Mu Sen Li

Effect of Micro-Addition Rare Earth and Chrome on Friction and Wear Behavior of Boronized Layer

Application of powder boronizing to mechanical industry has been restricted because of the brittleness of boronized layer, which inevitably leads to decrease of service life of boronized parts. Therefore, attention should be paid to reducing the brittleness of boronized layer without decreasing its high hardness. In the present paper, a study on the effect of micro-addition rare earth and chrome on friction and wear behavior of boronized layer was carried out using an MM-200 wear test machine. Compared with that of pure single Fe2B phase, the brittleness of the boronized layer containing minim rare earth and chrome elements, obtained by powder RE-chrome-boronizing, is reduced, which results in increasing the bearing capacity and wear resistance of the boronized layer. The friction and wear mechanism is also briefly analyzed.

Butyrate promotes visceral hypersensitivity in an IBS‐like model via enteric glial cell‐derived nerve growth factor

Altered visceral sensation is common in irritable bowel syndrome (IBS) and nerve growth factor (NGF) participates in visceral pain development. Sodium butyrate (NaB) could induce colonic hypersensitivity via peripheral up‐regulation of NGF in animals. Enteric glial cells (EGCs) appear to be an important source of NGF. Whether butyrate could induce visceral hypersensitivity via increased EGC‐derived NGF is still unknown.

Failure Analysis on the GCr15 Bearing Steel and the 20CrMo Carburized Steel Nuts of the Ball Screw Pair

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.

Application of Physical Polarization Water Treatment Technology on Circulating Cooling Water System of Power Plant

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.

The Optical Properties of Au/Ag Nanoparticles Coated with Diamond-Like Carbon Films

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.

Microstructure Analysis of Ti-Al Intermetallic Compound Aluminized Layer Generated in Low Temperature

By using mechanical energy aided aluminizing process, an aluminized layer of 20~180μm was obtained on titanium plate at a low temperature of 650~700°C for 3 hours. The aluminized layer consists of an outer layer of single-phase aluminium, an inner layer of (Al,Si)3Ti intermetallic compound and aluminium bipolar layer, the silicon element is riched in the Al3Ti intermetallic compound.

Fatigue Test and Failure Analysis of GD8020×1100 Ball Screw Unit

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.

Failure Analysis of GCr15 Steel Balls in Ball Screw Pair

Based on macro morphology, metallographic microstructure, field emission scanning electron microscope observations and microhardness testing, failure analysis of the GCr15 steel balls in the ball screw pair was dealt with in this paper. The experimental results showed that small scratches and pits were evenly distributed on the surface of the A steel ball which showed features of wear failure. Characteristics of the B steel ball surface morphology were contacted to fatigue failure. Microstructure observation on the cross-section of the B steel ball showed that martensite and carbides were uneven distributed which were caused by the uneven elements distribution in the raw materials. It was the main cause of this abnormal failure. Therefore, the quality of the raw materials needed to be strictly controlled and the reasonable heat treatment process should be adopted to ensure the quality of the steel balls.

Effect of Aging Treatment on the Microstructures and the Magnetic Properties of the Sintered Nd-Fe-B Magnet

The effect of aging processes on the microstructures and the magnetic properties of the sintered Nd-Fe-B magnet was investigated. The experimental results showed that the grain boundaries of the magnet treated by the two-stage aging processes became clear,smooth and continuous. Meanwhile, the Nd-rich grain boundary phase was precipitated at the grain boundary of the main phase to form a distinct phase separated from the main magnetic phase. The changes of the grain boundary microstructures of the sintered Nd-Fe-B magnet caused significant increase of its intrinsic coercive force.

Study on the Preparation of Silver Nanoparticles Coated with Diamond-Like Carbon Film and their Properties

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.