调制周期对Cr/CrN纳米多层膜的结构与性能的影响

采用多弧离子镀技术在65Mn钢表面制备了不同调制周期的Cr/CrN纳米多层膜.采用俄歇能谱仪(AES)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、纳米硬度仪、轮廓仪和划痕仪,分析了不同调制周期Cr/CrN纳米多层膜的成分分布、微观结构、力学性能、残余应力和结合强度.结果表明,Cr/CrN纳米多层膜的表面平整致密,截面层状调制结构清晰,其调制结构为Cr层-过渡层-CrN层的"三明治"结构,调制比约为1∶ 1.多层膜由CrN、Cr2N和Cr相组成,在CrN(200)方向上出现择优取向.当调制周期为80 nm时,多层膜的硬度值相对较高.随调制周期的增大,Cr/CrN多层膜的残余应力值减小,结合强度值先增大后减小.当调制周期为120 nm时,涂层的划痕临界载荷值相对较高,为69 N.     

CrN活塞环涂层的工艺制备与摩擦学性能研究

论文采用多弧离子镀技术在活塞环表面制备了CrN涂层,系统地研究了不同N2含量对CrN涂层的相结构和纳米硬度的影响规律.并采用CETR微动摩擦磨损试验机比较研究了Cr电镀层与CrN涂层的高温微动摩擦磨损性能,研究结果表明:随着N2含量的增加,薄膜由Cr2N(211)相过渡到CrN(220)相;膜层的纳米硬度随N2含量的增加而增大,并出现两个峰值;与Cr电镀层相比,CrN涂层主要以磨粒磨损为主,犁沟较窄且平滑,抗高温粘着磨损性能明显增强,而且摩擦系数较小,具有较好的摩擦匹配性能,更适合用于活塞环服役的高温磨损环境.     

Numerical Simulation of Airflow Field and Structure Improvement in Engine Compartment of Armored Vehicles with Electric Transmission

When the mechanical drive is changed into the electric transmission,the cooling system of the engine compartment should be altered to meet the new requirement for the increasing in equipment such as electric apparatus.In order to predict and analyze the rationality of cooling system in the virtual engine compartment,the numerical simulation of airflow fields in the engine compartment by using computational fluid dynamics（CFD） technique is necessary.An armored vehicle with electric transmission in the research is taken as the research object.The physical model and mathematical model for the computation of 3D air flow and heat transfer in the engine compartment of an armored vehicle with electric transmission is established.Turbulent flow in the compartment is described by using the standard k-ε two-equation turbulence model.The temperature and velocity fields of 3D air flow in the engine compartment are numerically simulated and analyzed based on different fan＇s flux.A theoretical basis for determination of the fan＇s flux is given by the simulation results.The positions of the air-vent shutter are analyzed.The simulation results show that the different positions of the air-vent shutter can lead to different cooling efficiencies.