Electrodeposition of metal powders

Molten salt protases for refining metals as diverse as Icad beryllium, magnesium, molybdenum and uranium have been described but are seldom used commercially. 

Empincally, it is well estabUsbed that powder formation is usually encouraged by  

The above factors are all consistent with the theory that powder deposition is a 

Technologically, electrodeposition competes with other preparation techniques including (t) chemical reaction (2) mechanical comminution and (3) atomization. 

The choice of technique is important not only from the standpoints of economics and convenience but also the properties of the metal powder are very dependent upon the production method. Chemical reactions generally yield cheap, porous, readily-compressible powders but alloy production is not possible. Mechantcall comminution is a convenient technique for brittle metals but results in an irregular particle shape. 

In most areas of technology, the electrodeposition of metal is carried out under electrolysis and electrode conditions which promote the formation of a smooth, compact film. Important examples include electroplating (Chapter 8, Section 8.1) and electroforming (Chapter 9, Section 9.1). 

As the current density is increased, however, the deposit generally becomes rougher in texture and higher in the active area (Chapter 8, Fig. 8.10) as mass transport control begins to exert an influence. Under conditions of significant mass transport control, the roughened deposit may become loosely adherent and disperse, i.e a metal powder is formed. This is the direct electrolytic method for metal-powder formation. Alternatively, for certain metals, the electrolysis conditions may be chosen to give a relatively coherent but brittle deposit which may be transformed to a powder by mechanical comminution. 

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Pavlovic, M. G. Electrodeposition of Metal Powders with Controlled Particle Grain Size and Morphology 24... 

This work was supported by the Ministry of Sciences, Technologies and Development of the Republic of Serbia under the research projects Electrodeposition of Metal Powders at a Constant and at a Periodically Changing Rate 1806/2002) and Surface Science and Thin Films (2018/2002). 

A. Calusaru, Electrodeposition of Metal Powders, Elsevier Scientific Publishing Company, Amsterdam Oxford New York (1979) 296. 

Popov KI, Pavlovic MG (1993) Electrodeposition of metal powders with crmtrolled grain size and morphology. In White RE, Bockris JO M, Conway BE (eds) Modem aspects of electrochemistry, vol 24. Plenum Press, New York, pp 299—391... 

Calusam A (1979) Electrodeposition of metal powders. Material science monogtaphy, vol 3. Elsevier, Amsterdam... 

Djokic SS, Nikolic ND, Zivkovic PM, Popov KI, Djokic NS (2011) Electroless depositirai and electrodeposition of metallic powders a comparison. ECS Trans 33 7-31... 

The relatimis between the decisive characteristics of metal powder and the cmiditions of electrodepositiOTi have not been established so far in a semiquantitative way. Hence, electrodeposition of metal powders can be regarded as largely empirical, an activity in which there is much art and little science. We hope that this will change with the publication of this chapter. 

Hydrometallurgical processes, i.e. production of Ni, Co, Cu, or similar metals, are well established in practice. Similarly, the electrodeposition of metallic powders has been extensively studied over the last century. A significant portion of this book is devoted to electrodeposition of metallic powders. The study of electroless deposition of metal powders has to a certain extent been neglected. The formation of metallic powders occurring during electroless deposition of metallic powders is considerably less investigated than its electrolytic counterpart. 

Electrodeposition of metal powders (section 4.4) provides an interesting case under certain conditions, not only is growth favoured at the high points, but the increased surface roughness may act as a turbulence promoter. The result (Fig. 2j8(c)) IS a severe thinning of the Nemst diffusion layer. 

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