Fabrication of Antireflective Sub-Wavelength Structures on Silicon Nitride Using Nano Cluster Mask for Solar Cell Application

We have developed a simple and scalable approach for fabricating sub-wavelength structures (SWS) on silicon nitride by means of self-assembled nickel nanoparticle masks and inductively coupled plasma (ICP) ion etching. Silicon nitride SWS surfaces with diameter of 160–200 nm and a height of 140–150 nm were obtained. A low reflectivity below 1% was observed over wavelength from 590 to 680 nm. Using the measured reflectivity data in PC1D, the solar cell characteristics has been compared for single layer anti-reflection (SLAR) coatings and SWS and a 0.8% improvement in efficiency has been seen.     

Practice of application of refractory concrete in industrial furnaces

The Teploograzhdenie Research-and-Production Company has developed refractory concretes with service temperature of 1150–1650°C which have been successfully used as car bottom lining in tunnel furnaces, block lining of the hearth and lower parts of thermal furnace walls (together with the Termostal’ JSC), lining of roof panels of a continuous furnace, and burner stones. __________ Translated from Novye Ogneupory, No. 11, pp. 18–19, November, 2006.     

Effect of a low-amplitude shock wave with residual pressure on hexagonal boron nitride

We have performed shock-wave loading of hexagonal boron nitride under pressures of10.8–16 GPa in the range of initial temperatures of20–500°C in flat recovery ampoules allowing one to sustain residual pressures of ∼1 GPa. To form a plane shock wave, a gas gun was used. Application of a residual pressure under the action of a shock wave with an intensity of16 GPa increased the yield of wurtzite boron nitride by4 to5 times. This explained on the basis of the assumption of wurtzite formation from the amorphous phase in high-temperature zones of adiabatic shear in the residual regime. Center of High Dynamic Pressures, Mendeleevo 141570. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 5, pp. 122–127, September–October, 1997.     

Using ferrosilicon nitride of nitro-fesil grade in gate and spout components

Development results are presented for the new NITRO-FESIL strengthening additive, which is intended for gate and spout parts in blast furnace production. Researches on the high-temperature process in the ferrosilicon-nitrogen system have provided a new industrial technology for making materials based on silicon nitride. The technology is characterized by the absence of energy consumption, complete ecological safety, and a product distinguished by good working properties. Translated from Novye Ogneupory, No. 9, pp. 45–50, September, 2008.     

Ceramic made from SHS silicon nitride powder

A ceramic made from a powder of silicon nitride which is obtained by self-propagating high-temperature synthesis is investigated. Yttrium-aluminum garnet and mullite are used as sintering aids. The strength of the material obtained reaches 540 MPa. __________ Translated from Steklo i Keramika, No. 3, pp. 17–19, March, 2007.     

Improvement of the properties of AZ91D magnesium alloy by treatment with a molten AlCl3–NaCl salt to form an Mg–Al intermetallic surface layer

A process for surface modification of AZ91D magnesium alloy has been carried out in AlCl₃–NaCl molten salts melt at 573 K for 7 h. The process was used to form a diffusion alloying layer on the surface of the sample to improve corrosion resistance. The diffusion alloying layer was mainly composed of Mg–Al intermetallic compounds. The continued immersion test in 5% NaCl solutions displayed that molten salt diffusion-treated specimen had better corrosion resistance compared to the untreated AZ91D specimen. The polarization test indicated that the Mg–Al intermetallic compounds of the layer were an effective corrosion barrier to decrease the corrosion rate for AZ91D magnesium alloy when exposed to 3.5% NaCl solutions. The microhardness values of the Mg–Al intermetallic compounds were higher than those of the substrate.     

Neutron scattering method in studying and certifying surface hardening processes in ceramic plates

The possibility of certifying and checking surface hardening of ceramic plates by neutron scattering methods using neutron radiation diffraction (Bragg and small-angle) is demonstrated. The surface hardening of corundum plates by modifying their surface using magnetron spraying and subsequent fusion of the hardened layer using en electron beam has been performed by the authors for the first time. __________ Translated from Novye Ogneupory, No. 6, pp. 82–86, June, 2007.     

Detonation of ammonium nitrate and dynammons with and without inert additives

The detonation velocities of 10–60 mm thick, flat charges of ammonium nitrate and mixtures of it with various liquid and solid fuels plus added inert components in varied amounts and dispersions are determined experimentally. These explosives have been used for cladding of flat metal stock with areas of up to 12 mm ² by explosion welding with thicknesses of the cladding layer ranging from 1 to 30 mm and of the base layer, from 4 to 120 mm. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 3, pp. 114–119, May–June 1999.     

Physicomechanical properties of refractory Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–Si<Subscript>3</Subscript>N<Subscript>4</Subscript>–C materials with ACPC

A study has been made on the effects of the amount of silicon nitride and graphite on the physicomechanical properties of Al₂O₃–Si₃N₄–C composites for lining purposes. Adding 2.5–5.0 wt.% silicon nitride and 0.5 wt.% reactive alumina improves the properties, raises their apparent density, and increases the mechanical strength, while reducing the open porosity. Optimized compositions have been determined for refractory materials of Al₂O₃–Si₃N₄–C composition, and it has been found that to attain the higher values of physicomechanical properties the amount of graphite should constitute 5–10 wt.%.     

Properties and applications of some structural refractory ceramic materials based on nonmetal nitrides

New composite ceramic materials developed at the Central Materials Research Institute, including nitride-oxide composites based on hexagonal boron nitride and nitride composites based on silicon nitride are described. Some important technological aspects of the production of articles and parts from these materials are considered. Data on the properties and main applications of the composites are reported. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 3, pp. 34–35, March, 1997.     

Properties of the surface layer and combustion behavior of metallized solid propellants

The properties of the surface layer of burning metallized solid propellants are analyzed on the basis of available experimental data. A general physical concept of processes in the surface layer is developed. The structure called a skeleton layer is shown to play a key role in combustion. The factors influencing the properties of the skeleton layer are determined, and the effect of these of properties on the properties of condensed combustion products and the propellant burning-rate law is studied. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 4, pp. 156–165, July–August, 2009.     

The nature of noctilucent clouds and the Earth’s ozone layer

It has been revealed theoretically that hydrogen self-ignites at a height of120 km and burns up nearly completely at heights of165–200 km. Still higher, its concentration falls off in proportion to pressure because of burning and, therefore, hydrogen does not leave the terrestrial atmosphere. The water vapor that forms during hydrogen combustion descends and changes, under definite temperature conditions, to very small pieces of ice at a height of ∼85 km, the number of which is enough to form noctilucent clouds which are easily observable in twilight. Atomic oxygen forms during the same process of hydrogen combustion. Atomic oxygen combines with molecular oxygen to form ozone. It is noted that the power of this source of ozone is proportional to the hydrogen concentration near the Earth’s surface and can be higher than that of all other sources. Apparently, this circumstance will make it necessary to develop a new approach to clarify the causes of the appearance of the ozone layer and ozone “holes.” The energy released during hydrogen combustion is sufficient to account for the existence of the thermosphere. Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 4, pp. 3–13, July–August, 1997.     

Mechanism of formation of a heated ground layer by an intense air burst

A mathematical modeling study demonstrated the fundamental possibility of the formation of a heated layer (a meter-long layer of erosion vapor and air with temperatures of a few thousand degrees and a density 20–50 times lower than the normal air density) at the ground surface under the action of the long-distance traveling fireball radiation from an intense explosion at a moderate radiant flux density of about 1 GW/m² for a time of about 10 msec. The results of the numerical study agree with data from observations of the heated layer effect in nuclear-weapon tests. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 100–106, July–August, 2006.     

Effect of conditions under which powdered lanthanum is heated on its interaction with air

Thermogravimetric, differential-thermographic, chemical, and x-ray phase analysis methods are used to study the effect of the rate at which powdered lanthanum is heated in air on the nature of the reaction products. It is found that for heating rates of up to 150 K/min the interaction with air ends in the formation of lanthanum oxide. At heating rates of 150–600 K/min, a nitride phase is formed along with La₂O₃. Further increases in the heating rate lead to formation of the oxide phase only. The reasons for this behavior of lanthanum are examined. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 1, pp. 85–88, January–February 1999.     

Phase composition of superhard ceramics based on sphalerite boron nitride with a metal-like binder

X-ray phase analysis is used to determine the optimum range of the proportion of metal-like binder and sphalerite boron nitride in a superhard ceramics. Composites with 25–40% mixture of TiN + TiB₂ in the cutting layer obtained by directed impregnation have an elevated wear resistance.     

Effect of an Iron Catalyst and Process Parameters on Si-Based Ceramic Materials Synthesized From Rice Husks

Silica and carbon are naturally occurring in rice husks (RH) and these were used for the production of ceramic materials made of Si, C, N and O as the main constituents. The various “silicon-based” ceramics were produced from the thermal decomposition of rice husks and posterior heat treatment at temperatures varying from 1200–1450 °C under a pure nitrogen atmosphere. FeSO₄ in various concentrations was introduced to the decomposed rice husk prior to the heat treatment. The formation of various Si/C/N/O ceramics in general and silicon nitride in particular, were studied with respect to the concentration of FeSO₄ (4–10%) as well as temperature (1200–1450 °C). The formation of different phases were confirmed by XRD and FT-IR analysis. Morphology and surface properties of the products have been studied using SEM. The maximization of whiskers of the ceramic products was also studied through microstructural analysis. Elemental analysis of the whiskers product was analyzed through EDX. The chemical analysis of raw rice husk was also carried out.     

Molecular stratification nanotechnology in antiadhesive modification of fabric fibres

The dependence of the oil-repellent effect on the structure of a modifying layer of fluorocarbons was established. Formation of a nanosize monomolecular adsorption layer is optimum for attaining the greatest effect. It is useful to conduct molecular stratification from chlorocarbon medium (perchloroethylene) for the necessary orientation of the molecules of the fluorocarbon amphiphilic substance. Cationization of the surface of textile fibres is required for forming a nanosize layer from aqueous solution. __________ Translated from Khimicheskie Volokna, No. 2, pp. 34–40, March–April, 2008.     

Fabrication of Porous Anodic Alumina with Ultrasmall Nanopores

Anodization of Al foil under low voltages of 1–10 V was conducted to obtain porous anodic aluminas (PAAs) with ultrasmall nanopores. Regular nanopore arrays with pore diameter 6–10 nm were realized in four different electrolytes under 0–30°C according to the AFM, FESEM, TEM images and current evolution curves. It is found that the pore diameter and interpore distance, as well as the barrier layer thickness, are not sensitive to the applied potentials and electrolytes, which is totally different from the rules of general PAA fabrication. The brand-new formation mechanism has been revealed by the AFM study on the samples anodized for very short durations of 2–60 s. It is discovered for the first time that the regular nanoparticles come into being under 1–10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultrasmall nanopores. Under higher potentials from 10 to 40 V, the surface nanoparticles will be less and less and nanopores transform into general PAAs.     

Silicon carbide articles for linings of reactors for the production of aluminum chloride

The technological parameters of the production of silicon carbide refractories with a silicon nitride binder are investigated. An experimental industrial batch of refractories has been produced by the Semiluki Refractory Plant and shipped to the Kaustic Production Association to be used in linings of reactors for the production of aluminum chloride. Translated from Ogneupory, No. 9, pp. 15 – 17, September, 1995.     

Surface Tension and the Gibbs Approach

In the Gibbs capillarity equation, it is necessary to use the excess surface tension whose value is a function of the position of the dividing surface. The thermodynamic properties of disperse systems can be determined with the Guggenheim approach, since there are reliable experimental methods of determining the thickness of the interface layer for polymer dispersions. __________ Translated from Khimicheskie Volokna, No. 3, pp. 60–61, May–June, 2005.