Copper Deposition on RP Parts: An Experimental Investigation

Abstract

These days the growing demand of plastic has brought in a drastic change in the scope of usage of plastic and therefore, it is further being improved to make it more commercially viable. Metallization is a step to develop a conductive layer over a non-conductive material such as plastic. The idea of metallization substitutes the use of strategic metal by metal coated plastic. The properties like easy moulding, light weight and corrosion resistance constitute a natural advantage of plastic over metal. Metallization provides metallic finish and lustre to the substrate, making it considerable for decorative purposes. On the other hand, it augments metallic properties, making it useful for technological purposes. With metallization, the plastic gains properties like thermal conductivity, electrical conductivity, strength, hardness and weatherproofing which makes it possible to utilise the advantages of both metal and plastic in combination. Thus, it has broadened the spectrum of application of metallized plastics. As a result, metallized plastic is widely used in fields like oil and gas, automotive industry, electrical and electronic industry, chemical processing, textile, aerospace, providing finish on fashion items such as shoes, name badges, as well as on consumer electronics products including laptop cases and cell phones, etc. The popular conventional means of metallization have not only been unfriendly to the environment but also is hazardous to manual labourers engaged in the coating industry mainly because of the use of toxic substances such as palladium, chromium and sulphuric acid during etching. In the present work, Acrylonitrile Butadiene Styrene (ABS), a thermoplastic has been chosen as the substrate. ABS is largely being used in the automobile sector for being toughest in its lot. The electric wire arc thermal spraying method has been used to deposit copper on the ABS plastic. This method deposits a thick layer of coating but without the involvement of any toxic components. The work studies the various aspects of the coating behaviour with respect to spraying stand-off distance. Taguchi’s L27 orthogonal array has been used to design the experiments throughout the work to save money and time in the experiment. Physical properties like porosity, surface roughness, micro-hardness, surface residual stress, electrical resistance, thickness, tensile strength, coating density and adhesive strength have been studied to characterize the coating further. Microstructural analysis along with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) have also been performed in
support of obtained results. The tribological aspects like sliding wear and erosive wear have been studied and optimised using Taguchi optimisation. Attempts have been made to study the suitability of the coatings at different operating conditions. With the help of analysis of variance (ANOVA), the influence of selected process parameters used during the fabrication of substrate and coating, over various output parameters has been studied with an attempt to determine the best parametric setting for each of them.