Electrochemical Conversion of Oxide Precursors to Consolidated Zr and Zr−2.5Nb Tubes

Abstract

Porous tubular oxide precursors have been fabricated from the ZrO2 powder and its mixture with the Nb2O5 powder, and directly metallised to pure Zr or the Zr−2.5Nb Zircaloy tubes through electrochemical reduction and deoxygenation that induces in situ consolidation or sintering of the metallized tubes in molten CaCl2 at ∼900 °C. This new process is simple, fast, and low in energy consumption, promising a new technology for the fabrication of zirconium/Zircaloy tubes, which are the crucial materials in nuclear reactors and chemical plants. Also reported in this paper is the mechanism of the electrochemical process, correlating the cyclic voltammogram of ZrO2 powder in a metallic cavity electrode with the morphological and compositional analyses of the products from potentiostatic electrolysis of porous ZrO2 pellets.

Development of the Fray-Farthing-Chen Cambridge Process: Towards the Sustainable Production of Titanium and Its Alloys

“…50 kWh/kg Ti for the Kroll process), 57 the current efficiency is still low (e.g., 15% to achieve £ 3000 ppm oxygen in Ti) 42,54,57 when compared with that for chromium (Cr) extraction (e.g., > 70% @ < 2000 ppm oxygen in Cr) 49 and zirconium (Zr) extraction (e.g., 45% @ 1800 ppm oxygen in Zr). 58 To cope with these issues, some improvements in the FFC-Cambridge process have been made, 42,54,57 as elaborated below. 1.…”

“…20,28 Another feature of the FFC-Cambridge process is that it proceeds in the solid state, and the electrolytic products retain the shape closely to the original shape of the oxide precursors, although shrinkage would occur. 36,58,84 By taking advantage of this unique ability, different shapes of Ti-6Al-4V components (such as hollow spheres, hollow miniature golf club heads, and cylindrical cups) were produced from their slip-cast oxide precursors. 36 Figure 4 displays the photographs of different nearnet-shape products from the FFC-Cambridge process.…”

“…36 The versatility of the FFC-Cambridge process for near-net-shape production has been further demonstrated by fabricating hierarchically structured titanium foams for tissue scaffold applications, 84 and Zr and Zr-2.5Nb tubes for nuclear reactor application. 58 …”

Electrochemical Preparation of Porous Ti–13Zr–13Nb Alloy and It's Corrosion Behavior in Ringer's Solution

“…Besides pure Ti, Ti alloys including TiNi, TiFeNi, TiW, TiZr have already been prepared in a similar approach [10][11][12][13] . It was found that the obtained metal/alloys had a porous matrix consisting of interconnected homogeneous nodular metallic particles, which could be due to their porous oxide precursor 14,15) . Moreover, the porosity, oxygen content and phase composition of the obtained metal/alloys can be easily controlled by electrolysis conditions such as temperature, cell voltage and electrolysis time.…”

Near-Net-Shape Production of Hollow Titanium Alloy Components via Electrochemical Reduction of Metal Oxide Precursors in Molten Salts

“…This was recently demonstrated in the production of Zr and Zr-2.5Nb tubes from their metal oxide precursors. [17] This study applies this unique characteristic capability of the FFC-Cambridge Process in the near-net-shape manufacture of titanium alloy components in complex shapes, particularly hollow structures, directly from a mixture of metal oxides. The workhorse alloy, Ti-6Al-4V, has been chosen as the target due to its superior properties and majority share (>50 pct) of the relevant market.…”