Nano-explosive Bead Milling Binder Coating
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Solution Overview
Problem
Current methods for producing nanocrystalline high explosive (HE) molding powders face challenges in achieving uniform binder coating and preventing crystal ripening, leading to increased sensitivity and suboptimal performance, especially in small critical diameter applications.
Innovation Solution
A method involving bead milling of a mixture of a water-soluble binder and insoluble crystalline HE in a liquid, followed by spray drying to produce nano-sized HE crystals uniformly coated with a binder, with crystal sizes below 1000 nm and compositions ranging from 50 to 99 weight percent HE, effectively reducing sensitivity and improving detonation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If batch slurry coating of crystalline HE with binder is used, then binder coating is achieved, but nanocrystals agglomerate and coating uniformity is poor
Solution Approach 1:
The binder is dissolved in the liquid medium before the nanocrystals are introduced. This preliminary preparation of the binder solution ensures that the coating material is ready and uniformly distributed in the liquid phase before coating occurs, preventing agglomeration and ensuring uniform coverage of the nanocrystal surfaces.
Solution Approach 2:
A liquid medium serves as an intermediary between the binder and nanocrystals. The binder dissolves in this liquid to form a slurry, which then uniformly coats the nanocrystals. This intermediary liquid phase prevents direct contact and agglomeration of nanocrystals while enabling uniform binder distribution.
2Ease of manufacture
If nanocrystals are dispersed in aqueous slurry for coating, then coating process is enabled, but nanocrystals ripen and crystal size increases
Solution Approach 1:
The invention changes the parameters of the dispersion medium by using a non-aqueous liquid or a specifically controlled aqueous slurry with adjusted composition and pH. This parameter modification prevents Ostwald ripening while maintaining the ability to perform the coating process, thereby controlling crystal size throughout manufacturing.
Solution Approach 2:
The liquid medium is specifically selected or modified to have properties that counteract Ostwald ripening before it can occur. By preemptively choosing a medium that suppresses crystal growth and ripening, the invention prevents crystal size increase during the coating process while maintaining manufacturing feasibility.
3Use of energy by moving object
If conventional HE crystal sizes are used, then sufficient energy output is achieved, but sensitivity to shock and impact is high
Solution Approach 1:
The invention changes the critical parameter of crystal size from conventional micrometer scale to nanometer scale (below 1000 nm). This parameter change fundamentally alters the sensitivity characteristics of the explosive while maintaining adequate energy output, as the nanocrystalline structure provides both insensitivity and sufficient detonation performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in HE molding powders with significantly reduced shock and impact sensitivity, improved detonation characteristics, and prevents crystal ripening, enabling safe and economical production suitable for small dimension applications like boosters.
Implementation Method 1
adding a binder soluble in a liquid and a crystalline high explosive material insoluble in such liquid to form a mixture; agitating said mixture such that the water soluble binder generally dissolves
Implementation Method 2
bead milling that mixture to create the desired nano-sized explosive material crystal particles with a mean crystal size below 1000 nm in diameter
Implementation Method 3
The resulting suspension of HE in a solution containing the dissolved binder ingredients is then spray dried to provide the desired HE molding powder granules
Data Source
AI summary
A method for manufacturing nano-sized insensitive high explosive molding powder usable as a booster HE is provided herein. The method preferably involving the steps of dissolving a binder in a liquid and suspending crystalline high explosive to said liquid, grinding that suspension in a bead mill until the crystalline high explosive is nano-sized, and precipitating the binder and crystalline high explosive using a spray dryer to produce granules containing nano-sized crystalline high explosive. The liquid may be water or an organic solvent so long as the binder is highly soluble in the liquid and the crystalline high explosive is generally insoluble in the liquid. A fatty alcohol, water defoaming/dispersant/surfactant agent can be added to the dissolved binder/suspended crystalline high explosive, to aid in the manufacturability.