Transparency of aluminum. Transparent aluminum will replace bulletproof glass

Aluminum oxynitride (or AlON) is a ceramic composed of aluminum, oxygen and nitrogen. The material is optically transparent (> 80%) in the ultraviolet, visible and half-wave ranges of the electromagnetic spectrum. Manufactured abroad by Surmet Corporation under the ALON brand. Recently, Russian scientists have developed a technology for producing transparent aluminum, somewhat different from imported analogues.

Description

The development of a unique alloy has opened up new prospects in the defense industry, science and construction. According to official data, ALON:

• 4 times stronger than hardened;
• 85% harder than sapphire;
• almost 15% more reliable than spinel made from magnesium aluminate.

By the way, the mineral spinel is a direct competitor to transparent aluminum and is inferior to oxynitride in a number of parameters.

ALON is the hardest commercially available polycrystalline transparent ceramic. Combination of optical and mechanical properties makes this material a leading candidate for lightweight, high-performance armored products such as bulletproof and explosion-proof glass and elements for infrared optical systems. Transparent impact-resistant windows, portholes, slabs, domes, rods, tubes and other products are also produced from aluminum oxynitride using traditional ceramic powder processing technologies.

Mechanical properties

Aluminum oxynitride has outstanding characteristics:

• 334 GPa.
• Shear modulus: 135 GPa.
• Poisson's ratio: 0.24.
• Hardness according to the Knoop method: 1800 kg/mm ​​2 with a load of 0.2 kg.
• Fracture resistance: 2 MPa m 1/2.
• Flexural strength: 0.38-0.7 GPa.
• Compressive strength: 2.68 GPa.

Optical and thermal properties

When testing transparent aluminum, the following indicators were obtained:

• Heat capacity: 0.781 J/K.
• Thermal conductivity: 12.3 W/(m K).
• Thermal expansion coefficient: 4.7×10 -6 /°C.
• Transparency range: 200-5000 nm.

ALON is also resistant to radiation and damage from various acids, alkalis and water.

Receipt

Transparent aluminum oxynitride is made using a powder sintering process similar to others. While the US Navy is busy developing a new bulletproof material called artificial spinel, Surmet Corporation is already producing its own version of “armored glass” called ALON.

A special powder developed in Raytheon laboratories is placed in molds and kept at very high temperatures. The composition of the mixture may vary slightly: the aluminum content is approximately 30% to 36%, which does not significantly affect the characteristics (the difference is only 1-2%).

The heating process causes the powder to rapidly liquefy and cool, leaving the molecules loosely arranged as if they were still in liquid form. It is this crystalline structure that gives transparent aluminum a level of strength and scratch resistance comparable to sapphire.

Manufactured products are subjected to heat treatment (compaction) at elevated temperatures, followed by grinding and polishing until transparency is achieved. The material can withstand temperatures up to 2100 °C in inert gases. Grinding and polishing significantly improve impact resistance and other mechanical properties.

Domestic analogue

Russian scientists created transparent aluminum in 2017. According to specialists from the National Research Nuclear University "MEPhI", the production technology has been significantly improved. In the manufacture of compacts, the spark plasma sintering technique is used.

Unlike foreign colleagues, domestic developers do not pass the electric discharge through an external heating element, but directly through the mold. Scientists say that domestic transparent armor is comparable in strength characteristics to cubic zirconia, but at the same time has high impact strength.

Comparison of aluminum armor with bulletproof glass

Traditional bulletproof glass consists of multiple layers of polycarbonate sandwiched between two layers of glass. Similarly, transparent aluminum armor consists of three layers:

• outer layer - aluminum oxynitride;
• middle layer - glass;
• the back layer is a polymer substrate.

However, the similarities end there. Aluminum armor can stop the same small-caliber gun bullets as traditional bulletproof glass, but it will still be transparent even after being fired without the telltale cracks. In addition, ALON's strength is much higher.

Aluminum oxynitride armor can be made into almost any shape. She is not afraid of sand, gravel, or dust. Resistance to very high. Despite excellent properties transparent aluminum, this material is not widely used. The biggest limiting factor is cost (3-5 times more expensive than traditional bulletproof glass). ALON is currently used primarily for observation instrument lenses and missile sensors.

The developed method (spark plasma sintering) is a new modification of the already known hot pressing method. The principle of the procedure is as follows: it is passed through the prepared mold electrical impulse, the action of which leads to rapid heating.

The difference from existing technology is that the electric current does not pass through an external heating element, but directly through the pressed workpiece. This significantly reduces cycle times. As a result of the heating process, the powder liquefies and cools almost instantly, while the molecules remain arranged in a free order, as if they were still in liquid form. Thanks to this crystalline structure, transparent aluminum acquires a high degree of strength and resistance to damage. The resulting material is 85% stronger than sapphire and 15% more reliable than spinel made from magnesium aluminate.

Specialist Nikita Rubinkovsky, who deals with this issue, explained:

“Among the currently available medium-density ceramics, aluminum oxynitride has a fairly high strength, comparable to YAG (yttrium aluminum garnet) and cubic zirconia (stabilized zirconium dioxide). And in terms of the most important characteristic for armor protection, impact strength ALON (aluminum oxynitride, which is practically transparent) surpasses all transparent materials, including quartz glass, fused quartz, spinel and leucosapphire.”

Currently, these materials are already quite common in the production of military equipment and equipment. For example, aluminum oxynitride ALON is popular, the stability and strength of which is several times higher than aluminosilicate glass. This material has high heat resistance and does not deform under the influence of temperatures up to two thousand degrees Celsius.

Recently, with the development of new technologies, the problem of increasing the penetrating power of artillery shells and firearms has arisen. Therefore, scientists and experts in the field are trying to develop new and improved armor materials and structures that would provide reliable protection.

The closest properties are observed in transparent polycrystalline ceramics, which is a ceramic based on aluminum oxynitride. With its help, you can produce materials of various shapes, using long-tested traditional ways sintering and molding of ceramics.

According to many experts, ALON can be used for a variety of commercial and military purposes. This material is currently the hardest among all transparent polycrystalline ceramics. The effective combination of mechanical and optical characteristics makes ALON a leader in the production of armored clothing and equipment. By using new technology can be produced:

• explosion-proof glass;
• bulletproof and impact-resistant windows;
• details of infrared optical systems;
• portholes;
• windows and domes for space devices;
• plates, rods, tubes and other parts.

ALON material is also not affected by ionizing radiation (radiation), and is not damaged or deformed under the influence of acidic chemical compounds, alkaline substances and water.

Traditional bulletproof glass has multiple layers of polycarbonate sandwiched between two layers of glass. In turn, the new transparent aluminum consists of three layers:

• outer layer – transparent polycrystalline ceramics;
• middle layer – glass;
• the inner layer is a polymer lining.

Also, unlike traditional bulletproof glass, aluminum armor, after being hit by a bullet from a small-caliber weapon, will remain as transparent as it was. Moreover, there will not even be characteristic scratches left on it.

Currently, clear aluminum is not yet widely used commercially. One of the main reasons is the rather high cost. The production costs of the new material are several times higher than the cost of traditional bulletproof glass. ALON material is mainly used today in the production of lenses for observation devices and missile sensors.

If you have any questions, leave them in the comments below the article. We or our visitors will be happy to answer them

The news that scientists have invented Transparent Aluminum Armor is not new. However, it is too early to say that many people know about this news, so today read about this interesting discovery that has received significant practical application.

The discovery is called AION, or aluminum oxynitride, and is a compound of aluminum, oxygen and nitrogen, creating a transparent ceramic solid that is four times stronger than tempered glass. Currently produced under the ALON brand.

Interestingly, quartz-aluminum oxynitride is intended to replace the rather familiar bulletproof glass. However, its functions do not end there. By polishing ALON, it can be used to make glass for a porthole; moreover, it cannot be scratched using conventional methods, and also has excellent impact resistance. With all these indicators, ALON is twice lighter and thinner than conventional bulletproof glass. Thus, ALON has literally burst into several niches at once and is improving its position every year.

It is also important that the ALON production process is not technologically sophisticated, which makes the task easier for manufacturers. However, you won’t be able to create it at home, however, so that you understand how the whole process of creating aluminum oxynitride occurs, we’ll tell you about it.

1. A method for producing cast aluminum oxynitride in combustion mode, including preparing a reaction mixture of starting components containing chromium VI oxide, aluminum oxide, aluminum and aluminum nitride, placing the reaction mixture in a SHS reactor in a form of refractory material made of quartz, graphite or stainless steel, ignition of the mixture followed by the reaction of its components in combustion mode in a gas atmosphere of nitrogen, or a mixture of nitrogen with air, or a mixture of nitrogen with argon under a pressure of 0.1-10 MPa, after completion of the synthesis, the target product in the form of an ingot of aluminum oxynitride is separated from the ingot of aluminide chromium, while the reaction mixture is prepared at the following ratio of components, wt.%

• Chromium oxide VI 37.3-41.0
• Aluminum 31.0-34.0
• Aluminum oxide 22.7-25.0
• Aluminum nitride up to 9.0

2. The method according to claim 1, characterized in that a functional layer of aluminum oxynitride powder is placed between the reaction mixture of components and the wall of the mold.

At the moment, ALON has begun to be used in a more multifaceted way; for example, Microsoft companies, when developing “smart watches,” use aluminum oxynitride in the body of their development. So, who knows, maybe even the production of aluminum structures using ALON is just around the corner, but one can only dream of something like this if the cost of the material decreases.

Engineers at the U.S. Navy Research Laboratory have developed a process for making a durable, low-cost glass replacement. The transparent material is made using low-temperature sintering from artificially obtained spinel crystals.

Spinel is a mixed oxide of magnesium and aluminum, a mineral found in nature. In its natural form it comes in different colors. For example, red spinel is indistinguishable to the eye from ruby, so previously these two minerals were confused with each other. One of the famous British Crown Jewels, the Black Prince's Ruby, is actually a spinel.

This material is very hard and can resist impact and abrasion when exposed to rain, salt water or sand. In addition, it transmits infrared radiation, so it can be useful in the manufacture of various devices. Unlike glass, the material does not crack across the entire surface - instead, when impacted, a small piece simply breaks off from it. The final product can be polished and sanded.

Hot press

Previously, engineers tried to obtain this material using high temperatures (2000 degrees or more). But this process was both expensive due to energy consumption and ineffective - the need to separate the finished material from the surface of the crucible led to the appearance of defects. Sintering uses a hot press, which turns a powder blank into a final polycrystalline product.

Attempts to produce large spinel panels by sintering have been made before. However, the material turned out cloudy, with small islands of transparency. Engineers managed to improve the quality of the product by adding about 1% lithium fluoride to the raw material, which, when melted, acts as a lubricant and allows the spinel crystals to line up correctly relative to each other.

Raw materials for production are available in abundance, which makes the cost of products minimal. Due to the simplicity of the technology, products of any shape can be made from the material. The possibilities for use are vast: curved windows (e.g. airplane windows), instrument lenses, watch glasses, smartphone screens (stronger than gorilla glass), lenses for cameras and binoculars. The military is interested in using this material as transparent armor - compared to modern bulletproof glass, the weight of the finished product will be at least 2 times less.

sources

http://geektimes.ru/post/249766/

http://www.sciencedebate2008.com/unusual-aluminum/

http://www.findpatent.ru/patent/211/2117631.html

Some more interesting and unusual technologies: for example, Asphalt without puddles. Are there any prospects? , and here’s how railroad rails are welded. Let me remind you how a computer can work in an aquarium and whether we will have plastic roads. The original article is on the website

The news that scientists have invented Transparent Aluminum Armor is not new. However, it is too early to say that many people know about this news, so today read about this interesting discovery that has received significant practical application.

The discovery is called AION, or aluminum oxynitride, and is a compound of aluminum, oxygen and nitrogen, creating a transparent ceramic solid that is four times stronger than tempered glass. Currently produced under the ALON brand.

Interestingly, quartz-aluminum oxynitride is intended to replace the rather familiar bulletproof glass. However, its functions do not end there. By polishing ALON, it can be used to make glass for a porthole; moreover, it cannot be scratched using conventional methods, and also has excellent impact resistance. With all these indicators, ALON is twice lighter and thinner than conventional bulletproof glass. Thus, ALON has literally burst into several niches at once and is improving its position every year.

It is also important that the ALON production process is not technologically sophisticated, which makes the task easier for manufacturers. However, you won’t be able to create it at home, however, so that you understand how the whole process of creating aluminum oxynitride occurs, we’ll tell you about it.

1. A method for producing cast aluminum oxynitride in combustion mode, including preparing a reaction mixture of starting components containing chromium VI oxide, aluminum oxide, aluminum and aluminum nitride, placing the reaction mixture in a SHS reactor in a form of refractory material made of quartz, graphite or stainless steel steel, ignition of the mixture followed by reaction of its components in combustion mode in a gaseous environment of nitrogen, or a mixture of nitrogen with air, or a mixture of nitrogen with argon under a pressure of 0.1-10 MPa, after completion of the synthesis the target product in the form of an ingot of aluminum oxynitride is separated from the ingot chromium aluminide, wherein the reaction mixture is prepared at the following ratio of components, wt.%

• Chromium oxide VI 37.3-41.0


• Aluminum 31.0-34.0


• Aluminum oxide 22.7-25.0


• Aluminum nitride up to 9.0

2. The method according to claim 1, characterized in that a functional layer of aluminum oxynitride powder is placed between the reaction mixture of components and the wall of the mold.

At the moment, ALON has begun to be used in a more multifaceted way; for example, Microsoft companies, when developing “smart watches,” use aluminum oxynitride in the body of their development. So, who knows, maybe even the production of aluminum structures using ALON is just around the corner, but one can only dream of something like this if the cost of the material decreases.

Engineers at the U.S. Navy Research Laboratory have developed a process for making a durable, low-cost glass replacement. The transparent material is made using low-temperature sintering from artificially obtained spinel crystals.

Some more interesting and unusual technologies: for example, Asphalt without puddles. Are there any prospects? , and here’s how railroad rails are welded. Let me remind you how a computer can work in an aquarium and whether we will have plastic roads.

Science. Transparent aluminum

Scientists at Oxford University have created a transparent form of aluminum by bombarding the metal with the world's most powerful X-ray laser. Until now, transparent aluminum has only been described in science fiction.

In reality, the exotic form of the material will be of help both for nuclear energy and for understanding what exactly happens in the cores of huge planets.

The authors of the experiment took a piece of thin aluminum foil and directed a laser at it, the main energy of which was generated in the X-ray range of electromagnetic radiation. The impact was approximately 10 million GW of energy per square centimeter and led to a phenomenal result.

At normal temperatures and pressures, aluminum is a lattice of atoms with a huge number of free electrons. The brief pulse of the laser knocked an electron out of each aluminum atom, allowing photons to pass directly through the material and making the aluminum virtually invisible to ultraviolet light. Although the metal was heated to extremely high temperatures, it retained its rigidity: a phenomenon, scientists believe, similar to what happens in the cores of giant planets like Jupiter.

“What we have created is absolutely new form a substance that no one has ever seen,” one of its authors, physics professor Justin Wark, comments on the result of the experiment. - Transparent aluminum is just the beginning. Physical properties the material we have created are similar to the conditions inside large planets. We hope that by studying it we can better understand what happens during the formation of "miniature stars" created by powerful laser implosions (internal explosions). One day a person will learn to use the energy from such a process here on Earth."

The discovery was made possible by the creation of a new radiation source, ten billion times brighter than any synchrotron in the world (for example, such as the British “Diamond Light Source”, generating light beams in the range from infrared to x-rays). This powerful laser machine, called the FLASH laser, is located in Hamburg, Germany, and produces extremely brief bursts of soft x-rays, each more powerful than a power plant that powers an entire city. With the support of colleagues from other countries, scientists from Oxford concentrated all this energy into a spot whose diameter is thinner than 1/20 the width of a human hair. It was at such a high intensity of laser radiation that aluminum became transparent.

So far, the invisibility effect has only lasted for an extremely short period of about 40 femtoseconds, but it demonstrates that such an exotic state of matter can in principle be created in practice.

“What’s especially remarkable about our experiment is that we turned ordinary aluminum into this exotic new material in one stage, using a very strong laser. For a short period of time, the sample looks and behaves like a completely different material, as if we had transformed every aluminum atom into silicon. For us, this is almost the same as if we managed to obtain pure gold using light,” adds Professor Wark.

The researchers believe that the approach they used is ideal for creating and studying exotic states of matter. Its significance is multifaceted and very important for planetary science, astrophysics and nuclear energy.

The team hopes to continue studying the properties of hot dense matter, planning to use new, even stronger X-ray lasers for this purpose in the future.

The joint efforts of specialists from several universities made it possible to develop a new scheme for processing aluminum oxynitride. To produce the transparent material, the researchers used spark plasma sintering technology.

This technique is an improved and somewhat modified hot pressing method. It implies the use electric current, which is passed through the mold and the raw materials used. In this case, an external heater is not used. Thanks to the pulsed current, the material is quickly heated with a minimum operating cycle.

One of the creators of transparent aluminum, graduate student of the Institute of Nuclear Physics and Technology N. Rubinkovsky, points out that the resulting ALON has high strength characteristics relative to modern ceramics. It can be compared to yttrium aluminum garnet or cubic zirconia. In terms of impact strength, it is superior to quartz iron, spinel and other materials with transparent qualities.

Anyone who watched the legendary “Star Track” remembers that a substance with similar properties was present in part 4 of the film. The window openings of the spacecraft were filled with transparent aluminum. Materials with such qualities have been used in technology for a long time. Aluminum oxynitride is approximately 4 times more scratch resistant than regular aluminosilicate glass. It is able to withstand high temperatures reaching 2100°C.

Modern small arms and small-caliber artillery are being improved every day, which raises the question of developing new means of defense. This problem is especially acute for armor materials with transparent properties. In this case, polycrystalline ceramics or those made from aluminum oxynitride are relevant. From the presented materials you can obtain products of almost any shape using traditional technology forming and sintering.

ALON can be used to meet both military and industrial needs. For example, it is used to make transparent armor and windows for rockets sent into space.

More details at:

Internet - association of enterprises of Russian industry:

https://www.rosprom.org/news/metallurgy/rossiyskie_uchenye_razrabotali_tekhnologiyu_polucheniya_prozrachnogo_alyuminiya/

Video: Aluminum