Fine, monophasic silicon carbide powder has been synthesized by direct solid-state reaction of its constituents namely silicon and carbon in a 2.45 GHz microwave field. Optimum parameters for the silicon carbide phase formation have been determined by varying reaction time and reaction temperature. The powders have been characterized for their particle size, surface area, phase composition (X-r...

High-silicon steels have long been known to possess exceptional resistance to tempering, but the reasons for this effect were unknown. We report here a study of the third stage of tempering of these steels, in which cementite is formed. In a 0.75 wt% C 1.4 wt% Si alloy steel, tempered for 1 hour at 380°C, it is found that silicon atoms are rejected from the growing cementite into the ferrite ma...

The surface chemistry of pristine, 6-nm silicon nanoparticles has been investigated. The particles were produced in an RF plasma and studied using a tandem differential mobility analysis apparatus, Fourier transform infrared spectroscopy (FTIR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and transmission electron microscopy. Particles were extracted from the plasma, which operat...

Accumulating epidemiological evidence indicates that exposure to fine air pollution particles (APPs) is associated with a variety of adverse health effects. However, the exact physiochemical properties and biological toxicities of fine APPs are still not well characterized. We collected four types of fine particle (FP) (diesel exhaust particles [DEPs], natural organic combustion [NOC] ash, synt...

Four-dimensional propagation-based phase contrast X-ray tomographic microscopy experiments were performed on an Aluminum29.9mass% Silicon alloy during coarsening. Using propagation-based phase contrast, changes in the three-dimensional morphology of primary silicon particles were captured and the resulting evolution of the microstructure is discussed. While morphologies at earlier times are com...

We report on strongly enhanced electron multiplication in thin silicon membranes. The device is configured as a transmission-type membrane for electron multiplication. A subthreshold electric field applied on the emission side of the membrane enhances the number of electrons emitted by two orders of magnitude. This enhancement stems from field emitted electrons stimulated by the incident partic...

The thickness of the unresponsive layer of silicon on a surface barrier detector was undetectable. Alpha particles passed through the layer at normal incidence and at 60◦ with respect to the plane of the detector. Electronic drift obscured the difference between the two measured energies. The minimum detectable thickness of silicon for the system is (70± 8) μg/cm, or (30± 3) μm. Future experime...

The adhesion forces of microto nanoscopic particles on surfaces are the main topic of this dissertation. As a model system, the contact between colloidal particles and smooth silicon and glass substrates are investigated. To achieve information about their adhesion forces, particles are detached from the substrates on the timescale of tens of nanoseconds. For this purpose a laser is focussed on...

(1) Background: The assessment of airborne particulate matter (PM) and ultrafine particles (UFPs) in battlefield scenarios is a topic of particular concern; (2) Methods: Size distribution, concentration, and chemical composition of UFPs during operative military training activities (target drone launches, ammunition blasting, and inert bomb impact) were investigated using an electric low-pressu...

abstract: in this study, al 2 o 3 –sic nanocomposites have been fabricated by mixing of alumina powder containing 0.05% weight magnesium oxide and silicon carbide nano powders, followed by hot pressing at 1650 0 c. the mechanical properties of al 2 o 3 -sic nanocomposites containing different volume fraction (2.5, 5, 7.5, 10 and 15%) of nano scale sic particles were investigated and compared wi...