Three Dimensional Microstructures from Metal Carbonyls

Abstract

Abstract3D-LCVD of nickel and iron carbonyls was studied in order to grow 3-D metal forms under static or scanning Nd:YAG-laser beam. In addition to growth, emphasis was also placed on the prevention of the simultaneous decomposition of carbon monoxide, which interferes with the metal growth process. This was essential, because the fairly high precursor gas pressures of the metal carbonyls are very tempting for the 3D-LCVD. Parameters to be optimized included precursor pressure, laser power, laser scan speed and spot size. In order to optimize the growth parameters, the microstructures of the resulting forms were studied using SEM. Comparison between static and scanning growth is presented with the building philosophy in mind, e.g. whether to build structures layer by layer, from modules or in conjunction with another process to compensate for their shortcomings. The substrates used included steel, graphite and porous bronze.The results indicated different microstructures for iron and nickel, which were dependent on the total/precursor pressure. In the scanning experiments, nickel produced very thin films of high reflectivity, whereas iron produced a structure which could be described as a crystalline spider's web. The static experiments produced solid rods in the case of nickel, whereas with iron, the rods were hollow, even with same spot sizes. Moreover, an evident change in the microstructure of the nickel forms as a function of pressure was observed. The 3-D growth rate of the static experiments seemed very promising for the forthcoming scanning experiments.