Papers by Author: Mu Sen Li

Abstract: Failure analysis on the GCr15 bearing steel and the 20CrMo carburized steel nuts was performed after two sets of fatigue tests of GD8020×1100 ball screw pair. By means of scanning electron microscopy observation, energy dispersive analysis and microhardness testing, it is found that there is an obvious indentation, slight pitting and microcracks on the raceway of the GCr15 bearing steel nut and shows the characteristics of contact fatigue failure. The nonuniformity of microstructure and the lower carbon and chromium content in the indentation, leading to local lower hardness, account for the nut failure. While the raceway of the 20CrMo carburized steel nut is more rough with scratches caused by the damaged steel balls so as to show the characteristics of wear failure. Therefore there are different failure ways for the different nuts made by different steels and heat treatments under the same fatigue testing condition.

Abstract: By means of chemical composition testing, scanning electron microscopy observation, metallographic observation and hardness gradient detection etc, analysis of the typical failure samples from a well-known brand GD8020×1100 ball screw unit in the fatigue test was carried on. Results show that there is no obvious surface wear of the ball screw, showing the normal contact fatigue failure. But severe surface wear happens on the raceway of nut A with obvious flaking and many local cracks; which is the main reason leading to the failure of ball screw unit. So effective measures to avoid earlier failure of the ball screw unit can be put forward by controlling the steel quality strictly and improving the hardness and depth of the hardened layer on the raceway of nut A.

Abstract: Ag nanoparticles (NPs) had most prominent local surface plasma resonance effect (LSPR) among the all metals. Diamond-like carbon (DLC) film had good biological compatibility, wear resistance, corrosion-resisting and high transmission ability in the visible and near-infrared range. Since the Ag NPs were easily oxidized in air,a new LSPR interface between them and an ultra-thin DLC films was formed by means of a plasma enhanced chemical vapor deposition (PECVD). The morphologies and properties of the Ag NPs deposited ultra-thin DLC films were studied by using Raman spectrometer, X-ray photoelectron spectrometer (XPS) , field emission scanning electron microscope (FESEM) and atomic force microscope (AFM) and so on. And the optical tramsmission sensitivity of the new LSPR interface was also examined. The results indicated that the DLC films deposited in a shorter time had a higher sp³ bond content of carbon atoms and more sensitive to refractive index of surrounding media. Moreover, to obtain the optimal morphologies and the sensing property, the deposition time for forming the DLC films should be controlled within 30 seconds.

Abstract: Physical polarization Water Treatment (PPWT) is a new technology that takes advantage of polarization electric field polarizing water molecules to achieve the purpose of scale inhibition and dissolution as well as killing bacteria and algae. The PPWT device made by Shandong Langkun Energy Conservation & Environmental Protection Technology Co., Ltd and running in the biomass power plant of Shandong Kaitai Group Co. achieved the effects of scale inhibition and solution which are even more superior to the traditional method of chemical dosing. It brings annual water conservation of 147600 m³ and economic benefits of hundreds of thousands to millions for forsaking chemical dosing for a 15MW power unit. Therefore, Considerable economic and social benefits and the goals required by the state to the enterprises of energy saving, emission reduction and environmental protection are achieved.

Abstract: Ag nanoparticles (NPs) have prominent local surface plasma resonance effect (LSPR), and Ag NPs exhibit sharpest and strongest bands among all metals. Diamond-like carbon (DLC) film have good biological compatibility and also have high transmissibility in the visible and near-infrared region. A new LSPR interface between Ag NPs and ultra-thin DLC film was formed by Plasma Enhanced Chemical Vapor Deposition. The morphologies and properties of the Ag NPs coated with DLC film were studied with SEM and AFM. The results indicated that the thickness of DLC film increased with the deposition time. LSPR peak became sharper after depositing for 1 or 2 min. DLC film was prior to nucleate on the surface of Ag NPs, and it has high content of sp² bonds near the interface. The sensitivity of new LSPR interface deposited for 20s was about the half of the sensitivity of bare Ag NPs and the sensitivity significantly decreased with deposition time. This result is helpful to understand the behavior of the new LSPR interface and to improve its sensitivity.

Abstract: The band microstructure has an adverse effect on the comprehensive mechanics performance of Cr-Mo steel used for ball screw. This paper dealt with the different annealing processes combined with the forming mechanism of the banded structure. It shows that the annealing with long time can basically eliminate the band microstructure.

Abstract: This paper dealt with the fracture failure of a GCr15 steel ball screw nut. Through testing and analysis of hardness, microstructure, scanning electron microscopy and energy dispersive spectrum meter, it was found that there are local carbide network, few oversized carbide particles and metallic inclusions. The analysis showed that carbide network was failed to be eliminated through spheroidizing annealing treatment, while the presence of non-uniform carbide particles and metallic inclusions easily induced the crack and consequently led to the fracture of the nut.

Abstract: The vapor and gas permeabilities of the polyethylene films, casting polypropylene films and nylon films were tested in the paper. The keeping fresh performances were analyzed. It was found that the life time of vegetable packaged by films with high gas permeability is longer. The films with high vapor permeability reduce the accumulation of water droplets, but the leaves of vegetable change from green to yellow for lack of oxygen. It shows that the gas permeability of the film is more important than its vapor permeability for the vegetable storage. The family should choose the films with high gas permeability and appropriate vapor permeability to store vegetables.

Abstract: Abstract. Noble metal nanoparticles have prominent surface effect, quantum size effect and active outer-shell electrons, they cause these particles to present unusual optical phenomenon, display the strong local surface plasma resonance (LSPR) effect. DLC films have good biological compatibility, good wear resistance and corrosion-resisting, it also has high transmissibility in the visible and near-infrared region. A new LSPR interface between diamond-like carbon films and the Au/Ag NPs was formed by Plasma Enhanced Chemical Vapor Deposition (PECVD), The optical and electrical properties of the samples were studied with ultraviolet-visible absorption spectrophotometer and Raman spectrometer. The results indicate that their transmittance decreased with the increase of the film thickness.

Abstract: The field emission scanning electron microscope is applied in this paper to analyze the surface topography of diamond crystal synthesized at high pressure and high temperature. The research shows that parallel steps, jagged steps, hexagonal hills exist on (111) plane of diamond. The topography has a relation to the growth way of diamond. The (111) planes of diamond crystal mainly grow in layer mode.