nanomateriale2

=Nanostructuri la metale si aliaje=

Nanoparticule metalice
Proprietatile metalelor se schimba la scara nano. Ex: Aurul galben la scara macro, rosu sau chiar incolor la scara nano. Aurul macro este foarte stabil nu reactioneaza chimic cu oxigenul si sulful. Aurul nano reactioneaza rapid chimic si poate fi utilizat drept catalizator. Efectul LSPR (Localised Surface Plasmon-Resonances) - Metale nobile, aur, argint, platina, paladiu in forma nano, prezinta efectul LSPR. Cand lumina loveste suprafata unui metal pentru anumite lungimi de unda, se produce propagarea luminii de-a lungul suprafetei, ducand l aun fenomen de conductie electrica de suprafata. Fenomenul este difierit la scara macro si la scara nano. Forma si dimensiunea materialului afecteaza energia efectului.Particulele cu efect LSPR interactioneaza cu alte molecule chimice sau biochimice. Practic particulele metalice pot fi utilizate ca senzori. Se folosesc in detectia optica si in chimia analitica. parametrul utilizat este indicele de refractie. Se considera ca efectul va fi foliositor in aplicatii legate de: terapia cancerului, celule solare, interconectare optica, camer LED.

Intarirea unor materiale
Aplicatii in industria aerospatiala si de automobile. Se introduce in otel o pulbere de titan in stare nano, obtinand proprietati speciale de durabilitate, robustet, rezistenat la coroziune si la temperatura.

Aplicatii ecologice

 * Fierul in stare nano, se utilizeaza pentru decontaminarea apelor si a solului. In stare nano efectul de decontaminare este de 10-1000 de ori mai puternic
 * Argintul in stare nano este utilizat pentru capacitatilelui antibacteriene puetrnice. Reduc sau previn aderarea bacteriilor la suprafete.

Metale nanocristaline
Sunt metale cu cristale la scara de 100nm. Au proprietati mecanice si ficzice exceptionale.EX: Al, Mg, Al-Mg Ti, Ti-Al Unele aliaje au proprietati magnetice exceptionale. Ex: Finemet, Fe-Si-B cu Nb si Cu Pulberi magnetice nano sunt disperasate in matrici nemagnetice sau se realizeaza depuneri subtiri nanocomposite. Aplicatii in stocarea magnetica a informatiei.

Ferofluide
Sunt suspensii coloidale de materiale fero sau ferinmagnetice intr-un solvent organic sau in apa.Sunt de fapt materiale superpara magnetice cu o mare susceptibilitate magnetica. Cand ferofluidele sunt supuse la un camp magnetic intens, formeaza spontan structuri regulate. Au aplicatii in Aplicatii:
 * inginerie mecanica, suspensia auto si sistemele de franare. Au coeficient de frecare foarte mic.
 * ICT, reduc frecare ala HDD
 * biomedicale medicamente

Electronic devices
Ferrofluids are used to form liquid [|seals] around the spinning drive shafts in [|hard disks]. The rotating shaft is surrounded by magnets. A small amount of ferrofluid, placed in the gap between the magnet and the shaft, will be held in place by its attraction to the magnet. The fluid of magnetic particles forms a barrier which prevents debris from entering the interior of the hard drive. According to engineers at Ferrotec, ferrofluid seals on rotating shafts typically withstand 3 to 4 psi.

Mechanical engineering
Ferrofluids have [|friction]-reducing capabilities. If applied to the surface of a strong enough magnet, such as one made of [|NdFeB], it can cause the magnet to glide across smooth surfaces with minimal resistance.

Aerospace
NASA has experimented using ferrofluids in a closed loop as the basis for a spacecraft's [|attitude control] system. A [|magnetic field] is applied to a loop of ferrofluid to change the [|angular momentum] and influence the rotation of the spacecraft.

Analytical Instrumentation
Ferrofluids have numerous [|optical] applications because of their [|refractive] properties; that is, each grain, a [|micromagnet], reflects [|light]. These applications include measuring [|specific viscosity] of a liquid placed between a [|polarizer] and an [|analyzer], illuminated by a [|helium-neon laser].

Medicine
In [|medicine], ferrofluids are used as [|contrast agents] for [|magnetic resonance imaging] and can be used for [|cancer] detection. The ferrofluids are in this case composed of [|iron oxide] nanoparticles and called SPION, for "Superparamagnetic Iron Oxide Nanoparticles" There is also much experimentation with the use of ferrofluids in an [|experimental cancer treatment] called [|magnetic hyperthermia]. It is based on the fact that a ferrofluid placed in an alternating magnetic field releases [|heat].

Heat transfer
An external magnetic field imposed on a ferrofluid with varying susceptibility (e.g., because of a temperature gradient) results in a nonuniform magnetic body force, which leads to a form of [|heat transfer] called [|thermomagnetic convection]. This form of heat transfer can be useful when conventional convection heat transfer is inadequate; e.g., in miniature microscale devices or under [|reduced gravity] conditions. Ferrofluids are commonly used in [|loudspeakers] to remove heat from the [|voice coil], and to passively [|damp] the movement of the cone. They reside in what would normally be the air gap around the voice coil, held in place by the speaker's magnet. Since ferrofluids are paramagnetic, they obey [|Curie's law], thus become less magnetic at higher temperatures. A strong magnet placed near the voice coil (which produces heat) will attract cold ferrofluid more than hot ferrofluid thus forcing the heated ferrofluid away from the electric voice coil and toward a [|heat sink]. This is an efficient cooling method which requires no additional energy input.[|[][|6][|]]

Optics
Research is under way to create a [|Adaptive optics shape-shifting magnetic mirror] from ferrofluid for Earth-based astronomical [|telescopes].[|[][|7][|]]

Art
Some art and science [|museums] have special devices on display that use magnets to make ferrofluids move around specially shaped surfaces in a [|fountain] show-like fashion to entertain guests. Sachiko Kodama is known for her ferrofluid art. The Australian electronic rock band, [|Pendulum], used ferrofluid for the music video for the track, Watercolour. The design house Krafted London was responsible for the ferrofluid FX in the video. The post-metal band [|Isis] also uses a Ferrofluid in the music-video for 20 Minutes/40 Years. CZFerro, an American art studio, began using ferrofluid in its productions in 2008. The works consist of ferrofluid displayed in a unique suspension solution. These works are often used as [|conversation pieces] for offices and homes.
 * Film1
 * Cum functioneaza ferofluidele
 * Cum puten fabrica ferofluide