Research On Underwater Explosive Welding And Coating Consolidation

Based on theory of explosive processing and underwater shock wave, the paper proposed underwater explosive welding and underwater explosive compaction. For the difference as density, compressibility, and sound velocity between water and air, underwater shock wave shows better property like higher velocity, higher pressure and shorter loading time compared with air shock wave.Using the unique property of underwater shock wave, we welded some functional material with thin thickness and/or high hardness, which are difficult to bond together by traditional explosive welding methods. This paper introduced underwater explosive welding from numerical simulation, parameter setting, welding set-up and laminate characterization. Graded density impactor was prepared by underwater explosive welding, and tested capability of producing quasi-isentropic compression at two-stage light gas gun facility.Also, this paper prepared nano-partical dispersion strengthened coating on pure copper surface using underwater explosive welding. This coating-substrate structure could ensure copper work in high temperature and/or high abrasion area. Numerical simulation, equipment and macro, micro structure characterization was given in this paper, respectively.Main works are as follows:This paper built up an entire theory of underwater explosive welding from numerical simulation, parameter choosing, equipment setting and laminate characterization. Using finite element method, the paper simulated the propagation of the underwater shock wave, deformations of the flyer and the base plate, and the pressure distribution during the welding process. The welding parameters are evaluated by explosive welding window. This paper designed the underwater explosive welding set-up form detonation, explosive, distance and sealing method. Parallel underwater explosive welding are carried out for thin-thickness functional material to research the welding possibility by this technology. Inclined underwater explosive welding experiments on tool steel with copper foil were carried out to investigate effects of initial hardness on interfacial features for identical compositional materials under identical welding conditions. In the research of tool steel welding, phase transition caused by impacting of paltes was firstly advanced.Using underwater explosive welding technology, we fabricated graded density impactor and tested quasi-isentropic compression at two-stage light gas gun facility. Multi layer plates were bonded in a super short duration for the high speed of underwater shock wave, with flat, parallel and high strength interface. By adjusting parameter, we protected the thin-thickness, fragile plate in the multi layer laminate. This paper introduced the different compression results at two-stage light gas gun facility by homogenous and graded density impactor. Doppler system was used to record the velocity profile to evaluate the capability of producing quasi-isentropic compression. Numerical simulation was carried out to prove the experimental result.We developed a process technology, which can fabricate dispersion strengthened coating on substrate. Mechanical alloy, die pressing, pre-co sintering and underwater shock wave compaction were carried out to prepare aluminum dispersion strengthened coating on copper. Dispersion strengthened copper has almost the same electrical and thermal conductivities as pure copper but exhibits excellent strength at elevated temperatures and better creep and arc erosion resistance. Numerical simulation by finite element method gave the deformation of the coating layer, and the pressure distribution during the compressing process.