In what areas are translucent ceramics used?

Light-transmitting ceramics are used in the military industry, mainly in missiles.

Most teenagers, especially male teenagers, like to read books and articles about modern weapons and equipment. Everyone knows that Sidewinder missiles have the ability to track targets!

Indeed, this ability of Sidewinder missiles was learned from Sidewinder. Zoologists tell us: There is a sunken "cheek pit" between the rattlesnake's eyes and nostrils. There is a film in this "cheek pit", and the film is covered with nerve endings and a kind of mitochondrion. This organelle can expand and contract with changes in temperature, and it can sense subtle changes in the surrounding temperature of just one thousandth of a degree. In the dark night, the reason why rattlesnakes can attack unexpectedly and devour voles like lightning relies on this sensitive organelle.

Military scientists were inspired by the predation of rattlesnakes. As long as a sensitive sensor is installed on the head of the missile, it can automatically guide it to the target. Therefore, military scientists designed and developed an infrared sensor for the head of the missile. Detector, the mission of this detector is to detect and capture even the extremely weak infrared rays radiated from the enemy aircraft, not to mention the high-temperature gas ejected from the enemy aircraft's engine. However, in order to withstand the high-speed airflow and erosion of rain and snow during the flight of the missile, a protective cover is required on the detector on the head of the missile. This protective cover must have sufficient strength and hardness. That's because the surface temperature of the head of a missile flying at high speed can exceed several thousand degrees Celsius. This means that one of the requirements for the protective cover material must be able to withstand ultra-high temperatures.

Research and comparison show that non-translucent ceramics are the only ones that can undertake this task. It is the only one that is most suitable for making protective covers for Sidewinder missile head detectors.

In the early 1930s, people had learned that a high-efficiency light source could be obtained by using sodium vapor discharge. However, due to the limitations of various conditions at the time, a novel lamp could not enter the practical stage. This is because sodium vapor discharge will produce high temperatures exceeding 1000°C. In the first chapter of this book, we have talked about that sodium is a very active metal and is highly corrosive, and it is made of glass. The lamps could not pass the high temperature barrier. Because a suitable lamp material that had both the best of both worlds (high temperature resistance and resistance to corrosion) could not be found for the time being, the plan to develop high-pressure sodium lamps had to be shelved.

In 1957, the advent of the world's first light-transmitting (also known as transparent) ceramic enabled the implementation of the plan to develop high-pressure sodium lamps. Studies have shown that the melting point of light-transmitting ceramics is as high as 2050°C, and it is not corroded by sodium vapor in an environment of 1600°C, and it can pass 95% of light. With these conditions in place, it can be said that "everything is ready except for the east wind." After the efforts of relevant scientists, the high-pressure sodium lamp finally came to the ground in 1960. After continuous improvement, it has been put into practical use.

We say that high-pressure sodium lamp is an electric light source with high luminous efficiency. Let us compare it with some other lamps. Tests have shown that the luminous efficiency of ordinary incandescent lamps is only 10 lumens/watt, the luminous efficiency of high-pressure mercury lamps is 50-60 lumens/watt, and the luminous efficiency of high-pressure sodium lamps is as high as 110-120 lumens/watt. This means that with the same power, one high-pressure sodium lamp can be used as much as two high-pressure mercury lamps, and the light color is soft and silvery white. Objects can be seen clearly under high-pressure sodium lamps without dazzling the eyes. For areas crisscrossed by rivers and coastal cities, this novel lamp has special appeal - the light of high-pressure sodium lamps can penetrate dense fog without being scattered, so it is particularly suitable as a car's headlight.

It is also worth mentioning that the average life of high-pressure sodium lamps is as long as 10,000 to 20,000 hours, which is twice as long as the life of high-pressure mercury lamps, more than 10 times longer than ordinary incandescent lamps, and is currently the longest service life. The longest lamp.

In addition to the development of high-pressure sodium lamps, light-transmitting ceramics are also suitable for the development of other novel lamps, such as potassium lamps, rubidium lamps, cesium lamps and metal halide lamps.

In summer, the sun is blazing, and it will be much more comfortable if you wear a pair of sunglasses. Yes, strong sunlight can make you unable to open your eyes. If you happen to pass by a welder who is welding the handrails of a pedestrian bridge that has just been installed, your eyes will be stimulated by the strong light of the arc and you will not be able to see the things around you for a while. If you wear sunglasses, the glare of the arc will not cause any interference to your eyes. Welding workers must wear a mask when operating. The function of this mask is roughly similar to sunglasses. It is now clear that sunglasses have the function of nourishing the eyes and protecting the eyes from the glare of bright light.

Speaking of the irritation of strong light to the eyes, when an atomic bomb explodes, the situation is even more serious - strong light radiation can make people unable to see clearly and even make it difficult to walk. However, nuclear test workers have a heavy responsibility. They must watch the entire process of the atomic bomb explosion. And in the preparation stage for the explosion, they had a lot to do. At that time, it was not possible to operate while wearing sunglasses. The total time from pressing the button - the explosion of the atomic bomb - to the appearance of optical radiation is only 3 seconds. This means that it is obviously too late to wear sunglasses after the atomic bomb is detonated.

In military and national defense, on the industrial front, and in daily life, people urgently need a kind of automatically dimming goggles.

This kind of goggles can automatically and quickly darken when encountering strong light, and can return to its original bright state when the dangerous light disappears. Now, with light-transmitting ceramics, people's dreams can come true: there is a kind of light-transmitting ceramic that can transmit light, resist high temperatures, resist corrosion, and have high strength. To put it more vividly, there is an automatic closing and opening system in the lenses of ceramic goggles. With this novel goggles, welding workers no longer have to hold a mask in one hand and a welding gun in the other when operating - they put on the mask when welding and take off the mask once the welding is finished. With this kind of goggles, nuclear test workers can wear them to carry out various preparations before nuclear explosions.

This new member of the sunglasses family brings good news to people who need to work under bright light.