Study On Electron Beam Ablation Characteristics Of Tungsten Base Alloy

With the development of modern weapons.All sorts of long-distance precision kill weapons emerge in endlessly.The range of traditional artillery and rocket began to emerge insufficient.In order to solve this problems.Using small Ramjet Engine with high performance have became an important means.Small Ramjet Engine needs to produce a great deal of energy in a relatively short time.Which requires the nozzle throat liner has a good reliability.Reference for related research status at home and abroad,this paper use tungsten copper alloy and tungsten nickel iron alloy as imaginary material.Using SOLO type HCPEB bombardments samples to simulate thermal shock phenomenon,Then studying the microstructure morphology,microhardness,XRD phase,properties of the sanples.Purpose is to explore possible high quality tungsten nozzle throat liner material.Using high strength(13KV and 180A)HCPEB respectively 0 times,20 times and40 times,80 times bombardments tungsten copper alloy specimens.Microscopic morphology characteristics shows that with the increase of number of bombardment,greater damage to the specimen surface structure.Embodied in tungsten skeleton grains melting reunion form bulge.The dispersed phase of copper evaporation ablation and under the action of thermal stress stretching apart form pores.The surface microhardness decreased from 206kgf/mm2 to 157kgf/mm2,Shows that thermal shock effect of HCPEB lead to metal sample "soften".Analysis XRD test results,throughing waveform figure knows that the phase structure in the process of bombardment ablation has no obvious changes.,but the content changes.on the one hand,The ablation separation of W and Cu phase leads to the reduce of content.on the other hand,due to the relatively low melting point and boiling point of Cu(1083.4℃,2567℃)leads to it almost depleted.In terms of friction wear,grinding crack width increased from 551μm to 719μm,Shows that the transient temperature thermal shock significantly lowers its wear resistance.Friction coefficient increase first and then decrease but overall promotion.It can be explained by the thermal shock caused the reduce of surface roughness,but also reduces the ability of preventing micro crack.Use HCPEB with the same intensity and frequency,the test results of tungstennickel iron alloy shows the difference before and after 40 times bombardments.Microscopic morphology shows that before 40 times,metal sample destruction of organization structure is mainly from the pores of nickel iron binder phase area tear and tensile.After 40 times,tungsten grains began to melt.The movement of liquid metal broken the boundary and made pores filled,like got a "repaired".The surface microhardness dropped from the original 419kgf/mm2 to 394kgf/mm2 and then398kgf/mm2.IT shows that the "repaired" of organizational structure effectively curb hardness decline further.Analysis XRD test results,waveform figure shows that as the same as tungsten copper alloy.There have no obvious changes at phase structure in the process of bombardment,but detecting the trace of FeNi compounds.Content of each phase reduces because of evaporation and splashing.The difference is that Fe and Ni phase reduces larger but before 40 times the reduceing is relatively slow.This is mainly due to its relatively high boiling point.Wear and friction,the grinding crack width falls but rises after 40 times.It shows that the stability of the whole structure can largely influence the wear resistance of material.The friction coefficient curve appear unique trend of rise and fall after fall first.The cause of the last drop may be the "special layer" which forms by thermal stress wave.