Synthesis and Characterization of Cr, Eggshell and Grinding Sludge Reinforced Aluminum Based Metal Matrix Composites: An Ingenious Experimental Approach

This investigation deals with the utilization of industrial waste to develop aluminum-based composite. Waste eggshell (ES) generated from the food industry has been used as primary reinforcement material. Waste grinding sludge (GS) produced from the iron forging sector was utilized as secondary reinforcement content. Cr content has been further encapsulated to the composite material to prevent the composite material's grain growth. The composite material was developed by the stir casting process. Experimental results concluded that tensile strength, compressive strength, and hardness of base material (AA5052 alloy) had been improved by about 18.02 %, 23.40 %, and 49.53 respectively, by adding 4.5 % of ES, 4.5 % of GS, and 1.5 % of Cr. Microstructural analysis of the AA5052/4.5 % ES/4.5 % GS/1.5 % Cr composite shows the fair distribution of reinforcement content. XRD of the Al/4.5 % ES/4.5 % GS/1.5 % Cr composite shows the occurrence of Al, Fe2O3, CaCO3, CaO, and Cr phases. Corrosion weight loss and thermal expansion behavior of developed composite have also been explored to observe the ES, GS, and Cr addition in the aluminum alloy.

Multi response parameters optimization of ZA-27 nanocomposites

In this study, Taguchi-Grey relational analysis was used to investigate and optimize wear parameters such as sliding speed, reinforcement of Gr and reinforcement of Al2O3, and their effect on dry sliding wear performance of ZA-27 nanocomposites. Nanocomposites were synthesized via hot pressing process with pre-processing mechanical milling. Sixteen experimental tests were performed based on design of experiments which was created with the help of Taguchi L16 orthogonal array. Grey relational analysis (GRA) was applied for determination of optimal combination of parameters in order to improve tribological characteristics. Optimal combination of factors, obtained with Taguchi Grey relational analysis was sliding speed of 100 rpm, reinforcement content of 1 vol.% Gr and reinforcement content of 4 vol.% Al2O3. Validation of results was done by using Artificial Neural Network (ANN). Developed model had overall regression coefficient 0.99836, and output values showed good correlation with experimental results. Based on this research, it can be observed that nanocomposites with reinforcement of Gr and Al2O3 can be potentially employed in many industries as a good substitute for the base alloy. In addition, as a result of the analysis of the worn surfaces, it was determined that with the increase of the Al2O3 ratio, the hard Al2O3 nanoparticles turned the dominant wear mechanism into abrasive. Also, it was determined that the Gr nanoparticles appeared on the abrasive wear lines.

COMPARATIVE MECHANICAL PROPERTIES STUDIES ON HEAT & UNHEAT TREATED AL7075 ALLOY HYBRID COMPOSITES (IN PRESS)

In the present work, Al7075 based hybrid composites was developed using stir casting technique. Al7075 hybrid composites with different weight percentage of Mica, Graphite and E-glass fiber were developed to study the effect of these reinforcements on microstructure and mechanical properties, E-Glass fiber is kept constant at 0, 2, 4%, Mica is varied from 1-3% in steps of 1 and Graphite varied from 1-5% in steps of 2. It can be seen that the three peaks corresponding to Al were seen at 38º, 46º and 65º 2θ angles and small peaks related to all the three reinforcement mica, graphite and E-glass fiber were observed in the XRD pattern. Grain size analysis was examined using Clemex Image-Analyzer software, it was observed that decrease in grain size of Al7075 matrix was found to decrease with the increase in reinforcements, Hardness was found to increase with increase in reinforcement content whether it could E-glass fiber from 0% - 4% or mica from 1% - 3% or graphite content from 1% - 5%. Ultimate tensile strength increased with the increase in reinforcement content both before and after heat treatment.

Transverse Crack Behavior in Continuously Reinforced Concrete Pavement with Basalt Fiber Reinforcement

Continuously reinforced concrete pavement (CRCP) is a pavement structure with a high performance and long service life. However, the corrosion of the longitudinal steel can result in a poor bond relationship between the steel and the concrete, affecting the load transfer efficiency between the adjacent panels and being responsible for the development of CRCP distresses. Basalt fiber-reinforced polymer (BFRP) is corrosion-resistant and has the potential to be used in CRCP. In this paper, the layout of a CRCP test section with BFRP bars constructed on G330 National Road in Zhejiang Province, China, is presented. An analytical model is proposed to predict the crack behavior of CRCP with BFRP reinforcement, with the predicted results are compared to field-measured ones. A sensitivity analysis of the BFRP design parameters on the crack spacing and crack width is conducted as well. The results show that the mean values for field-measured crack spacing and crack width are 4.85 m and 1.30 mm, respectively, which are higher than the results for traditional CRCP with steel due to the lower elastic modulus of BFRP. The analytical predictions agree reasonably well with the crack survey results. The higher the elastic modulus of BFRP, the reinforcement content (with both BFRP spacing and diameter related), and the bond stiffness coefficient between the BFRP and concrete, the less the crack spacing and crack width will be. Given the same or similar reinforcement content, a lower diameter with a smaller spacing is recommended because of its contribution to a smaller crack spacing and width.

Effect of NaOH Treatment on the Flexural Modulus of Hemp Core Reinforced Composites and on the Intrinsic Flexural Moduli of the Fibers

This paper describes the potential of using hemp core waste in the composite industry. These lignocellulosic residues can be used to produce environmentally friendly and economically viable composites and improve the overall value chain of hemp production. To this purpose, hemp core residues were alkaline treated at different NaOH concentrations and then mechanically defibrated. Hemp core fibers were mixed with polypropylene and injection molded to obtain testing specimens. The effect of sodium hydroxide on the flexural modulus of composites was studied from macro and micro mechanical viewpoints. Results showed remarkable improvements in the flexural modulus due to the presence of hemp core fibers in the composites. At a 50 wt % of reinforcement content, increments around 239%, 250% and 257% were obtained for composites containing fibers treated at a 5, 7.5 and 10 wt % of NaOH, respectively. These results were comparable to those of wood composites, displaying the potential of hemp core residues. The intrinsic flexural modulus of the hemp core fibers was computed by means of micromechanical analysis and was calculated using the ratios between a fiber flexural modulus factor and a fiber tensile modulus factor. The results agreed with those obtained by using models such as Hirsch and Tsai–Pagano. Other micromechanical parameters were studied to fully understand the contribution of the phases. The relationship between the fibers’ intrinsic flexural and Young’s moduli was studied, and the differences between properties were attributed to stress distribution and materials’ anisotropy.

Research on the Strengthening Advantages on Using Cellulose Nanofibers as Polyvinyl Alcohol Reinforcement

The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating internal mixer and then processed by means of injection molding. It was found that CNF were able to improve the tensile strength of PVA in 85% when 4.50 wt % of CNF were added. In addition, the incorporation of a 2.25 wt % of CNF enhanced the tensile strength to the same level that when 40 wt % of microsized fibers (stone groundwood pulp, SGW) were incorporated, which indicated that CNF possessed significantly higher intrinsic mechanical properties than microsized fibers. SGW was selected as reference for microsized fibers due to their extended use in wood plastic composites. Finally, a micromechanical analysis was performed, obtaining coupling factors near to 0.2, indicating good interphase between CNF and PVA. Overall, it was found that the use of CNF is clearly advantageous to the use of common cellulosic fibers if superior mechanical properties are desired, but there are still some limitations that are related to processing that restrict the reinforcement content at low contents.