A new kind of nontoxic, water-soluble copolymer consisting of isobutylene and maleic anhydride was used to gelcast alumina ceramics at room temperature in air. The polymer acts as both a dispersant and a gelling agent. The influence of the polymer on zeta potential, rheological and gelling behavior of the alumina slurry was studied. Copolymers with a lower molecular weight had greater dispersing ability. Copolymers with a larger molecular weight had greater gelling ability. Alumina slurries with solids loading up to 58 vol% were prepared by adding copolymer (0.3 wt%, relative to the powder) with both short and long molecular chains. Increasing solids loading from 50 to 58 vol% decreased the linear shrinkage from 4.63% to 1.50% after drying, and from 14.51% to 13.18% after sintering, respectively. A solids loading of 56 vol% was associated with the highest flexural strength, as high as 534 MPa.

Mechanical strain triggers changes in inherent molecular structure, especially in polymeric and biological materials. Unlike conventional techniques, we demonstrate a novel dynamic mechanical characterization method to study the effect of this structural evolution with strain on elastic properties. During tensile characterization of small diameter fibers, we quantitatively measured the viscoelastic properties as a continuous function of strain. While this approach is useful to characterize the elastic properties of metal microwires independent of applied strain, it is extremely important for fundamental understanding of molecular changes and their effect on the viscoelastic properties in materials such as polymer fiber and spider silk.

Achieving control of crystalline quality is a key barrier to developing thermoelectric (TE) nanowires. We show that the structural properties of free-standing Bi2(Te.97Se.03)3 nanowire arrays on substrates can be improved by postdeposition annealing. Nanowires were electrochemically deposited into anodized aluminum oxide nanopore templates formed directly on metallized Si(100). The templates were chemically removed prior to annealing in a 3% H2/Ar environment to prevent microcrack formation that results from thermal stresses. Grain sizes grew exponentially with annealing temperature until reaching the full 75-nm diameter of the nanowires at 300 °C; growth was linear above this temperature since grains could grow further only in the axial directions. Crystalline quality, along with the development of the preferred (110) orientation for optimal TE properties, improved with increasing annealing temperature between 200 and 400 °C. However, continued loss of Te composition with annealing led to a mixed phase of Bi2Te3 and Bi4Te3 at 500 °C.

Gold–silver (Au–Ag) bimetal dispersed SiO2 composite films were fabricated via a chemical solution approach combining sol–gel with a spin-coating process, and they were investigated by transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and ultraviolet-visible absorption spectra. TEM image indicated that Ag and/or Au nanoparticles (NPs) had a spherical structure with large size distributions. The XPS results demonstrated that the presence of both Ag and Au NPs in the composite film is in each metal state. The optical absorption spectra of the composite film further confirmed the formation of nanosized Au and Ag particles, given by the two surface plasmon resonance (SPR) peaks. Unlike other Au–Ag composite films, these two SPR peaks had almost the same intensity, which is rarely obtained by a chemical approach. Compared to optical absorption spectra calculated by the modified Mie theory, the location and intensity of SPR peaks had a little difference, which could be attributed to large size distributions of Ag and Au bimetal NPs in the composite film along with the experimental process. In addition, the intensity of both SPR peaks was content-related.

Ordered 30-nm Co1−xSnx (0 ≤ x ≤ 0.78) nanowire arrays have been prepared by co-electrodeposition of Co and Sn into pores of homemade anodized aluminum oxide (AAO). The magnetic properties of the Co1−xSnx nanowires are presented as a function of Sn content (x), annealing, electrolyte pH, electrodeposition frequency, and wave form. The result of energy-dispersive x-ray spectroscopy (EDX) showed anomalous co-deposition for Co and Sn. The nanowires have uniaxial magnetic anisotropy with easy magnetization direction along the nanowire axis due to the large shape anisotropy. As-deposited and annealed alloy nanowires, determined by x-ray diffraction (XRD), have amorphous phase. The nanowires electrodeposited at different pH and the electrodeposition frequencies have significantly different magnetic properties. Magnetization measurement showed that variation in magnetic properties of the nanowire arrays rooted in surface formation of Co(OH)2 and Sn(OH)2 in upper pH. The XRD patterns of Co and Co0.97Sn0.03 of nanowires obtained at pH = 2 and 4 obviously illustrated that pH affects the crystal structure of Co nanowires but has no effect on alloy nanowires. Moreover, the precipitation process was affected by raising the electrodepositing frequency via changing the rate of reduction of solute ions. The electrodeposition wave form has no significant effect on nanowire magnetic properties. The considerable enhanced coercivity has been measured in annealed nanowires. Experimental data demonstrate that the optimized composition for annealed Co1−xSnx nanowire is around Co0.93Sn0.07 in which the coercivity (Hc) has a maximum value of 2030 Oe.

Aluminum matrix fly ash (AMFA) cenosphere composites were fabricated using the stir casting technique. The used type of fly ash cenosphere, which accounted for over 60% in all fly ash particles, was in narrow and small size (2–30 μm). During synthesis, effects of several key technological parameters on microstructure and properties were investigated using orthogonal experimental design. The optimal technological parameter was achieved as: melt temperature of 700 °C + stirring rate of 1200 r/min + stirring time of 6 min + fly ash cenosphere content of 13 wt%. With this optimal technological parameter, as-cast and forged composites were manufactured. Their tensile strengths were measured and improved maximally by 50% when the cenosphere content is 13 wt%. Such size and content of fly ash cenosphere and technological parameter could largely improve the properties of composites, which should be introduced into the production process of AMFA composites.

Atomically thin films, such as graphene, graphene oxide, hexagonal-boron nitride (h-BN), and molybdenum disulfide (MoS2), have attracted intensive studies to explore their properties and potential applications as next generation materials due to their outstanding mechanical, electrical, thermal, and optical properties. The study of the mechanical behavior of this class of materials is in particular interesting as it not only physically determines the potential application fields where these materials can be utilized but also has revealed unique mechanical size effects and phenomena. Researchers have been studying the mechanical properties such as elastic modulus, strength, friction, and fracture behavior of atomically thin films for over a decade now. Here, we review recent results of the mechanical characterization and understanding of this class of materials.