Graphene material allows the phone to charge for 2 seconds in a car
Not long ago, Tsinghua University's research team released an invention of "smart graphene artificial throat", which uses the advantages of porous graphene materials to create an integrated acoustic device that is suitable for wear and tear, and is expected to solve hoarseness in the future. The "talking" problem of people.
Internationally, researchers at institutions such as the University of Cambridge in the UK reported that they have found a new way to “wake up†the superconductivity of graphene, which can be used to make supercomputers.
Graphene is the hottest new material. In the field of aviation, people use "a rare element" to describe a material that is as light as air and hard as steel. Previously, titanium alloys were the ideal choice for this quality, and the “up-and-coming†graphene was considered to be a step closer to the “favous elements†of human dreams.
What is graphene?
At present, the world's thinnest, lightest and strongest material is 100 times stronger than the strongest steel.
Like diamond, graphite is a form of carbon. The difference is that diamond is the hardest thing on earth due to its different atomic structure. Graphite is one of the softest minerals, often made of graphite rods and pencil lead. Graphene is stripped from the graphite material and consists of only one layer of carbon atoms on a flat surface.
It can be said that one of the characteristics of graphene is thin, which is the thinnest material in the world. It is only one atom thick, about 0.3 nanometer. It is one hundred thousandth of the thickness of A4 paper, and fifty of the hair. One in ten thousand. At the same time, it can conduct electricity. The movement speed of electrons in graphene reaches 1000 km/s, which is 1/300 of the speed of light. Lightweight, tough, conductive, and thermally conductive... Graphene has many imaginative spaces.
Dr. Kong Yuexi, deputy director of 55 microwave millimeter wave monolithic integration and module circuit research institutes of China Electric Power Co., Ltd., said that the hardness of graphene is very strong, 100 times stronger than the strongest steel nowadays; the electronic speed of graphene is also very high. It is 10 times higher than silicon and is very suitable for the development of next-generation UHF electronic devices. In addition, graphene is also a master of heat conduction, 10 times stronger than the most conductive metal silver.
The properties of graphene are also very "fun". For example, when a drop of water rolls on the surface of graphene, graphene is keenly "perceived" to subtle motion and produces a continuous current. This feature gives scientists a new way to get electricity from the flow of water.
"Graphite can induce single electrons. The movement of charged particles on the surface of graphene can cause rapid movement of electrons in graphene to realize sensing and power generation process." Lin Shisheng, an associate professor at the School of Information and Electronic Engineering of Zhejiang University, said that graphite This property of olefins can be used in a variety of applications in energy and electronic sensing, such as the use of graphene-coated umbrellas for power generation in rainy days, or sensitive sensor components.
It is these comprehensive properties that have made graphene unprecedented. Some people even began to predict that the emergence of graphene will lead to an industrial revolution caused by material advancement.
How to get graphene
The first time in the world to get a single layer of graphene, it is "sticky" by transparent glue.
For the first time, people obtained graphene, using a "simple and rude" approach.
Graphene itself exists in nature. Graphene is a thin layer of carbon atoms, and a hexagonal ring is formed between the atoms, and the rings are connected to form a honeycomb plane. It is layered on top of graphite, and 1 mm thick graphite contains about 3 million layers of graphene. The pencil is gently slid across the paper, leaving traces of several to dozens of layers of graphene. Previously, this two-dimensional structure of carbon has always existed in people's conjectures, but it is difficult to peel off a single-layer structure. The key challenge is how to layer graphite into extremely thin sheets.
Many people have this experience in the student era. When writing typo on paper, they use scotch tape to glue the typo. But no one thought that it was such a simple way to let people discover the mysterious graphene.
The manufacture of graphene is simply to make the graphite thinner, not to cut, not to grind, but to stick. In 2004, Heim and Novoselov of the University of Manchester in the United Kingdom used a transparent adhesive to repeatedly affix and tear a piece of graphite. The thickness of the graphite sheet gradually decreased, eventually forming a graphene with a thickness of only 0.335 nm. There is only one atomic thickness of graphene. This is the first time in the world to get a single layer of graphene, and the two scientists won the 2010 Nobel Prize in Physics.
Dr. Wu Yun, a senior engineer of 55 microwave millimeter-wave single-chip integration and module circuits in China Electric Power, gave a demonstration to the reporter. He glued a small piece of graphite on the tape and then pulled it over. After sticking for half an hour, the tape was covered with gray graphite and then transferred to a clean piece of silicon with tape.
Wu Yun said that at this time, not all graphene was seen, because graphene is not only very thin, but also has a transmittance of more than 97%. It is almost completely transparent, and the human eye cannot see it at all. To find it, it has to be found. Through special technical means. However, this is already a multi-layered graphite sheet, and then the technical means are used to locate and determine the number of layers, and finally the single-layer graphene produced can be found.
Experts say this is just the first method of producing graphene. The mechanical peeling method evolved from the tape paper sticking method is only one method for preparing graphene in the laboratory. At present, with the advancement of technology, high quality graphene can be produced more.
What will graphene bring?
With graphene materials, the phone screen can be easily bent or even folded
The appearance of graphene is expected to bring surprises to our lives. The charging of the mobile phone can be “second chargeâ€, the screen of the mobile phone can be easily bent or even folded, and the car can use the graphene conductive static tire to avoid the deflagration of the frictional electricity... From aerospace and electronic information to energy saving and environmental protection, the characteristics of graphene are utilized. The field is likely to change dramatically.
The use of graphene instead of silicon can improve the performance of electronic chips. Researchers are currently introducing the production and application of graphene into the semiconductor industry, and the technological revolution triggered by graphene is likely to start with our common small chips.
The basic material of the electronic chip is silicon. However, as the components on the chip become denser, the distance between the two components on the highest-end chip is less than 10 nanometers, reaching the limit of silicon material. What should I do if I want to continue to improve performance? Researchers are beginning to try to replace the role of silicon with graphene.
"The device made of graphene can theoretically reach ten times or even hundreds of times the frequency of silicon, and can be applied on the radar to greatly improve the resolution of the radar. Moreover, it has a wide range of applications in communication and imaging." Moreover, the current development and production equipment of graphene is the same as the production equipment of ordinary semiconductor equipment. The existing technology development can be based on mature equipment and technology, which lays a foundation for the subsequent engineering development.
Researchers are still doing another big thing. They allowed graphene to adhere to gold foil with a thickness of only 50 nanometers, and then transferred the graphene completely to a soft plastic sheet in a new way.
Kong Yuexi said that graphene can be transferred to any substrate desired by any scientific researcher, such as a plastic substrate dedicated to electronic devices. It is flexible and suitable for transistor fabrication. A special graphene transfer technique is used to attach a gold foil with graphene to a plastic sheet, and based on this, a functional electronic device is prepared on the plastic sheet. Most critically, such electronic devices can be easily bent. In the future, whether it is a foldable display screen or a wearable device that can be implanted into the human body, it is possible to implement such a graphene device.
Another area of ​​application in which graphene is expected is the storage of electrical energy. At the Tianjin Power Research Institute, researchers here are conducting research on the most advanced capacitors . Capacitors, like batteries, can be used to store electrical energy. Its advantage is that it charges quickly, can be filled in a few minutes, and can be reused tens of thousands of times. But it doesn't store as much power as a battery, and it can't be used in life by storing enough power.
“This is the slurry of modified graphene that we have already done. Next we will apply these pastes to the aluminum foil through the coater and become the positive electrode used in our graphene capacitors.†18 Dr. Ding Fei, executive deputy director of the National Defense Science and Technology Key Laboratory of Chemical and Physical Power Technology, said that capacitive materials have a crucial impact on the performance of capacitors. Through further research on graphene materials, researchers are making the storage capacity of capacitors closer to the battery step by step, while at the same time it has ultra-fast charging speed, which can bring more convenience to people's lives. “The modified graphene capacitors we are doing can be filled for a few minutes, and their energy density is expected to be close to the energy density of existing lithium batteries after a while.â€
Energy density refers to the amount of energy stored in a certain space or mass of matter. The higher the energy density, the stronger the storage capacity of the substance. According to Ding Fei, the sample of modified graphene capacitors they have developed has an energy density that is more than three times that of conventional capacitors. Although still in the laboratory research stage, the powerful capabilities of graphene materials allow the R&D team to see the broad prospects for the application of modified graphene capacitors.
In the future, when charging facilities are getting better and better, electric vehicles use graphene batteries, which may take two or three minutes to fill the electricity.
Gao Tao, director of the 55-year-old director of the China Electronics Division and director of the microwave and millimeter wave monolithic integration and module circuit, believes that even under laboratory conditions, the magical properties of graphene are still not completely released. At the same time, there are still many challenges at the technical level, and there is still a long way to go in real large-area applications. However, by strengthening the combination of demand and research, we have made important breakthroughs in the preparation of graphene materials and device development. Graphene, a new generation of strategic emerging materials, will greatly change people's lives.
The die casting process involves the use of a furnace, metal, die casting machine, and die.
The metal, typically a non-ferrous alloy such as aluminium or zinc, is melted in the furnace and then injected into the dies in the die casting machine. After the molten metal is injected into the dies, it rapidly cools and solidifies into the final part, called the casting parts.
The castings that are created in this process can vary greatly in size and weight, ranging from a couple of ounces to 100 pounds. One common application of die-cast parts are housings - thin-walled enclosures, often requiring many ribs and bosses on the interior.
Metal housings for a variety of appliances and equipment are often die cast.
Several automobile components are also manufactured using die casting, including pistons, cylinder heads, and engine blocks. Most home appliances also need lightweight and r aluminum die castingheat dissipation . Other common die cast parts include propellers, gears, bushings, pumps, and valves.
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