Rare earth ceramic oxides are used in several applications including, phosphors, gas sensors, fuel cells, catalytic converters, and corrosion protection. These materials exhibit attractive properties such as fracture toughness, stiffness, and high strength-to-weight ratios. Synthesis of rare earth oxides includes a long list of techniques, but electrodeposition is one that has not been used as extensively as other techniques. This chapter discusses in detail the electrochemical synthesis of lanthanum, cerium, and praseodymium oxides. The physical and chemical properties of the electrodeposited oxides are characterized by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, and other techniques. The electrochemical synthesis and post-treatment of other rare earth oxides, such as gadolinium, terbium, samarium, neodymium, europium, and dysprosium oxides are also covered in this chapter. Two main mechanisms of electrodeposition for rare earth oxides are discussed in detail.
Part of the book: Advanced Ceramic Processing
Composite coatings can demonstrate improved property performance as compared to metals and alloy materials. One category of composite coatings is composed of metal or metal alloys with a dispersed phase of nonmetallic nanoparticles. The addition of these nanoparticles has been found to improve corrosion, wear resistance, and hardness. Producing metal composite coatings using electrochemical techniques can be advantageous due to reduced production cost, lower working temperatures, and precise control of experimental parameters. Metal coatings such as zinc have been successfully co-deposited with TiO2, SiO2, CeO2 and mica particles and nickel has been co-deposited with a number of materials including TiO2, SiC, Al2O3, PTFE and silicates. Zinc-nickel alloys have long been studied for a number of properties, most notably corrosion resistance and recently their tribological properties. This chapter reviews the literature on electrodeposition of ZnNi nanocomposite coatings. Although there has been much work done on composite coatings, there is much less literature available on composite coatings with zinc-nickel alloys. So in this review, we look at the general trends for nanoparticle incorporation, deposition mechanisms, system stability, microstructures of the coatings and general corrosion trends.
Part of the book: Nanocomposites