Surface layers preparation physical vapor deposition

Saha et al. [109] have proposed an improved ion deposition methodology based on a dual ion-beam assisted deposition (dual IBAD) method. Dual IBAD combines physical vapor deposition (PVD) with ion-beam bombardment. The unique feature of dual IBAD is that the ion bombardment can impart substantial energy to the coating and coating/substrate interface, which could be employed to control film properties such as uniformity, density, and morphology. Using the dual lABD method, an ultralow, pure Ft-based catalyst layer (0.04-0.12 mg Ft/cm ) can be prepared on the surface of a GDL substrate, with film thicknesses in the range of 250-750 A. The main drawback is that the fuel cell performance of such a CL is much lower than that of conventional ink-based catalyst layers. Further improvement... 

This chapter concerns composite films prepared by physical vapor deposition (PVD) method. These films consist of dielectric matrix containing metal or semiconductor (M/SC) nanoparticles. The structure of films is considered depending on their formation by deposition of M/SC onto dielectric substrates as well as by layer-by-layer or simultaneous deposition of M/SC and dielectric vapor. Data on mean size, size distribution, and arrangement of M/SC nanoparticles in so obtained different composite films are given and discussed in relation to M/SC nature and matrix properties. Some models of nucleation and growth of M/SC nanoparticles by the diffusion of M/SC atoms/molecules over a surface or in volume of dielectric matrix are proposed and analyzed in connection with experimental data. 

Another type of carbon layer useful for the preparation of biocompatible surfaces includes chemical and physical vapor deposition. The preparation of the carbon layers on pol3rtetrafluoroethylene (PTFE) by photoinduced CVD from acetylene and their physical properties and chemical structure have been studied. These properties related to the adhesion and proliferation of human umbilical endothelial cells (HUVEC) seeded thereon were characterized [39]. 

Thin films are usually prepared from the vapor phase, but they can al.so be obtained from liquid or solid phases by applying physical or chemical driving forces, or various combinations of the latter [1-3). In principle, two types of film may be identified from the point of view of surface analysis one in which the film is deposited on a substrate (workpiece), and the other in which the film is created as a result of the modification of the surface atomic layers of a substrate. In the latter case there is a strong involvement of the constituents of the solid substrate. A brief survey of the most frequently applied deposition and implantation techniques is presented below. 

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