Irrigation with reclaimed water at Portland Aluminium

Through extensive laboratory and field based analysis of soil chemical and physical processes, this research identified and addressed key management issues associated with the sustainable irrigation of municipal wastewater onto sandy water repellent soils, overlaying a shallow aquifer, in an environmentally significant coastal system.

Aluminium smelter wastewater : groundwater fluoride fate

This study assessed the viability of utilising groundwater systems to manage Portland Aluminium's trade waste water stream. A mathematical groundwater model was created to assess laboratory and field results. Fluoride was modelled for spatio-temporal longevity in the system. All models indicate that fluoride will ultimately exit the site to the seaward boundary.

Performance of wrought aluminium and magnesium alloy tubes in three-point bending

This present work examines the load carrying capacity, energy absorption and fracture characteristics of wrought magnesium and aluminium alloy tubes in three-point bending. Magnesium alloy AZ31, and aluminium alloys 6063 and 7075, were extruded into cylindrical tubes of both equivalent thickness and mass. A strong thickness effect was present meaning that the AZ31 tube had significantly higher load and energy absorption performance than an equivalent mass 6063 tube, albeit not as high as the 7075 tube. Hinge formation and maximum load was delayed for the magnesium alloy, meaning that a high energy absorption rate persisted to higher deformation displacements than the aluminium alloys. It was also found that fracture during deformation was dependent on the indenter diameter, tube thickness and lower support separation.

Towards a more holistic approach to quality improvements in aluminium die casting

This work evaluates the feasibility of using a holistic approach, based on dynamical system theory,
to reduce porosity defects in high pressure aluminum die casting. Quality improvements, from a
dynamical system perspective mean the ability to move the die casting process out of its natural
equilibrium to a more beneficial state and the ability to maintain this new process state. This more beneficial state may be achieved in several ways. One way is to increase the amount of forcing to overcome natural process resistance. This forcing approach is represented by typical continuous intervention policy, with modifications in die/part design and/or process parameters. An alternative approach is to reduce the amount of natural process resistance, in particular the amount of process disturbance, allowing the process to move out of its natural equilibrium with much less forcing. This alternative uses the self-regulating ability of dynamical systems thus decreasing the amount of human intervention required. In this respect, the influence of vacuum on time on chattering at the first stage of the casting shot was identified as a good process candidate for testing using dynamical system theory. A significant reduction in porosity defects was achieved, which also set the process on a path of slow but consistent self-improvement.

Ceramic-polymer interface in composite electrolytes of lithium aluminium titanium phosphate and polyetherurethane polymer electrolyte

Composite electrolytes of the lithium-ion-conducting ceramic Li_1.3Al_0.3Ti_1.7(PO₄)₃ and polyetherurethane/lithium triflate polymer electrolyte have been prepared. Microscopy has shown that adhesion between the ceramic and polymer phases is poor, with gaps up to 1 μm at the interface. When dry, the composites are no more conductive than the pure polymer electrolyte. Exposing the samples to the vapour of solvents such as DMF, acetonitrile or water produces a significant increase in conductivity, over and beyond simple plasticization of the polymer. Pretreating the ceramic with a compatibilizing agent improves adhesion at the interface with the polymer, but decreases overall conductivity in the case investigated.

Aluminium speciation in 1-Butyl-1-Methylpyrrolidinium Bis(trifluoromethylsulfonyl)amide/AlCl3 mixtures

Aluminium speciation: Aluminium speciation in NTf₂ ionic liquids has a strong influence on its electrodeposition from the liquid mixture. This work probed the nature of these species and proposes that the electroactive species involved are either [AlCl₃(NTf₂)]⁻ or [AlCl₂(NTf₂)₂]⁻ (e.g., see figure).


Electrodeposition of aluminium is possible from solutions of AlCl₃ dissolved in the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (C₄mpyrNTf₂) ionic liquid. However, electrodeposition is dependant on the AlCl₃ concentration as it only occurs at concentrations >1.6 mol L⁻¹. At these relatively high AlCl₃ concentrations the C₄mpyrNTf₂/AlCl₃ mixtures exhibit biphasic behaviour. Notably, at 1.6 mol L⁻¹ AlCl₃, aluminium can only be electrodeposited from the upper phase. Conversely, we found that at 3.3 mol L⁻¹ aluminium electrodeposition can only occur from the lower phase. The complex chemistry of the C₄mpyrNTf₂/AlCl₃ system is described and implications of aluminium speciation in several C₄mpyrNTf₂/AlCl₃ mixtures, as deduced from Raman and ²⁷Al NMR spectroscopic data, are discussed. The ²⁷Al NMR spectra of the C₄mpyrNTf₂/AlCl₃ mixtures revealed the presence of both tetrahedrally and octahedrally coordinated aluminium species. Raman spectroscopy revealed that the level of uncoordinated NTf₂⁻ anions decreased with increasing AlCl₃ concentration. Quantum chemical calculations using density functional and ab initio theory were employed to identify plausible aluminium-containing species and to calculate their vibrational frequencies, which in turn assisted the assignment of the observed Raman bands. The data indicate that the electroactive species involved are likely to be either [AlCl₃(NTf₂)]⁻ or [AlCl₂(NTf₂)₂]⁻.

Phosphonium ionic liquids as lubricants for aluminium-steel

The performance of a series of novel room temperature ionic liquids (ILs) based on the trihexyl(tetradecyl)phosphoniumcation (P66614 +) and a number of novel anions have been studied in pin-on-disk tests using a 100Cr6 steel ball on AA2024 aluminium disks.

The anions coupled to the (P66614 +) cation include diphenyl phosphate (DPP-), dibutyl phosphate (DBP-), bis (2,4,4-trimethyl pentyl) phosphinate (M3PPh-) and bis(2-ethyl hexyl) phosphate (BEH-).

More traditional anions such as bis(trifluoromethanesulfonyl) amide (NTf2 -) and bromide (Br-) were also investigated. Experiments were conducted at various loads to assess the IL film forming abilities.

The results suggest that the structure of the anion is important in forming a surface film that reduces the friction and wear of the aluminium disk. At 30N five of the six ILs tested showed a 30-90% reduction in wear, as determined from wear scar depth measurements, compared to fully formulated diesel oil.

The IL lubricant with a diphenyl phosphate anion achieved the lowest wear coefficient, showing a better performance than a typical fluorine-containing IL anion, NTf2.

To further investigate wear mechanisms and surface interactions the wear scars were analysed using a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS).

Cyclic deformation behaviour of ultrfine-grained aluminium

Ultrafine-grained aluminium was produced by cryo-rolling and their deformation response under cyclic loading was investigated. Shear banding and grain coarsening were recognized as the main damage mechanism reducing their performance under cyclic loading. However presence of precipitates in ultrafine-grained A1 can actively hinder the operation of cyclic softening mechanisms and increase microstructural stability under cyclic loading.

Mechanically alloyed and spark plasma sintered aluminium/precious metal oxide composite materials

Air-atomised pure aluminium powder with additions of 10 at.% of AgO, PtO₂ or PdO was mechanically alloyed (MAed) by using a vibrational ball mill, and MAed powders were consolidated into bulk materials by a spark plasma sintering (SPS) process. Mechano-chemical reactions among pure Al, precious metal oxide and stearic acid, added as a process control agent, during the mechanical alloying (MA) process and subsequent heat treatments were investigated by X-ray diffraction. The mechanical properties of MAed powders obtained under various heat treatment conditions and those of the SPS materials were evaluated by hardness tests. Mechano-chemical reactions occurred in Al/precious metal oxide composite powders during 36 ks of the MA process to form AlAg₂, Pt and Al₃Pd₂ for the Al-AgO, Al-PtO₂ and Al-PdO systems, respectively. Further solid-state reactions in MAed powders have been observed after heating at 373 K to 873 K for 7.2 ks. The hardness of MAed powders initially increased significantly after heating at 373 K and then generally decreased with increasing heating temperatures. The full density was obtained for the SPS materials under the conditions of an applied pressure of 49 MPa at 873 K for 3.6 ks. All the SPS materials exhibited hardness values of over 200 HV in the as-fabricated state.

Anodising AA5083 aluminium alloy using ionic liquids

Aluminium, as the current collector in lithium batteries, has shown reduced corrosion susceptibility in room temperature molten salts (1, 2). Moreover, previous studies have established that corrosion mitigation is achieved on magnesium alloys using ionic liquids pretreatments (3, 4). This paper investigated the anodisation of AA5083 aluminium alloy in Trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfony) ([P6,6,6,14][NTf2]) ionic liquid by applying a constant current followed by holding at the maximum potential for a period of time. Potentiodynamic polarisation results show that the treated surfaces were more corrosion resistant in 0.1 M sodium chloride solution compared with the control specimen. The anodising treatment was effective both in shifting the free corrosion potential to more noble values and in suppressing the corrosion current. Optical microscope and optical profilometry images indicated that an anodising film was deposited onto the alloy surface, which is thought to have inhibited corrosion in chloride environment. Further characterisation of the anodising film will be carried out in future work.