滑动电接触界面沉积层对电枢熔化的抑制效应研究

维持良好的滑动电接触性能是实现电磁轨道发射高频率和高效率工作的重要保证。重复发射时,轨道表面沉积层影响电枢表面熔化特性,进而改变接触状态,从而影响滑动电接触性能,因此有必要对沉积层作用下的电枢熔化特性进行分析。首先,通过分析沉积层受热过程,建立了沉积层熔化判断模型,并提出沉积层熔化判断条件;其次,基于沉积层熔化特性,建立了沉积层作用下的电枢熔化磨损计算模型,分析不同电流条件下沉积层熔化特性发现,载流量越大,沉积层熔化范围越大,并且启动低速阶段沉积层能够发生熔化,高速阶段沉积层不容易发生熔化;最后,开展重复发射试验,通过理论分析结合试验验证对电枢熔化的抑制特性进行研究。结果表明:沉积层厚度随着发射次数逐渐增加,沉积层全部熔化状态下,电枢最大熔化深度随发射次数呈逐渐减小的趋势。模型计算结果与试验测量结果变化趋势相同,说明沉积层熔化对电枢熔化有抑制效应。该文所建立模型及分析结果对深入理解重复发射时枢轨界面熔化磨损机理、提高滑动电接触性能具有重要意义。

Micromorphology and texture of niobium coating electrodeposited in NaCl−KCl−CsCl molten salt system

A low-toxicity and environment-friendly NaCl−KCl−CsCl−K_(2)NbF_(7) system was used to prepare Nb coatings on Mo substrates.The effects of temperature,current density and electrodeposition time on the micromorphologies and textures of the electrodeposited Nb coatings were studied.The results showed that Nb coatings obtained at 30−70 mA/cm^(2) in the temperature range of 700−750℃ were continuous and compact,with a hardness range of 2.16−2.45 GPa.As the columnar crystals grew with time,the preferential growth orientations of the Nb coatings changed from<200>to<211>and then became disordered.With increasing polarization,the morphologies of the Nb coatings changed from hexagonal star-like surface to conical or pyramid-like surface.