Review on the fracture processes in nanocrystalline materials

An overview of experimental study, computer simulations and theoretical models of fracture of nanocrystalline materials is presented. The key experimentally detected facts on ductile and brittle fracture processes are discussed. Special attention is paid to computer simulations and theoretical models of nucleation and growth of nanocracks and nanopores in deformed nanocrystalline materials. Also, we discuss mechanisms for fracture suppression in such materials showing good ductility or superplasticity.     

High-strain-rate superplasticity of nanocrystalline aluminum alloy 1570

The structure and mechanical properties of nanocrystalline aluminum alloy 1570 obtained by means of severe plastic deformation have been studied. Being tested in a temperature range from 300 to 400°C, the alloy exhibits high-strain-rate superplasticity. At 400°C, the superplasticity is manifested in a very broad range of strain rates, extending from 5 × 10^?3 to 1 s^?1.     

Optical properties of strain-compensated InAs/InGaAsN/GaAsN superlattices

The optical properties of heterostructures comprising InAs/InGaAsN quantum wells in strain-compensated GaAsN/InGaAsN superlattices have been studied. It is demonstrated that, using such superlattices of various design and thickness and with additional InAs monolayer spacers, it is possible to control the wavelength of room-temperature emission from InGaAsN quantum wells within 1.3–1.6 μm without deteriorating the output radiation characteristics, which opens additional prospects for the development of lasers on GaAs substrates for telecommunication applications.     

Converting harmonic oscillations into chaos

A new simple model of a system with chaotic dynamics, based on the equations of bistable systems, is considered. The possibility of converting harmonic signals into chaotic oscillations, which represent intermittent irregular and switching quasi-regular motions, is demonstrated by numerical methods. The mechanism of chaotization is analyzed using the results of numerical calculations.     

Refractories for handling steel outside a furnace

A range of refractories is presented for handling steel outside a furnace, which are produced by the Borovichi Refractories Corporation. The refractory characteristics and working features are given. Translated from Novye Ogneupory, No. 9, pp. 29–35, September, 2008.     

Highly resistant dispensing nozzles based on zirconium dioxide for profiled CBCM. Part 1. Structure and physicomechanical properties of materials based on zirconium dioxide for producing CBCM dispensing nozzles

Technology is developed for preparing refractory components made of partially stabilized zirconium dioxide using an isostatic compaction press. Technology is provided for manufacturing dispensing nozzles using combined and separately stabilized zirconium dioxide, and also indices of the refractories obtained and imported materials are compared. __________ Translated from Novye Ogneupory, No. 3, pp. 127–131, March 2008.     

A light refractory concrete for thermal insulation

Compositions have been developed for nonshrinking vibrocast thermally insulating light refractory concretes with densities of 1.0, 1.3, 1.5, and 1.8 g/cm³ for temperatures of use up to 1400°C. The structure and properties have been examined for the concrete of density 1.3 g/cm³. __________ Translated from Novye Ogneupory, No. 4, pp. 29–32, April, 2008.     

Total and Fractional Performance of Granular Dust Traps in Refractory Production

Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms, which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The main factors are identified that influence the performance. The results are of interest to experts in related areas of industry such as building materials and engineering ceramics and so on. Translated from Novye Ogneupory, No. 4, pp. 64–67, April, 2008.     

Refractory objects and materials for continuous steel casting

In the OAO Borovich Refractory Combine production has been assimilated for a complete set of refractories for continuous steel casting, i.e. from a pipe for protecting a stream of metal to a submerged nozzle. In technical and life characteristics the products correspond to that of world analogs, they provide accident free steel pouring, make it possible to reduce the specific consumption of refractories per ton of steel, to increase CBCM productivity, to reduce billet scrap, and to reduce steel cost. Translated from Novye Ogneupory, No. 8, pp. 4–9, August 2008.     

Formation of the complex oxide NaNdTiO<Subscript>4</Subscript>

The processes of phase formation in the Na₂CO₃-TiO₂ and Na₂CO₃-TiO₂-Nd₂O₃ systems are investigated in the temperature range 600–900°C. The high-temperature solid-phase reactions underlying the process of formation of complex oxide NaNdTiO4 are studied. It is established that the synthesis of the NaNdTiO₄ compound occurs through the reaction of the intermediate product Na₈Ti₅O₁₄ with neodymium oxide in the temperature range 720–780°C. The optimum method is proposed for synthesizing NaNdTiO₄, which makes it possible to reduce the temperature of the synthesis, to avoid the formation of impurities, and to obtain the product in a finely dispersed state.