A Kind of Anodized Aluminium Shock Wave Detectors

For making a layer of insulated film, which are both thin, intact, even, compact, and with a higher electric insulating intensity, on a shaped pure aluminium wire (35 mm in length and 1 mm in diameter), we first measured a polarized curve of one half hemispherical end of the aluminium wire based on the anodization principle, and obtained an important technical condition that the aluminium insulated film can be grown steadily in the region of 3 ~13 V at the environment temperature of 50~60 ℃. And then, we confirmed a series of applied operating steps and relevant technical parameters. Therefore, a good experimental recipe, which can be used to direct mass-producing shockwave velocity detectors with a good performance in coherence and reliability, has been determined naturally. At the same time, the influences of temperature condition in electrolysis system and sealing method with boiling water on the film's physical quality and electric insulating intensity were revealed. With the technique, a Al2O3 film of 4~15 m has been made uniformly, which possesses insulating ability of D.C 250 V for 1 min duration. Furthermore, the physical appearance and electric insulating intensity of these detectors are undistinguishable, relative to the original when put them into the liquefied nitrogen for 4 h. The switched on and off consistencies of these probes are measured to be not over 20 ns tested by an impacter forging hammer of 300 Nm. Actually, the performance will be further improved under a higher shock pressure.