焊接气溶胶10nm尺度粒子的G-P转变

G-P CONVERSION OF PARTICLES OF ORDER 10 NM IN WELDING AEROSOL

利用DMPS方法和ATEM电镜方法,首次实现对焊接气溶胶粒子谱分布及其分级粒子形貌、成分及相结构的综合分析,得到焊态下E4303和E5015常用焊条10nm尺度粒子群的分布函数为D_(E4303)～LN(0.042μm,1.37)和D_(E5015)～LN(0.054μm,1.42),具有遵循对数正态分布及金属蒸发所形成粒子的特征;探讨了焊接气溶胶10nm粒子群的形核机制,证实它们是Fe_3O_4多晶体,系以蒸气→粒子的G-P转变方式均质形核,其控制环节是Fe(g)→Fe(l)的物理凝聚过程。提出焊接电弧的气溶胶粒子形核区模型,对分析G-P转变过程及形核机制有重要意义。

It is realized to systematic analysis of the paniculate size distributions and shape, composition, crystal structure for grade particles of welding aerosol, for the first time, by means of DMPS (Differential mobility particle sizer) method and ATEM (Analytical transmission electron microscopy) method. The distribution functions of particles of order 10nm for the E4303 and E5015 electrodes are shown as DplE4303-LN(0.042μm, 1.37) and DplE5015-N(0.054 μm, 1.42) during welding. The results show that the particles of order 10nm follow lognormal distribution and relate to metal vaporizing. The G-P conversion (Gas to Particle Conversion) process and nucleation mechanism of 10 nm particles of welding aerosol have been investigated. The crystal structure of particles of order 10 nm is confirmed as Fe3O4. The particles of order 10nm are generated according to the homogeneous form by way of G- P conversion and its controlling reaction is physical condensation process of Fe(g)-Fe(l).The model of particulate nuclea-tion zone in welding arc is put forward. It is important to analysis G-P conversion process and nucleation mechanism of welding aerosol particle.