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

利用渗透修复源效应，即高压电子在渗透过程中渗入金属材料熔化，从而实现表面改性。利用自行研制的500KV超高压电子束热源对金属进行表面改性。用500千伏电子束(功率0.3~3kW，束流扫描速度0.75~2 mm/S，束流直径4~7 mm)对粘贴在SM400、SK4钢上的热喷涂合金粉末(80%Ni2O%Cr，厚度0.3~0.6 mm)进行辐照。粉末和部分母材瞬间从材料内部熔化，从而抑制了溅射和内部缺陷，如气孔。获得了熔深为0.4~0.8 mm，粉末元素含量较高(Ni：-4O%，Cr：-10%)的焊道，并用高速摄像机观察了焊道成形过程中的熔结现象。研究发现，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，这种周期性的过程抑制了飞溅。仅含13%Ni的5%112S04焊道的冲蚀试验结果与不锈钢(SUS3O4)的冲蚀试验结果相近。这意味着，通过合理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.