Bai Yang Lou

Research on Tribological Property of Micro-Arc Oxidation Film on AZ91D Magnesium Alloy

Magnesium alloys were treated by micro-arc oxidation at a constant applied current density. The friction and wear properties were investigated by optical microscope and universal friction and wear tester in 3.5%NaCl solution. The result reveals that the film formed by micro-arc oxidation enhances the corrosion resistance of the magnesium alloys. The Ecorr of micro-arc oxidation film improved 94mV than the Ecorr of magnesium alloys matrix. Wear resistance of the film was weakened in 3.5%NaCl solution. The wear mechanism of film depends on the load. Abrasive wear was predominant at low load. Peeling wear was predominant at high load, which result from damage of the film adhesion.

The Influence of Micro-Arc Oxidation on Corrosive-Wear Behavior of Magnesium Alloy

Using an alternative pulse current source and in silicate solution electrolyte，a uniform coating on the surface of AZ9lD alloy was fabricated by micro-arc oxidation(MAO) with current density of 40mA/cm2. Friction wear testing machine was used to study the wear behavior under corrosive environment of the film and scanning electron microscopy(SEM)were used to study microstructures of film and worn surface．The result shows that the corrosion resistance of micro-arc oxidation film is large better than that of magnesium alloy. The corrosive solution great weaken the abrasion resistance of the coating. As the influence of the corrosive solution, the wearing mechanism is varying with the loading. Abrasive wear is the main mechanism when the loading is small, if the loading is large enough, the binding force will be destroyed and the coating will peel off from magnesium alloy.

Synthesis and Characterization of Thermo-Sensitive Copper/Paraffin Nanocomposites

Thermo-sensitive copper/paraffin nanocomposites were prepared by high energy ball milling. Fourier transform infrared spectrometer (FTIR), x-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the composition, phase and microstructure of the composites. Furthermore, their thermal sensitivity was investigated. Results reveal that the phase of composites is mainly composed of copper, paraffin and a small amount of cuprous oxide copper. Nanoparticles homogeneously covered by paraffin form the similar core-shell structure. The mass ratio of copper to paraffin has an obvious influence on the thermal sensitivity.

Numerical Simulation of Mold Filling and Solidification Process of a Disc Aluminum Alloy in Pressure Die Casting

The numerical simulations of mold filling and solidification process for the A380 aluminum alloy were done by the supposed mathematical model. The casting defects in the process of mold filling and solidification were predicted by the result of the casting simulation. The casting defects of simulation are well compared with the practice. Some measures presented were improved for the existing technological process.

The Effects of Nano Pt/Carbon Black Compound Coating on the Electro-Catalysis Properties of the Graphite Electrode

The modification of Nano Pt and carbon black compound coating on the fuel cell’s graphite electrode by the method of vacuum ion plating and ethanol catalytic combustion. The microstructures and the electro catalysis properties of the electrode surface before and after the modification were analyzed and tested with the methods of scanning electron microscope(SEM), transmission electron microscope(TEM), electrochemical workstation and so on. The effects of nano Pt and carbon black on the electrode’s electro catalysis properties were investigated. The Study results have shown that carrying on electrochemical properties test to the graphite electrode which has been treated with nano Pt and carbon black compound surface modification, there will be three oxidation peaks in its cyclic voltammograms and the background current will be higher. Compared with the nano Pt surface modification, the electrode which has been treated with nano Pt and carbon black compound surface modification has better ethanol electro catalysis properties. The high specific surface area acquired from the nano carbon black surface modification and the synergic action of the catalytic material Pt can improve the ethanol electro catalysis properties of the electrode effectively.

Effect of Pressure on Microstructure and Properties of High Silicon Electrical Steel by EB-PVD

The effect of pressures on microstructure and properties of as-deposited high silicon electrical steel by EB-PVD during hot pressing was studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the phase composition and morphology; the density and electrical resistivity were measured using the bottle method and four-probing method, respectively. It was found that the density increased from 7.25×103 kg/m3 to 7.5 ×103 kg/m3, while the electrical resistivity decreased from 85µΩ•cm to 75µΩ•cm with the increase of the pressure from 30 MPa to 60 MPa.

Synthesis and Characterization of Copper/Paraffin Nanocomposites for Thermal Actuation

The copper/paraffin nanocomposites were synthesized by high energy ball milling. Observation of the microstructure, comparison and ascertainment of the particle size of the composite were analyzed by transmission electron microscope. Then the composite was put into a home-made copper tube (5 mm in diameter, 20 mm in length, closed at one end) by thermoforming process, and its thermal sensitivity was measured using thermo-controlled optical micro measuring equipment. The effects of milling time on the microstructures and the thermal sensitivity of copper/paraffin nanocomposites were investigated. The results showed that different milling time caused the changes in particle size and shape of the composite, and had a significant effect on its thermal sensitivity. With increasing milling time, the thermal sensitivity of composite gradually increased.

Phase Composition and Magnetic Structure of High Silicon Electrical Steel by EB-PVD

High silicon electrical steel prepared by EB-PVD was subjected to high temperature rapid thermal annealing and subsequent pack rolling. The phase composition and Fe configurations were characterized by X-ray diffraction and Mössbauer spectroscopy. The results show that the as-deposited, as-annealed and as-rolled samples mainly consist of DO3 ordering phase and the as-deposited electrical steel is composed of six kinds of Fe sites corresponding to 333.8KOe, 319KOe, 302 KOe, 284 KOe, 249 KOe, 196 KOe, respectively, while the Fe site corresponding to 196 KOe hasn’t been found in the other two samples. Moreover, the other two samples show a larger Fe site occupancy corresponding to 284 KOe.

Numerical Simulation Research of Micro-Injection Molding Simulation

According to the basic theory and process of conventional injection molding, using the CAE software, numerical simulation research of the injection molding characteristic for micro thin-wall plastic parts are put forward. The effects of process parameters (melt temperature, mold temperature, injection pressure, injection rate) on molding characteristic of micro thin-wall plastic parts are discussed by single factor method, compare the significance of each factors.The simulation results showed that volume could be improved with the increase of melt temperature ,molding temperature, injection pressure and injection rate.

The Fracture Analyse of Titanium Bone Implant

The titanium and its alloys are getting used more and more as for human implant in recent years. In this paper, the broken titanium palmer-bone implant was investigated with field emission scanning electron microscopy (SEM) and X-ray spectrometer and then the reasons of implant fracture was researched. The material composite analysis result shows that the implant is made of industrially pure titanium in which the microelements aluminum, calcium and vanadium are on the high sides. The macro analysis result indicates that the implant did not deform remarkably before cracking. The micro analysis result indicates that there is coarse crystalloid fracture in the SEM macrograph, suggesting that the implant material has low fracture strength. The implant fails in mixed cleavage fracture and intergranular fracture accompanied by fatigue fracture in part region, suggesting that the main fracture type was brittle fracture.