Novel Electrodeposited Ni-Based Nanocomposite Precursors for Nitriding and Low Temperature Chromizing
Two types of Ni-base nanocomposites were prepared by co-deposition of Ni with nano-sized particles of Cr or CeO2, respectively. Both Ni-Cr and Ni-CeO2 nanocomposites were mainly composed of nanocrystalline Ni matrix, in which certain content of nanoparticles of Cr or CeO2 randomly dispersed. The Ni-Cr nanocomposite was used as a precursor for preparing a novel hard Ni/CrN coating by plasma nitriding at 560oC. The Ni-CeO2 nanocomposite was used as a precursor to develop a novel oxidation-resistant chromia-forming coating by low temperature chromizing using a conventional pack-cementation method. The microhardness of the nitrided layer on the Ni-Cr nanocomposite and the oxidation resistance of the chromizing coating on the Ni-CeO2 nanocomposite were both greatly increased, in comparison to the corresponding counterparts, which were obtained by plasma nitriding on a conventional coarse-grained Ni-Cr alloy with similar Cr content and by chromizing on a coarse-grained Ni metal, respectively. The relationships among the microstructures of the nanocomposite precursors and the nitrided/or chromized coatings, and their properties were investigated and discussed.
Shigeji Taniguchi, Toshio Maruyama, Masayuki Yoshiba, Nobuo Otsuka and Yuuzou Kawahara
X. Peng et al., "Novel Electrodeposited Ni-Based Nanocomposite Precursors for Nitriding and Low Temperature Chromizing", Materials Science Forum, Vols. 522-523, pp. 331-338, 2006