Solid Freeform Fabrication Based on Micro-Plasma Powder Deposition

 Micro-plasma powder deposition (MPPD) for solid freeform fabrication (SFF) was developed in Plasma Arc Welding Laboratory. The relationship between the geometric features of the deposited layers and the welding parameters is investigated. The arc length is controlled through the monitoring of arc voltage. The microstructure and the properties of the deposited layers are analyzed.  The experimental results show that the MPPD process is a promising welding-based solid freeform fabrication technology that is capable of building relatively small-size parts with low cost. The result of building parts with functionally graded components by the MPPD process is shown as well.

 A transferred plasma arc exists between the torch nozzle and the substrate, and generates a molten pool on the surface of the substrate. The metal powder is fed into the molten pool by the carrier gas (argon) through the powder feed nozzle. Then, the fed powder is melted under the high temperature of the plasma arc. With the moving away of the plasma arc, the molten metal solidifies to form a deposited layer.

Schematic diagram of micro-plasma powder deposition

Experimental Set-up for micro-plasma powder deposition

                                                                   (a)                                                             (b)

                                (c)                                                                                  (d)

Test parts: (a) Part in the form of a cylinder, (b) Part in the form of a vase,

(c) Part in the form of a cone, (d) Part in the form of a bar

Pictures of the functionally graded composition test part and the microstructures 

Hardness distribution on the cross section of the test FGC part