Ignition and dust explosion properties of machined chips of various flame retardant magnesium alloys

Abstract

Ignition temperatures and dust explosion properties (minimum explosible concentration and minimum ignition energy) of machined chips of flame retardant magnesium alloys (AZX611 (Mg-6Al-1Zn-1Ca, mass%), AXM4102 (Mg-4Al-1Ca-0.2Mn) and AZX912 (Mg-9Al-1Zn-2Ca)) and aluminum alloy (A6005C (Al-0.6Si-0.6Mg)) were investigated. Ignition temperature of the flame-retardant magnesium alloy chips (＜300 μm) measured by DTA (Differential Thermal Analysis) slightly increased with increasing calcium concentration, regardless of particle size of chips. As a result of the tests of minimum explosible concentration, the flame-retardant magnesium alloys exhibited significantly lower values than A6005C. In particular, AZX912 had lower value than the other magnesium alloys, due to smaller particle size of the AZX912 chips than the other magnesium alloys. The minimum ignition energy of AZX611 and A6005C was also evaluated. As a result, a significantly lower value was observed in AZX611 compared to A6005C. On the other hand, the value of AZX611 was higher than the literature value due to larger particle size. A series of experiments indicated that the dust explosion properties were strongly dependent on particle size rather than alloy composition (calcium concentration).