced thermal conductivities. This can provide rapid thermal storage while retaining the storage density. This study can give insights into the rational design of salt hydrates for thermal storage.
The influences of Er content on the interfacial microstructure shear properties and creep properties of Sn58Bi joints were investigated in this study. The intermetallic compound composition of Sn58Bi-xEr/Cu was Cu6Sn5 compound. The addition of Er suppressed the activity of Sn element, decreased the driving force for the growth of Cu6Sn5 intermetallic compound and decreased the thickness of Cu6Sn5 intermetallic compound layer. The shear properties and creep durability of Sn58Bi-xEr/Cu welded joints were improved to a certain extent. At the Er content of 0.1%, the shear strength and creep durability properties of the solder alloy are relatively optimal. When wt%Er was more than 0.1%, with the increasing Er content of rare earth elements, the internal organization of the joint interface is coarsened, and the flatness of the IMC layer at the interface is reduced, which leads to the decrease of the creep performance of the final joint.
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