Inhibition of corrosion on AA2024-T3 by rare earths & mercaptoacetate

The use of the aluminium alloy AA2024-T3 has long been associated with a strong vulnerability to localised corrosion. Dealloying and pitting corrosion can occur on and around intermetallic particles when exposed to aggressive environments such as sodium chloride electrolytes. Specific combinations of rare earths and organic compounds have demonstrated strong synergistic inhibition on the AA2024-T3 alloy. This work has focused on rare earths and organic compounds containing thiol functional groups. It is believed that the sulphur in the thiol group can form protective films over the surface of copper-rich intermetallic particles due to the affinity between copper and sulphur. Previous studies with the multiwell tests have identified that solutions containing sodium mercaptoacetate provided strong inhibition at pH 3 and 6. This work presents the initial findings from the polarisation tests and constant immersion corrosion experiments in the presence of sodium mercaptoacetate.

Comparative study on thermodynamical and electrochemical behavior of Al88Ni6La6 and Al86Ni6La6Cu2 amorphous alloys

Two amorphous ribbons with the compositions of Al₈₈Ni₆La₆ and Al₈₆Ni₆La₆Cu₂ were made using the meltspun method, and their thermal response and electrochemical behavior were studied comparatively. Differential scanning calorimetry (DSC) and electrochemical polarization measurements indicated that Al₈₆Ni₆La₆Cu₂ exhibited slightly higher crystallization temperature (T_x), lower melting point (T₁) and better corrosion resistance in 0.01 mol · L⁻¹ NaCl alkaline solution. These results demonstrated that Cu (2%) addition could slightly promote the glass forming ability, but it could greatly improve the corrosion resistance of Al₈₈Ni₆La₆ alloy in 0.01 mol · L⁻¹ NaCl alkaline solution.

Luminescence and microstructure of Sr2Mg(BO3)2 doped with Eu

Sr₂Mg(B0₃)₂ doped with Eu was synthesized respectively in air and weak reducing atmosphere (combustion of carbon particle), whose photoluminescence characteristics and structure were also studied at room-temperature. In air, the fluorescent body's color was white for different synthesized temperatures. At room temperature, the sample was excited and showed red typical emission spectrum of Eu³⁺ whose emission apex were sharp near 612 nm and emission spect~m was made up of the charge transformation band (CTB) of Eu^{3 +} and excitation spectrum of 4f→4f high energy level transition, then reached the area of VUV. However, under reducing atmosphere (combustion of carbon particles), the color of the sample yielded was yellow, whose color became deeper with increasing temperature and showed phase transition. Using UV excitation, the luminescence of yellow sample was very weak. In a complicated broad spectrum at visible light area, the red emission spectrum of Eu²⁺ was not observed. Crystal structure and luminescence of the sample were completely different from the results of Diaz and Keszler. Two samples were prepared under oxidation and reducing atmosphere at high temperature, which were different on crystal structure and microstructure. By studying Sr₂Mg(B0₃)₂:Eu³⁺ a series of directional faults or educts were found, because Eu^{3 +} ions substituted for Sr^{2 +} ions. However, microstructure of Sr₂Mg(B0₃ )₂: Eu^{2 +} is more complicated, whose excitation spectrum might be excited by Eu^{2 +}. By XRD patten of the samples, phase transitibn could be found. Twins and clusters that were formed from point defect such as interstitial atom and big angle crystal boundary could be found by TEM.

Synthesis and structural diversity of rare earth anthranilate complexes

Four structural classes have been established for rare earth anthranilates, which have been prepared from the lanthanoid chloride or triflate and anthranilic acid (anthH) followed by pH adjustment to 4. [La(anth)3]n is a polymeric complex with nine coordinate lanthanum and bridging tridentate (O,O,O′) anthranilate ligands, whereas [Nd(anth)3(H2O)3] · 3H2O is monomeric with nine coordinate neodymium and solely chelating (O,O) anthranilate groups. Both chelating (O,O) and bridging bidentate (O,O′) ligands are observed in dimeric [Er2(anth)6(H2O)4] · 2H2O, in which erbium is eight coordinate and the water ligands are in a trans arrangement. A polymer is observed for [Yb(anth)3(H2O)]n with solely bridging bidentate (O,O′) ligands and seven coordination for ytterbium. The NH2 groups of the anthranilate ligands are not coordinated to the metal but is unusually involved in hydrogen-bond networks with water molecules for Ln = Er, Yb.

Influence of praseodymium - synergistic corrosion inhibition in mixed rare-earth diphenyl phosphate systems

Mixed rare-earth organophosphates have been investigated as potential corrosion inhibitors for AA2024-T3, and previously have shown synergistic inhibition behavior; however, the mechanism was not identified. In this paper, a key factor contributing to corrosion inhibition of AA2024-T3 with mischmetal diphenyl phosphate [Mm(dpp)3] is the unique stability of Pr(dpp)3 compared to other key rare earths in mischmetal. Although increasing pH causes precipitation of other components, the Pr compound is stable at higher pH. Electrochemically, a synergy is evident when Ce(dpp)3 and Pr(dpp)3 are combined. Raman mapping indicates the Pr(dpp)3 inhibitor leads to a more uniform coverage of the alloy.

Issues in Australian foreign policy : July to December 2010

Two unforseen developments impeded the Labor government’s capacity to pursue its foreign policy objectives in the period under review. Firstly, Labor’s precarious standing in the parliament tilted the government’s policy agenda in favour of issues that the Greens prioritised. Gillard addressed some of these issues, for instance by holding the parliamentary debate on Afghanistan and by pursuing Japan over whaling in the Southern Ocean, but not to the degree that the Greens demanded. Immigration was emblematic of the government’s travails. The Greens advocated an increase in the refugee intake, but the Coalition favoured the resumption of offshore processing. Just when Labor’s proposed Timorese solution was becoming a realistic possibility, the High Court’s decision devalued the entire notion of offshore processing. The only consolation for the government was that the court had reduced the options available to all political parties.

Secondly, the Wikileaks saga revealed that Rudd may no longer be — and perhaps never was — Labor’s trump card in the realm of foreign policy. American assessments of the foreign minister’s character and judgment were in parts scathing. The Obama administration, nonetheless, appeared to readily and usefully absorb his analysis of Chinese politics. Quite how revelations of Rudd’s conversations with Clinton will affect his relations with the leaders of the Chinese Communist Party is another matter. It may well be that Rudd’s influence on Chinese leaders was always wildly overestimated, but in any case it seemed likely that the foreign minister would spend some time rebuilding ties with Beijing in 2011.

A third development — which hitherto had applied more in the realm of perception than reality — similarly threatened to limit the options open to future Australian governments of all stripes: the intensifying debate over alliance management that Hugh White’s essay instigated. Judgments about what sort of region — and what sort of China — Australia will face were imprinted in issues such as the rare earths find and the AUSMIN meeting. By the end of 2010, few issues could be discussed without reference to the China factor.

Rare earth-based corrosion inhibitors

Corrosion inhibitors are an important method for minimizing corrosion; however traditional inhibitors such as chromates pose environmental problems. Rare earth metals provide an important, environmentally-friendly alternative. This book provides a comprehensive review of current research and examines how rare earth metals can be used to prevent corrosion and applied to protect metals in such industries as aerospace and construction. Chapter 1 begins by examining the important need to replace chromate, and then goes on to discuss the chemistry of the rare earth metals and their related compounds. Chapter 2 considers the techniques that can be used to identify corrosion inhibition mechanisms and to test the levels of protection offered to different metals by rare earth compounds. Subsequent chapters consider in more detail how rare earth elements can be used as corrosion inhibitors in different forms and for different metals. This includes discussion on the potential of rare earth elements for self-healing, tunable and multifunctional coatings. Finally, chapter 10 considers the cost and availability of the rare earths and the potential health and environmental risks associated with extracting them. Provides a review of current research and examines how rare earth metals can be used to prevent corrosion and applied to protect metals in such industries as aerospace and construction. Includes discussion on the potential of rare earth elements for self-healing, tunable and multifunctional coatings. Considers the cost and availability of the rare earths and the potential health and environmental risks associated with extracting them.