Papers by Author: Chuan Zhen Huang

Abstract: In the paper, the Voronoi tessellation model is used to represent the microstructure of ceramic tool materials. And a finite element model based on cohesive element method has been developed to investigate the fracture behavior of the microstructure. The influences of mesh densities and cohesive parameters on the cracking patterns have been discussed. It is found that the enhancement of the grain boundary strength is beneficial for raising the fracture resistance of single-phase ceramic tool materials.

Abstract: A new three-dimensional Monte Carlo (MC) model in presence of pores of microstructure evolution for three-phase nano-composite ceramic tool materials is successfully established to simulate the grain growth during sintering process in this paper. The defect-free microstructure evolution and microstructure evolution in presence of pore are simulated and investigated. The results show that the new MC model can well simulate the grain growth and pores shrinkage during densification process. Compared with defect-free system, the grain growth velocity can be slow down obviously owning to the existence of pores.

Abstract: The cutting performance and wear mechanisms of whisker-toughening ceramic cutting tools synthesized by carbothermal reduction process have been studied when cutting the hardened alloy steel 40Cr. It is indicated that the wear resistance of ceramic tools is affected by the molar ratio of C and N in tool materials. At low cutting speed, the main tool wear mechanisms are abrasive wear and oxidation wear. At middle and high cutting speed, the tool wear mechanisms are controlled by abrasive wear, adhesive wear, diffusion wear and oxidation wear simultaneously. Adding whiskers to the matrix material is one of the effective means to improve the wear resistance of ceramic cutting tools.

Abstract: The interfacial energy and diffusion phenomenon of the Al₂O₃(012)-SiC (011) interface model are studied based on molecular dynamics. The interfacial energy increases firstly until reaches its maximum 0.459J/m² at the temperature of 1500K and then decreases. The relationship of diffusion coefficients for each kind of atoms is C>Si>O>Al. Diffusion coefficients of atoms increase at first and then decrease as the temperature goes up. This indicates the diffusion mechanism has been changed during the temperature rising process.

Abstract: In this paper, a comprehensive experimental investigation on the surface roughness of metal kerf in abrasive waterjet cutting metal material is presented. Orthogonal experimental design method and analysis of variance are utilized in researching the effects of processing parameters on the roughness of smooth zone. By analyzing, it could be concluded that lower waterjet pressure, smaller cutting speed and abrasive grit, larger abrasive flow rate and appropriate standoff are favorable to generate smooth metal kerf. A verification experiment was conducted using an optimizing cutting condition. The result indicates that the surface roughness of metal kerf has been improved effectively.

Abstract: TiC-based ceramic cutting tools with three different particle size levels of Al₂O₃ additives were fabricated and tested. Theses tool materials were identified as TA, TA10A5 and TA30A5 respectively in this study. Another commercial cutting material identified as LT55 was used in this study as baseline to investigate cutting performance by comparing the flank wear size. The experimental results showed that multi-scale nanocomposite ceramic tool TA10A5 had much better wear resistance than the other tools when turning at a lower speed. The wear mechanisms were mainly adhesive wear in the rake face. While cutting at a higher speed, the breakage failure occurred for the tools TA10A5 and TA30A5.

Abstract: A floor typed spatial robot of abrasive water jet machining is designed, which can be applied to machine three-dimensional complicated work-pieces. Its merits are simple structure and flexible moving. The structure and transmission programmer are discussed in detail. The working range of the abrasive water jet robot is analyzed to meet the need of the various sized work-pieces. The motion of the each joint is realized by means of various transmission programmers. The precise movement of the robot is realized by the stepping motor, and the required power of the robot is calculated.

Abstract: High pressure abrasive water jet (HPAWJ) machining has many advantages in hard brittle material processing. In this paper, the hole formation on stone by HPAWJ is analyzed based on brittle and plastic fracture theories. The formation and construction of jet are studied. The distribution of jet velocity, abrasives and energy in the jet-beam section of HPAWJ is analyzed. It is shown that the cross-section of the hole is characterized by a ‘Reverse-bell’ shape on stones by a HPAWJ. The jet velocity of HPAWJ gets lower from jet center to jet margin and it’s distribution is consistent with normal distribution function along with jet center. The concentration of abrasives becomes smaller from jet margin to jet center and it’s distribution is consistent with normal distribution function along with jet margin. The distribution of jet velocity, abrasives and energy in the section of HPAWJ is modeled.

Abstract: In this paper, the influence of the incidence angle and abrasive mesh on the polishing quality is analyzed during AWJ polishing process. Through the study on the jet flow structure, it is obtained the standoff of AWJ polishing is chosen within the jet basic section. According to the experiments for AWJ Polishing quartz, it is better to remove material by ductile removal mechanism choosing small incidence angle, low pressure and small abrasive size. The ductile removal mechanism of the polished material is a necessary condition for the ideal polishing results

Abstract: A TiC whisker toughening Al₂O₃-based ceramic cutting tool composite named ATW30 was developed by a two-step in situ synthesis technology. The fracture toughness, flexure strength and Vickers hardness of the composite were 7.63MPa•m^1/2, 800MPa and 19.5GPa, respectively. Compared to a (W, Ti)C particle strengthening Al₂O₃-based ceramic cutting tool composite named SG4, ATW30 was with lower flexure strength and Vickers hardness but much higher flexure strength, and therefore obviously higher wear resistance at either lower or higher cutting speed. The dominant wear mechanism on the flank face of ATW30 is abrasive wear at lower cutting speed and adhesive wear at higher cutting speed. Because of the appearance of the adhesive wear, the wear resistance of ATW30 at higher cutting speed is lower than that of itself at lower cutting speed.