Metal powder is the base materials for the production of metallic component through the conventional powder metallurgy route or the emerging field of additive manufacturing. In any of these process routes, the properties of the finished product depends on the character of the base powder from which it is produced which is equally dependent on the process of production of the base powder. Therefore, there are different methods for producing metal powders with each method offering different particle morphology and purity. These methods include crushing (for brittle material), machining, mechanical pulverization, slotting, electrolysis, atomization of liquid metal using water, nitrogen, argon, or a combination of these, and reduction of metal oxides in hydrogen or using carbon. These metal oxides could be materials such as iron ore or iron oxide generated from pickling plants, in steel strip mills. Other methods include reduction of metal oxide with higher carbon containing, metal powder, chemical decomposition of metal carbonyls, and electrolytic processing of cathodic deposition from molten metal salts; and in some instances, recycling (Sharma, 2011). Each of these methods provides different particle morphology and characteristics. An illustration of typical powder shapes produced from some of these processes is shown in Figures 1 and 2.
New materials that can be tailored for individual applications are in constant demand. As the range of uses for powder metallurgy, hard metals and electronic materials expands, customer requirements are causing materials companies to come up with new products that have the necessary properties. Nickel can bring a number of benefits to these and other industries. It can improve the mechanical and fatigue properties of alloy steels, enhance conductivity and magnetic properties of electronic materials, act as a binder for holding together particulate materials and be used in filtration components in the form of high porosity products. These applications rely on high purity fine nickel powders and other special nickel forms being adapted to meet specific materials needs, for which a versatile production and processing technology is needed. The nickel carbonyl gas process fulfils these needs.
The Nickel Carbonyl Process
Nickel powder can be made by a number of different processes, including atomisation from melts or precipitation from solutions. However, these techniques tend to give relatively large particles and can be difficult to control economically at fine particle sizes. The nickel carbonyl gas process on the other hand tends to produce much finer particles, and with sufficient production know-how plus the latest computerised process controls, the particles produced can be precisely controlled to very accurate shapes and tolerances.
