|
Ultrasonic Atomization
Ultrasonic atomization is a process in which a liquid, in contact with a surface vibrating at ultrasonic frequencies, forms standing Capillary wave, capillary waves that lead to the ejection of fine droplets. As the amplitude of these waves increases, the wave crests can reach a critical height where the cohesive forces of the liquid are overcome by the surface tension, leading to the ejection of small droplets from the wave tips. Mechanism and principles The formation of droplets during ultrasonic atomization remains complex and not fully understood, though several theories attempt to explain it. One leading theory, the capillary wave hypothesis by Lang, suggests that droplets form at the peaks of capillary waves on the liquid surface. Lang developed a formula that relates droplet size to capillary wavelength. The average diameter estimation was obtained using a constant that was later adjusted by Yasuda to better predict smaller droplet sizes in the micrometer range. This pred ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid
Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to that of a solid, and much higher than that of a gas. Therefore, liquid and solid are classified as condensed matter. Meanwhile, since both liquids and gases can flow, they are categorized as fluids. A liquid is composed of atoms or molecules held together by intermolecular bonds of intermediate strength. These forces allow the particles to move around one another while remaining closely packed. In contrast, solids have particles that are tightly bound by strong intermolecular forces, limiting their movement to small vibrations in fixed positions. Gases, on the other hand, consist of widely spaced, freely moving particles with only weak intermolecular forces. As temperature increases, the molecules in a liquid vibrate more intensely, causi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wettability
Wetting is the ability of a liquid to displace gas to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. These interactions occur in the presence of either a gaseous phase or another liquid phase not miscible with the wetting liquid. The degree of wetting (wettability) is determined by a force balance between adhesive and cohesive forces. There are two types of wetting: non-reactive wetting and reactive wetting. Wetting is important in the bonding or adherence of two materials. The wetting power of a liquid, and surface forces which control wetting, are also responsible for related effects, including capillary effects. Surfactants can be used to increase the wetting power of liquids such as water. Wetting has gained increasing attention in nanotechnology and nanoscience research, following the development of nanomaterials over the past two decades (i.e., graphene, carbon nanotube, boron nitride nanomesh). E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mist
Mist is a phenomenon caused by small droplets of water suspended in the cold air, usually by condensation. Physically, it is an example of a Dispersion (chemistry), dispersion. It is most commonly seen where water vapor in warm, moist air meets sudden cooling, such as in Exhalation, exhaled air in the winter, or when throwing water onto the hot stove of a sauna. It can be created artificially with aerosol canisters if the humidity and temperature conditions are right. It can also occur as part of natural weather, when humid air cools rapidly, notably when the air comes into contact with surfaces that are much cooler than the air (e.g. mountains). The formation of mist, as of other Suspension (chemistry), suspensions, is greatly aided by the presence of nucleation sites on which the suspended water phase can congeal. Thus even such unusual sources of nucleation as small particulates from volcanic eruptions, releases of strongly polar gases, and even the magnetospheric ions associa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-entropy Alloy
High-entropy alloys (HEAs) are alloys that are formed by mixing equal or relatively large proportions of (usually) five or more elements. Prior to the synthesis of these substances, typical metal alloys comprised one or two major components with smaller amounts of other elements. For example, additional elements can be added to iron to improve its properties, thereby creating an iron-based alloy, but typically in fairly low proportions, such as the proportions of carbon, manganese, and others in various steels. Hence, high-entropy alloys are a novel class of materials. The term "high-entropy alloys" was coined by Taiwanese scientist Jien-Wei Yeh because the entropy increase of mixing is substantially higher when there is a larger number of elements in the mix, and their proportions are more nearly equal. Some alternative names, such as multi-component alloys, compositionally complex alloys and multi-principal-element alloys are also suggested by other researchers. Compositionall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium Alloys
Titanium alloys are alloys that contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness (even at extreme temperatures). They are light in weight, have extraordinary corrosion resistance and the ability to withstand extreme temperatures. However, the high cost of Titanium#Production, processing limits their use to military applications, aircraft, spacecraft, bicycles, medical devices, jewelry, highly stressed components such as connecting rods on expensive sports cars and some premium sports equipment and consumer electronics. Although "commercially pure" titanium has acceptable mechanical properties and has been used for orthopedics, orthopedic and dental implants, for most applications titanium is alloyed with small amounts of aluminium and vanadium, typically 6% and 4% respectively, by weight. This mixture has a solid solubility which varies dramatically with temperature, allowing it to undergo precipitation strengtheni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium Alloys
Zirconium alloys are solid solutions of zirconium or other metals, a common subgroup having the trade mark Zircaloy. Zirconium has very low absorption cross-section of thermal neutrons, high hardness, ductility and corrosion resistance. One of the main uses of zirconium alloys is in nuclear technology, as cladding of fuel rods in nuclear reactors, especially water reactors. A typical composition of nuclear-grade zirconium alloys is more than 95 weight percent zirconium and less than 2% of tin, niobium, iron, chromium, nickel and other metals, which are added to improve mechanical properties and corrosion resistance. The water cooling of reactor zirconium alloys elevates requirement for their resistance to oxidation-related nodular corrosion. Furthermore, oxidative reaction of zirconium with water releases hydrogen gas, which partly diffuses into the alloy and forms zirconium hydrides. The hydrides are less dense and are weaker mechanically than the alloy; their formation results ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium Alloy
Magnesium alloys are mixtures of magnesium (the lightest structural metal) with other metals (called an alloy), often aluminium, zinc, manganese, silicon, copper, rare earths and zirconium. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminium, copper and steel; therefore, magnesium alloys are typically used as cast alloys, but research of wrought alloys has been more extensive since 2003. Cast magnesium alloys are used for many components of modern cars and have been used in some high-performance vehicles; die-cast magnesium is also used for camera bodies and components in lenses. The commercially dominant magnesium alloys contain aluminium (3 to 13 percent). Another important alloy contains Mg, Al, and Zn. Some are hardenable by heat treatment. All the alloys may be used for more than one product ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-speed Photography
High-speed photography is the science of taking pictures of very fast phenomena. In 1948, the Society of Motion Picture and Television Engineers (SMPTE) defined high-speed photography as any set of photographs captured by a camera capable of 69 frames per second or greater, and of at least three consecutive frames. High-speed photography can be considered to be the opposite of time-lapse photography. In common usage, high-speed photography may refer to either or both of the following meanings. The first is that the photograph itself may be taken in a way as to appear to freeze the motion, especially to reduce motion blur. The second is that a series of photographs may be taken at a high sampling frequency or frame rate. The first requires a sensor with good sensitivity and either a very good shuttering system or a very fast strobe light. The second requires some means of capturing successive frames, either with a mechanical device or by moving data off electronic sensors very qu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Spin-off
University spin-offs (also known as university spin-outs) are companies that transform technological inventions developed from university research that are likely to remain unexploited otherwise. They are a subcategory of research spin-offs. Prominent examples of university spin-offs are Genentech, Crucell, Lycos and Plastic Logic. In most countries, universities can claim the intellectual property (IP) rights on technologies developed in their laboratories. In the United States, the Bayh–Dole Act permits universities to pursue ownership of inventions made by researchers at their institutions using funding from the federal government, where previously federal research funding contracts and grants obligated inventors (wherever they worked) to assign the resulting IP to the government. This IP typically draws on patents or, in exceptional cases, copyrights. Therefore, the process of establishing the spin-off as a new corporation involves transferring the IP to the new corporati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warsaw University Of Technology
The Warsaw University of Technology () is one of the leading institutes of technology in Poland and one of the largest in Central Europe. It employs 2,453 teaching faculty, with 357 professors (including 145 titular professors). The student body numbers 36,156 (as of 2011), mostly full-time. Its 19 Faculty (division), faculties (divisions) covering almost all fields of science and technology are located in Warsaw, with the exception of one, which is in Płock. The Warsaw University of Technology has about 5,000 graduates per year. According to the 2008 ''Rzeczpospolita (newspaper), Rzeczpospolita'' newspaper survey, engineers govern Polish companies. Warsaw Tech alums make up the highest percentage of Polish managers and executives. Every ninth president among the top 500 corporations in Poland is a graduate of the Warsaw University of Technology. Professor Kurnik, the rector, explained that the school provides a solid basis for the performance of managers by equipping its student ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metallic Glasses
An amorphous metal (also known as metallic glass, glassy metal, or shiny metal) is a solid metallic material, usually an alloy, with disordered atomic-scale structure. Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms. Amorphous metals are non-crystalline, and have a structure of liquids and glasses, glass-like structure. But unlike common glasses, such as window glass, which are typically electrical insulator (electricity), insulators, amorphous metals have good electrical conductivity and can show metallic luster. Amorphous metals can be produced in several ways, including extremely rapid cooling, physical vapor deposition, solid-state reaction, ion irradiation, and mechanical alloying. Small batches of amorphous metals have been produced through a variety of quick-cooling methods, such as amorphous metal ribbons produced by sputtering molten metal onto a spinning metal disk (melt spinning). The rapid cooling (million ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Powder Bed Fusion
Selective laser melting (SLM) is one of many proprietary names for a metal additive manufacturing (AM) technology that uses a bed of powder with a source of heat to create metal parts. Also known as direct metal laser sintering (DMLS), the ASTM standard term is powder bed fusion (PBF). PBF is a rapid prototyping, 3D printing, or additive manufacturing technique designed to use a high power-density laser to melt and fuse metallic powders together. History Selective laser melting is one of many proprietary powder bed fusion technologies, started in 1995 at the Fraunhofer Institute ILT in Aachen, Germany. A research project run by Wilhelm Meiners, Konrad Wissenbach, and Andres Gasser resulted in the so-called basic ILT SLM patent. The ASTM International F42 standards committee has grouped selective laser melting into the category of "laser sintering", although this is an acknowledged misnomer because the process fully melts the metal into a solid homogeneous fully dense mass, unli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
