The improvement of environmental protection characteristics and the addition of technological content are the constant theme of scientific research of pyrotechnics, so that the types of pyrotechnics are brewing. The pyrotechnics ignited and flew high and exploded, so the effect would be good. Therefore, the firework shells are filled with a lot of gunpowder for launching and blasting. For example, after launching a 20-centimeter-diameter fireworks bullet, it needs to rise to an altitude of about 200 meters before it bursts, allowing us to appreciate the colorful stars. The radius covered by these stars can be about 80 meters.
Don't underestimate the stars, their temperature is not low. When shining, their temperature can exceed 1000 ℃! It is at such a high temperature that various special metal materials filled in the fireworks can absorb the energy of satisfaction and announce the brilliant brilliance. This is the flame reaction often talked about in the middle school. It is precisely because different metal atoms can emit different colors of light at high temperature, we can see the fireworks of different colors.
However, the flame reaction has a very serious flaw, that is, high temperature is generally required. So, we saw a little bit of fireworks in the fireworks show, the temperature is very high. Generally in the process, we use metal combustibles to reach such temperatures, such as aluminum, magnesium, etc. Aluminum burns so much heat that it can melt iron (melting point about 1500°C). Even if the pyrotechnic residue falls to the ground, the internal temperature can reach 300 ℃, it is not just "a little hot". Therefore, it is very important to regulate a safe interval.