In an era of democratic discontent, more and better participation in policy making has become a standard expectation. Yet it is rarely clear what counts as participation, and how the many practices loosely bundled under the label should be understood. This paper has a modest undergrowth-clearing objective: to examine assumptions behind competing typologies of participation, and to propose a classification framework less laden by idealist notions of democracy.
Transition metals such as Mo, W, Ta, Cr, and W can be used to significantly enhance the localized corrosion resistance of A1. Since these elements exhibit very low solubilities in aluminum, a nonequilibrium alloying method, such as sputter deposition, must be used to produce single-phase alloys. The addition of approximately 9 atom percent W to A1 can shift its pitting potential in the positive direction as much as 2600 mV. Heat-treatment of these nonequilibrium alloys results in the precipitation of a second phase that is detrimental, but not catastrophic, to corrosion performance. Surface analysis of the AI-W passive film formed as a function of applied anodic potential reveals that it remains thin throughout the polarization sequence and contains very little oxidized solute, regardless of the applied potential. The oxidized W present in the film is in the form of WO2 and WO3 (or WOg2). Previously, it was proposed that the enhanced passivity for sputter-deposited A1-Mo, A1-Cr, and A1-Ta alloys was a result of the oxidized solute in the film (MoO~ 2, CrOOH, or Ta20~), making the film less susceptible to chloride attack by electrostatic-repulsion, oxide-structure modification, or oxidized-solute barrier-layer formation mechanisms. The results of this investigation reveal that the electrostatic-repulsion or oxidized-solute barrierlayer mechanisms are not responsible for the dramatic enhancement in the passivity of A1 with the addition of W. Instead, the small amount of oxidized W in the passive film may interact synergistically with the hydrated aluminum oxide structure to form a more protective film.
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