Optimizing the overall configuration of a He-cooled W-alloy divertor for a power plant

A number of different He-cooled divertor configurations have been proposed for magnetic fusion energy (MFE) power plant application. They range in scale from a plate configuration with characteristic dimension of the order of 1 m, to the ARIES-CS T-tube configuration with characteristic dimension of the order of 10 cm, to the EU FZK finger concept with characteristic dimension of the order of 1.5 cm. All these designs utilize tungsten or tungsten alloy as structural material. This paper considers the characteristics of the different divertor configurations and proposes the possibility of optimizing the design by combining different configurations in an integrated design based on the anticipated divertor heat flux profile.     

Reactive ion etching of PECVD silicon nitride in SF6 plasma

The reactive ion etching of PECVD silicon nitride thin films has been investigated using SF₆ plasma. Effects of variations of process parameters such as pressure (50–350 mTorr), RF power (50–250 W), gas flow rate (3–130 sccm) and additions of O₂ and He (0–50%) in SF₆, on the PECVD silicon nitride etch rate and selectivity to the AZ 1350J photoresist were examined. An etch rate of 1 μm/min has been obtained under the condition of 150 mTorr, 100 W and 60 sccm. Experimental results also indicated a maximum etch rate at approximately 30% O₂ while addition of He showed only dilution effect. A nitride/photoresist selectivity ranging from 1 to 3:1 has been obtained.     

Evaluation of crack-Growth resistance curve for a particulate ceramic–Metal composite

A technique is described to evaluate the crack growth resistance behaviour in brittle ceramic-base materials. In this method, the crack increment measurements during the stable crack propagation process are not required. The crack growth resistance curves are studied for a particulate ceramic–metal composite in the system lanthanium chromite–chromium. Experiments were performed with standard fracture mechanics single-edge notched beam specimens in a temperature range from room temperature up to 1100°C. Effect of temperature on crack growth resistance behaviour is discussed.     

Development of rugged and crack-resistant structures in ceramics (review)

The paper considers methods for increasing crack resistance in ceramics, including microcracking in local stress areas, reorientation of crack movement, polymorphous martensite transition in partly stabilized zirconium dioxide, and bridging of cracks with a plastic phase or crystals with highly nonisometric shape (plates, needles, fibers) in the context of the irreversibility and nonequilibrium, producing self-organization, and a synergetic approach. The possibility of increasing crack resistance due to diffuse polymorphous transitions, twinning, and mechanochemical reactions is discussed.     

Design of polymeric dispersants for waterborne coatings

Block and random copolymers of ammonium methacrylate and dimeth-ylaminoethyl methacrylate have been synthesized and tested as dispersants of various organic and inorganic pigments in formulations for waterborne paints. Blockiness of the co-monomer distribution is a prerequisite for good color characteristics in the final paint. It is however noteworthy that a tapered diblock (one-step anionic synthesis), a diblock copolymer with a regular change in composition from one block to the other one, has an interfacial activity quite comparable to the parent “pure” diblock copolymer (two-step anionic synthesis). The most interesting observation is that the poly(dimethylaminoethyl methacrylate) anchoring block can impart stability to dispersions of pigments as different as iron oxide, a blue Cu-phthalocyanine pigment, and a red organic pigment based on pyrrole in representative aqueous paint formulations. This type of diblock copolymer is promising for the design of universal dispersants. Center for Education and Research on Macromolecules (CERM), Sart-Tilman, B6, 4000 Liège, Belgium. Rijksstraatweg 31, P.O.Box 3, 2170 BA Sassenheim, The Netherlands.     

Adsorption processes in the technology of polymer composite materials with magnetic properties

The selection of a model of an adsorption solution was substantiated. Satisfaction of the Larionov criterion [3] indicates that the selected parameters of the adsorption phase do not contradict the physical picture of adsorption. The basic thermodynamic characteristics of adsorption of phenol-formaldehyde oligomer on the solid surface of ferromagnetic disperse fillers were calculated. The correlation of the limiting adsorption value, adsorption layer thickness, and adhesive strength in polymeric magnetic materials was demonstrated. Translated from Khimicheskie Volokna, No. 3, pp. 50–52, May–June, 1998.     

Characteristics of phase transitions in poly[bis(trifluoroethoxy)phosphazene]

The data on phase transitions in bis(trifluoroethoxy)phosphazene were examined and generalized. Their nature was determined and the mechanism of the transitions was described. Schemes were proposed for the phase transitions that take into account the conditions of fabrication and thermal history of the samples. Translated from Khimicheskie Volokna, No. 5, pp. 24–27, September–October, 1998.     

Efficiency of using ion-exchange fibre materials for removal of surfactants from wastewaters

A comparative analysis of the efficiency of removing surfactants from wastewaters by different fibre chemisorbents was conducted. In studying the chemical stability of the chemisorption materials with respect to aggressive media, their good resistance to weakly basic and acid media was determined. Translated from Khimicheskie Volokna, No. 4, pp. 48–50, July–August, 1998.     

Development of a novel metal hydride–air secondary battery

A laboratory metal hydride/air cell was evaluated. Charging was via a bifunctional air gas-diffusion electrode. Mixed nickel and cobalt oxides, supported on carbon black and activated carbon, were used as catalysts in this electrode. At 30mAcm–2 in 6m KOH, the air electrode potentials were –0.2V (oxygen reduction) and +0.65V (oxygen evolution) vs Hg/HgO. The laboratory cell was cycled for 50 cycles at the C/2 rate (10mAcm–2). The average discharge/charge voltages of the cell were 0.65 and 1.6V, respectively. The initial capacity of the metal hydride electrode decreased by about 15% after 50 cycles.