Zong Wei Niu

Effect of Whisker Content on Mechanical Properties and Microstructure of Hydroxyapatite-SiCw Composite Bioceramics

Theory calculation result indicates that the maximal critical content of SiCw in hydroxyapatite-SiCw composite bioceramics is 23.7%. Hydroxyapatite-SiCw composite micropowder was synthesized using in-situ composite method, and hydroxyapatite-SiCw composite bioceramics with different content of SiCw were produced by hot pressing sintering method. The microstructures of the materials were analyzed by SEM, and the mechanical properties were tested. The results show that the mechanical properties of composite material are the best when the whisker content is 20~23.7%.

Process Parameter Optimization and Experiment Study of Aero-Engine Blade in Electrochemical Machining

Because the process of blade in electrochemical machining(EMC) can be effected by many factors, such as blade shapes, machining electrical field, electrolyte fluid field and anode electrochemical dissolution, different ECM machining parameters maybe result in great affections on blade machining accuracy. Regard some type of aero-engine blade as research object, five main machining parameters, applied voltage, initial machining gap, cathode feed rate, electrolyte temperature and pressure difference between electrolyte inlet and outlet, have been evaluated and optimized based on BP neural network technique. From 3125 possible machining parameter combinations, 657 optimized parameter combinations are discovered. Furthermore, the final optimized ECM process parameters have been obtained. To verify the validity of the optimized ECM parameter combination, a serial of machining experiments have been conducted on an industrial scale ECM machine, and the experiment results demonstrates that the optimized ECM parameter combination not only can satisfy the manufacturing requirements of blade fully but has excellent ECM process stability.

Experimental Investigation for Characteristics of Localized Dissolution of Micro-Holes in Electrochemical Machining Aided by Ultrasonic Wave

Electrochemical micro-machining (EMM) has become one of the main machining methods for production of miniaturized parts and components. Utilizing the developed EMM set-up, the effects of ultrasonic wave frequency on characteristics of localized dissolution and accuracy of micro-hole in EMM are investigated and evaluated. The experiment results demonstrate that the accuracy of micro-hole and characteristics of localized dissolution can become better with the increase of ultrasonic wave frequency. The accuracy of micro-hole machined by 26KHZ can improve about 30% than that by 16KHZ. Moreover, the ability of localized dissolution by 26KHZ can be increased about 27%-30%.

Influence of Process Parameters on Surface Morphology of Ceramic Layer Prepared by Micro Arc Oxidation on Aluminum Alloy 6061

Alumina ceramics film which has high hardness, wear resistance and erosion resistance can be obtained using micro arc oxidation on the surface of aluminum alloy. The process parameters have great influence on the surface morphology of alumina ceramics film prepared by micro arc oxidation. In this research, the alumina ceramics film was gotten using micro arc oxidation with different process parameters. The surface morphology of ceramics film was analyzed using scanning electron microscope (SEM). The SEM photograph was processed using ImageJ software. The dimensions of holes diameter and porosity on the surface of ceramics film were investigated. The influence regularity of process parameters such as current density, impulse frequency, duty ratio and process time to the surface morphology of alumina ceramics film was researched. This can provide basis for the optimization of process parameters.

Surface Integrity of Sintered NdFeB Permanent Magnet after EDM

In this study, the machining parameters of electrical discharge machining (EDM) are varied to study the effects of electrical discharge energy on material removal rate and surface roughness of NdFeB magnet. Moreover, the micro-cracks on the machined surface induced by EDM are also examined. The experimental results reveal that the MRR increases with the electrical discharge energy. The surface cracks on the machined surface are more serious when the discharge energy is higher. Thus, using EDM process to machine sintered NdFeB magnet depends on setting the machining parameters to prevent surface crack.

The Measurement of the Velocity Outside the High Pressure Water Jet and Abrasive Water Jet Nozzle Based on the Energy Transfer Method

The energy transfer method is used to measure the flow velocity of the outside the high pressure water jet (WJ) and Abrasive water jet (AWJ) nozzle. The impact forces of the flow measured by the piezoelectricity ergometer will be transformed to the velocity value, the average velocity of the flow outside the nozzle will be obtained. The result indicates the velocity will reduce along the direction of the flow, and the velocity of the AWJ flow will reduced greatly than the WJ flow, which indicates that the length of the core part of the AWJ flow is shorter than the WJ Flow, the stand-off should be within the 0mm-15mm ranges to gain the most effective machining.

Process Parameters Optimization for Green Manufacturing of Laser Cladding Based on Artificial Neural Network

Laser cladding is a new developed green manufacturing process. The main process parameters include the power of laser beam, the diameter of laser facula, the scan speed and the quantity of powder supply. It’s difficulty to analyse the influence of the process factors to the product quality because the effect mechanism is quiet complicated. Model of Artificial neural network for the optimization of process parameter in laser cladding manufacturing was developed in this paper. And proper process parameters were achieved which can provide guide for the practice production.

Process Parameter Optimization and Experimental Study of Micro-Holes in Electrochemical Micromachining Using Pulse Current

Electrochemical micro-machining (EMM) has become one of the main machining methods for production of miniaturized parts and components. Utilizing a developed EMM set-up, sets of experiments have been carried out to investigate the influences of some of the predominant electrochemical process parameters such as pulse frequency, feed rate of tool, machining voltage and ultrasonic frequency on the machining accuracy of micro-holes. According to the present investigation, the most effective zone of pulse on time and ultrasonic frequency can be considered as 15-50μs and 26KHZ, respectively, which can gives a desirable machining accuracy for micro-holes. A machining voltage range of 6-10V can be commended to obtain high machining accuracy. From the micrographs of the machined micro-holes, it may be observed that a lower value of electrolyte concentration with moderate machining voltage and moderate value of pulse on time will produce more accurate shape of micro-holes.

Effects of Electrical Discharge Energy on Machining Performance of Sintered NdFeB Magnet

Sintered NdFeB permanent magnet is widely used in many areas because of its excellent magnet property. In this study, the machining parameters of electrical discharge machining (EDM) are varied to study the effects of electrical discharge energy on material removal rate and surface roughness of NdFeB magnet. Moreover, the micro-cracks on the machined surface induced by EDM are also examined. The experimental results reveal that the MRR increases with the electrical discharge energy. The number of surface cracks on the machined surface increases with the enhancement of discharge energy Thus, using EDM process to machine sintered NdFeB magnet depends on setting the machining parameters to prevent surface crack.

Effect of Ultrasonic Vibration of Tool on Electrical Discharge Machining of Sintered NdFeB Magnet

Sintered NdFeB magnet is widely used in many areas because of its excellent magnet. This paper studies the effect of ultrasonic vibration of tool on electrical discharge machining of it. Experiments were carried out on self-made equipment and material removal rate(MRR) against pulse-on time, MRR versus peak current and machined surface results with and without ultrasonic employment were analyzed. Results show that MRR of the ultrasonic assisted electro-discharge machining would be up to five times higher than MRR of the conventional EDM for small pulse durations and low discharge currents. The machined surface of US/EDM is finer than EDM because of less arcing and short circuit pulses. There are less cracks on the surface.