Zirconium/Potassium Perchlorate (ZPP)

Pyrotechnic

The pyrotechnic zirconium/ potassium perchlorate (“ZPP”) is a mixture of fuel (high purity micron range Zr powder) and an oxidizer (milled potassium perchlorate). ZPP has been widely used in electro-explosive devices for many years as a composition that converts the electrical energy applied to a bridgewire into sufficient heat and hot particles to initiate a downstream transfer charge or explosive output. ZPP is used in defense, automotive initiators and in the NASA Standard Initiator where it plays a critical role in initiating various pyrotechnic events in space applications. ZPP has the advantages of affording a rapid pressure rise, generating only minor gas, emitting hot particles, being very thermally stable (>450 °C) and having a long shelf life.

ZPP
Zirconium/Potassium Perchlorate (ZPP)
Key Features Specifications

Key Features

Why We Like It

Due to the demanding nature of applications that utilize ZPP it has been extensively investigated and the chemical, physical and output properties of mixtures with a variety of stoichiometries are well known. Under the right conditions ZPP can meet the 1 amp/ 1 watt/ 5 minute no-fire safety requirement imposed by U.S. military design specifications (e.g., MIL-I-23659). This is partially due to the high thermal conductivity of ZPP mixtures that effectively move heat away from the bridgewire and into the bulk material under no-fire conditions. In addition, ZPP has been demonstrated to function normally at both extremely high and extreme low (cryogenic) temperatures when manufactured and loaded under optimum conditions. In more extreme environments ZPP may be utilized as a bridgewire slurry to insure consistent ignition. ZPP is electrically conductive due to the zirconium content, which renders it particularly vulnerable to electrostatic discharge and which makes it a safety hazard during handling and loading in ordnance items. ZPP is typically produced with ~5% Viton B as a binder and may contain smaller percentages of graphite as well. Viton is incorporated to provide some level of electrostatic sensitivity protection while the purpose of the graphite is to act as a lubricant to increase packing density and as a reaction rate modifier. At Pac Sci EMC, ZPP is typically prepared via a wet process which affords safety benefits over other methods of production while producing a product that is extremely homogeneous and consistent.

Specifications

How You Should Handle It
ZPP is not particularly sensitive to moisture but should be stored in a low humidity environment. Components containing ZPP are typically hermetically sealed and can have a long operational lifetime. The extreme ESD sensitivity of ZPP requires both assembly personnel and hardware used in manufacturing processes to be efficiently grounded and have extensive PPE. Even with
safeguards in place, inadvertent ignition of ZPP mixtures are not uncommon and may produce an audible crack along with an intensely bright flash.
Additional Comments
APD personnel at Pac Sci EMC are currently engaged in development of an ESD safe non-conductive replacement for ZPP called BI-820. If successful, this mixture of organic fuel and
oxidizer, in optimized ratio, may provide an output similar to other pyrotechnic systems, but would have the benefit of being non-conductive both prior to and after ignition as well as being
stable at very high temperatures. Details related to BI-820 may be found in U.S. Patent Application 2020/0223766 A1.