Fabrication of various shaped tungsten micro pin arrays using micro carving technology

- Micro carving technology on tungsten was developed by combining laser beam machining and electrochemical etching.
- Micro carving technology is capable of fabricating different shapes of tungsten micro pin arrays with sharp cutting edges.
- The shape of each pin was pre-determined by the designated laser scanning path.
- The core micro pin structures in various shapes were revealed using electrochemical etching.
- The relative composition of tungsten and oxygen on the cross section by EDS reflects the results by laser scanning path control.

This paper describes a state of the art in micro-structuring high strength metallic materials. Tungsten micro pin arrays in a variety of shapes are fabricated using a micro carving technology, which combines laser beam machining and electrochemical etching processes. First, micro pin arrays were rough-shaped by laser beam machining along a pre-defined scanning path to control their structural shape. The micro pin array in this stage had near-conical shape of structures due to a recast layer. Next, the genuine shape of micro pin arrays came to the surface via electrochemical etching process to elute the recast layer into electrolyte. Quantitative elemental analysis with energy-dispersive spectroscopy (EDS) was implemented to characterize the formation of recast layer on a micro pin structure after the laser beam machining process. The atomic percentage EDS maps indicated that higher percentage of tungsten was detected on the core micro pin structure, whereas relatively large percentage of oxygen was found on the recast layer (O 9%, W 91% in the center area, and O 53%, W 47% in the outer area).