Preliminary Results on Pulsed Laser Deposition of PMMA on Nitinol Substrate

Corrosion includes a series of processes, chemical and electro-chemical reactions through all the metals, generally speaking, passes from the initial to a modified status. This transformation is possible because in nature the metals can be found in complex forms: oxides, phosphates, carbonates, nitrate compounds or hydroxides whose free energy is lower than of the metal in initial state giving a justification for the tendency of the metals to pass to a lower energy form. The goal of the work paper is to improve the resistance of corrosion of a metallic intelligent material, nitinol alloy, through superficial deposition by laser ablation of polymeric materials. Approximately one third of the metal production in the world is affected by corrosion and 10 % of the production is completely lost because of the corrosion destructions (1-3). The shape memory alloys NiTi have a very good resistance at corrosion but the presence of Ni in the chemical composition of alloy cause reserves in the applications with long periods of time of this material. Being known the toxical and cancerous character of Ni it is very important to prevent the access in the human body. The raw materials used in industry can suffer a direct chemical attack while the electro-chemical attack appears only in metals due to the possession of free electrons. The synthetic materials are exposed to destruction only through chemical attack because they do not have free electrons (4-6). In order to obtain a superficial cover PMMA (Poly(methyl methacrylate)) is a resistant and a light material (ρ=1.17…1,20 g/cm 3 ) with the chemical formula of (C 5 O 2 H 8 ) n and the melting point 200 °C. It has an impact resistance higher than that of a glass or polyester but lower than polycarbonate or other polymers used in engineering. PMMA is flammable at 460 °C and burns forming, CO 2 , water, CO and compound with low molecular weight including formaldehyde. The PMMA material is dissolved in organic solvents and has a low resistance at many