it has been found that the freeze drying of the resulting water based dcpa slurry constantly produces an extremely dry finely ground dcpa powder which is especially suitable for combination with anhydrously produced ttcp per the process of u s pat nos 5 522 893 5 542 973 and 5 695 729 this combination of ttcp and dcpa was found to be especially stable in accelerated aging and standard aging tests freeze drying of an aqueous slurry of fine particles can produce very dry particles these are especially well suited for long term storage as a powdered mixture with a material such as ttcp which can have its properties degraded when exposed to moisture in the preferred milling operation dcpa powder of 14 15 u03bcm particle size are mixed with deionized water to form thin slurry with a solids concentration of about 33 by weight it is pumped into a 600 ml bead mill with 0 6 to 0 8 mm zirconia balls at a rate of under 16 ml min such a mill may be the dyno mill im model kdl manufactured by wa bachofen ag in switzerland the discs moving the zirconia balls are preferably rotating at about 10 m sec or higher and more preferably at 14 0 m sec or about these are two of the speeds indicated as choices on the dyno mill kdl the slurry which exits the bead mill is a thick paste which indicates the dcpa particles have been made much finer with an increased surface area the resulting particle sizes are.