Increasing the number of uses of the refractories in the slide gates of large steel-teeming ladles

Conclusions A method of enrichment of brucite by washing and sorting of it was developed. An experimental lot of composite slide gate plates for two teemings from the 300-ton steel teeming ladles of Magnitogorsk Metallurgical Combine was prepared from enriched fused brucite at Magnesite Combine. The physicochemical indices of the plates were 97.9 wt.% magnesium oxide with a nonequiaxiality of the periclase crystals of 1.94, 0.3% silica, 0.2% iron oxide, compressive strength 110 N/mm², and open porosity 12%. Under conditions of repeated openings and closings the plates made it possible to provide 100% quality teeming of the first heat and to direct 60% of the slide gates to repeated teeming, which was done with 32%. For a final experimental verification it would be desirable to prepare a larger experimental production lot of refractories using the method developed with specific repeated use.Translated from Ogneupory, No. 2, pp. 47–51, February, 1988.     

Modular concepts of quality assurance in chemical reactor engineering

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 3, pp. 34–36, March, 1992.     

Optical Control of the Parameters of Substrates in Silicon-Carbide Epitaxial Structures

Semiconductors - Silicon carbide SiC is the basic material of modern extreme and power electronics. The characterization of substrates and SiC-based epitaxial multilayers requires advanced on-line...     

Supersonic plasmatron nozzle profiling with the real properties of high temperature working gas

The effects of real gases (excitation of vibrational degrees of freedom, dissociation and ionization) taken into account for supersonic nozzle profiling. The paper presents the method of the supersonic nozzle profiling for non-monotonic dependence of adiabatic index on temperature. The results of nozzle profile calculation for two sets of input parameters, based on independently determined specific heat for molecular nitrogen N₂ and products of its thermal decomposition in the temperature range of 260–10⁵ K and atmospheric pressure are presented. The experimental set-up based on proposed method of supersonic nozzle has been developed and manufactured. The gas velocity at different distances from the nozzle outlet has been measured. Results show the existence of the supersonic and transsonic flow regimes after the nozzle.     

An examination of the role of plasma treatment for lean NOx reduction over sodium zeolite Y and gamma alumina Part 2: Formation of nitrogen

NO_x reduction with NO₂ as the NO_x gas in the absence of plasma was compared to plasma treated lean NO_x exhaust where NO is converted to NO₂ in the plasma. Product nitrogen was measured to prove true chemical reduction of NO_x to N₂. With plasma treatment, NO as the NO_x gas, and a NaY catalyst, the maximum conversion to nitrogen was 50% between 180 and 230 °C. The activity decreased at higher and lower temperatures. At 130 °C a complete nitrogen balance could be obtained, however between 164 and 227 °C less than 20% of the NO_x is converted to a nitrogen-containing compound or compounds not readily detected by gas chromatograph (GC) or Fourier transform infrared spectrometer (FT-IR) analysis. With plasma treatment, NO₂ as the NO_x gas, and a NaY catalyst, a complete nitrogen balance is obtained with a maximum conversion to nitrogen of 55% at 225 °C.

For γ-alumina, with plasma treatment and NO₂ as the NO_x gas, 59% of the NO_x is converted to nitrogen at 340 °C. A complete nitrogen balance was obtained at these conditions. As high as 80% NO_x removal over γ-alumina was measured by a chemiluminescent NO_x meter with plasma treatment and NO as the NO_x gas.

When NO is replaced with NO₂ and the simulated exhaust gases are not plasma treated, the maximum NO_x reduction activity of NaY and γ-alumina decreases to 26 and 10%, respectively. This is a large reduction in activity compared to similar conditions where the simulated exhaust was plasma treated. Therefore, in addition to NO₂, other plasma-generated species are required to maximize NO_x reduction.     

Experiments on the study of effect of microparticles anomalistic penetration into solid bodies

At certain conditions interaction between high velocity (up to 3 km/s) flows of microparticles with dimensions 20–70 μm and solid bodies could result in their super deep penetration (SDP) into those bodies. For SDP-effect to be studied a number of experiments were carried out. The X-ray analysis of microparticles acceleration has shown the advantage of acceleration of microparticles in mixture with the extender (porofor) because it makes it possible to regulate the flow density, its velocity and impact duration by means of the extender concentration variation. Experiments have been performed on the impact of microparticle flows with velocities in the range 1–2.6 km/s on copper and iron substrates. Results of metallographic investigations of cross-sectional and lengthwise grinds of substrates indicate that some tungsten particles penetrate into a target. The diameter of channels in the substrate material, which are formed due to particles penetration, is in the range 2–15 μm.