Black box claims to be indestructible, but why don't planes use this material?

Black box is one of the special electronic recording equipment for aircraft, which is called aviation flight recorder. It is equipped with flight data recorder and cabin sound recorder, and all mechanical parts and electronic instruments of the aircraft are equipped with sensors connected with them. It can record the relevant technical parameters and cockpit sound half an hour before the plane stops working or crashes, and release the recorded parameters again when necessary for flight experiments and accident analysis. The black box has strong fire resistance, pressure resistance, shock and vibration resistance, seawater (or kerosene) immersion resistance and magnetic interference resistance. Even if the plane is completely damaged, the data recorded in the black box can be well preserved. All the causes of air crashes in the world are found through black boxes. I am already familiar with it. By the way, this is the black box called the "witness" of the air crash. It can provide evidence for investigators and help them understand the truth of the accident. Aircraft black box [1] In fact, the black box is a recording instrument on the aircraft and a flight data recorder. It can record altitude, speed, heading, climb rate, descent rate, acceleration, fuel consumption, landing gear retraction, Greenwich Mean Time, as well as flight parameters such as aircraft system working conditions and engine working parameters. The other is the cockpit voice recorder. It is actually a radio call recorder, which can record all kinds of calls on the plane. The four audio tracks on this instrument record the dialogue between the pilot and the ground command organization, the dialogue between the pilot and the co-pilot, the speeches of the captain and the stewardess to the passengers, threats, explosions, abnormal engine sounds and various sounds in the cockpit. The black box can provide investigators with the operation of various systems before the plane accident. Because the air crash happened in a short time, sometimes the pilot and all the flight attendants were killed at the same time, it will be very difficult to investigate the cause of the accident, and the flight data recorder can provide people with the flight status of the plane and the working conditions of the equipment on board at the moment of the plane crash and some time before the crash. Cockpit language recorder can help people analyze the cause of the accident according to the conversation of the crew on board, so as to make a correct conclusion about the accident. In order to withstand the violent impact and high temperature flame when the plane crashes, the black box has a thick steel plate and multiple layers of heat insulation and anti-collision materials. Moreover, in order to be as safe as possible, the black box is usually installed in the safest place at the tail of the plane, that is, the part that is least likely to be damaged when it crashes. When the plane crashes, the black box can withstand 30 minutes of barbecue in the flame of 1 100℃, 5 minutes of extrusion by a 2-ton object, and can be soaked in gasoline, engine oil, oil essence, batteries, acid solution and seawater for several months. Even with this protection, the black box is still damaged in some air crashes, so the international aviation agency has formulated stricter standards. The recording medium has been improved from magnetic tape to static storage recorder, which can withstand greater impact, similar to the memory chip in the computer.