The black box is a device that was designed to aid in the investigation of incidents, especially in aviation. Firstly, understand that black box is just a term, it is not even a box, neither is it even black. It is majorly painted orange and looks more like a cylinder that is mounted on two big pieces of metal. It does not really resemble a tape recorder but resembles an air compressor more.
It comprises two components, which are the flight data recorder (FDR), and the cockpit voice recorder (CVR). The black box is basically made of titanium or stainless steel, which also helps it to survive a plane crash. The black box is designed to be sustained inside a 2000 degree fire burning for an hour.
It can crush with 5000 pounds per square inch of pressure for some minutes to sustain its impact. It was tested to hit at any material at 3400 times the force of gravity, and still maintain its good state. The box can survive a 10ft of a 500lb weight object of any kind, relatively, being dropped on it. With all these, a black box would survive almost every plane crash.