AbstractComposite ceramic coatings of alumina (A1203) containing some molybdenum disulfide (MoS2) were electro-codeposited on to Al metal substrates by a combination of anodic sparks deposition of A1203 and electrophoresis of MoS2. The microstructures were characterized by XRD, XPS, SEM, EDS, SNMS,TEM, SAD and relative wear resistance measurements. The coatings consisted mostly ofa-A1203 with some γ and βpresent as well. The coatings were porous and microcracked. SEM showed them to consist of circular “splats” which had rapidly crystallized from the molten state in areas ofdielectric breakdown in the coating. In the TEM the microstructure was seento contain “sets” of parallel, elongated grains having a single crystallographic orientation. The grains were separated by dislocated, low angle grain boundaries or microcracks. The sets intersected at irregularly curved interfaces and were mechanically interlocked. Quantitative SNMS indicated that up to 26 wt% MoS2 was incorporated in coatings fabricated from 5g\1 solutions. SEM\EDS as well as TEM\SAD\EDS identified 1-3μm particles of MoS2 incorporated into the 5g\1 solution derived coatings. These coatings exhibited a 50% lower wear rate than pure alumina coatings deposited under the same conditions.
Plasma assisted pyrolysis for processing of composite ceramic coatings based on silazane precursor and TiB2 filler applied onto a sintered steel
