Nanomaterials
Nanomaterials are small-sized materials. The typical dimension spans from subnanometer to several hundred nanometers. A nanometer (nm) is one billionth of a meter, or 10-9m. One nanometer is approximately the length equivalent to 10 hydrogen or 5 silicon atoms aligned in a line.
Small features permit more functionality in a given space, but nanotechnology is not a simple continuation of miniaturization from micron meter scale down to nanometer scale.
Materials in the micrometer scale mostly exhibit physical properties the same as that of bulk form; however, materials in the nanometer scale may exhibit physical properties distinctively different from that of bulk.
Materials in this size range exhibit some remarkable specific properties; a transition from atoms or molecules to bulk form takes place in this size range.
In order to explore the novel physical properties and phenomena and realize the potential applications of nanomaterials, the ability to fabricate and process nanomaterials and nanostructures is the first corner stone in nanotechnology.
Solid Freeform Fabrication
Solid Freeform Fabrication (SFF) is an approach to fabricating mechanical components that is additive vs. subtractive, such as machining. SFF is also known as Rapid Prototyping (RP).
In SFF, multiple layers of material, each representing a cross section of a desired three-dimensional structure, are deposited one at a time to form a laminated stack.
By using hundreds or even thousands of such layers, extremely complex, freeform, three-dimensional shapes can be produced. SFF technologies in commercial use include StereoLithography (SL), Three-Dimensional Printing (3D P), Fused Deposition Modeling (FDM) and Laminated Object Manufacturing (LOM), to name a few.
SFF technologies are characterized by a number of significant features. First, they are extremely versatile, producing extremely complex shapes (including shapes having internal features that would be impossible to produce by subtractive methods).
Second, they typically involve a fixed process with just a few simple process steps repeated again and again to form each layer, and so can easily be implemented in a single process tool and be automated.
Use of EGR to reduce emissions in automotive engineering
For some years, the automotive manufacturers are strongly looking on vehicles pollution. Concerning the diesel engine, one of the most constraining problems is the NO2 emission, which has to drastically reduce.
One manner to reduce this emission is the EGR (Exhaust Gas Recirculation) system. EGR injects a portion of the exhaust gas back into the cylinder, so it mixes with the fuel and air (Note that the exhaust adds to the fuel and air; it does not replace any of it).
The added mass in the cylinder is harder to heat up, so the combustion events have lower temperatures (600oC instead of more than 1300oC with no EGR system).
Considering that above 1300oC oxygen and nitrogen rejoin to make nitrogen oxides (NO, NO2, etc…), the EGR system reduces drastically the NO2 emission.
Nanomotors in nanotechnology
Currently, no man-made nanomotor exists that can impact nanotechnology in the way that the steam engine defined the industrial revolution.
However, while the first prototypes of synthetic nanomotors are studied, nature provides us with a wide range of biological nanomotors, which have evolved to perform a wide range of functions with an amazing efficiency.
While the center stage is occupied by motor proteins such as myosin, which is, for example, responsible for muscle contraction, biological motor designs include motors based on ribonucleic acid (RNA) pulling on double-stranded deoxyribonucleic acid (DNA) to package it into the protein shell of a virus; ribosomes moving along RNA while synthesizing a new protein; or even a membrane protein aiding the process of hearing.
Nanoemulsions
Just as colloidal dispersions of solid nanoscale particulates have received considerable attention, colloidal dispersions of deformable nanodroplets — nanoemulsions — are beginning to receive significant attention.
Although many basic principles of emulsification are already known for isolated droplets in relatively mild shear flows, the new principles of emulsification that govern nanodroplet rupturing and coalescence in extreme shear at high ø are still being discovered.
Quantitative theoretical predictions of droplet size distributions that include the combination of these two effects are sorely needed. Once formed, nanoemulsions can be manipulated and controlled in very precise ways.
Ultracentrifugal fractionation provides model monodisperse dispersions of nanoscale droplets in the size range from roughly a = 10 to 100 nm.
Scanning Tunneling and Atomic Force Microscope
Atomic Force Microscope (AFM) was invented by Binnig and introduced in 1985 by Binnig, Quate and Gerber as an offshoot from the Scanning Tunneling Microscope (STM).
While the STM is an ingenious instrument, which has shattered many paradigms about how to access the world of single atoms, the actual device is quite simple and grants an instructive appreciation of the concepts of atomic-scale imaging.
The AFM is somewhat more complicated and the additional challenges faced by AFM show up clearly in a direct comparison. STM and AFM have stimulated a revolution in surface science.
These techniques can image the surface of many materials with atomic resolution and provide information about the structure and organization of atomic and molecular adsorbates on surfaces.
The tip and its associated force or field can also be used to manipulate atoms and molecules to form unique structures.
Nanomedicine
Burgeoning interest in the medical applications of nanotechnology has led to the emergence of a new field called nanomedicine. Most broadly, nanomedicine is the process of diagnosing, treating, and preventing disease and traumatic injury, of relieving pain, and of preserving and improving human health, using molecular tools and molecular knowledge of the human body.
It is most useful to regard the emerging field of nanomedicine as a set of three mutually overlapping and progressively more powerful technologies. First, in the relatively near term, nanomedicine can address many important medical problems by using nanoscale-structured materials with biological systems.
Nanostructured materials and devices hold great promise for advanced diagnostics and biosensors, targeted drug delivery and smart drugs, and immunoisolation therapies.
Nanosintering
Nanosintering is the sintering of nanometer size powders. For certain nanomaterial applications, sintering of powders while retaining grain sizes in the nanometer range becomes a critical processing step. Fully dense specimens with nanosize features are most important for structural, magnetic, electric or electronic applications.
The focus in the consolidation of out-of-equilibrium powders has been the retention of the metastable condition of the initial structures. The inevitable coarsening tendency and small specimen size produced by nanopowder densification generats at least some controversies on nanomaterial properties.
The sintering process of powder materials with particle in the nanometer range reveals thermodynamic and kinetic aspects of metastable powder densification, methods for full densification of metastable powders and their ability to maintain the metastability features. Specific features related to cold compaction, pore size, distribution, and their effects on sintering and grain coarsening, sintering mechanisms, and scaling laws are also applicable to nanopowder sintering.
Nanoengineering
Nanoengineering is based on fundamental theory, engineering practice, and leading-edge technologies in fabrication of nanoscale systems, subsystems, devices, and structures that have dimensions of nanometers.
Nanoengineering deals with devising (synthesis), design, analysis, and optimization of nanoscale structures, devices, and systems that exhibit and utilize novel physical (electro-magnetic, electromechanical, electrochemical, optical, etc.), chemical, electrochemical, and biological properties, phenomena, and effects that can be discovered, examined, and predicted by nanoscience (fundamental laws).
Using the pure sizing classification, the dimension of nanosystems and their components (nanostructures) is from 10-10 m (atom/molecule size) to 10-7 m, that is, from 0.1 to 100 nm. To fabricate nanostructures, nanotechnology is applied.
Nanostructures have been proposed as environmental cleaning agents, chemical detection agents, for the creation of biological (or artificial) organs, for the development of nanoelectronic mechanical systems (NEMS), and for the development of ultrafast, ultradense electrical and optical circuits.
Rapid Tooling
Rapid Tooling (RT) is an offshoot of Rapid Manufacturing (RM), which itself is the next stage of Rapid Prototyping (RP). RP offers tremendous flexibility in the design stage, and can satisfy the demand for parts by making tools, which can be used for mass production of the demanded parts. The role of RT starts here by the fabrication of such tools.
In the manufacture of tools, RT has found great success in some industries but many have found its application to be limited. As advances in machined tooling have driven out cost and time, RT’s advantages have lessened, and its limitations remain unchanged.
The most often used technologies for RT allow the production of tooling inserts in metal. However, secondary operations are also required to deliver the required accuracy and surface finish demanded of a tool.
When added to the process, RT often offers only a slight time and cost advantage over machined tooling.
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