Propagation of the Chain Explosive‐Decomposition Reaction in Silver Azide Crystals

The velocity of the chain explosivedecomposition reaction in silver azide whiskes has been measured (1500 m/sec). The measured velocity is identified as the propagation velocity of the diffusion front of holes generated in the course of explosive decomposition.     

Uniaxial stretching of poly(keto‐ether‐imide) films

Narrow strips of various fully imidized polyimide films were stretched under constant load either isothermally or during a temperature ramp. The effects of process variables (load and temperature) on modulus, failure strain, and tensile strength of the stretched films were characterized and room temperature moduli of up to 16 GPa were documented. Several materials that undergo strain‐induced crystallization were identified as candidates for further property optimization. Polym. Eng. Sci. 44:1360–1367, 2004. © 2004 Society of Plastics Engineers.     

Stabilizing quartz slip in the production of immersion sheaths

Conclusions A technology was developed for stabilizing quartz slip for making immersion sheaths at the Podolsk refractories factory using electrolytes, enabling us to reduce the slip preparation time by 19–22 h, reducing its viscosity with a reduction in the water content from 22 to 17–20%, reducing the loss of greenware. In the conditions of KTs-2 of the Novolipetsk plant, the experimental nozzles showed a resistance similar to that of nozzles obtained by the traditional method used at Podolsk.Translated from Ogneupory, No. 7, pp. 5–6, July, 1980.     

Airborne differences in odors emitted byRattus norvegicus in response to reward and nonreward

To test the hypothesis that rats (Rattus norvegicus) emit airborne, differential odors in response to reward and nonreward, donor rats received random sequences of rewarded and nonrewarded placements in small compartments and an airstream transported odors from these compartments to test rats in a separate chamber. When donors remained in the compartments during, or were removed just prior to, air transport, test rats utilized transported odors as discriminative cues signaling their own reward and nonreward for a lever-press response. When the airstream was passed through a clean compartment containing paper flooring extracted from donor compartments, test rats were not able to discriminate. Test trials to assess for control by food odors suggest that donor-produced odors, rather than food odors per se, provided the discriminative signals for test rats. Results confirm the existence of somewhat volatile, although apparently stable, odors emitted in response to reward and nonreward, and implicate a differential in amount and/or type of odor produced by donors to these two events as the source of discriminative control.     

Service of forsterite refractories in regenerator roofs of open-hearth furnaces

Conclusions The Panteleimonov Refractories Plant produced a large industrial batch of forsterite roof brick for the lower structure of open-hearth furnaces. Tests carried out at the Donetsk Metallurgical Factory showed that it is desirable to use these forsterite refractories: the life of the regenerator roofs was four campaigns in the main roof with an adequately large residual thickness.Investigations established that the changes in the forsterite brick during service in the roof of regenerators are similar to the changes in bricks during service in other structural elements, but the destruction processes occur much more slowly.Translated from Ogneupory, No. 8, pp. 31–38, August, 1968.     

Neutron Damage in Single Crystal Aluminum Oxide

Synthetic aluminum oxide crystals were irradiated with fast neutrons to a dose of 1.8 × 10²⁰ nvt and examined by. transmission electron microscopy. As-irradiated crystals contained damage on a fine scale, revealed by diffraction contrast, and showed a 28% increase in Knoop diamond hardness compared with unirradiated material. Annealing above 600° C decreased the hardness and caused the small defect clusters to grow, forming dislocation loops on [10     0] planes with 1/3(10     1) Burgers vectors. High temperature annealing caused the loops to interact to give dislocation segments. These tended to align with the (10     0) and (1120) directions, and some of them had 1/3(10     1) Burgers vectors. Grown-in dislocations also began to climb but showed evidence of impurity pinning. Isolated platelike precipitates on [10     1] planes were observed in samples annealed at high temperatures. Possible effects of the observed damage on physical properties are considered; there is qualitative agreement between predictions and existing data.     

Technological features of casting zirconia parts

Conclusions Alkaline slips made of zirconium dioxide stabilized with calcium oxide, which have been obtained by grinding the materials in a rubber-lined zirconium-ball mill, exhibit poor casting properties and a tendency to stratification. The green ware obtained shows a low bulk density of the order of 2.5 g/cm³. The inadvisability of preparing material for casting in this way is further confirmed by the need to restore a large number of the grinding balls which quickly wear out during operation. In order to obtain a uniform degree of fineness of the material, the grinding time for zirconium balls, as opposed to the process in metal mills, should be increased.A sharp improvement in the casting properties of slip, an increase in the porosity of the green ware and a reduction in shrinkage during firing can be obtained by casting acidic slips treated with hydrochloric acid. This determines the technological advisability of washing the stabilized ZrO₂ with acid after grinding, and the possibility, therefore, of grinding for a shorter period in steel metal-ball mills.The most favorable conditions for casting slip made of stabilized ZrO₂ treated with hydrochloric acid are a moisture content of about 30% and a pH value of 1.5–2. Here the densityof the casting is 2.8 g/cm³ and the density of the fired part 5.45 g/cm³. The casting properties of slip are improved and the density of the green ware is raised by 0. 2 g/cm³ if the materials are left to stand for 2 to 4 days after treatment.     

Récupération sélective du vanadium dans l'effluent d'un procédé de fabrication du blanc de titane

The selective recovery of vanadium from an effluent of a manufacturing process for titanium white (oxide) has been made. The process retained is based on the partial neutralization of the effluent by means of calcium carbonate and on the separation of metal hydroxides from calcium sulfate and the solution. The hydroxides are thereafter calcined in the presence of a sodium salt, so that sodium vanadate may then be extracted by washing with water. Vanadium is finally precipitated by the addition of ammonium chloride or pH adjustment. The experimental results obtained in the laboratory study of the effluent neutralization, the calcination and leaching of the hydroxides and the vanadium precipitation are presented and discussed. The yields obtained in the various stages and their interdependance are also discussed.