Recycling and characterization of carbon fibers from carbon fiber reinforced epoxy matrix composites by a novel super-heated-steam method.

In order to manufacture high quality recycled carbon fibers (R-CFs), carbon fiber-reinforced composite wastes were pyrolysed with super-heated steam at 550 °C in a fixed bed reactor for varying reaction times. The mechanical and surface properties of the R-CFs were characterized with a single fiber tensile test, interface shear strength (IFSS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The surface analysis showed that there was no matrix char residue on the fiber surfaces. The tensile strength and IFSS values of the R-CFs were 90% and 115% compared to those of virgin carbon fibers (V-CFs), respectively. The recycling efficiency of the R-CFs from the composites were strongly dependent on the pyrolysis temperature, reaction time, and super-heated steam feeding rate.

Effects of Corrosion on Mechanical Properties of Welded Carbon Steel Pipe in District Heating Water.

This study examined the effect of corrosion on mechanical properties of welded carbon steel pipe in district heating water. To evaluate the corrosion properties, potentiodynamic tests were conducted and a galvanostatic test was used to accelerate corrosion. Tensile tests and microstructure observations were performed to figure out the degradation of the corroded region, and stress intensity factors were calculated. As a result of the potentiodynamic tests, welded carbon steel pipe showed uniform corrosion and the total charge was calculated. Using the galvanostatic test, the current density at the equivalent aging time was applied to the specimens. The tensile tests showed that according to corrosion damages, mechanical properties were degraded due to corrosion. Through the microstructure observations and calculations of stress intensity factors, the corrosion of the welded carbon steel pipe induced the degradation of mechanical properties. The mode of fracture was changed from ductile to brittle fracture with increasing aging time.