Continued from page 1
Much as
traditional process,
Microplasmic process is an electrochemical process, but there ends
similarity. The Microplasmic process is radically different from
traditional anodizing processes in many respects. The distinguishing features of
process may be summarized as follows.
· The process employs alkaline electrolytes whose composition is extremely critical to
coating rate and
properties of
anodic film that is formed. The pH of
electrolyte is in
range 8 -12 and is thus environmentally sound. · The process employs Alternating Currents at high voltage and high current. Because of
high voltage, a microplasma surrounds
electrodes and
oxygen ions produced in
plasma diffuse through
anodic film into
aluminum substrate to react and form more anodic film. · The high voltage and high current allow
production of anodic films of
same thickness as that of
traditional process in a fraction of
time. · Because
voltages are higher than
breakdown voltage of
film formed, open channels are not necessary for sustaining
process and hence dense thick layers of nonporous film can be readily formed. · Because
process employs AC power,
productivity is increased. · The power from an electrical utility supply can be used with proper controls to
electrochemical tank thus making
process less capital intensive. There is no need for power rectification and waveform smoothing. · The temperature of
electrolytic bath need not be precisely maintained. Indeed, successful coatings can be obtained even if
temperature excursions are as much as 10-20 oC, further simplifying
process. · The electrolytic composition itself is quite variable for different types of coatings. · Because of
high density of
coating, practically there is no change in
dimension of
anodized part, and a completely finished part can be coated without major post processing finishing operations. The Microplasmic Process, however, produces an outer soft coating of about 15% that may be buffed off;
remaining inner layer, is an extremely hard ceramic layer. · Above all, unlike with
traditional anodization process, aluminum alloy parts of any composition can be successfully anodized by
Microplasmic Process. Even more importantly, a variety of ceramic "alloy" coatings, such as Al2O3.SiO2, Al2O3.MgO, Al2O3..CaO etc. can only be produced by
Microplasmic Process. · The Microplasmic Process is also suited for a hard coating inside surface of a part i.e. cylindrical, conical or spherical hollow parts. Many coating processes in
market, like CVD, PVD, IVD, PEPVD, Sputtering, Thermal Spraying etc. are unable to coat inside surface of a long part.
4.0 Applications
Because
microplasmic process produces a thick, well bonded ceramic coating on a variety of reactive light metal alloys, it can be used for a broad range of applications. The primary application could be
replacement of heavier metallic alloys or
more expensive composite materials required by
aerospace and automotive industries by light metals (e.g., Al, Ti, Mg, and their alloys) coated by
Microplasmic Process. Other applications can be divided into
following categories: Chemical, Mechanical, Thermal, Electrical and Electronics, and combinations of these.
· Chemical: The ceramic coating can resist both aqueous and moderately high temperature and is resistant to strong acids and bases. Thus it can be used in chemical, and food processing industries. · Mechanical: The hardness of
film is over 1300 kg/mm2 and thus
film can be used to resist sliding, abrasive and erosive wear. In addition
friction coefficient is low and thus can be used in marginally lubricated systems. · Thermal: The thermal conductivity of
anodic film is much less than of metals. Thus anodized parts can be used to maintain uniform distribution of temperature and resist thermal shock. · Electrical and Electronic: The dielectric breakdown strength of
Microplasmic film is comparable to that of alpha Al2O3 and hence can be used as an insulating film on electrical and electronic components.
Additionally,
Microplasmic Process is also well suited for hard coating interior surfaces (such as those of hollow cylindrical and conical parts), recesses, blind holes, threaded sections, and so on.
Many coating processes in
market, such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Plasma Enhanced Physical Vapor Deposition (PEPVD), Sputtering, Thermal Spraying, etc. are unable to coat
inside surface of a long part. Thus, where appropriate these expensive coating processes can be readily replaced by
Microplasmic Process.
Microplasmic Corporation
Contact Information: Microplasmic Corporation 17 Esquire Drive Peabody, MA, USA Tel (978) 531-9145 Fax (978) 531-3671 Email: info@microplasmic.com Company Website http://www.microplasmic.com/ Public Relations Website http://www.microarcanodizing.com/

Jerry Patel: BS degree Mechanical Engineering - Fairleigh Dickinson University MS degree Engineering Management - Northeastern University Nannaji Saka, Ph.D: BS - Mechanical Engineering - Andhra University in India MS - Metallurgical Engineering - Indian Institute of Technology PH.D - Materials Engineering from - Department of Materials Science and Engineering at MIT.