Decorative Composite Layers

Résumé

Part of the materials used in the chemical industry, metallurgical, machine construction, can be coated, as with time it occurs either a decrease of its properties, or even a process of advanced faulting, because of the stresses suffered.
The paper presents the structure of some composite coatings with the nickel matrix also pointing out their decorative aspect. The layer is obtained through electrochemical methods, using as a complementary phase carbure and oxide particles (Al₂O₃, ZrO₂, B₄C, SiC) with contents of cca. 4-6%. The maintaining times in electrolyte ranged from 10 to 60 minutes.
The macro and microstructural analysis had as objectives: the exterior aspect at composite depositions; the adherence of the film deposited at the support; the width of the deposition; the film compactity; the size, shape and orientation of the grains in the deposited layer; the distribution of the disperse phase in the metallic matrix.
The microstructures of the composite films Ni + Al₂O₃ and Ni + SiC, performed in cross and longitudinal sections, reveal a dispersion relatively uniform of the aluminum oxide particles and respectively, silicon carbure in the Nickel matrix, a uniform deposition, lack of pores, a good compactity, a very good adherence at the metallic frame.