H. Lv, J. Wang, C. Zhai, F. Li, B. Sun, Shanghai Jiao Tong University, Shanghai, China
Thermal spray coatings of new MoB/CoCr cermets were developed. The mechanical behaviors of HVOF-Sprayed MoB/CoCr novel composite coatings were evaluated via Vickers microhardness. Microstructure of the coatings on 316L stainless steel substrates, as well as powders, were studied with optical microscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD). X-ray microanalysis of the coatings were carried out using energy dispersive x-ray spectrometer (EDS) attached to the SEM. The distribution of microhardness values of the coatings were analyzed via Weibull statistic, Weibull analysis revealed bimodal distribution of Vickers microhardness values. Such distribution was attributed to the presence of melted and unmelted phases in the resultant coating produced from the microstructured powder feedstock. The excellent mechanical properties are due to the MoB/CoCr powder and coatings consist of complex ternary transition metal boride as hard particles, which has many exceptional mechanical properties.
Summary: The mechanical behaviors of HVOF sprayed MoB/CoCr cermet coating is evaluated by Vickers microhardness. The distribution of microhardness values of the coating is analyzed by Weibull statistics. The pores of the MoB/CoCr coating is studied using Mercury Intrusion porosimeter (MIP). The Weibull analysis revealed unimodal distribution of Vickers microhardness values. The indentation analysis illustrates anisotropic hardness of the as-sprayed coating, the cracks are parallel to the substrate. The pores of MoB/CoCr coating generally appear to be of equal size and show a very homogeneous distribution.
