Xin Shao

Synthesis, Characterization, and Tribological Behavior of Oleic Acid–Capped Calcium Borate Hydrate

In this article, a series of calcium borate, molecular formula 4CaO·5B2O3·7H2O (CB), was hydrothermally synthesized using borax and calcium nitrate. Furthermore, a of oleic acid–capped calcium borate (OAMCB) was prepared and characterized by means of Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), thermogravimetry (TG), and X-ray diffraction (XRD). In addition, the friction and wear properties of OAMCBs as additives in poly-alpha-olefin (PAO) were investigated using Cu-Cr-Zr alloy–AISI 52100 steel couples. Our results showed that the OAMCB improved the friction and wear by forming an interfacial boundary lubrication layer.

Synthesis, characterization and tribological behavior of oleic acid-capped core-shell lanthanum borate-SiO2 composites

Purpose – The purpose of this paper is to investigate the tribological properties of poly-alpha-olefin (PAO) with nano/microstructure core-shell lanthanum borate-SiO2 composites (OCLS). Design/methodology/approach – Oleic acid-capped core-shell lanthanum borate-SiO2 composites were synthesized by an easy way. The composites were characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). The friction and wear behaviors of the quenched AISI 1045 steel specimens sliding against AISI 52100 steel under the lubrication of PAO containing OCLS were comparatively investigated with PAO containing SiO2 additive on an Optimol SRV reciprocating friction and wear tester. On the other hand, the tribological properties of the PAO containing OCLS were also investigated on four-ball tester. Findings – The diameter of OCLS was about 20 nm, and the thickness of the SiO2 shell was less than 5 nm. The ratio of oleic acid (OA) is about...

The Electrical conductivities and Tribological properties of Vacuum Hot-Pressed Cu/Reduced Graphene Oxide Composite

The nanoscale reduced graphene oxide/copper (rGO/Cu) pellets were synthesized by reducing aqueous solution of graphene oxide and CuSO4. The Cu/rGO composite disks with high conductivity were fabricated by a vacuum hot-pressing sintering method. The composites were characterized by transmission electron microscopy, field emission scanning electron microscopy, x-ray diffraction. The results show that the vacuum hot-pressing sintering process can produce Cu/rGO composite successfully. The conductivities and wear resistance of the sintered Cu/rGO disks are improved, respectively, as rGO nanosheets being added into the matrix and/or increasing sintering temperatures, which are attributed to the destruction of the pores and the increasing compactness.

Preparation and electrical properties of sintered copper powder compacts modified by polydopamine-derived carbon nanofilms

In this study, copper (Cu)/polydopamine (PDA) composite was fabricated by vacuum hot-press sintering of micrometer-sized Cu particles covered with PDA film tailored at the nanometer scale thickness. The resultant compacts exhibited much higher electrical conductivity than the uncoated counterparts. Analyses of sintered samples using scanning and transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy revealed the conversion of PDA into carbonized PDA (cPDA). The increased mass density and grain growth are likely responsible for improved electrical conductivity of the composite material.