Fabrication of Polycrystalline Cubic Boron Nitride/Metal Composite Particles by Surface Metallization Followed by Electroless Deposition Technique

Polycrystalline cBN/copper composite abrasive particles were prepared by an electroless powder coating process. Ti metallization and tin/silver metallization techniques were used to improve the coating process by depositing an autocatalytic metallic layer on the surface of the cBN particles. Metallized, as well as un-metallized, cBN particles were further coated by copper using electroless deposition. Electroless copper coating of un-metallized and metallized cBN particles by 90 wt.% of copper were achieved. The surface morphology, the composition and the crystalline phase identifications of the metallized cBN particles, as well as the 10 wt.% cBN /copper composite powders, were investigated by field emission scanning electron microscopy, an energy-dispersive spectrometer and an X-ray diffractometer. The results show that the surface of the Ti metalized and tin/Ag-metallized cBN particles were covered by the nanosized Ti or Ag layer, respectively, which enhanced the deposition of the copper during the electroless deposition bath. The results also showed that the deposited layer on the metallized cBN particles was composed mainly of metallic copper. The produced 10 wt.% cBN/copper composite particles also underwent thermo-gravimetric analysis to investigate its stability at high temperature. It was revealed that the Ti-metallized cBN/copper composite powder has higher stability at 800 °C under the environmental conditions than the tin/silver-metallized and the un-metallized cBN/copper composite particles, respectively.

Wide Range Responsivity Photodetector of Zr-Au-Ag Oxide NPs Prepared By Pulsed Laser Ablation

Metal-ceramic composite particles are of increasing interest due to their potential applications in photodetectors as well as next-generation catalysts. The zirconium-gold system has received little attention due to the lack of controllable preparation methods. Well-known methods for the deposition of gold Nano shells on zirconium spheres, however, should be adaptable for similar zirconium-based materials. Here, we present a method to synthetic approach to the well-controlled deposition of gold on the surface by laser ablation. The results shed light on the parameters governing the preparation of zirconium _ gold composite particles and our synthetic approach provides a promising tool for future developments in complex nanomaterials design. As well as studying the structural and optical properties of gold, silver and zirconium nanoparticles by preparing those particles in the above method and studying the properties of the resulting materials as a photodetector. The surface morphology, structure, and composition of the layer were studied using a variety of spectroscopic diffraction and real-space imaging techniques, including SEM, EDX and AFM.

Synthesis of Silver Nanoparticles–Chitosan Composite Particles Spheres and Their Antimicrobial Activities

Synthesis of silver nanoparticles–chitosan composite particles sphere (AgNPs-chi-spheres) has been completed and its characterization was fulfilled by UV–vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and zetasizer nano. UV–vis spectroscopy characterization showed that AgNPs-chi-spheres gave optimum absorption at a wavelength of 410 nm. The XRD spectra showed that the structure of AgNPs-chi-spheres were crystalline and spherical. Characterization by SEM showed that AgNPs-chi-spheres, with the addition of 20% of NaOH, resulted in the lowest average particle sizes of 46.91 nm. EDX analysis also showed that AgNPs-chi-spheres, with the addition of a 20% NaOH concentration, produced particles with regular spheres, a smooth and relatively nonporous structure. The analysis using zetasizer nano showed that the zeta potential value and the polydispersity index value of the AgNPs-chi-sphere tended to increase with an increased NaOH concentration. The results of the microbial activity screening showed that the AgNP-chi-Spheres with highest concentration of NaOH, produced the highest inhibition zone diameters against S. aureus, E. coli, and C. albicans, with inhibition zone diameters of 19.5, 18.56, and 12.25 nm, respectively.

Energetic and magnetic directional aggregation properties of KPA@Fe3O4 composite particles prepared via a microcrystalline co-precipitation route

The development of new electromagnetic interference materials has attracted much attention in the information warfare. Herein, a novel KPA@Fe3O4 composite particle was synthesized via a microcrystalline co-precipitation method. X-ray diffractions, scanning electron microscopes and vibrating sample magnetometer measurements were used to characterize the products. The results indicated that the surface of the potassium picrate (KPA) crystals was covered by magnetic Fe3O4 nanoparticles, and composite particles exhibited excellent magnetic properties. Furthermore, the thermal behavior of the composite particles was investigated by differential scanning calorimetry, which showed that the composite particles inherited the energetic property of pure KPA crystals when the mass fraction of magnetic component was 50%, or 65%. As for the composite particles with 75% magnetic component, the thermal stability of was poor. In addition, the magnetic directional aggregation performance of composite particles was analyzed by dynamic simulation, which moved toward the magnetic source. For the composite particles with 50% magnetic component, the maximum concentration was about 63 times of the initial concentration, and the peak velocity was 0.63 m/s. With the mass fraction of magnetic component increasing to 65%, the concentration and velocity of the composite particles generally increased at the corresponding moment. As the mass fraction of magnetic component increased to 75%, the change of them was not obvious. Therefore, the composite particles with Fe3O4/KPA mass ratios of 65/35 had the best comprehensive properties. The excellent energetic and magnetic directional aggregation properties can allow the composites to be used in many potential applications in the information warfare.