Electrodeposited gold composite coatings

Abstract

The special properties exhibited by electrodeposited composite coatings have ensured industrial applications for them as a result of the high specification demands of modern technology. Recent advances in the understanding of the mechanism offormation of such coatings, including those involving gold matrices, and awareness of the properties of the latter, justify interest in theirpotential applications.The past two decades have seen a steady increase in our knowledge and understanding, and most importantly our application of composite coatings formed by electrodeposition from aqueous suspensions of inert particles. A number of systems have progressed to the stage of having become completely accepted in high-technology industrial applications. These have evolved largely as a result of the improved wear resistance characteristics imparted by the composite coatings. Such applications have included the incorporation of silicon carbide particles into nickel electrodeposits on the contacting faces of Wankel engine housings (1), and cobaltchromium carbide composite coatings for high-temperature dry slidingwear in gas-turbine aeroengines (2, 3, 4). E. C. Kedward (4) has reviewed research carried out in the field of electrodeposited composite coatings to 1973.It is, in fact, a measure of the understanding and appreciation of the properties which can be achieved by incorporating second phase particles into deposits that practical applications have also been found for electroless (autocatalytic) composite coatings. The inherent corrosion resistance of electroless nickel, its high hardness in the heat-treated form, and the fact that it can be deposited F. 1E éctbaal'yrnYdacoriteptohthe^reëpi [ ó eléctradcjwsitéd ldalumit a compo i6 s3 Au testrit t ttte hnene s of. he jarticírs.(0 02 n Sf arireterl n1y a''low`wIume perenu&e u. µhe camposite , 1s técuur^d to 0flpto crb4l <ië"siscáárë dn stic lIy ;E1:ftgr_(to) uniformly upon both the exposed and recessed surfaces of configurationally complex objects, combine with the tribological improvements afforded by codepositing such particles as silicon carbide or polytetrafluoroethylene (PTFE) to ensure its ready commercial utilisation (5 -8). A recent paper by D.J. Kenton (9) in which the effects of different combinations of codeposited silicon carbide, calcium fluoride, alumina and PTFE on the abrasive wear, adhesive wear and sliding fiction characteristics of electro less nickel are discussed, confirms the beneficia) results previously reported.In view of the above, it is perhaps surprising that gold-based electrodeposited composite coatings have not attracted more attention in industry in recent years. This review will therefore discuss present knowledge of the deposition of gold composites gained not only from work on such deposition, but also from studies of the electrodeposition of other metal composites. The mechanical and tribological properties of electrodeposited gold composite coatings which have been produced will also be reviewed.

Electrochemical Co-Deposition of Gold and Carbon Nanocapsules from a Colloidal Suspension

“…Co-deposition mechanisms.-Gold composites formation has been reported to involve adsorption of ionic species on the surface of the particles in the galvanic bath, diffusion of the charged particles to the cathode, reduction of the adsorbed ions and strong anchoring of the particles to the cathode surface. 28 Incorporation of carbon nanocapsules into gold can be then described with a three-step model based on the previously proposed by Eroglu et al 29 the capsules onto the surface and (3) incorporation in the growing gold film by gold salt reduction on the capsule surface. In the present work, in which conductive particles are co-deposited with the metal, when the carbon nanocapsules reach the metal surface, they are strongly trapped and gold salt reduces on the nanocapsule surface.…”

“…Diffusion layer 28 where N c is the particle flux (particle/cm 2 s), the kinematic viscosity of the electrolyte (cm 2 /s), D C de diffusion coefficient of the particles (cm 2 /s), c C,∞ the bulk concentration of the particles (particles/cm 3 ), c C,0 the surface concentration of the particles (particles/cm 3 ), the rotation speed (rad/s), θ the surface coverage, K the Langmuir adsorption constant (cm 3 /mol), k inc the incorporation rate constant (particles cm 5 /A 2 ), r C the particle radius (cm), a a constant (A/cm 2 ), i Au the current density for gold deposition (A/cm 2 ) and b a constant (rad/s).…”

Фотоуправляемые Обратимые Изменения Электронных И Колебательных Спектров Фотохромного Диарилэтена В Различных Наноструктурированных Системах

“…Наночастицы серебра с размерами 30-40 nm были получены цитратным восстановлением ионов серебра в водном растворе [35], а с размерами 8−10 nmборгидридным восстановлением серебра в водном растворе [36]. Наночастицы золота с диаметром около 20 nm были приготовлены цитратным восстановлением золота в водном растворе [37,38]. Для приготовления коллоидных пленок серебра и золота использовался метод послойного осаждения коллоидов серебра (или нанокомпозитных систем из частиц благородных металлов с оболочкой из молекул фотохромных ДАЭ) путем окунания стеклянной подложки в коллоидный раствор и последующего высушивания [26].…”

Properties of ECD Gold Composite with Nanostructured Carbon-Based Materials

“…The study and development of composite gold electrodeposition has been an alternative approach to this issue for twenty years ( 2 ). In this lapse of time, electrodeposition processes of gold matrix composite with dispersion of hard particles, such as Al 2 O 3 (3) and TiN (4), or polymeric particles, such as PTFE for dry selflubricating layers (5), were studied.…”