The Research Of Wire Electrical Explosion Spring Method By Continuous Wire Feeder In A Constraining Pipe

The electrical explosion spraying as a means of surface modification is theapplication of the wire explosion phenomenon. The electrical explosion spraying havemany advantages，such as：the spraying process has a small heat affection to thesubstrate，the coating are compact and has high bonding strength with Substrate，thismethod especially suitable for spraying materials of high melting point，etc. But thecurrent methods have two aspects problems：one is the explosion spraying materialsdon’t have enough constraint degree；the other is the spraying materials can not bereplaced automatically，spraying efficiency is low，it is need using artificial method toplace spraying material between the two electrodes before each sprayingIn order to improve materials utilization efficiency and spraying efficiency，thispaper use continuous wire Feeder to transmit wire between two electrodes. Electrodesimport transient electric current to the wire by the way of gaseous discharge，the metalmelt， and explosion. The explosion materials are restraint by high densitypolyethylene pipe，eject from the port side and strike on the substrate surface formingcoating. Initial experiment had proved this method can achieve high density coating，analyzed the change of coating thickness with spraying distance，got the conditions oflarge areas spraying.In order to better understand the characteristics of the coating obtained by theway of electrical explosion in a constraining pipe. The spraying material ismolybdenum，the initial charging voltage is8kv、10kv、12kv respectively，thespraying distance range is0～25mm. The tests of the coating are carried out by themeans of mechanical scraping firstly. The bonding strength are test by Rockwellhardness，using SEM to analysis the coating surface and section.The experimental results show that：when the spraying distance is small，thecoating surface is smooth and has characteristics of liquid metal solidification，incross-section，the coating has a large compact with substrate；When the sprayingdistance is greater，The coating surface not only have characteristics of liquid metalsolidification，but also have spherical particles，the number of particles increases withspraying distance becoming greater，the bonding strength of coating becomes lower；When the spraying distance go beyond a certain value，the coatings are easy to dropout of substrate by the means of mechanical scraping，most of this type of coating areformed by solid particles hitting the substrate surface，the bonding strength are lowand lie in HF-5～HF-6level，it is difficult to observe coating section. The increase ofinitial charging voltage，can decrease the maximum spraying distance of obtaining coating of liquid metal solidification. But there are no exact reasons for thisphenomenon，which need to be further researched.