2 research outputs found
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Design of a Solid Freeform Fabrication Diamond Reactor
Solid Freeform Fabrication (SFF) has progressed from the visualization aided
stage of computer aided designs (CAD) to rapid prototyping of structural parts.
Among the promising techniques for producing structural prototypes is the technology
ofchemical vapor deposition (CVD) ofpolycrystalline diamond. This paper
discusses the thermodynamic and kinetic theories that suggest that structural
diamond may be rapidly deposited at rates approaching 1 mmJhr from the vapor
phase at metastable thermodynamic conditions. The design of a reactor that will
produce structural diamond prototypes is discussed. This reactor combines downstream
microwave plasma enhanced chemical vapor deposition (DMWPECVD)
with a scanned CO2 laser that locally heats the substrate to diamond deposition
temperatures. The input:Fases are H2, 02' CH4, and Ar. The operating pressure range
of the reactor is 1 x 10- to 7 x 102 Torr. The reactor is designed for in situ determination
of deposit thickness while deposition occurs as well as having the capacity
of fitting on an existing resonance enhanced multiphoton ionization time of flight
mass spectroscopy (REMPITOFMS) apparatus that will allow for plasma diagnostics
immediately above the heated substrate. Plasma diagnostics will be
employed to determine the active metastable species that results in diamond
deposition so that optimization can be made ofthe operating parameters to maximize
diamond selectivity and deposition rate.Mechanical Engineerin
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Selective Area Laser Deposition - A Method of Solid Freeform Fabrication
Mechanical Engineerin