Geometric Influence of Hard Phase on Corrosion Performance between WC-Reinforced Coatings Prepared by High-Velocity Oxygen-Fuel Spray and Electric Contact Strengthening

Several kinds of WC-reinforced coatings were prepared by high-velocity oxygen-fuel spray (HVOF) and electric contact strengthening (ECS), respectively, and their corrosion behaviors in 3.5% NaCl solution were investigated. The microstructure, element distribution, phase and corrosion resistance of these coatings were compared. The results showed that, compared with HVOF-sprayed coatings, the ECS-prepared coatings were denser and with lower porosity. Simultaneously, the ECS coatings that used raw powder commercial WC-12Co retained the original spherical geometry of the hard phase. In open-circuit potential measurements, these ECS coatings gave higher stable potentials (Eocp). In potentiodynamic polarization tests, although the corrosion currents (icorr) of the homogeneous coatings were approximately the same, these ECS coatings still exhibited higher corrosion potentials (Ecorr). The spherical geometric distribution of the hard phase led to a bounded diffusion model caused by the diffusion change of corrosion products

The subcellular localization of Ca-HMGB.

<p>A–C: Before RLO challenge. D–F: After RLO challenge. A, D: Immunostaing hemocyte with anti-HMGB; B, E: Imaging of nuclei using the nucleic acid stain DAPI; C, F: Merged.</p

mRNA expression levels of LITAF, Myd88, TGFβ and AIF-1 in hemocyte monolayers.

<p>Samples were collected at 0, 1.5, 4, 8 and 12 h after Ca-HMGB protein (1 ug/ml) incubation. Expression levels were assessed by real-time RT-PCR and seawater-incubated groups were used as controls. Expression levels were assessed using 28SrDNA gene for normalization. *p≤0.05 when compared to control value. (A) LITAF; (B) Myd88; (C) TGFβ; (D) AIF-1.</p

SDS-PAGE and western blotting analysis of Ca-HMGB.

<p>(A) SDS-PAGE analysis of pET32a-Ca-HMGB expressed in <i>E. coli Rossetta</i> (DE3. M, Protein mark; 1, No induction; 2, 0.5 mM IPTG induction; 3, Purified Ca-HMGB. (B) Western blotting analysis of anti-CaHMGB (1∶5000). 0, pre-immunized rabbit serum; 1, anti-CaHMGB.</p