4-30-02
NEAR EARTH ASTEROID UTILIZATION AND CARBONYL METALLURGICAL PROCESSES
This
paper examines the carbonyl metallurgical processes and their applicability to
space manufacturing. The carbonyl
metallurgical processes are Chemical Vapor Deposition (CVD) processes. Metals such as nickel are digested by
exposure to carbon monoxide (CO) gas under controlled conditions. The resulting nickel tetra-carbonyl
(Ni(CO)4) is transported to the inside of a suitably shaped
inflatable, wherein the nickel tetracarbonyl comes in contact with a heated
surface. Upon contact with a heated
surface, the nickel tetracarbonyl decomposes to produce a Chemical Vapor
Deposited nickel metal coating.
Carbonyl
digestion:
The chemical equation for the carbonyl digestion of nickel metal is as follows:
Ni +
4(CO) - Ni(CO)4(gaseous molecule)
In this
reaction, nickel metal is digested by the exposure to carbon monoxide, producing
nickel tetracarbonyl (Ni(CO)4).
This reaction is preferably done at near 75 degrees Celsius at virtually
all pressures.
Digestion
conditions for Ni + CO to produce Ni(CO)4, range from 60 psi CO
carbon monoxide overpressure to 200 psi CO overpressure, at a temperature of 75
degrees C. INCO uses fluidized bed
technology at 1000 psi CO overpressure to extract nickel in mining
operations. Digestion of Ni from
ores can also be accelerated through the use of ultrasonic
energy.
Carbonyl
decomposition:
Nickel tetracarbonyl is usable as a Chemical Vapor Deposition (CVD) reagent. When the gaseous nickel tetracarbonyl comes into contact with a heated surface, a nickel coating is the result of the decomposition of the nickel tetracarbonyl. The deposition of nickel from the gaseous molecule (nickel tetracarbonyl) is the reverse reaction of the digestion:
Ni(CO)4
+ heat – Ni(metallic coating) + 4(CO)
This
decomposition occurs between 35 and 300 degrees C, with optimal results at 175
degrees C or greater, when coating forms.
As in other equilibria reactions, the temperature of the nickel
tetracarbonyl decomposition is increased with increasing carbon monoxide
overpressure. As little as 1% nickel tetracarbonyl content in an atmosphere of
carbon monoxide can be a useful CVD gaseous composition.
Near
Earth Asteroids as raw materials sources:
The
digestion of the metal fraction of stony-iron Near Earth Asteroids involves more
complex chemistry than the simple digestion/deposition of nickel
metal.
The
metallic fraction of stony-iron Near Earth Asteroids is a mixture of the
following metals: Fe (iron), Ni (nickel), Co(cobalt), Pt(platinum),
Pd(palladium), Ir(iridium), Rh(rhodium) and other metals. The use of the carbonyl digestion
process involves the extraction/volatilization of metal carbonyl molecules. Iron is digested by carbon monoxide to
produce Fe(CO)5 iron pentacarbonyl, while the nickel is converted to
Ni(CO)4 nickel
tetracarbonyl. The iron
pentacarbonyl is not readily used in CVD processes to produce coatings, making
the iron pentacarbonyl an undesirable digestion product. Likewise, the cobalt octacarbonyl is not
suitable for CVD coatings. Luckily
the volatilization characteristics of Fe(CO)5 iron pentacarbonyl;
Ni(CO)4 nickel
tetracarbonyl and, {Co(CO)4}2 cobalt octacarbonyl are
sufficiently different to allow for their selective condensation and
separation.
The
boiling points for the following molecules are as follows:
Fe(CO)5 -
102.8 degrees C,
Ni(CO)4 -
37 or 43 degrees C, depending on reference used,
{Co(CO)4}2 -
very high temp, >> than Fe(CO)5 temp., also known to
decompose @ 52 degrees C.
It can be
seen that the nickel tetracarbonyl has the highest vapor pressure, and can be
separated to give high-purity nickel tetracarbonyl for deposition uses. The iron and cobalt carbonyls are used in
other metallurgical work. The
platinum group metals are digested in the carbonyl gas stream by the addition of
halides (F2, Cl2, Br2, I2), to
produce metal-carbonyl-halide molecules.
The platinum group carbonyl halide molecules are used in other
metallurgical processes. The
platinum group metals have a very high terrestrial value and can be used as
currency and collateral in the financing of the development of a space
industrial infrastructure.
Boron strengthened nickel coatings:
In an
expired patent by Bill Jenkin, the inclusion of diborane in the nickel
tetracarbonyl gas stream produces an alloy coating of nickel/boron. The resultant boron-hardened nickel
coating shows an increase in strength to 200 Kpsi tensile strength, with a
Rockwell Hardness value of 40 to 50. Steel is between 100 KPSI to
150 KPSI in tensile strength. Nickel
(without boron) deposited from nickel tetracarbonyl has tensile strength in the
range of 80 to 90 Kpsi, and a Rockwell Hardness of 10 to 20. The Ni/B alloy strengths lend themselves
to the production of pressure vessels, habitats, framing networks, framing mesh
systems, mirrors, and other structural components required for the construction
of on-orbit habitats and space stations with and without artificial
gravity.
Pressure
vessels made with the boron-hardened Nickel coating, can have thinner walls when
compared to pressure vessels made of other materials. This manufacturing
advantage in component strength/mass ratio will be very important in the
manufacture of habitats and industrial capacity in space.
Inflatables
as forms:
The types
of inflatables and forms used in making space stations and space industrial
infrastructure components are extensive.
These forms provide shaped/heated surfaces for the exposure to nickel
tetracarbonyl, wherein, Chemical Vapor Deposited (CVD) coatings of nickel and
its alloys, produce components.
Conclusion:
Carbonyl
metallurgical processing can be used to produce habitats and industrial capacity
in space.
Bibliography
and sources of information:
1. The Kinetics of Nickel Carbonyl
Formation
W.M.
Goldberger: and D.F. Othmer
Polytechnic
Institute of Brooklyn, N.Y.
I&EC
Process Design and Development
Vol. 2,
No. 3, July 1963
pp.
202-209
2. Bill Jenkin
Akron,
Ohio
3. International Nickel
(INCO)
Richard Westfall
Galactic Mining Industries,
Inc.
4838 Stuart
Street
Denver, Colorado
80212-2922
303-433-1978
