With the rapid development of modern science and technology, many amorphous materials with novel functions have come out one after another, and have become leaders with a wide range of applications.
<h1>Liquid crystals frequently blossom</h1>
In 1888, when the Austrian botanist Lenitzl was doing experiments, he found that a substance called cholesterol benzoate methyl had two melting points: at 148.5 ° C. This crystal becomes an opaque fluid, and at 178.5 ° C, it becomes a clear liquid. German physicist Raymond used a polarized light microscope to observe a milky white fluid with a temperature between 145.5 and 178.5 ° C, and found that this substance has both the characteristics of a liquid and some electrical and optical properties of the crystal. Raymond therefore concluded that this fluid was another form of matter, and named it "liquid crystal".
After further research by scientists, it was found that liquid crystal material is composed of a variety of rod-like molecules arranged in different arrangements. Different sequences of liquid crystals, each with different fields of application. Some can be used for temperature indication, crack detection, medical diagnosis: some can be used for meteorological chromatography, electronic display, nuclear magnetic resonance and other aspects. Among them, the time display of various electronic watches can be said to be the most prominent use of liquid crystals. Through the change of the range of disturbance in the liquid crystal by the weak electric field, the molecular arrangement is changed according to the "8" shape, so as to achieve the role of displaying time. With the increasing development of television technology, the role of liquid crystals has also entered a newer and broader field. People use liquid crystals to make display panels to replace the display tubes of television sets, so as to make LCD TVs as thin as paper.
In recent years, scientists have found that liquid crystals can be used as special thermochromic materials. Using it to dye cloth, make clothes, people will see the part of the clothes that come into contact with the body, and will change color as the ambient temperature changes. At a temperature of 28 ° C, the clothes are red: at 33 ° C, the clothes are blue-green: while when the temperature is below 28 ° C, the garment appears black. This is very beneficial for people to adapt to different environments. If the adhesive tape is made of liquid crystal thermochromic dye and attached to the skin, it can show the abnormality of the skin temperature. For patients with tumors, because the temperature of the tumor is higher than normal, it can be used to quickly detect the tumor under the skin. Facilitates timely detection and treatment.
<h1>The "supercritical fluid" of gas and water blending</h1>
Supercritical fluids were first discovered by French scientists as early as 1822. At present, many countries in the world are conducting research and development and utilization of "supercritical fluids".
Pressurizing the water in an airtight container will increase the boiling point of the water. When the pressure reaches 220 atmospheres and the temperature reaches 374 ° C, the density of water expanding due to high temperature is exactly the same as that of water vapor compressed due to high pressure. At this time, there is no difference between the liquid and gaseous states of water, and they are completely blended together to become a new gas that presents a high-pressure and high-temperature state. At this time, the water changes from a general state to "supercritical water". The above pressure and temperature that causes water and gas to blend are called "tipping points". Water that exceeds the "critical point" state is supercritical water. In addition to water can become a supercritical state, there are carbon dioxide, methanol and other substances, which can also become supercritical fluids at high temperatures and high pressures. The critical point of supercritical carbon dioxide was measured at 31 °C and 73 atmospheres, while methanol required 239 °C and 79 atmospheres.
Scientists have proven that the properties of supercritical fluids are very strange. It can both diffuse like a gas and penetrate into other objects, and like a liquid, it can dissolve solid substances and extract certain substances from them. At the same time, supercritical fluids also have a strong oxidation capacity, the substances that need to be treated are put into supercritical water, filled with oxygen and hydrogen peroxide, and this substance will be oxidized and hydrolyzed. Some can also spontaneously combust, emitting flames in the water. In addition, supercritical fluids can also be mixed with substances such as oil, with special material binding force.
Scientific research results confirm that supercritical fluids have a wide range of applications. Germany uses supercritical water, oxygen at 500 ° C, and then, the pvc plastic is treated, 99% is decomposed, very little chloride is generated, thus avoiding the past burning plastics to produce toxic chlorides to environmental pollution problems.
Scientists have used supercritical methanol and carbon dioxide to synthesize resins, pharmaceuticals and pesticides, with the same promising results. Methanol and carbon dioxide both act as catalysts and convert themselves into part of a synthetic material. A researcher at the University of Tokyo who uses supercritical fluids to extract raw materials such as oligosaccharides and formic acid and lignin from rice husks, waste paper, sake lees and waste wood, has now been put into practical applications. In high-tech fields such as semiconductor manufacturing, replacing chlorofluorocarbon-containing detergents with supercritical carbon dioxide can play a role in degreasing, separating oils, and removing impurities. The advantage is that it is easy to operate, the effect is good, and it does not pollute the environment.
<h1>The current variant has a promising future</h1>
In 1947, an American named Winslow successfully completed an experiment. He applied an electric field to a suspended solution of plaster, lime, toner, olive oil and water, only to see that the solution quickly became solid. Moreover, the stronger the electric field applied, the stronger the strength of the solid. When the electric field is undone, the solid can quickly become a liquid. Therefore, scientists call this phenomenon "Winslow phenomenon" or "electrothermal phenomenon", and call suspended liquids that can change with the control of electric fields "current variants".
Studies have confirmed that electrostatic suspension liquids are composed of micron-sized particles dispersed in the oil. Due to the difference in the dielectric constants of suspended particles and oil bodies, under the action of the electric field, the particles will produce the phenomenon of separating the positive and negative charges of the particles from the two poles, so that one end is positively charged and the other end is negatively charged. Under the action of electrostatic suction, the positive and negative electrodes are attracted and arranged into a chain structure. The stronger the electric field, the stronger the chain. When the electric field strength increases to a certain value, the attraction between the polarized suspended solid particles exceeds the confrontation of the applied force, so that the fluidity can disappear and become a solid that cannot flow. When the electric field is removed, the polarization phenomenon of suspended particles disappears, and there is no longer static attraction between each other, so the suspended particles return to a state where they can flow.
Current variants are in flux and need to rely on water to function in the middle. Usually, the solution contains 5% to 10% water, and the performance of the current variant can be played normally. Less than or more than this ratio reduces the performance of the current variant. When there is completely no water, the phenomenon of electroregulation will completely disappear. However, water is a substance that evaporates easily, and current variants containing moisture are not ideal in terms of stability, durability, and service life. Therefore, the development and utilization have been greatly restricted, and the progress has not been fast for a long time. In order to make the current variant have a wider range of applications, people continue to develop new anhydrous current variants, laying a foundation for broadening the application field of the current variant.
Current variants now show their skills in the use of automotive clutches and brakes. In the event of an emergency, the driver only needs a few thousandths of a second after pressing the button to achieve the role of shifting gears or braking. American aerospace manufacturing experts have used the capabilities of current variants to produce devices that can automatically reinforce the horizontal wing blades of helicopters. When the blade is suddenly in distress during flight and causes vibration and is about to break, the current variant filled in the blade can become solid, which plays a role in automatic reinforcement.
In recent years, scientists have also used current variants to create new bionic intelligent materials, and have now made breakthroughs in artificial "biological muscles". The process of making the current variant soft and hard through the opening and closing of the electric field is like the tension and relaxation of the muscles, so as to achieve the function of automatic adjustment with the external environmental changes.
<h1>Novel magnetic-liquid material</h1>
Magnetic liquid is an ultra-fine powder of iron, nickel, cobalt and other ferrous substances, uniformly dispersed in water, lubricating oil, silicone oil and fluoroether oil and other carrier liquids, and mixed after grinding. Because the surface of each particle forms a very thin layer of elastic coating, under the action of gravity, strong magnetic field, centrifugal force, etc., particles will not polymerize and precipitate, which has the function of preventing iron particles from sticking to each other.
It has been determined that under the action of the applied magnetic field, its "specific gravity" will change with the change of the strength of the external magnetic field. The magnitude of the change can range from less than 1 gram per cubic centimeter to more than 20 grams. This strange property of the magnetic liquid makes it a new material with great development. As early as 1965, foreign countries used magnetic fluids to solve the sealing problem in aerospace. In recent years, many countries have used this space sealing technology to solve the dripping of steam, water and oil in industrial production. By injecting the magnetic fluid into the gap between the spiral pulp shaft and the shaft seat, it can become a sealing ring between the two, maintaining excellent sealing performance in high-speed operation. In this regard, magnetic fluids can also be used for seals for advanced instruments such as electron microscopes, high-speed centrifuges, rotary cathodes of ray tubes, and vacuum smelting furnaces. Not only can it ensure normal operation in the vacuum state, but also has corrosion resistance and radiation resistance, which can meet the needs of various occasions.
In the production of textile, instrumentation, and electroacoustic equipment, magnetic fluid can also play a role in lubricating heat dissipation. Using the characteristics of the "specific gravity" of the magnetic liquid changing with the change of the magnetic field, it is also possible to sort various non-ferrous metal particles and determine the specific gravity of an unknown metal substance. It is also possible to recover waste oil from ballast water from large tankers and oil diffused to the sea, contributing to the prevention of pollution of the natural environment.