Formation of a Calcium Phosphate Layer with Immobilized Cobalt Chromite Nanoparticles on Cobalt−Chromium Alloy by a Laser-Assisted Biomimetic Process

Abstract

The biocompatibility and osteoconductivity of metallic biomaterials can be achieved by calcium phosphate (CaP) coating. We recently developed a laser-assisted biomimetic (LAB) process for rapid and area-specific CaP coating on several materials. In the present study, the LAB process was applied to cobalt–chromium (Co−Cr) alloy, a metallic biomaterial widely used in orthopedic and dental applications. The LAB process was conducted by irradiation of unfocused pulsed laser light onto the substrate immersed in supersaturated CaP solution. The LAB-processed substrate formed CaP on the irradiated surface within only 5 min and was coated with a micron-thick CaP layer within 30 min by the effects of laser-induced surface modification and heating. Ultrastructural analysis with transmission electron microscopy revealed that the resultant CaP layer was integrated with the underlying substrate through two intermediate layers, an upper chromium oxide layer and a lower Co-rich (Cr-deficient) alloy layer. The CaP layer was loaded with a large number of cobalt chromite (CoCr2O4) nanoparticles. The results obtained offer new insights into the mechanism of CaP coating in the LAB process and future applications of LAB-processed Co−Cr alloys.

Direct Magnetic Reinforcement of Electrocatalytic ORR/OER with Electromagnetic Induction of Magnetic Catalysts

“…PVA was easily hydrolyzed in BA solution due to the formation of borate diol bonds. [ 30 ] After adding PTFE emulsion into the PVA‐BA solution, the PTFE quickly crosslinked with PVA to form stable sol. Finally, the addition of cobalt acetate endowed the stable sol with sufficient interactions in nanoscale to form complex network of PTFE·Co2+·PVA that ensured the uniformly distribution of cobalt in the system.…”

Microporous Organic Polymers: A Synthetic Platform for Engineering Heterogeneous Carbocatalysts

“…Notwithstanding, the carbonization of 2 contrarily caused nanofibers in 2 c exhibiting diameters ranging from 0.1 to 0.3 μm (Figure 2e), while cracked plates were found in 3 c (Figure 2f) as compared to the case of sulfur‐containing 2 c . Thermal transformation observed in 2 and 3 would be attributed to the elemental fusion of sulfur atoms into the carbon matrices through polycondensation, accompanied by the release of pyrolysis gases such as SO 2 or H 2 S at temperatures exceeding 500 °C, [28–30] and the formation of textured carbonaceous materials would be beneficial for manipulating the surface‐derived properties [31–34] . Moreover, high‐resolution transmission electron microscopy (HR‐TEM) revealed the formation of amorphous structures in the carbonaceous materials with no detectable impurities, as shown in Figure S3.…”

Regulating Capacitive Performance of Monolithic Carbon Sponges by Balancing Heteroatom Content, Surface Area and Graphitization Degree

“…Figure a shows that two broad peaks appear at 1370 cm −1 and 1620 cm −1 , corresponding to the D‐band and G‐band, respectively. The D‐band reflects the E 2g vibration mode of carbon atoms, and the G‐band is generated by the sp 2 ‐bonded carbon atoms in the materials . The D‐band to G‐band intensity ratio ( I D / I G ) is used to evaluate the graphitization degree of carbon materials .…”

“…Thus, electrode materials play an irreplaceable role in supercapacitors . Over the past years, diverse types of materials, such as carbonaceous materials, conducting polymers, transition metal oxides/hydroxides and hybrid composites, have been studied as supercapacitor electrodes . It is well known that the specific surface area is one of the most important factors for improving electric double‐layer capacitance, as the energy storage is directly proportional to the contact area between the electrode and electrolyte .…”