Manufacturing & Prototyping

Separation and Sealing of a Sample Container Using Brazing

This process is an alternative to a prior explosive welding process. A special double-wall container and a process for utilizing the container are being developed to enable (1) acquisition of a sample of material in a “dirty” environment that may include a biological and/or chemical hazard; (2) sealing a lid onto the inner part of the container to hermetically enclose the sample; (3) separating the resulting hermetic container from the dirty environment; and (4) bringing that hermetic container, without any biological or chemical contamination of its outer surface, into a clean environment. The process is denoted “S3B” (separation, seaming, and sealing using brazing) because sealing of the sample into the hermetic container, separating the container from the dirty environment, and bringing the container with a clean outer surface into the clean environment are all accomplished simultaneously with a brazing operation. This container and process were conceived as a superior alternative to the double-wall container and process described in “Explosion Welding for Hermetic Containerization” (NPO-20868), NASA Tech Briefs, Vol. 27, No. 8 (August 2003), page 46. As in the previously reported case, the present container and process were originally intended to be used to return samples from Mars to Earth, but could also be used on Earth to store and transport material samples acquired in environments that contain biological and/or chemical hazards.

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Diamond Smoothing Tools

Machined surfaces could be made much smoother. Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors.

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Fabrication of Buried Nanochannels From Nanowire Patterns

Sacrificial nanowires are buried, then etched away to form buried channels. A method of fabricating channels having widths of tens of nanometers in silicon substrates and burying the channels under overlying layers of dielectric materials has been demonstrated. With further refinement, the method might be useful for fabricating nanochannels for manipulation and analysis of large biomolecules at single-molecule resolution. Unlike in prior methods, burying the channels does not involve bonding of flat wafers to the silicon substrates to cover exposed channels in the substrates. Instead, the formation and burying of the channels are accomplished in a more sophisticated process that is less vulnerable to defects in the substrates and less likely to result in clogging of, or leakage from, the channels.

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Passivating Stainless Steel Parts

Procedures for commonly used stainless steels can use citric or nitric acid solutions. Maximizing the natural corrosion resistance of parts and components machined from stainless steels. It can make the difference between satisfactory performance and premature failure. Incorrectly performed, passivation can actually induce corrosion.

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Manufacturing Diamond Under Very High Pressure

Pure or doped diamond is crystallized from molten carbon and in solid state. A process for manufacturing bulk diamond has been made practical by the invention of the High Pressure and Temperature Apparatus capable of applying the combination of very high temperature and high pressure needed to melt carbon in a sufficiently large volume. The rate of growth achievable in this process is about ten times the rate achievable in older processes. Depending on the starting material and temperature-and-pressure schedule, this process can be made to yield diamond in any of a variety of scientifically and industrially useful forms, including monocrystalline, polycrystalline, pure, doped, and diamond composite. (Doping makes it possible to impart desired electrical and optical properties, including semiconductivity and color.) The process can also be used to make cubic boron nitride.

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A Method of Assembling Compact Coherent Fiber-Optic Bundles

The method is based on hexagonal close packing. A method of assembling coherent fiber-optic bundles in which all the fibers are packed together as closely as possible is undergoing development. The method is based straightforwardly on the established concept of hexagonal close packing; hence, the development efforts are focused on fixtures and techniques for practical implementation of hexagonal close packing of parallel optical fibers.

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Fabrication of Submillimeter Axisymmetric Optical Components

Surfaces of components can be arbitrarily shaped to optimize spectral responses. It is now possible to fashion transparent crystalline materials into axisymmetric optical components having diameters ranging from hundreds down to tens of micrometers, whereas previously, the smallest attainable diameter was 500 m. A major step in the fabrication process that makes this possible can be characterized as diamond turning or computer numerically controlled machining on an ultrahigh-precision lathe. This process affords the flexibility to make arbitrary axisymmetric shapes that have various degrees of complexity: examples include a flat disk or a torus supported by a cylinder (see figure), or multiple closely axially spaced disks or tori supported by a cylinder. Such optical components are intended mainly for use as whispering-gallery- mode optical resonators in diverse actual and potential applications, including wavelength filtering, modulation, photonic generation and detection of microwaves, and research in quantum electrodynamics and quantum optics.

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