Stefan Toma

By Stefan Lucian Toma, Radu Armand Haraga, Daniela Lucia Chicet, Viorel Paleu and Costica Bejinariu

Obtained by different spraying technologies: in atmospheric plasma spray, High Velocity Oxygen Fuel (HVOF) or laser cladding, the layers of hard alloys with a high content of WC and TiC find their industrial applications due to their high hardness and resistance to wear. Recognized as being a process associated with welding, the arc spraying process is a method applied industrially both in obtaining new surfaces and for reconditioning worn ones. This chapter presents the technology for obtaining ultra-hard layers based on WC and TiC - by the arc spraying process, using a classic spray device equipped with a conical nozzle system and tubular wire additional material containing ultra-hard compounds (WC, TiC). To study both the quality of deposits and the influence of thermal spray process parameters on the properties of deposits with WC and TiC content, we approached various investigative techniques, such as optical scanning microscopy (SEM), X-ray diffraction, and determination of adhesion, porosity, Vickers micro-hardness and wear resistance.

Part of the book: Welding

By Stefan Andrei Irimiciuc, Norina Forna, Andrei Agop, Maricel Agop, Stefan Toma and Doriana Forna Agop

Understanding the underline fundamental mechanism behind experimental and industrial technologies embodies one of the foundations of the advances and tailoring new materials. With the pulsed laser deposition being one of the key techniques for obtaining complex biocompatible materials with controllable stoichiometry, there is need for experimental and theoretical advancements towards understanding the dynamics of multi component plasmas. Here we investigate the laser ablation process on Cu-Mn-Al and Fe-Mn-Si by means of space-and time-resolved optical emission spectroscopy and fast camera imaging. In a fractal paradigm the space–time homographic transformations were correlated with the global dynamics of the ablation plasmas.

Part of the book: Practical Applications of Laser Ablation