Chengbiao Wang

TL;DR: In this article, the magnetic and dielectric properties of the as-prepared Ni-Zn ferrites were investigated using X-ray diffraction data, showing that the saturation magnetization and the coercivity increased with increasing substitution level, x, and the Curie temperature fluctuating between 308 and 320°C.

TL;DR: In this article, the microstructural and electrical properties of ZnO-Pr 6 O 11 based varistors, which are composed of different doping amounts of TiO 2, were investigated through X-ray diffraction and scanning electron microscopy analyses.

TL;DR: In this article, a new kind of sulfur and phosphorus-free organomolybdenum oil-based additive N, N-bis (2-hydroxyethyl)-dodecanamide molybdate (NNDM) was prepared.

TL;DR: In this article, an amphiphilic comb-like terpolymer (PASA) was used as a viscosifying additive for low-solid drilling fluid under high temperature and salinity.

Abstract: A series of tungsten-gradually doped diamond-like carbon (DLC) films with functionally graded interlayer were prepared using a hybrid technique of vacuum cathodic arc/magnetron sputtering/ion beam deposition. With ‘compositionally graded coating’ concept, the deposition of wear-resistant carbon-based films with excellent adhesion to metallic substrate was realized. In the films, a functionally graded interlayer with layer sequence of Cr/CrN/CrNC/CrC/WC was first deposited onto the substrate, and then, a DLC layer doped with gradually decreasing content of W was coated on. The W concentration gradient along depth of the film was tailored by adjusting the W target current and deposition time. The characterized results indicate that the microstructural, mechanical and tribological properties of these films show a significant dependence on the W concentration gradient. A high fraction of W atom in carbon matrix can promote the formation of sp 2 sites and WC 1 − x nanoparticles. Applying this coating concept, strongly adherent carbon films with critical load exceeding 100 N in scratch test were obtained, and no fractures or delaminations were observed at the end of the scratched trace. The hardness was found to vary from 13.28 to 32.13 GPa with increasing W concentration. These films also presented excellent tribological properties, especially significantly low wear rate under dry sliding condition against Si 3 N 4 ball. The optimum wear performance with friction coefficient of 0.19 and wear rate of 8.36 × 10 −7 mm 3 /Nm was achieved for the tungsten-gradually doped DLC film with a graded W concentration ranging from 52.5% to 17.8%. This compositionally graded coating system might be a potentially promising candidate for wear-resistant carbon-based films in the demanding tribological applications.