Study Of The Preparation Of Titanium Carbide Coating On Graphite Surface And Bombardment Performance Of High Current Electron Beam

The collector is one of the important components in the HPM source,which is used to receive the high-current electron beam after the beam wave coupling.Graphite,as a commonly used high-current electron beam collector material,has disadvantages such as easy gas release on the surface and carbon pollution,which limits its application in HPM sources.TiC has the characteristics of high melting point,low density,low atomic number and dense structure,etc.It is a very good electron collector coating material.In this paper,chemical vapor deposition?CVD?method was used to prepare TiC coating on graphite surface.The influence mechanism of deposition temperature,substrate characteristics and other process parameters on the composition structure,micro-morphology and electrical conductivity of TiC coating was studied.TiC coatings with different thicknesses were obtained.At the same time,the electron beam bombardment resistance of TiC coated graphite targets with different thicknesses was studied through two methods of numerical simulation and experiment.The preparation of layers and the improvement of HPM system performance provide guidance and for future reference.The main research contents are as follows:?1?The effects of substrate characteristics and deposition temperature on the micro-morphology,crystal structure and basic properties of TiC coating were studied.The results show that at 1000? deposition temperature,the TiC grains on the graphite surface grow along the?111?crystal plane;the diamond grains on the quartz and Al₂O₃surface grow along the?200?crystal plane;The TiC grains on the sapphire surface are amorphous grains;the TiC coating prepared on the graphite surface has the best surface resistivity,0.002?·cm.On the surface of the graphite substrate,as the deposition temperature increases,the TiC grains transform from?200?crystal face phosphor flake grains to?111?crystal face conical grains.The TiC coating surface resistivity increases with the deposition temperature the increase keeps decreasing.By analyzing the micro-morphology,crystal structure and basic properties of TiC coating,it is concluded that 1000? is the appropriate coating deposition temperature.?2?MCNP software was used to analyze the energy deposition of electrons in TiC/g-raphite materials and the temperature rise distribution caused by energy deposition.The results show that when the initial energy of electrons is low,and the energy is mainly deposited inside TiC.As the initial energy of electrons increases,the energy is mainly deposited inside graphite.When the initial energy of electrons is 1Me V,the thickness of TiC coating is 1?m,the energy deposited in TiC is only 0.8%of the initial energy of electrons;the thickness of TiC coating increases to 30?m,the energy of electrons deposited in TiC accounts for 29.5%of the initial energy.With the thickness of the coating,the temperature difference between the TiC coating and the graphite substrate increased from 335? to 590?.Accordingly,the increase in the interfacial stress between the two may cause heat to fall off,which that the TiC coating on the graphite surface should not be too thick.?3?The TPG1000 platform was used to study the electron beam resistance of TiC/graphite.The results show that after the action of the high-current electron beam,Ti and Ti N/graphite are damaged,while graphite and TiC/graphite are not damaged,indicating that the electron beam resistance of TiC/graphite is better than Ti and Ti N/graphite.The effect of coating thickness on the electron beam bombardment resistance of TiC/graphite was studied.The results showed that there was no coating peeling and structural damage on the surface of TiC/graphite with a coating thickness of1?m.The coating thickness was 5?m,10?m,20?m,and 30?m,serious coating shedding and cracking occurred on the surface of TiC/graphite,indicating that TiC/graphite with a coating thickness of 1?m had better resistance to electron beam bombardment.