Organo-aluminum compounds have been used for many years as electrolytes in the coating industry [1±7] and complexes of the type MX´2AlR 3 (where M is an alkali metal or quaternary ammonium salt, X is a halide, preferably fluoride, and R is an alkyl group having 1, 2, or 4 C-atoms) have been recommended. These can be used either as a melt or as solutions in an aromatic hydrocarbon. In recent years, ecological factors as well as the excellent corrosion-resistance associated with the aluminum layer have led to a considerable increase in interest in the electrolytic coating of metal parts and galvanic coating in a closed system at moderate temperatures (60±150 C) has already attained technical significance.To optimize the fuel consumption of vehicles, it will be necessary to decrease their weight by using a combination of various materials such as aluminum and magnesium and their alloys. Although the substitution of aluminum by magnesium can theoretically lead to a weight reduction of one third (due to the difference in density of the two metals), in practice the lower modulus of elasticity and the decreased stiffness shown by magnesium has to be compensated for with additional reinforcement.The substitution of aluminum by magnesium is also accompanied by a higher susceptibility to corrosion. The anisotropy associated with the hexagonal crystal system of magnesium limits the techniques available for working with this metal and, in automobile construction, casting has become the method of choice. The parts, reinforced where necessary, are susceptible to two types of corrosion: contact corrosion and normal surface corrosion. Contact corrosion is observed when magnesium comes into contact with a layer of a second metal or when steel screws are used in magnesium, and is a result of the large negative potential associated with magnesium. Upon contact with magnesium, a second metal having a more positive potential acts as a cathode and, depending upon the potential difference, more or less significant corrosion takes place. This effect is particularly noticeable where contact occurs between magnesium and various types of steel as well as with galvanized steel. Moreover, the galvanic coating of steel fasteners with pure aluminum is only partially effective because the products of magnesium corrosion are alkaline and attack the aluminum surface. [8] In this communication, we describe the development of a galvanic process for generating aluminum±magnesium coatings having various compositions and report some results on their physical properties including adhesion, ductility, and corrosion resistance.Electrolytes for the deposition of aluminum±magnesium coatings onto electrically conducting materials have been described: Connor et al. [9] have briefly mentioned that the electrolysis of AlBr 3 /LiAlH 4 /MgBr 2 (Mg/Al = 0.8) in diethyl ether gave a satisfactory metal surface containing Al (93 %) and Mg (7 %), while Eckert and Gneupel [10] used AlCl 3 / LiAlH 4 /MgBr 2 (Mg/Al = 0.6) in a mixture of tetrahydrofuran±diethyl ether±b...

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This paper, based on the Second Lakhtin Memorial Lecture, gives an overview of the developments in the process control of gas nitriding and describes the current status of nitriding of non-ferrous alloys. Control of the nitriding process involves both thermodynamic and kinetic factors. On this basis, Lakhtin developed concepts that provide the foundations for controlled gas nitriding processes. The progress in the development of sensors in the last few years offers new possibilities for gas nitriding and nitrocarburising process control. The control of the reaction gas composition leads to higher quality assurance. Adjusting defined nitriding and oxidation potentials enables surface activation of components which allows, for example, a uniform nitriding of stainless steels at temperatures of 300°C. There are significant differences between the nitriding behaviour of aluminium, titanium, and iron alloys owing to the different solubilities of nitrogen in the base metal, the differences between the nitriding and solidus temperatures, and the different oxygen affinities of the base metals. Considerable progress has been made in the field of plasma nitriding of aluminium alloys in recent years. An essential part of this is the evidence that commercial plants can be used for the plasma nitriding of aluminium alloys. New possibilities for the production of load specific nitrided layers on titanium alloys allow the nitriding process to be intensified and combined with solution treatment and subsequent aging.

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Zur Senkung des Fahrzeuggewichtes sollen zukünftig warmgewalzte Magnesium‐Blech‐Legierungen wie auch CFK‐Bauteile in die Karosseriestruktur integriert werden. Beide Leichtbaumaterialien sind mit verzinkten Stählen sowie mit Aluminium ohne aufwendige Korrosionsschutzmaßnahmen nicht kombinierbar. Aus elektrochemischen Untersuchungen wird bezüglich der Vorbehandlung von Magnesium eine oxidkeramische Oberflächenausbildung durch plasmachemische Oxydation als aussichtsreich eingeschätzt. Nach dem mechanischen Fügen mit Aluminium können derartige porenbehaftete Substrate mittels KTL in hoher Qualität lackiert werden, bevor der weitere Lackaufbau erfolgt. CFK‐Bauteile indessen haben – im Gegensatz zu Magnesium – elektrochemisch ein sehr edles Verhalten und verursachen starke Kontaktkorrosion an metallischen Anbauteilen, wenn die C‐Fasern durch den Bauteil‐Beschnitt frei liegen. Für das mechanische Fügen von CFK mittels Schraub‐ und Niettechnik eignen sich daher nur Verbindungselemente aus austenitischen Stählen oder aus Titan‐Legierungen (z.B. TiAl6V4). Aus Sicht der Materialverträglichkeit von CFK mit anderen Blech‐Materialien, vorzugsweise mit Aluminium, ist die Verklebung mit zusätzlicher Abdichtung entsprechender Flansche zwingend erforderlich.