S.F. Mansour

Bio: S.F. Mansour is an academic researcher from King Abdulaziz University. The author has contributed to research in topics: Dielectric & Ferrite (magnet). The author has an hindex of 31, co-authored 88 publications receiving 2186 citations. Previous affiliations of S.F. Mansour include Kafrelsheikh University & Zagazig University.

Physico-mechanical and morphological features of zirconia substituted hydroxyapatite nano crystals.

Abstract: Zirconia doped Hydroxyapatite (HAP) nanocrystals [Ca10(PO4)6−x(ZrO2)x(OH)2]; (0 ≤ x ≤ 1 step 0.2) were synthesized using simple low cost facile method. The crystalline phases were examined by X-ray diffraction (XRD). The crystallinity percentage decreased with increasing zirconia content for the as-synthesized samples. The existence of zirconia as secondary phase on the grain boundaries; as observed from scanning electron micrographs (FESEM); resulted in negative values of microstrain. The crystallite size was computed and the results showed that it increased with increasing annealing temperature. Thermo-gravimetric analysis (TGA) assured the thermal stability of the nano crystals over the temperature from room up to 1200 °C depending on the zirconia content. The corrosion rate was found to decrease around 25 times with increasing zirconia content from x = 0.0 to 1.0. Microhardness displayed both compositional and temperature dependence. For the sample (x = 0.6), annealed at 1200 °C, the former increased up to 1.2 times its original value (x = 0.0).

Physico-mechanical properties of Mg and Ag doped hydroxyapatite/chitosan biocomposites

Abstract: Nano-hydroxyapatite/chitosan (nano-HAP/CS) composites with high compressive strength were synthesized using microwave assisted co-precipitation. Co-Doping using Mg2+ and Ag+ was carried out simultaneously in HAP resulting in the formula: [MgxAgyCa(10−x−y)(PO4)6(OH2); 0 ≤ (x + y) ≤ 1]. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The results illustrated that the shape, size and crystallinity index of the prepared nano-HAP crystals were similar to those of natural bone. Doping by Ag+ was performed to produce an anti-bacterial effect, while Mg2+ dopant appeared to be a crucial factor in improving the mechanical properties. Furthermore, mechanical testing exhibited that the maximum compressive strength of the new composite was 15 MPa. The multifunctional non-sintered materials showed promising results in drug loaded bioceramics with improved mechanical features in bone tissue engineering.

Some physical and magnetic properties of Mg‐Zn ferrite

Abstract: Some physical properties (such as lattice parameter, density and porosity) and magnetic properties of the system Mg 1-x Zn x Fe 2 O 4 ; where x=0,0.1,0.2,0.3,0.4,0.5and 0.6 have been studied. It was found that the lattice parameter increases with increasing the zinc concentration. The composition dependence of the physical properties is divided into two regions. The first one is for x ≤ 0.3 and the second one is for x > 0.3. From the magnetization measurements, the basic composition (MgFe 2 O 4 ) shows the lowest magnetization, while the composition of x=0.4 shows the highest one. The behaviour of magnetization M versus composition shows also two regions for x 0.3. The behaviour of M versus x was discussed in the bases of cation distribution. From the B-H loops, the remanence induction B r , saturation induction B s and the coercive force H s were determined and studied with x. The Curie temperature T c was determined from the measurements of the initial permeability μ i versus temperature. It was found T c decreases with increasing Zn-content. Also paramagnetic temperature T was determined from the behaviour of M s vs. T. In general it was found T p > T c by about 7-10 K.

On the Mechanistic Origins of Toughness in Bone

Abstract: One of the most intriguing protein materials found in nature is bone, a material composed of assemblies of tropocollagen molecules and tiny hydroxyapatite mineral crystals that form an extremely tough, yet lightweight, adaptive and multifunctional material. Bone has evolved to provide structural support to organisms, and therefore its mechanical properties are of great physiological relevance. In this article, we review the structure and properties of bone, focusing on mechanical deformation and fracture behavior from the perspective of the multidimensional hierarchical nature of its structure. In fact, bone derives its resistance to fracture with a multitude of deformation and toughening mechanisms at many size scales ranging from the nanoscale structure of its protein molecules to the macroscopic physiological scale.

Structure and properties of lead-free solders bearing micro and nano particles

Abstract: Composite lead-free solders, containing micro and nano particles, have been widely studied. Due to grain boundary drag or Zener drag, these particles can refrain the solder microstructure from coarsening in services, especially for Cu6Sn5, Ag3Sn intermetallic compounds and the β-Sn phases. Due to dispersion hardening or dislocation drag, the mechanical properties of the composite solder alloys were enhanced significantly. Moreover, these particles can influence the rate of interfacial reactions, and some particles can transform into a layer of intermetallic compound. Wettability, creep resistance, and hardness properties were affected by these particles. A systematic review of the development of these lead-free composite solders is given here, which hopefully may find applications in microbumps to be used in the future 3D IC technology.