Application of inductively coupled microplasma jet on rapid manufacturing

Abstract

Metal rapid manufacture has received great attention in recent decades. Energy source with high power density is requisite for the metal deposition. Atmospheric pressure inductively coupled microplasma jet is commonly characterized by high temperatures, which is one of excellent candidates for metal rapid manufacture on a micro scale.In this paper, we investigate the microplasma jet driven by a 150 MHz very-high-frequency power supply at atmospheric pressure. A microplasma of 3 cm in length and about 3 mm in diameter can be produced at 90 W power applied, with gas temperatures above one thousand degree centigrade. The jet length rises first, and then decreases by increasing gas flow rate, showing a transition from laminar flow to turbulence. The jet length also increases by enhancing applied power, but then keeps a maximum value with further increasing power, which is attributed to the attainment of equilibrium between the energy absorption and losses in the transport process in plasma.Copper powders are carried by the argon flowing into plasma, and melted fast by the microjet. An alumina ceramic plate is used as a substrate, which is set on the substrate holder with a precisely controlled X-Y-Z manipulator. A copper spherical cap with 2 mm in diameter and a column with 1 cm in height are fabricated in a few seconds, respectively, on the alumina ceramic substrate. The Cu spherical cap is characterized by scanning electron microscopy. Particles obtained on the sample surface are far smaller than the source powders, indicating a melting process of copper powders in plasma, as well as high gas temperature exceeding the melting point of copper. The weak peak of Cu2+1O is present besides strong copper diffraction lines in X-ray diffraction pattern, suggesting that the weak oxidation happens during rapid fabrication.