| Much Literature covered the studies of desensitization on hexogen(RDX), but the most concerned about desensitization of RDX aimed at composition A and C, while the least about composition B. Velicky thought it was not suitable that desensitizers such as wax ect was added directly in the process of manufacture of composition B and suspected the usage of wax in the researches of modifications on composition B. However, his suggestions about pressure casting and coating RDX with additives beforehand were effective methods, no matter his suspects were correct or not.Composition B exists many disadvantages, and many investigations about it that related to performances, usage and storage of composition B were carried on extensively at home and abroad. The researches of modification on composition B made a great progress, but it was not completely as they wished. Some researches solved a few disadvantages of composition B, but brought another problems. Therefore, the research of modification on composition B is still the stress and difficulty nowadays. Our program tried to find right additives to desensitize composition B, solve the problems of exudation and fracture, and obtain composition B with good performances.The desensitizing technique for RDX was investigated. Stearic acid, polyethene and wax have good effects of desensitization on RDX, and the best desensitizers are wax kind of additives. The desensitizing effects of the four kinds of wax varied, and the best is no. 58 wax. The method of deep desensitization coating, which firstly coats RDX with wax then with polymer again, is able to decrease impact sensitivity to 0-12%. The deeply coated RDX is suitable for manufacture of composition B.The interface action between RDX and desensitizers and its effects on impact sensitivity were investigated. The linear relationships and empirical equations for HSO ,the drop hammer height in centimeters with 50% probability of explosion, versus adhesive work and spreading coefficient were found respectively. Selection of desensitizers for explosives beginning with interface studies, which provided a certaintheoretic reference for selection of desensitizers in formulation design, is an effective method.Influences of melt latent and hardness of additives as well as friction coefficient between additives and RDX, spreading coefficient for additives against RDX on impact sensitivity were investigated. Empirical formula for H50 versus these factors was obtained.Mechanisms for desensitization of explosives with desensitizers were discussed . Desensitizers mainly through such actions as filling some of micro voids in the porous explosive, coating the individual crystals of explosive or physically separating hotspots, absorbing heat energy generated by initial stimulating energy, alternating mechanical properties of the explosive and lubricating the explosive and so on, thus reduce the probability of generation and propagation of hotspots and desensitize the explosive.We initiated an experimental method for selection of additives for prevention of exudation, which based the gel experiments of the reciprocity of additives with exudates. The method, which selects additives according to the form of gel system and the quality of such system and beginning with investigations of the reciprocity of additives with ortho nitrotoluene (o-MNT), looks effective. According to these experiments, PS, AS, and ABS were able to prevent exudation effectively with increasing efficiency. The exudation of composition B modified with PS and AS respectively and casted at normal pressure was considerably decreased, which coincided with the gel experiments.The modified composition B casted with RDX coated with PS and AS with deep desensitization coating method respectively at normal pressure was improved over all. For example, it was not only the mechanical performance improved considerably, but also the axial direction expend percentages of composition B modified with PS and AS respectively and casted at normal pressure, whose maximum te... |
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