Yang Shengrong

Nano-tribological study on a super-hydrophobic film formed on rough aluminium substrates

A novel super-hydrophobic stearic acid (STA) film with a water contact angle of 166o was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine (PEI) film. The micro-tribological behavior of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces. The effect of relative humidity on the adhesion and friction was investigated as well. It was found that the STA monolayer showed decreased friction, while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area between the atomic force microscope (AFM) tip and the sample surface to be tested. Thus the friction and adhesion of the Al wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical composition. Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%, though the decrease extent became insignificant for the STA monolayer.

Tribochemical investigation of tungsten carbide/titanium alloy tribo-couples under aqueous lubrication

The present paper deals with the fundamental understanding on the tribochemical mechanism of tungsten carbide (WC) coating and titanium alloy tribo-couples system. The tribological experiments were performed with a Timken-type tester. Water containing water-soluble additives was employed as the lubricating media. The rubbed surfaces of the carbide coating were characterized with scanning electric microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Significant titanium transfer was observed. Results of XPS analyses show that the interfacial layers formed consist of multiple oxides which suggests that oxidative reactions predominate in frictional processes under aqueous lubrication. It is proposed that the oxide layer is responsible for the tribological behavior because it controls the diffusive and adhesive wear.

In situ triboreduction of organo-copper compound in titanium alloys tapping

Abstract In this paper, an organo-copper phosphate compound was synthesized and applied as a water-based lubricating additive in a tapping test of Ti–6Al–4V alloys. The results show that the Cu-containing compound plays an effective role in the metalworking. The machined surfaces were examined by scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. After Ar + etching, abundant metallic Cu was detected in the subsurface. This indicated that Cu(II) was reduced to Cu(0) via in situ triboreduction in the frictional process.

The tribological behaviors of various metallic cations in tapping of a titanium alloy

Abstract In this paper, various metallic cations, including Na + , K + , Ca 2+ and Ba 2+ , were introduced into water-based lubricating additives. Their tribological behaviors were investigated by the tapping test of a Ti-6Al-4V alloy. Among them, Ba-containing compound showed the best lubricating performance. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the surface morphology and chemical states of elements, respectively. It was found that the worn surface consisted of multiple oxides, which implies that tribooxidation predominated during the frictional process under aqueous lubrication. Furthermore, barium titanate (BaTiO 3 ) could be detected on the tapped surface, the existence of which was proposed to be responsible for its corresponding performance.

Effect of Compatibilization on Reciprocating Frictional Behavior of Polyamide 66/UHMWPE Blends

ABSTRACT The effect of compatibilization on the reciprocating frictional behavior of a polyamide 66 (PA66)/ultra-high molecular weight polyethylene (UHMWPE) blend was investigated. The influence of the amount of added maleic anhydride–grafted polyethylene (MAH-g-HDPE) on the phase morphology, compatibility, and viscoelasticity was explored using scanning electric microscopy (SEM), dynamic mechanical analysis (DMA), and capillary rheometry. In addition, the effect of MAH-g-HDPE on the reciprocating friction and wear performance of the PA66/UHMWPE blend was tested. The worn surface, transfer film, and wear debris were analyzed using SEM, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The results showed that the maleic anhydride groups in the MAH-g-HDPE improved the compatibility of PA66 and UHMWPE, and the addition of MAH-g-HDPE enhanced the interface bonding strength and lowered the polar difference between PA and UHMWPE. Therefore, the improved compatibility enhanced the wear resistance of the blend. During reciprocating sliding, UHMWPE transferred to the counterface prior to PA66 for the incompatible blend. The addition of MAH-g-HDPE promoted the adhesion and transfer of PA66 to the counterface.

花状O-MoS 2 添加剂的制备及摩擦学性能研究

利用一步水热法制备了氧并入二硫化钼(O-MoS 2 )纳米花，该纳米花由大量O-MoS 2 纳米片组装而成. 由于氧元素的并入，使得MoS 2 中(002)晶面间距从6.15 A增大至10.5 A. 利用SRV-I微振动摩擦磨损试验机考察了O-MoS 2 纳米花作为添加剂在PAO-8基础油中的摩擦学性能，结果表明：O-MoS 2 纳米花的加入可显著改善PAO-8油的减摩抗磨性能，这主要是由于膨胀的层间距有利于MoS 2 沿(002)晶面发生滑移. 其中，当O-MoS 2 纳米花的添加含量为0.1 mg/mL时，润滑油的抗磨损性能最佳.