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Monocrystalline Cu nanocolloid with 4.3 nm average particle size and 2.3～9.5 nm particle size distribution was successfully synthesized in situ by liquor-phase reduction synthesis, using copper acetate tetrahydrate as precursor, ascorbic acid as reductant, polyethylene sorbitan monooleate （Tween-80） as modifier, and liquid paraffin as solvent. The as-prepared copper nanocolloid was characterized by XRD, SAED, and TEM. Nano-lubricating oil with excellent dispersibility, chemical stability, and compatibility with other additives verified by TG-DSC, was achieved via adding as-prepared nano-copper into Mobil 1 5w-30 lubricating oil. The nano-lube’s physiochemical properties were characterized according to Chinese national standard. The tribological behavior of nano-lubricant was investigated on ball-on-disk UMT-Ⅱ tribometer and four-ball tribometer. The worn surface morphology was analyzed by means of SEM and EDS. Experimental results show as follows. The Mobil 1 5w-30 lube’s tribological property is markedly enhanced with the as-prepared copper nanocolloid as its additive. The as-prepared nano-Cu agglomerate discontinuous deposited, extrude, melt, spread, and form a film in micro-defects on the worn surfaces, then improve the friction-reducing, anti-wear ability, extreme pressure value, and extreme working ability of Mobil 1 5w-30 lubricant.

To synthesize morphology- controlled nano- copper with excellent lubrication properties as lubricant’s additive, chemical reduction synthesis method was used coalescing in situ via liquid paraffin as resolvent and modification with polyethylene glycol (PEG-2000). The as- prepared Cu nanopieces with 35.59 nm average length and 21.03 nm average width were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The tribological behavior of Mobil 1 5W-30 lubricating oil with nano- Cu were measured by ball- on- disk UMT- Ⅱ tribometer and analyzed by SEM and EDS. It is found that the tribological performance of Mobil 1 5W- 30 with nano- Cu is improved, and the optimization addition is 0.4% (Cu wt) with the lowest friction coefficient.

In order to synthesize morphology and structure-controlled nano-copper, chemical reduction synthesis method was used coalescing microwave-assisted and modification. Cu nanowires with diameters of 20 to 25nm and lengths of 1.2 to 2.1μm were yielded by reduction of copper acetate tetrahydrate of (1, 2)-propanediol system using ascorbic acid as a reductant, polyethylene sorbitan monooleate (Tween 80) as a modifier and by microwave-assisted heating. The microstructure of these nanowires has been characterized by XRD and TEM. The XRD patterns indicate that the lattice parameters of these Cu nanowires are enlarged about 1.162% while the lattice parameters of Cu nanospheres are reduced about 1.024%. The growth mechanism of Cu nanowires is also suspected. The anti--wear and reducing friction performance of liquid paraffin with either Cu nanowires or Cu nanospheres has been measured by ball--on--disk UMT--II tribometer. It is found that the tribological performance of liquid paraffin with nano-Cu is improved, and the enhancement of improvement with Cu nanowires is better than with Cu nanospheres.

High density brine drilling fluid has been widely applied in the high pressure and complex oil and gas fields. Effectively controlling high density brine drilling fluid loss is an important factor for reducing the reservoir damage and keeping well stability. Base on general drilling fluid formulations，the affecting factors of filtrate loss of high density brine drilling fluid were analysed through mass laboratory experiments. The results show that the main fctor was the content of caustic soda and bentonite, secondly the density and the shape of adding product. The combination of adding product is one of effective method to control the filtration property of high density brine drilling fluid. The results will provide reliable foundation for successful field application.

Fatigue failure of gears carrying heavy loads is the leading cause of gearbox breakdown in the large-scale earthmoving machinery. The fatigue life of gear is mainly determined by loads distribution. Taking the Wheel Loader as an example, this paper introduced an indirect test system of gear load under the loose soil conditions. Then the load data in time, amplitude and frequency field were respectively analyzed. The results show that the indirect measurement method proved workable, and the load data of gear is characterized by bi-modal. Therefore, to decrease statistical errors, mixture model must be adopted to fit these bi-modal signals.