Effect of ZrO2 Nanoparticles and Mechanical Milling on Microstructure and Mechanical Properties of Al-ZrO2 Nanocomposites

Nano-aluminum powders and nano-ZrO2 reinforcement particles were mechanically milled and hot-pressed to produce Al-ZrO2 nanocomposites. Microstructure and mechanical properties of Al-ZrO2 nanocomposites were investigated using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses and by performing hardness and compression testing. Uniform particle distribution was obtained up to 3 wt% of nano-ZrO2 particles using nano-sized aluminum powders as matrix powders and by applying a mechanical milling process. As the nano-ZrO2 reinforcement particles were uniformly distributed in the matrix, the relative density of the Al-ZrO2 nanocomposites increased up to 3 wt% nano-ZrO2 particles with an increase in milling time; on the other hand, the relative density decreased and the porosity increased with high-weight fractions (>3 wt%) of nano-ZrO2 particles due to the negative combined effect of less densification and an increase in the number of particle clusters. The hardness and compressive strength of the Al-ZrO2 nanocomposites improved despite increased porosity. However, the compressive strength of Al-ZrO2 nanocomposites with a high amount (>3 wt%) of nano-ZrO2 particles began to decrease due to the negative combined effect of the less densification of the powder particles and the clustering of nano-ZrO2 reinforcement particles. The brittle-ductile fracture occurred in the Al-ZrO2 nanocomposites

Effect of T-Joint Geometry on the Performance of a GRP/PVC Sandwich System Subjected to Tension

Mechanical performances of six sandwich type T-joints, used in marine applications subjected to tensile load, have been investigated both numerically and experimentally in this study. T-joints, each with different geometries, have been manufactured, Type A: continuous core in joint with right angle; Type B: core removed at joint; Type C: core with wedge fillet; Type D: core with 25 mm radius fillet; Type E: core with 70 m radius fillet and Type F: DK-CND1 of Toftegaard and Lystrup with overlaminate. The skin was a 5 mm thick orthophitalic polyester/glass laminated composite and the core was PVC (Divinycell H80). Due to absolute values of the maximum strain values of the T-joints, Type E shows promising performance under tension while Type B is the weakest. It is not recommended to use Type B in the structures subjected to tension. Grading from the strongest to the weakest of T-joints is Type C, D, A and F. Results of the numerical modelling and tests also affirm the utility of the 2D FE models for further studies of the strain distribution in such sandwich T-joints

Investigation of the wear resistance and microstructure of Al/SiC metal matrix composites as a function of reinforcement volume fraction and reinforcement to matrix particle size ratio applying artificial neural network

WOS: 000348243700005In this study, the influences of reinforcement volume fraction and the ratio of the reinforcement particle size to the matrix particle size on the wear behaviour of Al/SiC metal matrix composites were investigated by use of a model function obtained from an artificial neural network. Hardness and ball-on-disc wear tests were applied to Al/SiC composites manufactured via a powder metallurgy method. The results indicate that as the reinforcement volume fraction and the ratio of the reinforcement particle size to the matrix particle size increase, the wear loss decreases except in two cases; in the first case (vol.% = 15 %) declines and then increases where the value of the reinforcement to the matrix particle size ratio is about 1