Optimized design and experimental validation of sound absorption coefficient performance in aluminium metal foam by spark plasma sintering.

Determining the structural properties of aluminum metal foam is essential to predicting its acoustic behavior. Acoustic models are presented that show the relationship between the morphology of the absorber and the sound absorption coefficient (SAC). Optimizing the parameters affecting the SAC can be the maximum theoretically SAC achieved at each frequency. In the previous article (https://doi.org/10.32604/sv.2021.09729) the parameters of porosity percentage (Ω), pore size (D) and pore opening size (d) were optimized by the genetic algorithm and Lu model. In this study, the optimal aluminum metal foam was synthesized using Spark Plasma Sintering (SPS), with the maximum temperature of 420 °C and final pressure of 20 MPa in samples with thicknesses of 5, 10, 15 and 20 mm in different frequencies from 1000 to 6300 Hz. The crystal structure and microstructure of samples were investigated using XRD and SEM. Optimized metal foam SAC (0.67, 0.9, 1 and 1) and experimental peak SAC (0.44, 0.67, 0.76 and 0.82) were compared with the optimized SAC in 5, 10, 15 and 20 mm thicknesses, respectively. The values of the coefficient of determination (R2) according to multiple linear regression (MLR) for the two optimized SAC and experimental in thicknesses of 5, 10, 15 and 20 mm were 0.90, 0.95, 0.96 and 0.90, respectively. The results of this study show that porous metal foam can have a high absorption coefficient in any desired thickness and frequency by using the optimal morphology.

Evaluation of Microstructure and Mechanical Properties of Al-TiC Metal Matrix Composite Prepared by Conventional, Microwave and Spark Plasma Sintering Methods.

In this research, the mechanical properties and microstructure of Al-15 wt % TiC composite samples prepared by spark plasma, microwave, and conventional sintering were investigated. The sintering process was performed by the speak plasma sintering (SPS) technique, microwave and conventional furnaces at 400 °C, 600 °C, and 700 °C, respectively. The results showed that sintered samples by SPS have the highest relative density (99% of theoretical density), bending strength (291 ± 12 MPa), and hardness (253 ± 23 HV). The X-ray diffraction (XRD) investigations showed the formation of TiO2 from the surface layer decomposition of TiC particles. Scanning electron microscopy (SEM) micrographs demonstrated uniform distribution of reinforcement particles in all sintered samples. The SEM/EDS analysis revealed the formation of TiO2 around the porous TiC particles.

Synthesis of suitable SiO2 nano particles as the core in core-shell nanostructured materials.

The effect of surfactant on the luminescent intensity of SiO2 @Y2O3:Eu3+ particles with a core shell structure is described. Core-shell particles are used in phosphor materials and employing spherical particles with a narrow size distribution is vital for the enhancement of luminescent properties. Three kinds of different surfactants were used to synthesis SiO2 nano particles via a sol gel process. The results demonstrated that comb polycarboxylic acid surfactant had a significant influence on the morphology and particle size distribution. Somehow, particles with 100 nm size and narrow size distribution were produced. These particles had relatively uniform packing, unlike particles produced with other surfactants or without surfactant which had irregular assembly. The photoluminescence intensity of SiO2 @Y2O3:Eu3+ particles that was synthesized by comb polycarboxylic acid surfactant was higher than those which were produced without surfactant.