De-Guo Wang

In Situ Observation of Wax-in-Oil Flow in Rough Soft Contact

AbstractnIn this study, a direct observation of the dynamic behaviors of wax-in-oil flow at the rough soft contact was conducted using the optical fluorescent technique. A contact area was produced between a sliding rigid glass plate and a stationary polyurethane elastomer ball. A mixture of wax in oil was used with 90xa0% silicon oil and 10xa0% paraffin wax by weight content. It was found that wax particles played an important role at the rough soft contact, which includes the accumulating process from the inlet region of the contact area and passes through at the central region. The behavior of the entrapped wax particles depends on the soft lubrication. Experimental results show that when the speed of sliding friction has a small value, the accumulation and passing through processes of wax particles occur more slowly at the soft contact interface. A major change occurs in the scratch-like lines when the sliding speed increases with rapid change of the conformity between the sliding soft surfaces.n

Frictional behaviors of rough soft contact on wet and dry pipeline surfaces：With application to deepwater pipelaying

Elastic rubbers are widely used in nature and engineering. In order to better understand soft rough contact under dry and wet conditions during deepwater pipelaying process, various polyurethane (PU) discs both in PU-pipe and PU-steel sliding combinations have been investigated by using self-developed tribometer. The tribological test results show that the friction coefficient can be clearly seen: PU90< PU80 < PU70, under dry conditions. Experimental results also indicate that the two dramatic increases of the frictional coefficient exist in the rough soft PU-pipe contact. The potential influence of asperities and thin liquid film is discussed.

Effects of alternating current interference on corrosion of X60 pipeline steel

With rapid economic development in China, demand for energy and transportation is growing. Due to the limitations of factors such as terrain and traffic, a large number of buried oil and gas pipelines are parallel to high-voltage transmission lines and electrified railways over long distances. Alternating current (AC) corrosion of pipelines is very serious in such cases. In this work, laboratory experiments were carried out with an electrochemical method in a simulated soil solution at various AC current densities from 0 to 200xa0A/m2 and AC frequencies from 10 to 200xa0Hz. Experimental results indicated that with an increase in the AC current density, the corrosion potential of an X60 steel electrode shifted negatively, the anodic current density increased significantly, and the corrosion rate increased. Moreover, with an increase in the AC frequency, the corrosion potential of the X60 electrode shifted positively and the anodic current density decreased, which led to a decrease in the corrosion rate. Furthermore, the morphology of X60 electrodes indicated that uniform corrosion occurred at a low AC current density; while corrosion pits were found on the X60 electrode surface at a high AC current density, and deep corrosion pits seriously damaged the pipelines and might lead to leakage.

Preparation and Tribological Behavior of PAH/PAA Molecular Deposition Films

PAH/PAA polymer multilayer ultrathin film was prepared by molecular deposition technology. The morphology and nano-tribological behaviors of the film were investigated by using atomic force microscope (AFM). It has been found that the friction force of the PAH/PAA polymer molecular deposition film is obviously less then that of the glass substrate, and the friction force increased with increasing load. However, the friction force decreased in the beginning and increased in the sequel with increase in the number of layers, which might be attributed to the change of surface topography with different layers. Moreover, it was found that the profile of both topography and lateral force has good coherence by analyzing the AFM images.Copyright