Microstructural and Mechanical Properties of TiCX–Ni3(Al,Ti)/Ni Functionally Graded Composites Fabricated from Ti3AlC2 and Ni Powders

Guangming Zheng,Zhenying Huang,Qun Yu,Wenqiang Hu,Xingyang Qiu,A. Lixia,Yuanbo Wang,Yidan Jiao,Yang Zhou,Hongxiang Zhai 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.6

In this paper, a novel type of functionally graded material (FGM) was successfully fabricated from pure Ni and Ti3AlC2powder mixtures by hot-press sintering route at 1200 °C and 17 MPa. In each layer, Ti3AlC2particles transformed into TiCxphase, while the additional Al–Ti atoms decomposed from Ti3AlC2diffused into the Ni matrix, giving rise to the formationof γ′-Ni3(Al,Ti). Part of the submicron TiCxand Ni3(Al,Ti) particles were uniformly distributed in the Ni matrix, whilesome of the TiCxmaintained the original Ti3AlC2plate-like morphology. Both TiCxand Ni3(Al,Ti) content decreased from60Ti3AlC2/Ni layer to 10Ti3AlC2/Ni layer in a stepwise manner was fabricated. The microstructural analysis indicatesthat no cracks, delamination and step-type abrupt changes occured in the graded layer of the manufactured FGM. Flexuralstrength and Vickers hardness enhanced with the increasing Ti3AlC2content except for fracture strain and toughness. Theoverall fracture toughness and the flexural strength of FGM can reach 21.76 MPa m1/2 and 1329 ± 34 MPa, respectively. Theprepared FGM, herein, with a hard ceramic surface on one side to resist local plastic deformation, and a ductile metallicsurface on the other side to provide toughness.

Experimental investigation of cutting force, surface roughness and tool wear in high-speed dry milling of AISI 4340 steel

Guangming Zheng,Xiang Cheng,Li Li,Rufeng Xu,Yebing Tian 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

The high-speed dry milling of AISI 4340 steel was carried out with a CVD Al 2 O 3 /TiCN coated carbide tool. The relationships between cutting force, surface roughness and cutting parameter were conducted, and the influence of tool wear on cutting force and surface roughness was also investigated. The wear mechanism of coated tool was revealed by SEM micrograph and EDS analysis. Due to the lower tool wear rate, the increase of cutting forces and surface roughness R a was smaller at the initial wear stage and the steady wear stage, whereas the increase of cutting forces was improved suddenly when the flank wear was more than 0.25 mm. Additionally, the coated tool wear was mainly caused by adhesion, abrasion, oxidation and diffusion, accompanied with a little peeling and chipping. The research results are expected to provide optimum cutting parameters for high-efficiency machining of high-strength steel.

Failure Mechanisms of Graded Ceramic Tool in Ultra High Speed Dry Milling of Inconel 718

Guangming Zheng,Jun Zhao,Anhai Li,Xiaobin Cui,Yonghui Zhou 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

A graded ceramic tool material was fabricated by hot-pressing. Its cutting performance and failure mechanisms were investigated in dry face milling of Inconel 718 using round inserts at ultra high speeds ranging from 500 to 1600 m/min. The results showed that the microscopic chip shape was serrated type and the minimal cutting force was obtained at 900 m/min under this ultra high speed cutting conditions. Due to the enhanced mechanical properties and higher fracture resistance, the graded tool showed a selfsharpening characteristic. And the notch wear resistance of the graded tool was higher than that of the common reference tool under the same cutting condition. The failure mechanisms involved chipping, flaking, abrasive wear and adhesive wear. The mechanisms responsible for the higher cutting performance of the graded tool were determined to be the higher mechanical properties. The understanding of the failure mechanisms in ultra high speed milling processes can provide the guidance for the proper application of the tools, furthermore the guidance for tool materials design.

A bi-directional valveless piezoelectric micropump based on the Coanda effect

Zheng Zhang,Lipeng He,Jianwen Zhou,Dianbin Hu,Yi Hou,Guangming Cheng 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2

In this paper, the hydrodynamic characteristics of a piezoelectric micropump operate on the Coanda effect, and the mechanism of bi-directional pumping are analyzed by numerical simulation and experiments. The research focuses on the different positions of the fluid deflector and the influence on the output of the micropump. The results show that a closer fluid deflector to the inlet can produce greater vortices in the suction process due to the Coanda effect, and the backflow diminishing is more significant as well. Moreover, the different positions of the fluid deflector can cause a phenomenon that the micropump will achieve bi-directional pumping. As a finding, vortices arranged in pairs could improve the rectification efficiency of the micropump. The micropump achieves a maximum flow rate of 40.5 ml/min and back pressure of 5.76 cmH 2 o. In addition, the maximum flow rate per unit area can reach 305.2 μl/(min mm 2 ).

Cutting force, tool wear and surface roughness in high-speed milling of high-strength steel with coated tools

Yuan Li,Guangming Zheng,Xu Zhang,Xiang Cheng,Xianhai Yang,Rufeng Xu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11

The TiAlN+TiN coated tool, AlTiN coated tool and TiN/TiCN/TiAlN multi-coated tool were chosen for the high-speed milling of AISI 4340. The resultant cutting force and tool wear of coated tools were reviewed. The influence of cutting parameters and coating materials on the machined surface roughness was studied. The smallest resultant cutting force was obtained by TiN/TiCN/TiAlN multicoated tool. The main wear mechanisms of coated tool were chipping, collapse, the chipping of coating, adhesive wear, abrasive wear and crater wear. The minimal flank wear width was obtained by TiN/TiCN/TiAlN multi-coated tool. Among the selected cutting parameters, the lower surface roughness R a of 0.08~0.32 μm was achieved by the TiN/TiCN/TiAlN multi-coated tool and TiAlN+TiN coated tool. This work was conducive to the selection of coated tools and the optimization of cutting parameters in high-speed milling of AISI 4340, as well as to the promotion of high-efficiency and high-quality machining of hard-to-cut material.

Thermal management analysis of serial-connection three-chamber piezoelectric pump

Lipeng He,Xiaoqiang Wu,Zheng Zhang,Jingran Wang,Dianbin Hu,Yamei Liu,Guangming Cheng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

The design of a micropump with high performance and excellent reliability on thermal management still remains a challenge for electronic cooling. The performance of a piezoelectric pump with 3 chambers connected in series on thermal management was investigated for electronic cooling in this study. Two S-shaped channel heat sinks and the piezoelectric pump with 3 chambers connected in series were combined to form a loop cooling system. With water as the pumping medium, the tested pump has a flow rate most up to 690.6 ml/min at an input voltage of 220 V and an input frequency of 110 Hz. Suitability of the system has been demonstrated through simulation analysis and experimental verification for temperature control. A temperature reduction of 3 °C of CPU could be achieved at 250 mL/min flow rate generated by the piezoelectric pump with 3 chambers connected in series.

Research on metal flow law of micro-riblets based on multi-pass rolling

Xujie Gao,Huihang Wang,Guangming Zhu,Zheng Chang,Nana Guo,Zongshen Wang,Lihua Zhu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

Micro-riblets (grooves) can reduce surface friction in turbulent flow by up to 10 %. Furthermore, roll forming is an effective method for manufacturing large-area groove structures. In this study, the fluidity of metal during the multi-pass rolling of microgrooves was studied, and the reason for the accumulation of materials at the end of rolling was explained. A comparative analysis was conducted between single-pass rolling and multi-pass rolling. Then, according to the distribution of stress field and strain field, the force and flow tendency of the metal during rolling were studied. The gradually changing streamlined roller tooth profile promoted the flow of metal to both sides of the gear hob. Given the same reduction, the forming height of micro-grains during multi-pass rolling was 64.2 % higher than that during single-pass rolling.

Self-bending extrusion molding of distorted channels

Fanlei Min,Huiping Liu,Guangming Zhu,Zheng Chang,Xujie Gao,Bowen Yue,Nana Guo,Xiaoqing Zhai 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5

Using an integrated profile extrusion and bending forming process with a streamlined extrusion die, a new self-bending extrusion molding technology is proposed with an axis-distorted variable channel. By designing the streamlined extrusion die structure of the distorted central axis, the metal was made to flow non-uniformly in the die cavity, thereby directly extruding a bent profile. The central axis of the streamlined extrusion die is described by a trigonometric function and a Gaussian function. A numerical simulation was applied to analyze the metal flow pattern, equivalent strain, and strain-rate distribution during the self-bending extrusion process. The influences of the extrusion velocity and the addition of a bearing on the self-bending deformation profiles were investigated. During the extrusion process, the streamline at the center of the billet could describe the overall flow of the metal in the die cavity, and the distance between the point on the end face of the die outlet and the center of the die outlet directly determined the degree of extrusion and bending. The greater the distance was, the larger was the degree of bending. The metal strain on the convex edge of the die was greater than that on the concave edge of the die, with the extruded profile always bending toward the concave edge. The strain rate of the metal changed the fastest near the most convex point of the die. As the extrusion velocity increased or more bearings were added, the radius of curvature of the extruded profile increased nonlinearly.

Fabrication accuracy analysis of micromilling tools with complicated geometries by wire EDM

Xiang Cheng,Xianhai Yang,Guangming Zheng,Yumei Huang,Li Li 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6

The micromilling tool is one of the key factors affecting micromilling performance. The design and fabrication of micromilling toolsare still behind the increasing requirements in miniature component fabrication. How to estimate the fabrication accuracy of a newlydesigned micromilling tool is one of the urgent issues for micro tooling. This paper introduces an accuracy analysis method in the fabricationof micromilling tools by wire electrical discharge machining (WEDM) process. Taking two typical micro ball end mills into consideration,the micro tool fabrication process is kinematically modeled and analyzed. Analytical results show that the final fabricationaccuracy has a close relationship with the designed micro tool geometry. The fabrication procedures can be arranged based on the kinematicalanalysis, and the final fabrication accuracy also is affected by it. The radius errors of the fabricated micro ball end mill prototypeare within ±2μm, which is higher than that of commercially available similar ones. It verifies the proposed accuracy analysis method.

Thermal Shock Behavior of a Novel TiCx–Ni3(Al,Ti)/Ni Functionally Graded Composite

Qun Yu,Zhenying Huang,Guangming Zheng,Wenqiang Hu,Cong Lei,Yuanbo Wang,Yidan Jiao,Hongxiang Zhai 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

This paper focuses on the study of thermal shock behaviors of a novel TiCx–Ni3(Al,Ti)/Ni functionally graded material (FGM)fabricated from Ti3AlC2and Ni powders. Thermal shock resistance of resulted FGM was conducted by water quenching atdifferent temperatures, mechanical properties and microstructures after thermal shocks were correspondingly determined andcharacterized. The microstructure of the FGM after thermal shocks shows no cracks of instability failure between the transitionzones, and the reinforcement phases were closely combined with the matrix. Meanwhile, compared with the strengthof 1329 MPa without thermal shock, when the temperature of the thermal shock reached 800 °C and 1000 °C respectively,with 10 repeated heat-water quench cycles, the residual flexural strength of FGM decreased slightly, but it could still reach1100 MPa. Notably, the strength can still maintain at 843 MPa after 10 cycles of thermal shock at 1200 °C. Such excellentthermal shock performance may be the result of the good interfacial bonding and the special gradient structure, the oxidationlayer also plays a protective role.