Papers by Author: Chuan Zhen Huang

Abstract: In order to improve the machining efficiency of high strength steel 2.25Cr1Mo0.25V and tool life, intermittent turning performance of 2.25Cr1Mo0.25V with common carbide tools and advanced coated carbide tools was experimentally studied, cutting parameters and tool types were optimized. The results showed that the machining efficiency and tool life of advanced coated carbide tools were remarkably higher than that of common carbide tool; the tool life of quadrate coated tool was longer than that of circular tool. The cutting tool failure mechanisms were also discussed.

Abstract: The milling experiments of the annealed T10A steel were carried out in the various cutting conditions using the coated cemented carbide tool. The cutting parameters were designed by the multi-factor orthogonal experiment method, and the effects of cutting speed, feed, axial depth of cut and radial depth of cut on the cutting force and tool wear were investigated. The tool wear mechanisms were also discussed. Adhesion, abrasion, diffusion and oxidation were the main tool wear mechanisms. According to these investigations, the optimizing cutting parameter was recommended.

Abstract: TiC_xN_1-x whiskers were prepared using TiO₂ and carbon mixed powder as the starting powder at the atmosphere of nitrogen by the carbothermal reduction process. NaCl and NiCl₂ were added into the starting powder as the cosolvent and growth adds of impurities, respectively. An effect of the content of TiO₂ and carbon in the starting powder on the TiC_xN_1-x whiskers was investigated. It is found from SEM and XRD observations that three types of TiC_x N_1-x whiskers are obtained when the different mol ratios of C and Ti are applied. The growth of whiskers is not only urged by the droplet on the top of whiskers, but also initiated by the helical dislocations. The growth of TiC_xN_1-x whiskers is controlled by the vapor-liquid-solid mechanism as well as vapor-solid mechanism.

Abstract: A Monte Carlo Potts′ model with different ratios of grain boundary energy is proposed for the sintering process of two-phase nanocomposite ceramic materials. The grain growth process is successfully investigated, and the effect of grain boundary energy on the microstructure is discussed. The simulation results show that the competition between grain boundary and interfacial energies can affect the pinning effect of nano-particles, lead to various microstructure. The simulation results are in accordance with the experiments.

Abstract: In this paper, an experimental evaluation of the surface microstructural integrity of Si3N4 ceramics milled with abrasive waterjet was studied. The results show that the surface residual stress resulting from abrasive waterjet milling process for ceramics is compressive, and the compressive residual stress ranges from negative 203MPa to negative 19.6MPa. The results also show that the water pressure, the standoff distance, nozzle traverse speed and the lateral spacing have strong effects on the surface residual stress. The results also show that there is some enhancement in the hardness of AWJ milling surface, and it is affected by milling process parameters. The micro-topography of the milled surface cross section shows that there is a thin deteriorative layer in milled layer, in which no obvious crack is observed. Since the surface residual stress is compressive and the surface hardness increases, the milled surface deteriorative layer by AWJ could improve the surface quality.

Abstract: Micro abrasive air jet (MAAJ) cutting technology is being increasingly used in the precision machining of hard and brittle materials, due to its distinct advantages of negligible heat effect zone and small cutting force. In this paper, an experimental study on the kerf characteristics, especially for the effect of cutting parameters on the top edge definition, is presented. It shows that the top kerf edge is straight but not sharp. The top edge definition of the kerf improves with a decrease in the air pressure, while the effect of abrasive flow rate and nozzle traverse speed are hardly discernible. The optimum jet incidence angle for highest top edge definition of the kerf is 60°. The results of this paper may be useful for the cutting parameters optimization in the precision three-dimensional micro-structural machining.

Abstract: Micro abrasive air jet machining technology is being increasingly used in the fields of micro cutting. Since the aspect ratio is a major interest characteristics of kerf in micro cutting, an experimental investigation is carried out to study the effect of cutting process parameters on the aspect ratio in this study. It is found that the aspect ratio increases with an increase in air pressure, abrasive flow rate and jet incidence angle, while decreases with an increase in nozzle traverse speed. Furthermore a predictive model for aspect ratio is developed using the dimensional analysis technique. It is shown that the model predictions are in good agreement with the experimental results. The research results may be meaningful to efficiently control the aspect ratio.

Abstract: In this paper, a study on erosion mechanism of Ultrasonic Vibration Abrasive Waterjet is presented. Theoretical analysis of the total effective erosion kinetic energy of UVAWJ is performed. By using a UVAWJ machining system with an Ultrasonic Vibration Power Workbench, the comparative experiment is conducted. The erosion surfaces of the single crystal silicon substrate were measured by Optical Profiler and observed with Scanning Electron Microscope. The material removal mechanisms are discussed. It is concluded that the erosion by UVAWJ, with the aid of high-frequency ultrasonic vibration, can obtains a high material removal, less cracks and good finish surface.

Abstract: Si3N4/TiN nanocomposite tool and Si3N4/Ti(C7N3) nanocomposite tool were prepared. The cutting performance and wear mechanism of Si3N4-based nanocomposite ceramic tool was investigated by comparison with a commercial sialon ceramic tool in machining of 45 steel. Si3N4-based nanocomposite ceramic tool exhibits the better wear resistance than sialon at the relatively high cutting speed. The increased cutting performance of Si3N4-based nanocomposite ceramic tool is ascribed to the higher mechanical properties. Nano-particles can refine the matrix grains and improve the bonding strength among the matrix grains of Si3N4-based nanocomposite ceramic tool materials. It contributes to an improved wear resistance of the cutting tools during machining.

Abstract: A multi-scale and multi-phase nanocomposite ceramic cutting tool material Al2O3/TiC/TiN(LTN) with high comprehensive mechanical properties has been successfully fabricated by means of adding micro-scale TiC and nano-scale TiN particles. The cutting performance and wear mechanisms of this advanced ceramic cutting tool were researched by turning two kinds of hardened steel 40Cr and T10A respectively. Compared with the commercial ceramic tool LT55, LTN showed a superior wear resistance with certain machining parameters. The machining tests indicated that the new materials tool is suitable for continuously dry cutting of hardened steel with high hardness at high speed.