Development and characterization of ZnxCuyTizMo alloys for biomedical applications: A high-throughput gradient continuous casting approach.

The limited mechanical properties of pure Zn, such as its low strength and ductility, hinder its application as a material for biodegradable implants. Addressing this challenge, the current study focuses on the development of biodegradable Zn-based alloys, employing innovative alloy design and processing strategies. Here, alloys with compositions ranging from 0.02 to 0.10 weight percent (wt%) Cu, 1.22 to 1.80 wt% Ti, and 0.04 to 0.06 wt% Mo were produced utilizing a high-throughput gradient continuous casting process. This study highlights three specific alloys: Zn1.82Cu0.10Ti0.05Mo (HR8), Zn0.08Cu1.86Ti0Mo (HR7), and Zn1.26Cu0.13Ti0.06Mo (HR6), which were extensively evaluated for their microstructure, mechanical properties, electrochemical performance, potential as bioimplants, and cytotoxicity. These alloys were found to exhibit enhanced mechanical strength, optimal degradation rates, and superior biocompatibility, evidenced by in-vivo experiments with SD rats, positioning them as promising candidates for medical implants. This research not only introduces a significant advancement in biodegradable alloy development but also proposes an efficient method for their production, marking a pivotal step forward in biomedical engineering. STATEMENT OF SIGNIFICANCE: The limited mechanical properties of pure Zn have hindered its application in biodegradable implants. Our research primarily focuses on the alloy design and process strategies of biodegradable Zn-based alloys. We explore the ZnCuxTixMox alloys. This study introduces a high-throughput experimental approach for efficient screening of multi-component alloy systems with optimal properties. The ZnCuxTixMox alloys were designed and processed through gradient continuous casting, followed by homogenization and hot rolling. Our findings indicate that the Zn1.82Cu0.10Ti0.05Mo alloy demonstrates superior tensile, mechanical, and corrosion properties post hot rolling. The study suggests that Zn0.13Cu1.26Ti0.06Mo, Zn0.08Cu1.86Ti0Mo, and Zn1.82Cu0.10Ti0.05Mo alloys hold significant potential as biodegradable materials.

A novel fabrication method of copper-reduced graphene oxide composites with highly aligned reduced graphene oxide and highly anisotropic thermal conductivity.

Recently, metals with graphene and graphene oxide have been extensively used to enhance the mechanical and anisotropic thermal properties of composites. A novel facile fabrication approach of layer by layer self-assembly followed by hot press sintering was adopted to make copper-reduced graphene oxide composites. The microstructure and heat dissipation properties of pure copper and copper-reduced graphene oxide composites were analyzed with the help of SEM and continuous laser machine analysis. Thermal diffusivity of pure copper and copper-reduced graphene oxide composites was examined in different directions to measure the anisotropic thermal properties by using different volumetric percentages of reduced graphene oxide in the composites. Extraordinarily high anisotropic thermal conductivity of the copper-reduced graphene oxide composites was obtained at a very low concentration of 0.8 vol% reduced graphene oxide, with the difference between the thermal conductivity in-plane and through-plane being a factor of 8.82. Laser test results confirmed the highly anisotropic behavior of our copper-reduced graphene oxide composite with the remarkable property of heat dissipation. The three point bending test was also performed to check the flexural strength of the composites. At 0.6 vol% rGO, the flexural strength was noted (∼127 MPa), and it is 22% higher than that of pure sintered Cu. The high value of anisotropic thermal conductivity and higher flexural strength exhibited by the copper-reduced graphene oxide composite produced using a simple two-step fabrication method give us new hope to use these materials as heat sinks in thermal packaging systems.

Effect of surfactant concentration in electrolyte on the fabrication and properties of nickel-graphene nanocomposite coating synthesized by electrochemical co-deposition.

Long-time environmental protection of metallic materials is still required in the manufacturing and engineering applications. Nickel-graphene nanocomposite coatings have been prepared on carbon steel using sodium dodecyl sulfate (SDS) as a dispersant in the electrolyte by an electrochemical co-deposition technique. In this study, the effects of surfactants on graphene dispersion, carbon content in the coatings, surface morphology, microstructures, microhardness and corrosion resistance properties of the nanocomposite coatings are explored. The results indicate that the reasonably good graphene dispersion, coarser surface morphology and reduction in grain sizes are achieved upon increasing the surfactant concentration in the electrolyte. The surfactant also influences the preferred orientation of grains during electrodeposition; the (200) plane is the preferred orientation for the nanocomposite produced with SDS in the bath electrolyte. The microhardness, adhesive strength and corrosion performance of the nickel-graphene nanocomposite coatings are found to increase with the increasing concentration of sodium dodecyl sulfate in the deposition bath. Moreover, the influencing mechanism of surfactant concentration on the properties of nanocomposite coatings has been discussed.