An Experimental Validation Study of Ferrofluid Evaporation

Kerosene based ferrofluid was put into a test tube to evaporate under different conditions. The weight losses of samples were measured and the evaporation rates were calculated. The predictions of evaporation rates were made based on Bolotov’s model. It was found that the magnetic particles prevent the base fluid from evaporation and lower volume fraction leaded to higher evaporation rate. Bolotov’s model had a certain deviation but still well responsive to different variables. It was also found that the magnetic field made a difference to the evaporation rate.

The ratio of hydrogelator to precursor controls the enzymatic hydrogelation of a branched peptide

Here, we report an apparently counterintuitive observation, in which a lower volume fraction of a branched peptide forms a stronger hydrogel after an enterokinase (ENTK) cleaves off the branch from the peptide.

Influence of Partial Replacement of Si by Al on Microstructure and Properties of Nanostructured Martensitic Steel

Nanostructured martensitic steels comprising nanoscale-martensite and retained austenite were obtained by quenching–partitioning–tempering (Q–P–T) treatment. The influence of partial replacement of Si by Al on the microstructure and properties were studied. Results showed that with partial replacement of Si by Al, except nanoscale-martensite and retained austenite, a little ferrite was also clearly observed. By contrast, with partial replacement of Si by Al, although the ultimate tensile strength (1392 MPa against 1215 MPa) was slightly lower, the elongation after fracture (16.7% against 19.9%) and the toughness (equivalent to the area under the stress–strain curve) (43.1 × 106 against 37.1 × 106 J/m3) were relatively higher. This was because the retained austenite in the steel with partial replacement of Si by Al had higher carbon content, similar volume fraction of film-like morphology, lower volume fraction of blocky morphology and was surrounded by ferrite, which played significant role in the transformation-induced plasticity (TRIP) effect.

Dielectric Behavior of Barium Titanate/Carbon Fibers Composites

Conductor–insulator composites have been extensive researched for high dielectric constant. Most of them concentrated on metal polymers or metal ceramics. Barium titanate–carbon fibers composites were prepared by using a solid state reaction process with carbon fibers contents ranging from7 vol% to 23 vol%. Due to the high-aspect-ratio of carbon fiber, it was easy to produce a conducting network at much lower volume fraction. FESEM images illustrated that the carbon fibers influenced the densification and microstructure of the ceramics. Besides, addition of carbon fibers led to increase in dielectric permittivity, also had effects on the dielectric loss and ac conductivity. The dielectric and conductivity properties as a function of carbon fibers volume fraction were explained by the percolation theory.

Microstructure and Corrosion Properties of Mg-Zn-Ca-Zr Alloy for Biomedical Application

The microstructuresandcorrosion properties of the as-cast Mg-Zn-Ca-Zralloys were investigated in this study. The results showed that the alloy was mainly composed of -Mg solid solution,Zr particle and the secondary phase of Ca2Mg6Zn3. The grain size of alloy specimens decreased with the increment of Zr content. The corrosion resistances were found to increase from 0.3% to 0.5% and then decrease from 0.5% to 0.7%. The Mg-4Zn-0.5Ca-0.5Zr had the best corrosion resistance in SBF solution.This was attributed to a combination of (1) the uniform and fine microstructure of alloy, (2) continuous distributions of the secondary phases, and (3) a lower volume fraction of Zr particles.

The Study on Microstructural and Optical Properties of Nanocrystalline Germanium Films

The germanium film and Ge/Si multilayer structure were fabricated by magnetron sputtering technique on silicon substrate at temperatures of 500°C. Raman scattering spectroscopy measurements reveal that the nanocrystalline Ge occurs in both kinds of samples. Furthermore, from the atomic force microscopy (AFM) results, it is found that the grain size as well as spatially ordering distribution of the nc-Ge can be modulated by the Ge/Si multilayer structure. The room temperature photoluminescence was also observed in the samples. However, compared with that from the nc-Ge film, the intensity of PL from the nc-Ge/a-Si multilayer film becomes weaker, which is attributed to its lower volume fraction of crystallized component.

Effects of Ultrasonic Vibration Treatment on Microstructure of Heat-Resistant Al-Si Alloy

The influences of ultrasonic vibration (USV) treatment on the refining effects of primary Si particles and acicular five-element compounds with rich RE in high silicon Al-Si alloy with complex modification of P and RE were studied. The primary Si particles in this alloy was about 20 μm in size under direct USV for 2 min in the semi-solid temperature range, compared to about 30 μm in the alloy without USV. The primary Si particles in the former distributed more homogeneously and in regular shape, but had lower volume fraction of primary Si than that of the alloy without USV for the solid solubility of Si in α-Al matrix increased with USV. The eutectic Si of this alloy was modified moderately with 0.6% RE and long acicular compounds with rich RE formed which decrease the mechanical properties of alloy for the effect of cutting the matrix. Short rod-like compounds with rich RE about 10~15 μm in length were obtained with the combined effects of USV and T6 heat treatment.

HAYNES® 282™ Alloy: A New Wrought Superalloy Designed for Improved Creep Strength and Fabricability

A new wrought, gamma-prime strengthened superalloy, HAYNES 282 alloy, has been developed for high temperature structural applications, especially those in aero and land-based gas turbine engines. The new alloy possesses a unique combination of creep strength, thermal stability, and fabricability not found in currently available commercial alloys. The new alloy has excellent creep strength in the temperature range of 1200 to 1650°F (650 to 900°C), surpassing that of Waspaloy alloy and approaching that of R-41 alloy. This level of creep strength is realized despite the alloy having a significantly lower volume fraction of the strengthening gamma-prime phase. The lower gamma-prime content of the new alloy provides a considerable improvement in terms of fabricability and resistance to strain-age cracking, a problem often associated with this class of alloys. In this paper, the major characteristics and attributes of the new alloy including mechanical properties, oxidation resistance, thermal stability, and weldability are presented.

Angle of Incidence and Size Effects on Dependent Scattering in Fibrous Media

The influence of fiber size and angle of incidence on the radiative behavior of fibrous media containing closely spaced, aligned fibers is investigated by utilizing the dependent scattering theory. Numerical analyses are performed to calculate the coherent and incoherent scattering properties of dense fibrous media for several fiber sizes and angles of incidence. Results indicate that as the fiber concentration increases, the radiative properties deviate from their independent scattering values due to dependent scattering interactions. Dependent scattering becomes dominant at a lower volume fraction at normal than at oblique incidence. Increasing the fiber concentration causes the apparent refractive index of the fibrous medium to deviate from unity, thus giving rise to specular reflection due to Fresnel reflection.