Desensitizing Hafnium Powders by Nitridation

This Small Business Innovation Research Phase I project will nitride hafnium powder to desensitize its ignition potential in normal handling using a mechanically fluidized, machine already proved feasible to nitride steel, aluminum and titanium powder. The machine's axle- mounted horizontal retort is partially filled with powder. Internal atmosphere is controlled through axle ports while the exterior is heated. Rotation creates fluid-like intermixing And thermal transfer so temperatures are uniform and agglomeration is absent. Samples can be withdrawn without stopping operations. In a preliminary hafnium nitriding trial, 1.55 percent nitrogen was added. Experience indicates less than 0.25 percent may be adequate. In Phase I. the existing machine will nitride six hafnium samples for electrostatic detonation tests. To minimize sample sizes, the hafnium powder will sometimes be mixed with larger ine. powders and screen-separated after treatment. Time, temperature and pressure combinations will be varied to achieve a continuous nitride film with low total nitrogen content. Experience with other powders indicates desensitization may be achieved by converting only a few percent of hafnium to a nitride film. Phase I will prove treatment feasibility. Phase II will optimize production time, temperature and partial pressures, and confirm expected low production costs.