ICP微等离子体射流在快速成形制造中的应用

本文开展了大气压甚高频感应耦合(ICP)微等离子体射流的特性与应用研究.在150 MHz甚高频,功率为90 W条件下获得温度高达上千度的温热等离子体射流,射流长度近3 cm.随着气流量的增加射流将呈现层流到湍流的转变,长度先增后减;而功率对于射流长度的影响存在着一个上限,当等离子体吸收的能量与扩散损失的能量达到平衡时,射流长度将达到最大.利用这种ICP微等离子体射流进行了微尺寸金属铜的快速成形制造,得到了球冠状和柱状铜金属件.在扫描电子显微镜下观察到沉积物表面最小颗粒尺寸远小于铜粉颗粒;X射线衍射结果显示沉积物表面存在弱氧化物峰,这是沉积过程中空气被射流卷入所致.

Application of inductively coupled microplasma jet on rapid manufacturing

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.