revised第五章 热扩渗

1、 渗硼层厚度、表面硬度与渗硼时间渗硼时间（小时）渗硼层厚度（mm）硬度（HV）30.045112040.052112050.0671160氢氧化钠溶液 盐酸 硫酸 腐蚀后试样实物照片 渗硼与未渗硼试样在H2SO4、HCL介质中的腐蚀失重比较 试样的磨损失重比较 Fig.1 XRD patterns of AISI 1045 steel treated with different boriding agents at 1213K：(a) without Nd2O3 addition，(b)with Nd2O3 addition.Fig.2 Optical micrographs of bori

2、ded AISI 1045 steel subjected to different process temperatures: (a) 1093K, (b) 1093K with Nd2O3 addition, (c) 1213K，(d) 1213K with Nd2O3 addition.Fig.3 Boride layer thickness vs. boriding time for various process temperatures.Ktd 2 )(0RTQeKK )(lnln0RTQKKFig.4 Growth rate constant vs. temperature of

3、 borided AISI 1045 steel.2BF3 + B4C = 3BF2+ 3B + C G5 (5)3KF + 3BF3 + 2Nd2O3 = 4NdF3 + 3KO2 + 3B G6 (6)2KO2 = K2O2 + O2 G7 (7)2BF3 + 3B4C + Nd2O3 + 6O2= 2NdF3 + 2B2O3 + B + 3CO G8 (8)2BF3 + B4C + 3Fe + 2O2 = 3FeF2 + B2O3 + 6B + CO G9 (9)B4C + 2KF + Fe + 3O2 = 2B + FeF2 + 2K2O + B2O3 + CO2 G10 (10)2B

4、F3 + SiC + 3Fe + 3O2 = 3FeF2 + SiO2 + B2O3 + CO G11 (11)B4C + 2KF + 3O2 = B +BF2 + B2O3 + K2O + CO G12 (12) Fig.6 Changes of Gibbs free energy as a temperature for different reactions. Fig.7 Element mapping on the surfaces of the AISI 1045 steel borided at 1053 K Fig.8 Element mapping on the surface

5、s of the AISI 1045 steel borided at 1133 K. Fig.9 EDS spectrum of tiny sphere on surface of RE-borided AISI 1045 steel at 1133 K.Fig.10 Element mapping on the surfaces of the AISI 1045 steel borided at 1213 K.离子氮化离子氮化早在1932年就由一个德国人发明了，上世纪上世纪60年年代在德国、瑞士等国开始应用代在德国、瑞士等国开始应用。我国是70年代开始研制和应用的。原理原理： 就是把工件放入氮化炉中，抽真空至1.33Pa左右通入少量的氨气氨气，当气压升到70Pa左右接通电源，工件是阴极，在阴极与阳极间加上直流高压，就会产生辉光放电辉光放电。气体电离了了，氮离子氮离子、氢离子氢离子就会在电场作用下冲向工件表面，产生大量的热把工件加热到热把工件加热到520-550，氮离子和氮原子就会氮离子和氮原子就会在工件表面吸附、扩散，形成氮化层。保温一段时间后，断在工件表面吸附、扩散，形成氮化层。保温一段时间后，断电、停气、降温