دانلود کتاب Peter. Erosion in 81-mm mortar tubes

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(Греко В. Питер. Эрозия в 81-мм минометных труб).Report. Watervliet, N.Y.: Large Caliber Weapon System Laboratory. 1977. – 40 p.A laboratory erosion tester has been designed and developed for predicting the service performance of protective coating materials in the bores of mortar systems using rounds with tail fins. Due to the use of newly designed ammunition, the service life of 81-mm mortar tubes has been reduced to approximately one third of its original life as the result of the formation of three rings on annular groove erosion formed in the bore. Preliminary efforts to apply wear resistant bore coatings and test fire them in the field have been extremely costly and time consuming because of the large number of rounds required (approximately 7500).
The laboratory erosion tester has been designed to ignite the actual tail fin assembly (which causes the erosion) in a chamber which holds eight test specimens to be evaluated, at the same time. The erosion rate of the test, material can be increased so that less rounds are required, by merely reducing the distance of the jet stream and moving the specimens closer to the tail fin assembly which upon ignition, radially discharges the mixture of hot gases and associated burning particles, onto the specimen surface.
This progress report presents the erosive behavior of eight candidate coatings which have been tested in the laboratory erosion tester. Laboratory results have shown that a five mil thick cobalt or cobalt alloy deposit should be suitable to resist erosion and increase the service life of the 81MM mortar system. An overlay of 2/10 of a mil of chromium over cobalt further increases the erosion resistance. Further testing is necessary to specifically determine the best cobalt system and chromium conbination. The next effort would be to field test the coating in the actual mortar system to verify the laboratory results.