Influence of recycled carbon fiber addition on the microstructure and creep response of extruded AZ91 magnesium alloy

In this study,the recycled short carbon fiber(CF)-reinforced magnesium matrix composites were fabricated using a combination of stir casting and hot extrusion.The objective was to investigate the impact of CF content(2.5 and 5.0 wt.%)and fiber length(100 and 500μm)on the microstructure,mechanical properties,and creep behavior of AZ91 alloy matrix.The microstructural analysis revealed that the CFs aligned in the extrusion direction resulted in grain and intermetallic refinement within the alloy.In comparison to the unreinforced AZ91 alloy,the composites with 2.5 wt.%CF exhibited an increase in hardness by 16-20%and yield strength by 5-15%,depending on the fiber length,while experiencing a reduction in ductility.When the reinforcement content was increased from 2.5 to 5.0 wt.%,strength values exhibited fluctuations and decline,accompanied by decreased ductility.These divergent outcomes were discussed in relation to fiber length,clustering tendency due to higher reinforcement content,and the presence of interfacial products with micro-cracks at the CF-matrix interface.Tensile creep tests indicated that CFs did not enhance the creep resistance of extruded AZ91 alloy,suggesting that grain boundary sliding is likely the dominant deformation mechanism during creep.

Characterization of carbon fibers recovered through mechanochemical-enhanced recycling of waste carbon fiber reinforced plastics

In this study,we present the characterization of the carbon fibers recovered from the mechanochemical-enhanced recycling of carbon fiber reinforced fibers.The objectives of the study were to investigate the effect of our modified recycling method on the interfacial properties of recovered fibers.The reinforced plastics were recycled;the recycling efficiency was determined and the recovered fibers were sized using 1 wt%and 3 wt%concentration of(3-aminopropyl)triethoxysilane.We characterized the morphologies utilizing the electron spectroscopy for chemical analysis(ESCA),atomic force microscopy(AFM),FTIR-attenuated total reflection(ATR)spectroscopy and scanning electron microscopy(SEM).Although the surface of the fibers had no cracks,there was evidence of contaminations which affected the interfacial properties and the quality of the fibers.Results showed that the trends in the recovered and virgin fibers were similar with an increase in sizing concentration.The results highlighted the perspectives of increasing the quality of recovered fibers after the recycling process.

In-Situ Growing of Branched CNFs on Reusable RCFs to Construct Hierarchical Cross-Linked Composite for Enhanced Microwave Absorption

The recycling of carbon fibers and protection from unwanted microwave radiation are two important environmental issues that need to be addressed in modern society.Herein,branched carbon nanofibers(CNFs)were grown in-situ on recycled carbon fibers(RCFs)through the chemical vapor deposition method using nickel as catalysts and thiophene as aided-catalysts.The effect of thiophene on the growth morphology of CNFs was investigated.Correspondingly,branched CNFs-RCFs and straight CNFs-RCFs were respectively obtained in the presence and absence of thiophene.The microstructure and electromagnetic behaviour investigations have shown that the branched CNFs possess a typical multi-branched structure,with more defects,pores and a larger specific surface area than the straight CNFs,which lead to better impedance matching and adequate dielectric loss ability for the branched CNFs-RCFs.The reflection loss(RL)results show that the branched CNFs-RCFs exhibit an optimum RL of -23.6 dB at 1.5 mm and a best effective absorption bandwidth(EAB)of 7.5 GHz at 2.0 mm.This research provides an innovative microwave absorbing material with adequate absorbing strength and outstanding EAB,while also promoting the sustainable reuse of the RCFs resources.