Production of metal powders from melts by centrifugal atomization

Conclusions A study was made of centrifugal atomization of molten metals in argon at low argon consumption rates [(5.2–7.5) · 10^–3 NTP m³/kg]. Output with a single injector attained 30–40 kg/h. Increasing the molten metal head to 0.6–0.8 MPa and decreasing the nozzle diameter to 0.3 mm substantially increased the fineness of the powders. Raising the head still further influenced the effectiveness of atomization to a smaller extent, and decreasing the nozzle diameter to less than 0.3 mm coarsened the powders. Powders of magnesium, aluminum, and Br020 alloy. (20% Sn-Cu bronze) produced by centrifugal atomization of superheated (by about 30–50°K) melts in an inert atmosphere (argon) had spherical particle shapes, which imparted to them good flowability. The oxygen content of the powders was low (less than 0.08%).Translated from Poroshkovaya Metallurgiya, No. 12(276), pp. 5–10, December, 1985.     

Centrifugal pneumatic disintegration of melts. II. Production of tin-base powders and their main properties

Translated from Poroshkovaya Metallurgiya, No. 5(329), pp. 8–11, May, 1990.     

Properties of iron powders obtained from high-carbon melts by air atomization with subsequent decarburization

Conclusion The article examines the physical and processing characteristics of iron powders obtained by atomization and subsequent decementation. Experimental data, obtained by x-ray diffraction investigation, are presented on the influence of compaction pressure on the fine structure (second-type microdistortions, dislocation density, and mosaic-block size) of the powder particles.Translated from Poroshkovaya Metallurgiya, No. 10 (70), pp. 11–14, October, 1968.     

Effect of composition of copper-tin melts and bronzes on the particle size of powders produced by the electric-pulse disintegration of jets

Conclusions The results are presented of an investigation into the effect of composition of coppertin bronzes on the particle size distribution of powders and granules produced by the electric-pulse disintegration of a jet. On passing from copper to Cu-Sn alloys and then to pure tin, the proportion of fine fractions (< 160 m) grew from 7.5 to 22.7%, the amount of medium fractions also increased, and at the same time that of coarse fractions decreased, which was due to the surface tension of the melts falling from 1350 for pure copper to 540 mJ/m² for tin. Additions of 5% each of zinc and cadmium to Br 0–10 bronze resulted in the yield of fine fractions rising from 10 to 14.4 and 18.8%, respectively. The action of these elements consists in increasing the vapor pressure, which results in the generation of more powerful shock waves in the zone of the electric arcs appearing during breaks in the jet. The addition of phosphorus, which forms with copper a stable compound, has comparatively little effect on the particle size distribution of powders.Translated from Poroshkovaya Metallurgiya, No. 1(289), pp-1–4, January, 1987.     

Experimental study and modeling of the thermodynamic properties of Cu-Fe-Ni melts

The partial mixing enthalpy of nickel in ternary liquid Cu-Fe-Ni alloys is studied at 1873 K along sections characterized by ratios x _Cu: x _Fe = 3, 1, and 1/3 at x _Ni = 0–0.55. The investigations are undertaken using a high-temperature isoperibolic calorimeter. The temperature and composition dependence of the excess mixing Gibbs energy of liquid Cu-Fe-Ni alloys are described in terms of the Muggianu-Redlich-Kister model using the data obtained, the literature data on the activities of liquid alloy components, and the thermodynamic properties of melts of the boundary binary systems. This model is used to calculate isotherms of the thermodynamic properties of the liquid alloys over the entire composition range. The contribution of a ternary interaction to the integral mixing enthalpy of liquid Cu-Fe-Ni alloys is found to be mainly positive.     

Children's peer selection: Experimental examination of the role of self-perceptions.

Although previous studies have examined characteristics of children selected as friends, little research has examined the role played by characteristics of the selecting child. In 2 experimental studies that examined the role of self-perceptions in peer selection, participants (91 seventh graders in Study 1 and 83 third graders in Study 2) viewed various evaluations of themselves. Participants either believed evaluations were written by unfamiliar peers (Study 1) or were asked to imagine that the views of puppets were views of unfamiliar peers (Study 2). Participants were asked to select the pees they wished to meet and interact with. When evaluations were related to specific competence domains, 7th graders preferred positive peers to negative peers, whereas 3rd graders selected peers who viewed them as they viewed themselves. When evaluations were related to global self-worth, children's selections were unrelated to views of their own global worth. Selection of a globally negative peer was associated with attachment-insecurity/maternal-rejection and depressive symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)