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At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

NASA NTRS1990

Low-gravity electrodeposition of metals and metal/cermet composites

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Riley, Clyde↗

NASA NTRS1992

Vacuum Plasma Spraying Replaces Electrodeposition

Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

Holmes, Richard R.↗

NASA NTRS1993

Low-gravity electrodeposition and growth of polymer thin films with large third-order optical nonlinearities by electrochemical processes for devices: Thiophene-based polymers

It has been proposed that NLO thin film properties may be improved by low-gravity processing. Strong candidates for NLO thin film applications are the polythiophenes. Polymeric thiophenes are attractive materials due to their ease of preparation, stability, and high X(exp 3). A simple and convenient method for preparation of polythiophenes is electrochemical oxidation. We will apply some of our experience and lessons learned in low-gravity metal, metal/cermet electrode position to improve the quality of polythiophene(s) thin films. In low gravity electrode position of Ni at a high rate on an Au substrate often results in the production of an x-ray non diffracting surface. Cobalt metal deposition does not give this result nor does Ni when deposited similarly on a glassy carbon substrate. Co/Ni alloy composition produced during electrode position is strongly dependent upon the amount of convection. Code position of neutral inert cermets with metals is influenced significantly by the presence of gravity and the size of the cermets. Tracks left in the 1-g surfaces by unsuccessful particle occlusion indicate suspension of the large particles is not the only reason for poor volume percentages of the larger particles in the deposits. All size particles are more homogeneously distributed in the deposits in low-gravity electrocodeposition than in 1-g. Low gravity gives larger volume percentages for the larger particles in the deposits, while 1-g gives larger volume percentages for the smaller particles. Intermediate size particles give mixed results. The experimental cells were constructed with flat electrode end plates such that 1-g bench reference electrode positions could be carried out at various orientations with respect to gravity. A series of bench studies using similar designed cells are suggested so that convection modification can be applied to electrochemical thin film preparation. Convection effects can then be coupled with other parameter variations in current, temperature, concentration, solvent, electrolyte, and anode substrates to optimize the properties of NLO thin films before resorting to low-gravity processing.

Penn, Benjamin G.↗

NASA NTRS2001

Electrodeposition of Low Stress Nickel Phosphorous Alloys for Precision Component Fabrication

Nickel alloys are favored for electroforming precision components. Nickel phosphorous and nickel cobalt phosphorous are studied in this work. A completely new and innovative electrolytic process eliminates the fumes present in electroless processes and is suitable for electroforming nickel phosphorous and nickel cobalt phosphorous alloys to any desirable thickness, using soluble anodes, without stripping of tanks. Solutions show excellent performance for extended throughput. Properties include, cleaner low temperature operation (40 - 45 C), high Faradaic efficiency, low stress, Rockwell C 52 - 54 hardness and as much as 2000 N per square millimeter tensile strength. Performance is compared to nickel and nickel cobalt electroforming.

Engelhaupt, Darell↗

NASA NTRS2003

Electrodeposition of High Quality Nickel Phosphorous Alloys for Pollution Reduction and Energy Conservation

NASA and the University of Alabama in Huntsville have developed ecologically friendly, versatile nickel and nickel cobalt phosphorous electroplating processes. Solutions show excellent performance with high efficiency for vastly extended throughput. Properties include, clean, low temperature operation (40 - 60 C), high Faradaic efficiency, low stress and high hardness. A variety of alloy and plating speed options are easily achieved from the same chemistry using soluble anodes for metal replacement with only 25% of the phosphorous additions required for electroless nickel. Thick deposits are easily achieved unattended, for electroforming freestanding shapes without buildup of excess orthophosphate or stripping of equipment.

Engelhaupt, Darell↗

NASA NTRS2004

The present study seeks to explain the poor quality of solid electrodeposits in molten salts through a consideration of the effects of fluid flow of the electrolyte. Transparent cells allow observation of electrolyte circulation by a laser schlieren optical technique during the electrodeposition of solid zinc from the molten salt electrolyte, ZnCl2 - LiCl-KCl. Experimental variables are current, density, electrolyte composition, and cell geometry. Based on the results of earlier electrodeposition studies as well as reports in the literature, these parameters are identified as having the primary influence on cell performance and deposit quality. Experiments are conducted to measure the fluid flow patterns and the electrochemical cell characteristics, and to correlate this information with the morphology of the solid electrodeposit produced. Specifically, cell voltage, cell current, characteristic time for dendrite evolution, and dendrite growth directions are noted. Their relationship to electrolyte flow patterns and the morphology of the resulting electrodeposit are derived. Results to date indicate that laser schlieren imaging is capable of revealing fluid flow patterns in a molten salt electrolyte.

Sadoway, D. R.↗