The mechanical properties of hydroxyapatite (HA) have been improved by the addition of either (ZrO
2
) or hardystonite (HT) by many researchers. However, their dual effect on the tribo-mechanical, ...electrical, and antibacterial properties of HA has not been studied before. In this regard, nanocomposites of different contents of HA, HT, and ZrO
2
were synthesized by a high-energy ball mill and subsequent sintering process. Then, the prepared nanocomposites were characterized by different suitable techniques. Also, their electrical, physical, and tribo-mechanical properties were measured. Besides, their antibacterial effect against
S. aureus
and
E. coli
was assessed. The findings demonstrated that the gradual increase of HT and ZrO
2
content caused a slight increase in the samples’ porosity values; namely 4.3, 4.9, 6, 7.2, and 9.8%, having in mind that these values correspond to those of normal human bones. The maximum enhancement in the microhardness, strength, Young’s modulus, and longitudinal, bulk, and shear moduli was recorded for the sample with the maximum content of HT and ZrO
2
. They were 75, 21.56, 24, 36.36, 32.35, and 22.72%. Additionally, all the prepared samples showed an antibacterial effect against
S. aureus
bacteria, as indicated by the diameter of the inhibition zone (15, 16, 17, 17, and 18 mm). However, the successive increase in ZrO
2
contents was responsible for reducing the electrical conductivity of the prepared nanocomposites up to 3.99 × 10
‒7
S/m. The prepared samples may be valid for orthopedic purposes based on the results obtained. The simulation analysis using ANSYS showed that the material with the least stress and buckling under load assigned to the nanocomposite has a higher ZrO
2
content.
The present work employed the finite element model (FEM) to predict the influence of successive increases in borate (B2O3) contents, from 0 to 25 mol%, on mechanical properties and dynamic behavior. ...By feeding the isotropic elasticity characteristics of the phosphosilicate glass to the model, such as Young's modulus, density, and maximum compressive stress of the produced glass samples to fit the aim of their clinical use. The effect of successive addition of B2O3 on the in vitro bioactivity of the examined glasses in addition to examined after being dipped in simulated body fluid (SBF) at different times. Moreover, tracking the formation of hydroxyapatite (HA)-like layers on their surfaces using X-ray diffraction technique (XRD) technique and scanning electron microscopy (SEM). The results obtained indicated that increasing B2O3 content to 25% was responsible for improving the deflect resistance by 39%.On the other hand, neither shear stress nor principles stress was affected by this increase in B2O3 content. Moreover, the gradual increases in B2O3 contents were very helpful in improving the bioactivity of the samples. The prepared glasses can be successfully used in bone replacement applications from these promising results.
Abstract
More focus has recently been placed on enhancing the strength, elastic modulus, coefficient of thermal expansion (CTE), wear and corrosion resistance, and other qualities of aluminum (Al) ...alloys by varying the quantity of ceramics added for a range of industrial uses. In this regard, Al-4.2-Cu-1.6Mg matrix nanocomposites reinforced with nano-ZrO
2
particles have been created using the powder metallurgy approach. The microstructure and particle size distributions of the produced powders were analyzed using a diffraction particle size analyzer, XRD, TEM, and SEM. To achieve good sinterability, the powders were compacted and sintered in argon. The sintered nanocomposites' mechanical, elastic, and physicochemical characteristics were measured. Additionally, the behavior of corrosion, wear, and thermal expansion were examined. The results showed a decrease in the particle sizes of the Al-Cu-Mg alloy by adding ZrO
2
nanoparticles up to 45.8 nm for the composite containing 16 wt.% ZrO
2
. By increasing the sintering temperature to 570 °C, the densification of nanocomposites was enhanced. Also, the coefficient of thermal expansion and wear rate remarkably decreased by about 28 and 37.5% by adding 16 wt.% ZrO
2
. Moreover, microhardness yield, strength, and Young’s modulus were enhanced to 161, 145, and 64%, respectively, after adding 16 wt.% ZrO
2
. In addition, increasing the exposure time was responsible for decreasing the corrosion rate for the same sample.
In this work, AA 2024 wrought aluminium alloy was reinforced with Al2O3 nanoparticles to fabricate surface metal matrix nanocomposites (MMNCs) via friction stir processing (FSP). Processing ...parameters, namely, rotational speed, traverse speed and the number of processing passes, were investigated to study their effects on the wear resistance, mechanical properties and hardness behaviour of the MMNCs. The mechanical properties of the materials were evaluated in a tensile test, and their hardness and wear properties were determined through Vickers microhardness and weight loss tests, respectively. Microstructural observation revealed that the processing parameters influenced the mechanical properties, wear behaviour, and hardness properties of the MMNCs. Specifically, the FSP refined the microstructural grains to a level 19 times better than that achieved with base alloy, thereby fine-tuning the average base alloy grain size of 135 μm to an average of 7 μm. Increasing the number of passes improved wear resistance by an average of 39%–70%, and implementing a third round of FSP enhanced the ultimate tensile strength and Young’s modulus by 40% and 20% on average, respectively. Finally, the incorporation of Al2O3 nanoparticles increased the hardness of the MMNCs by an average of 42%.
Despite the great importance of nanocomposites in biomedical applications, some attractive nanocomposites such astitania/zirconia/calcium silicate (TiO
2
/ZrO
2
/CaSiO
3
) have not been studied ...before. In this regard, this work aimed to prepare these nanocomposites using a high-energy ball mill. Then, their powders were sintered at 1250 °C and characterized using FTIR spectroscopy, XRD technique and SEM. Moreover, mechanical properties were also measured. The in vitro bioactivity of the sintered nanocomposites was evaluated by soaking them in a simulated body fluid solution and then, examined by FTIR spectroscopy. Furthermore, the antibacterial behavior of these samples was tested against Gram− and Gram+ bacteria by shake flask method. Finally, in vitro cytotoxicity was tested against bone-like cells. The results pointed out that the successive increases in CaSiO
3
contents led to noticed decreases in mechanical and antibacterial properties of the resulting nanocomposites. Nevertheless, the presence of CaSiO
3
was responsible for giving the sintered samples the required bioactivity and densification behaviors. Notably, all investigated samples revealed excellent biocompatibility behavior. Based on the abovementioned properties, these nanocomposites can be used in orthopaedic and dental applications.
•Al alloy- graphene nanocomposites were produced by powder metallurgy.•The obtained nanocomposites exhibited excellent mechanical properties.•Corrosion resistance of nanocomposites was remarkably ...improved by added graphene contents.•CTE values of nanocomposites was reduced up to 34%.
Recently, a growing interest has been dedicated towards improving the properties of Al alloys for use in various industrial applications. In this sense, mechanical alloying technique followed by sintering process at 460 and 560 °C in argon atmosphere was used to prepare Al2024 alloy matrix nanocomposites-reinforced by different graphene contents up to 2 wt%. Both XRD technique and TEM were employed to characterize the prepared nanocomposites powders. Microstructure analysis was performed on the sintered composites using SEM. Moreover, the relative density, corrosion rate, thermal expansion and electrical properties of the sintered nanocomposites were measured. Furthermore, their mechanical properties were measured with ultrasonic non-destructive technique. SEM and TEM micrographs revealed a uniform distribution of graphene in the Al alloy matrix. The relative density, coefficient of thermal expansion (CTE) and electrical conductivity of the specimens sintered at 460 °C decreased until reached 90.9%, 13.6 × 10−6/°C and 8.41 × 105 S/m, respectively as the graphene content increased to 2 wt%, while they increased to 93.8%, 1.5 × 10−6/°C and 4.20 × 106 S/m as the sintering temperature increased to 560 °C. On the other hand, the mechanical properties of the nanocomposites such as microhardness, elastic modulus and yield strength were enhanced to 155, 134 and 97%, respectively after adding 2 wt% graphene and sintering at 560 °C. Additionally, the corrosion rate decreased from 5.74 to 2.73 and 5.34 to 2.59 for the sample having 2 wt% graphene and sintered at 460 and 560 °C with increased the exposure from 24 to 144 h, respectively.
The effect of isothermal multidirectional forging (IMF) on the microstructure evolution of a conventional Al⁻Mg-based alloy was studied in the strain range of 1.5 to 6.0, and in the temperature range ...of 200 to 500 °C. A mean grain size in the near-surface layer decreased with increasing cumulative strain after IMF at 400 °C and 500 °C; the grain structure was inhomogeneous, and consisted of coarse and fine recrystallized grains. There was no evidence of recrystallization when the micro-shear bands were observed after IMF at 200 and 300 °C. Thermomechanical treatment, including IMF followed by 50% cold rolling and annealing at 450 °C for 30 min, produced a homogeneous equiaxed grain structure with a mean grain size of 5 µm. As a result, the fine-grained sheets exhibited a yield strength and an elongation to failure 30% higher than that of the sheets processed with simple thermomechanical treatment. The IMF technique can be successfully used to produce fine-grained materials with improved mechanical properties.
In this study, brass (Cu/Zn) reinforced polymer composites with different proportions of brass powders were fabricated. Different types of nuclear shielding parameters such as mass and linear ...attenuation coefficients, radiation protection efficiency, half and tenth value layers, and effective atomic number values were determined experimentally and theoretically in the energy range of 0.060–1.408 MeV in terms of gamma-ray shielding capabilities of fabricated polymer composites. A high Purity Germanium detector (HPGe) in conjunction with a Multi-Channel Analyzer (MCA) and twenty-two characteristic gamma-ray energies have been used in the experimental phase. In addition, the exposure and energy absorption buildup factors of reinforced Cu/Zn composites were calculated, and relative dose distribution values were computed to verify them. Proton mass stopping power (ΨP), proton projected range (ΦP), alpha mass stopping power (ΨA), and alpha projected range (ΦA) parameters, which indicate the interactions of the produced composites with charged particle radiation, were investigated. Fast neutron removal cross-section (ΣR) results were determined to give an idea in terms of neutron shielding. According to the obtained results, it is reported that the CuZn20 coded sample’s ability to attenuate gamma-ray and charged particle radiation is more efficient than that of other prepared composites. A CuZn05 coded sample was found to be more suitable for neutron shielding capability.
In the current work, a hybrid nanocomposite Al-Si matrix was fabricated using the powder metallurgy method. Due to their superior mechanical strength, formability, and durability, aluminum composite ...matrices have considered attractive materials for structural and advanced applications. The incorporation of fly ash (FA) as one of the cheapest and lowest density reinforcement available during the combustion process with high-density ceramic particles such as vanadium carbide (VC) has significant benefits in the production process of such composites. The hybridization of VC and FA nanoparticles with different weight percentages were used to reinforce the Al-Si matrix under various sintering conditions. A scanning electron microscopy (SEM) and diffraction particle size analyzer were utilized to examine the microstructure of the prepared powder and particle size. In addition to the mechanical and physical properties, the wear and corrosion resistance were investigated for the fabricated samples. The results revealed that the addition of 10 wt.% VC and 10 wt.% FA nanoparticles caused a decrease in the Al-Si alloy particle sizes up to 47.8 nm and act as a barrier for dislocation movement. Also, the microhardness, yield strength, and ultimate copressive strength were enhanced by 75, 42 and 38%, respectively. Moreover, there was an increase of about 25% in the ultrasonic longitudinal and shear velocities, thus showing a significant improvement in the elastic moduli group of about 50%. Finally, the addition of VC and FA particles significantly affected the wear and corrosion resistance; hence, they increased by 40 and 67%, respectively.
The fabrication of the hybrid nanocomposite surface using friction stir process (FSP) has recently gained interest in material science researchers and developers due to its superior mechanical and ...microstructure properties. An AA6061 wrought alloy was used as the base matrix, which is reinforced with Al2O3 and BN ceramics nanoparticles in both hybrid and mono composite surface. The mechanical properties were investigated using a compression and microhardness test; and the highest mechanical properties were obtained for the AA6061/Al2O3-BN hybrid nanocomposite. The stress strain curve showed an improvement in the ultimate stress of the hybrid nanocomposite compared to the base alloy. The microstructures of the synthesized composites were evaluated using optical and scanning electron microscopy (SEM). The FSP has a significant effect on grain refinement where the AA6061 has been refined as receiving alloy by decreasing the grain size by 29 times. Furthermore, equiaxial grains were obtained due to stirring action and FSP pin tool thread design; hence the grain aspect ratio was improved by approximately 400%. The dispersion of the Al2O3 and BN nanoparticles was successfully achieved during the current investigation, as noticed in the SEM examination analysis. Thermal expansion and electrical conductivity were decreased with reinforce the metal matrix with ceramics Al2O3 and BN nanoparticles. Moreover, the hybrid nanocomposite exhibited the minimal values of the thermal expansion and electric conductivity properties.
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