Ni-B/SiC composite coatings were electrodeposited using trimethylamine borane as a boron source. The effects of bath composition and operating parameters on the microstructure and properties of the composite coatings were investigated. The results show that Ni-B/SiC composite coating exhibits uniform structure with a desirable interface. Incorporation of SiC particles led to a significant increase in hardness. Both boron and SiC content in the coating increases initially and then decreases as the current density increased. Incorporation of inert SiC particles also enhanced their corrosion resistance, which attributed to the dense structure, barrier effect and the reduction in the active surface area of Ni-B matrix. XPS analysis indicated that the as-deposited coating contains metallic nickel, oxide or hydroxide nickel, and the SiC particles. Owing to dispersion hardening of the added SiC particles and the reduction in the active surface area of Ni-B matrix, Ni-B/SiC composite coating shows superior anti-corrosion and wear resistance.

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Air-core printed-circuit (PC) quadrupoles and dipoles have been developed for the University of Maryland electron ring, currently under construction. The quadrupoles and dipoles are characterized by very small magnetic fields (about 15 G at the aperture edge) and small aspect ratios (length͞diameter , 1). We review the theory behind the design of the PC lenses and bending elements, and present general expressions for estimating the values of integrated field and integrated field gradient as functions of design parameters. The new quadrupole magnet represents an improvement over an earlier version which was based on an empirical approach. Further, we summarize the results of multipole content of the magnet fields as measured with a rotating coil apparatus of special construction. The results are compared with calculations with an iron-free magnetics code and are related to different types of errors in the manufacture and assembly of the PC magnets.

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