By Yingchun Guan, Chih-Hsing Liu, Gnian Cher Lim, Hong Yu Zheng and Ming Hui Hong

Carbonaceous deposits covering the surfaces of combustion engine components are known to cause abrasive wear, leading to increased oil consumption and reduce engine durability as well as performance. Remanufacturing is the process acting on end-of-life products to recover manufacturing standards and specifications. Dr. Yingchun Guan from Singapore Institute of Manufacturing Technology (SIMTech), Agency for Science, Technology and Research (A*STAR), and her co-workers have shown how laser technique may be used to remove stubborn carbonaceous deposits without degradation to substrate component.

Laser processing under normal atmospheric conditions may be considered as an environmentally friendly process where no chemicals were used. It has been demonstrated that micron to sub-micron sized surface particulates, corrosion spots as well as thin contamination layer may be cleanly removed without severe damage to the parent substrate. Typical applications include coating or paint removal, biomedical implants decontamination, artwork and cultural heritage conservation and restoration. [click to continue…]

By J. M. Amado, J. N. Montero, M. J. Tobar, A. Yañez

Functionally graded materials (FGM´s) are usually described as composite materials in which composition and structure varies gradually from one point to another. Traditional composites are based on homogeneous mixtures where the properties of the respective components are averaged according to their relative proportion. Therefore a compromise must be made between the desired properties of each constituent. In contrast, the need for a compromise is eliminated in FGM: the graded design ensures that the full performance of each component is obtained at some point of the composite material.

A wide range of processing methods is available today for the fabrication of graded structures with almost any material combination. Most of them rely on well established processing routes as powder metallurgy or melt processing. Direct metal deposition (laser cladding), for example, can be adopted for the production of FGM by feeding with mixed alloy powders with controlled compositions. This can be achieved by using pre-blended powders at desired mixing ratios or, even better, by using separately controlled powder hoppers. In this last case, mixing ratios can be changed online during processing. [click to continue…]