Papers by Author: Bao Yu Song

Abstract: In this article, a new type of visualizer for point contact flow field has been developed. The principle, constitution and application are introduced in details. The flow field of point contact area are captured and analyzed.

Abstract: In order to get PTFE(polyfluortetraethylene) composites of good friction and wear properties used in vacuum and low temperature conditions, do the tribological experiments of GF (glass fibre)/PTFE composites under vacuum and low-temperature environment. The results show that: with the increase of the GF size, the friction coefficient increases, with the increase of GF content, the friction coefficient increases.

Abstract: In order to generate electricity by converting wave energy into mechanical energy, a buoy-type wave energy generating device is designed, it includes overall design, reversing gearbox design and buoy design. The test stand of wave simulation is set up and the rationality of generating device is verified by generating experiment.

Abstract: Mechanical seal plays a very important role in rotating machinery for space exploration, but it is very difficult to estimate its friction performance by simulative experiment. In this paper, a experimental system for measuring friction properties of mechanical seal materials used in spacecraft is developed. It is able to provide some adjustable parameters in the experiment, such as environment temperature -60°C~60°C, load 100N~300N, rotational speed of 30r/min~110r/min and atmospheric pressure and high vacuum. Friction coefficients of babbitt graphite M120B and hard alloy YG6 are obtained by the test rig and the experimental results testify that the device can conduct simulative experiment effectively.

Abstract: Ultra-high strength boron steel is widely used in a new hot stamping technology which is hot formed and die quenched simultaneously in order to obtain stamping parts with 1500MPa tensile strength or higher. Tensile experiments were carried out with ultra-high strength boron steel in a range of temperature 500°C~860°Cand strain rate 0.01/s~1/s with the thermal simulation testing machine Gleeble 3800, and the stress-strain curves were obtained. The influences of the deformation temperature and strain rate on the stress-strain curves were analyzed. The results show that hot behavior at elevated temperature of ultra-high strength boron steel consists of strain hardening and dynamic recovery mechanism, which can be accurately described by the mathematic model. Keywords: Ultra-high strength boron steel, hot stamping, hot flow behavior

Abstract: In order to investigate the life of bearings lubricated by solid lubricant (BLSL), which are installed in the rotational parts of spacecraft, a test platform has been developed. The platform can test the life of BLSL working under the vacuum environment with high-low temperature cycle conditions. The test platform consists of three systems of loading, measurement, and power and speed control. A corresponding computer program was also developed to measure, monitor and record test data. The working life of deep groove ball bearings lubricated by MoS₂ solid lubricant was tested in 5×10^-4Pa vacuum. The surface observation and analysis for the damage condition of the failed bearings were also conducted.

Abstract: The effect of nano-calcium carbonate particles as additives on the titanium complex grease was investigated in this paper. Tribological properties of the titanium complex grease containing nano-calcium carbonate were evaluated with a four-ball tester. The morphology of wear scar of steel ball was observed using the sweep electron microscope. The chemical states of typical elements on the wear scars of steel balls were analyzed by means of the X-ray photoelectron spectroscopy. The results showed that the titanium complex grease including 3% or 5% nano- calcium carbonate has better antifriction and antiwear properties. The nano-calcium carbonate particles through generating calcium oxide and adsorption to form a protective film effectively inhibited the adhesive wear and contact fatigue of the friction surface to reduce wear.

Abstract: In order to investigate the material and lubrication of the moving parts of a space probe, a sliding frication tester was developed under vacuum and cryogenic environment. The tester includes the following four parts: driving system, loading system, measuring system and refrigerating system. A computer program was also developed to acquire and record the experimental data. Friction coefficients of component pairs of material GCr15-GCr15 were tested in different environments on the tester. The results show that in terms of the friction coefficient and life of the friction pair under vacuum and low temperature environment, the pairs with vacuum grease are far better than that without grease. The tester meets the design requirements.

Abstract: Tribological properties of the urea grease containing nano-silica were investigated with a four-ball tester, and its noise characteristics were evaluated with a BVT-1 bearing vibration tester. The results showed that the nano-silica has good effects on friction and wear resistances, the urea grease with 3% nano-silica has the least value of friction coefficient, and the urea grease with 2% nano-silica showed the best wear resistance. A proper amount of nano-silica can decrease the noise of the urea grease, and when lubricated by the grease with 1% nano-silica, the bearing achieved its lowest noise level as well as the best velocity values of both intermediate and high frequencies.

Abstract: The pressure-viscosity relationships of phosphate synthetic oil and other two kinds of similar atmospheric viscosity synthetic oils were studied using ultra-high pressure capillary viscometer. The pressure-viscosity relationship of phosphate synthetic oil is much better than the other two kinds of synthetic oils. The impact of pressure on viscosity is not limited to purely physical factors. The pressure can cause a variety of chemical reactions in some cases. The investigation results of mechanochemistry of phosphate synthetic oil at high pressure reveal that the physical state of phosphate synthetic oil changed from liquid into glassy amorphous state under high pressure, and the color varied from transparent into milky white. The mechanochemistry of phosphate synthetic oil was analyzed using the infrared spectroscopy and gel permeation chromatography, and the results indicate that under high pressure, the oxidation reaction of phosphate synthetic oil occurred, and the molecular weight distribution changed with the increase of the low molecular weight region. The reason of the mechanochemistry phenomena was that phosphate synthetic oil molecular chain disconnects to inform great radical. The great radical has strong activity, and reacts with other free radicals acceptor (oxygen, etc).