Effect of Different Contents of WC on Microstructure and Properties of NiCrMo Coatings Prepared by PTA

During the service process of the mechanized fishing boat, its low carbon steel hull and parts are extremely susceptible to Cl− erosion and seawater scouring, which cause a decrease in strength and lead to failure. To increase its service life and reduce maintenance costs, coating protection technology is widely used. In order to solve the problem of poor adhesion between paint coating and substrate and low strength of metal coating, NiCrMo-WC coatings with different WC contents (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) were prepared on the surface of Q235 substrate by plasma cladding technology. The coatings were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy spectrum analysis (EDS), etc. Its phase formation rule, microstructure and element distribution were studied. Microhardness test and electrochemical corrosion test were carried out. The study found that the 20 WC coating has the highest average hardness (563.1 HV). It is about 3.25 times of the Q235 substrate. It has the lowest friction, wear rate and lower friction coefficient, showing the best wear resistance. The 15 WC coating has the lowest self-corrosion current density (3.4934 × 10−7 A/cm2) and the lowest corrosion rate (0.0041 mm/a), which is only 3.7% of the corrosion rate of Q235 steel

The Stimulation of Macrophages by Systematical Administration of GM-CSF Can Accelerate Adult Wound Healing Process

Skin wound repair remains a major challenge in clinical care, and various strategies have been employed to improve the repair process. Recently, it has been reported that macrophages are important for the regeneration of various tissues and organs. However, their influence on wound repair is unclear. Here, we aimed to explore whether macrophages would participate in the wound healing process and to explore new possibilities of treatment for skin defects. We firstly created a mouse full-thickness skin defect model to observe the distribution of macrophages in the regenerating tissue and then detected the influence of macrophages on skin defect repair in both macrophage-depletion and macrophage-mobilization models. We found that the number of macrophages increased significantly after skin defect and persisted during the process of wound repair. The regeneration process was significantly prolonged in macrophage-depleted animals. RT-qPCR and ELISA assays further demonstrated that the expression of growth factors was perturbed in the regenerating tissue. The activation of macrophages by granulocyte-macrophage colony-stimulating factor (GM-CSF) injection could significantly improve wound healing, accompanied with an upregulation of the expression of various growth factors. In conclusion, the current study demonstrated that macrophages are critical for skin regeneration and that GM-CSF exhibited therapeutic potential for wound healing

Evaluation of TG202 inhibitor for tubing steels in 15% hydrochloric acid by electrochemical noise technology

Acid fracturing is an effective technology for increasing oil and gas production. However, the acid will cause serious corrosion to the tubing. In this paper, the inhibition performance of the TG202 inhibitor for acidizing of high temperature and high-pressure gas wells on N80 carbon steel and 13Cr martensitic stainless-steel tubing in 15% hydrochloric acid was studied by electrochemical noise technology. The results showed that with the increase of TG202 inhibitor content, the noise resistance increased and the corrosion rate of tubing steel decreased. Under the same condition, the order of corrosion rate of tubing steels: 13Cr > HP-13Cr > N80 > P110. The pitting corrosion of HP-13Cr and 13Cr is significant. The research showed that the TG202 inhibitor had a protective effect on tubing during acidizing. The inhibition mechanism of the TG202 inhibitor was discussed

Spontaneous polarization of ferroelectric heterostructured nanorod arrays for high-performance photoelectrochemical cathodic protection

Corrosion is a critical global problem for the steel industry and a grand challenge toward Net-Zero clean growth. TiO2 nanorods (TNRs) have been developed for photoelectrochemical cathodic protection (PCP) of coupled metal. However, the performance was hindered by their wide bandgap, weak visible-light response, and low separation efficiency of photocarriers. In this work, a unique multilayered coaxial nanorod array (TNRs/BTO/Ag NPs) structure has been proposed to enhance ‘hot’ electrons injection via inserting a ferroelectric semiconductor BaTiO3 (BTO) nanolayer between TNRs and Ag nanoparticles (Ag NPs). The spontaneous ferroelectric BTO nanolayer built a polar charge-induced electric field (PEF), resulting in a strong spontaneous polarization. Furthermore, the as-proposed structure can negatively shift the surface potential of the coupling 304 stainless steel by 0.80 V relative to its corrosion potential under simulated solar light illumination which is the record PCP potential among reported works. Based on comprehensive electrochemical and theoretical studies, the origin of the enhanced photo-generated carriers’ separation and depletion to the coupled metals is attributed to a synergic effect between PEF (the spontaneous polarization of BTO) and internal electric field (IEF) resulting from the cascade energy band alignment. Various promising applications can be envisioned from as-proposed multilayered coaxial nanorod array photoelectrodes

Towards energy level cascaded “quantum armours” combating metal corrosion

Stainless steels typically feature high toughness and good corrosion resistance. However, pitting corrosion can easily occur on stainless steel and the passivation film tends to be vulnerable under pressure or in brine environments. Metal corrosion is a long-standing challenge for the steel industry, forging a path to net-zero. Herein, by successive growth of a series of quantum confined nanocrystals such as quantum dots and nanorods with gradient band energy level alignment, high-performance photoelectrochemical cathodic protection for steel is demonstrated with remarkable mechanical and electrochemical stability. Under simulated solar light illumination, effective photoinduced protection can be realized for 304 stainless steel which enables long-term corrosion resistance in a 3.5 wt% NaCl solution. Unique nanotree-like structures and the quaternary material combination can store excess charges and release them gradually, enabling time-delay protection for metals after light excitation. Various promising functionalities as unique photoelectrodes can be envisioned arising from the proposed 3D nanotree morphology

Influence of Mussel-Derived Bioactive BMP-2-Decorated PLA on MSC Behavior in Vitro and Verification with Osteogenicity at Ectopic Sites in Vivo

Osteoinductive activity of the implant in bone healing and regeneration is still a challenging research topic. Therapeutic application of recombinant human bone morphogenetic protein-2 (BMP-2) is a promising approach to enhance osteogenesis. However, high dose and uncontrolled burst release of BMP-2 may introduce edema, bone overgrowth, cystlike bone formation, and inflammation. In this study, low-dose BMP-2 of 1 μg was used to design PLA-PD-BMP for functionalization of polylactic acid (PLA) implants via mussel-inspired polydopamine (PD) assist. For the first time, the binding property and efficiency of the PD coating with BMP-2 were directly demonstrated and analyzed using an antigen–antibody reaction. The obtained PLA-PD-BMP surface immobilized with this low BMP-2 dose can endow the implants with abilities of introducing strong stem cell adhesion and enhanced osteogenicity. Furthermore, in vivo osteoinduction of the PLA-PD-BMP-2 scaffolds was confirmed by a rat ectopic bone model, which is marked as the “gold standard” for the evidence of osteoinductive activity. The microcomputed tomography, Young’s modulus, and histology analyses were also employed to demonstrate that PLA-PD-BMP grafted with 1 μg of BMP-2 can induce bone formation. Therefore, the method in this study can be used as a model system to immobilize other growth factors onto various different types of polymer substrates. The highly biomimetic mussel-derived strategy can therefore improve the clinical outcome of polymer-based medical implants in a facile, safe, and effective way