Making a tantalum carbide (TaC) coating on Ta substrates is an effective way to improve the mechanical and anti-corrosion properties of Ta. However, conventional methods for making a TaC coating require high-temperature conditions of over 1600 °C to get a TaC thickness of > 20 μm. Herein, a TaC coating of > 20 μm thickness was prepared on a Ta substrate in molten CaCl 2 -CaC 2 at 850 °C for 4 h. In the molten salt electrolyzer, the Ta plate served as the anode where C 2 2− was oxidized and simultaneously reacted with Ta to form a TaC layer, and Ca 2+ was reduced and alloyed with C to form CaC 2 that can replenish the C 2 2− . The electrolytic TaC exhibited an average hardness of 962 HV that was 6 times of the bare Ta substrate. In the 3.5 wt% NaCl solution, the TaC coating displayed a higher corrosion potential and lower corrosion current density (0.48 V, 1.59 μA cm −2 ) than Ta substrate (0.35 V, 1.85 μA cm −2 ) and the mixtures of TaC and Ta 2 C (0.35 V, 1.78 μA cm −2 ), indicating its better corrosion resistance. The molten salt anodic carbidation may lead to a general way to prepare transition metal carbide coatings with enhanced carburizing kinetics at < 1000 °C. Graphical abstract
Jing Zhan,Li Li,Lili Yao,Zheng Cao,Weiwei Lou,Jianying Zhang,Jinsong Liu,Litao Yao
Modifying the drug-release capacity of titanium implants is essential for maintaining their long-term functioning. Titanium dioxide nanotube (TNT) arrays, owing to their drug release capacity, are commonly used in the biomaterial sphere. Their unique half open structure and arrangement in rows increase the drug release capacity. However, their rapid drug release ability not only reduces drug efficiency but also produces excessive local and systemic deposition of antibiotics. In this study, we designed a tantalum-coated TNT system for drug-release optimization. A decreased nanotube size caused by the tantalum nanocoating was observed through SEM and analyzed (TNT: 110 nm, TNT-Ta1: 80 nm, TNT-Ta3: 40 nm, TNT-Ta5: 20 nm, TNT-Ta7: <5 nm). XPS analysis revealed the distribution of the chemical components, especially that of the tantalum element. In vitro experiments showed that the tantalum nanocoating enhanced cell proliferation; in particular, TNT-Ta5 possessed the best cell viability (about 1.18 of TNT groups at 7d). It also showed that the tantalum nanocoating had a positive effect on osteogenesis (especially TNT-Ta5 and TNT-Ta7). Additionally, hydrophilic/hydrophobic drug (vancomycin/raloxifene) release results indicated that the TNT-Ta5 group possessed the most desirable sustained release capacity. Moreover, in this drug release system, the hydrophobic drug showed more sustained release capacity than the hydrophilic drug (vancomycin: sustained release for more than 48 h, raloxifene: sustained release for more than 168 h). More importantly, TNT-Ta5 is proved to be an appropriate drug release system, which possesses cytocompatibility, osteogenic capacity, and sustained drug release capacity.
危险品化学品经营许可证（带存储）