Formation of fine alloy layer by using the penetration heat source effect of electron.

将高压电子对金属材料的穿透愈合源效应应用于表面改性。利用自行研制的500 kV超高压电子束热源对金属材料进行了表面改性。用500 kV电子束（功率0.3 - 3 kW，束流扫描速度0.75- 2 mm/s，束径4- 7 mm）辐照涂敷在钢（SM 400，SK 4）上的热喷涂合金粉末（80%Ni20%Cr，厚度0.3 - 0.6mm）。粉末和一部分母材金属从材料内部瞬间熔化，从而抑制了溅射和内部缺陷，如气孔。获得了熔深为0.4 ~ 0.8mm、粉末元素（Ni：~ 40%，Cr：~ 10%）富集率较高的焊缝，用高速摄像机观察了焊缝成形过程中的内缩现象。发现合金粉末在母材上的熔化过程以几百毫秒的间隔重复进行，这种周期性的熔化过程抑制了飞溅。含镍量为13%的不锈钢（SUS 3 O 4）焊缝经5%112S04冲蚀试验后，其冲蚀率与不锈钢焊缝相近。这意味着，通过适当选择粉末的化学成分，可以进一步改善冲蚀性能。

The penetration heal source effect, that high voltage electrons penetrate deeply into metallic materials melting them during penetration process was applied to surface modification. Surface modification of metals was performed with the 500kV ultra high voltage electron beam heat source which is developing by the authors. Alloy powder for thermal spraying (80%Ni 2O%Cr, thickness : O.3-O.6mm) which was pasted on steels (SM400, SK4) were irradiated by the 500kV electron beam (power0.3-3kW, beam scanning speed : 0.75-2mm/s, beam diameter : 4-7mm) . Powder and a part of base metal were instantaneously melted from inside of materials, resulting suppression of sputtering and internal defects such as porosities. Weld beads having the penetration depth of 0.4-O.8mm with high concentration rate of powder elements (Ni : -4O%, Cr : -10%) were obtained.Nelting phenomena were observed by a high speed video camera during formation process of weld bead. It is found that the melting process of alloy powder on base metal was repeated with few hundreds millisecond intervals and this periodic process suppressed spattering. Result of 5%112S04 erosion test of weld bead containing only 13%Ni showed a similar value for stainless steel (SUS3O4). This means that further improvement of erosion property can be expected by properly selection of chemical composition of powder.