Nickel Powders from the Carbonyl Process
Nickel Powders from the Carbonyl Process
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.
The nickel carbonyl gas process is used as a way of refining impure nickel. Nickel reacts with carbon monoxide to form
nickel carbonyl gas (Ni(CO)4), which can be decomposed back to nickel metal at moderate temperatures with the recovery of
carbon monoxide. Using thermal shock decomposition, fine or extra fine nickel powders can be made. Refineries in North
America and Britain can each process up to 50,000 tonnes per year of nickel in his way, producing a wide range of different
products. The use of such large volumes of carbonyl gas in the refineries allows the economic production of a range of nickel
powders. New products can also be made by using the gas stream essentially as a coating medium. These new products include
nickel coated graphite particulates, nickel coated carbon fibres and the large scale commercial production of high porosity
nickel foam. Another benefit is that the process has no real waste products, with used gas is recycled back into the main
refinery process.
Nickel Powders for Powder Metallurgy
The nickel powders produced for powder metallurgy applications have been developing step by step over recent decades as
customer property specifications have become ever more stringent. Today, there are no ‘standard’ products, only certain
families of powders that are based on different morphologies and subsequently fashioned for individual customer applications.
Nickel powder production can now be controlled to give the powders the right particle size, density and especially particle
shape to enhance the properties of low alloy steel powder metallurgy parts. Additions of nickel to the alloy typically range
from 1.75-5%. Nickel-enhanced alloys are increasingly being used for making pressed and sintered parts, particularly in the
automotive field.
Powders
Copper powder is produced by many processes including
chemical precipitation, electrolytic deposition, oxide reduction, water atomization, gas atomization, and jet
milling. Accordingly, Cu powders are commercially available in a wide range of particle shapes and sizes. Electrolytic and
chemical powders exhibit poor packing and poor rheology in molding, so they have been largely unsuccessful
for MIM (Wada, Kankawa, & Kaneko, 1997). Characteristics of examples of the other types are summarized
in Table 20.2. Representative scanning electron micrographs are given in Fig. 20.4. These powders all have similar
particle sizes but different morphologies. Typical purities reported by the
manufacturers
are about 99.85 wt%; however, oxygen contents can range up to 0.76 wt%. Powders are usually shipped containing
desiccant and proper powder storage is essential to avoid oxidation between purchase and use.
It is important to try this experiment before doing it as a demonstration, as different samples of
aluminium powder can react differently. The induction
period for some samples can be quite long. However, this is an impressive and spectacular demonstration, proving that water
can be a catalyst. It also shows that aluminium is a very reactive metal, and that its usual unreactive nature is due to the
surface oxide layer.
The chemical properties of iodine are very similar to those of bromine and chlorine. However, its reactions are far less
vigorous. It can also act as an oxidant for a number of elements such as phosphorus, aluminium, zinc and iron, although
increased temperatures are generally required. Oxidation of finely dispersed aluminium with iodine can be initiated using
drops of water. The reaction is strongly exothermic, and the excess iodine vaporises, forming a deep violet vapour.
Titanium powder metallurgy can produce high
performance and low cost titanium parts. Compared with those by conventional processes, high performance P/M titanium parts
have many advantages: excellent mechanical properties, near-net-shape and low cost, being easy to fabricate complex shape
parts, full dense material, no inner defect, fine and uniform microstructure, no texture, no segregation, low internal
stress, excellent stability of dimension and being easy to fabricate titanium based composite parts.
Titanium alloys parts are ideally suited for advanced aerospace systems because of their unique combination of high
specific strength at both room temperature and moderately elevated temperature, in addition to excellent corrosion
resistance. Despite these features, use of titanium alloys in engines and airframes is limited by cost. The alloys processing
by powder metallurgy eases the obtainment of parts with complex geometry.
The metallurgy of titanium and titanium-base alloys has been intensely investigated in the last 50 years. Titanium
has unique properties like its high strength-to-weight ratio, good resistance to many corrosive environments and can be used
over a wide range of temperatures. Typical engineering applications of titanium alloys include the manufacture of cryogenic
devices and aerospace components.
Cosmetic boron nitrides
What are these famous"white powders" that cosmetic formulators love? Why are they so addictive when
you start touching them? How can they help to improve the sensoriality, even the sensuality of a cosmetic product? Which
quality to choose for which application?
Here are some questions that beauty technicians have been asking themselves since the appearance and
marketing of cosmetic grade boron
nitride powder.
But first let's talk about the cosmetic quality of boron nitride. In space, the association of BN
molecules can take two forms:
- BN hexagonal = honeycomb slats that can stack one on top of the other.
These two shapes have different properties, namely the hexagonal shape allows the sliding of the sheets,
which gives it a lubricating capacity. While the cubic shape is very rigid, which gives it great hardness.
The BN cosmetic is hexagonal in shape and comes in the form of white powder with a very lubricating but non-
greasy touch. Moreover, it is a material which is very resistant, inert and non-toxic and does not present any danger…
neither for the consumer, nor for the formulator which must guarantee the stability of its product. It is for all these
reasons that the popularity of BN is rising to the point of replacing more and more good old talc in cosmetic formulations.
The manufacturers of cosmetic raw materials have understood this well and present to date several ranges of
different qualities, thus bringing many cosmetic properties to the BN : - Soft and silky touch - Slippery touch improves
the spreading of the product on the skin - Light reflector for a soft focus effect - Opacity, transparency, pearly luster or
even glitter depending on the crystal form - Sebum absorber - Mattifying effect - Good compaction agent - High adhesion to
the skin for high hold or even non-transfer effect - High chemical stability, unaffected by pH
These powders are thus used as well for care products as make-up products and in all types of cosmetic
formulations; emulsions, anhydrous casts, compact powders, even lotions where they bring several properties quoted.
1.Superfine powder
Superfine powder is not just a functional material, but
also established a solid foundation for the compounding and development of new functional material. The excellent performance
of superfine powder exsites in its surface effect and volume effect. the smaller the size of powder, the larger the ratio
between Area and volume. Because the BET (surface area) of superfine particle is large, and easy to agglomerate, so we need
to do surface treatment/modify to the powder and make it easy dispersing and maximize its performance.
2.Surface modification of powder
surface modification of powder is to use inorganic substance and organic substance coating the surface of
powder either by physical method or chemical process. By coating layer to the powder, the powder is recognized as composite
powder that has "core" and "shell layer". and different shell layer could improve the performance of
powder such as anti-corrosive, durability, light, thermal and chemical stability etc. by effecting its
hydrophily,hydrophobicity,hydrophily, hydrophobicity, catalytic etc.
It is mainly applied in the production of powder metallurgy, electronic materials, friction materials, oil
bearing, electrical contact materials, conductive materials, medicine, diamond products and machinery parts. In high-tech
fields of petroleum catalysts, lubricants, conductive decorative coatings and electromagnetic shielding materials, the nano-
copper powder is also widely used.
Processing and application technology of
superfine copper powder has been a major bottleneck for development of the industry. Silty soft copper,
grinding processing difficulties, easily oxidized in moist air. Water atomization high cost, low yield, non-uniform
particles, and unstable quality. In addition, many newly developed production technology, part of the complex process, the
electrical equipment that require high investment, low production yield, high cost, wide particle distribution, environmental
pollution, energy consumption, quality instability and other issues, but also did not become a mainstream technology. Newly
developed chemical reduction method can only produce nano-copper powder, and its production process is still in the
laboratory research stage, secondary pollutants to deal with difficult due to the high cost of raw materials, low production
yield and high cost led to products for sale The high price odd enable customers difficult to accept, in particular, is not
ideal in many areas of nanoscale copper powder effect. In addition, unlike the ultra-fine copper powder metal copper, and
easily oxidized to copper oxide in the air, only the protection of nitrogen, sealed package, but also affect the large-scale
promotion and application of ultra-fine copper powder.