Browsing by Author "Zhao, Jingwei"

Now showing 1 - 10 of 10

A review of modern advancement in micro drilling techniques
(Elsevier, 2017-08-01) Hasan, Mahadi; Zhao, Jingwei; Huang, Zhenyi; Jiang, Zhengyi
The demand for micro drilling with a diameter in a range of a few microns to several hundred microns is increasing in industries such as electronics, aerospace, medicine and automobiles, due to a significant uptake in the use of miniaturised products and devices. In order to satisfy the demand, a number of different micro drilling techniques have been developed. There has been, however, no report which explains, compares and contrasts all of these micro drilling techniques. This study examines the lasts micro drilling methods and techniques, categorises them into different groups, highlights recent developments and new trends, and depicts the future requirements in the field of micro drilling. Both conventional and non-conventional micro drilling techniques used in modern age applications are categorized. Conventional micro drilling makes use of drill bits of different configurations such as twist, spade, D-shaped, single flute, compound drill and coated micro drill, while non-conventional micro drilling involves electrical, chemical, mechanical and thermal means which include laser, EDM, ECM, SACE, electron beam, ultrasonic vibration or combinations of these approaches. We present here, a comparative study of conventional and non-conventional micro drilling techniques in order to show the potential and versatility of various micro drilling methods
Analysis and characterisation of WC-10Co and AISI 4340 steel bimetal composite produced by powder-solid diffusion bonding
(Springer Nature, 2019-05-01) Hasan, Mahadi; Zhao, Jingwei; Huang, Zhenyi; Wei, Dongbin; Jiang, Zhengyi
Cermet and steel material bonding is a challenging task, due to their large difference of physical properties, e.g. coefficient of thermal expansion. In this study, a hot compaction diffusion bonding method was employed to fabricate a small-dimensional bimetallic composite of WC-10Co and high strength AISI 4340 steel, where the cermet was used in powder form and the steel as solid. The bimetal composite was characterised by microstructural analysis and mechanical properties evaluation. The interface microstructure reveals a successful metallurgical bonding between the cermet and steel materials. The influence of sintering temperature (1050–1250 °C) was examined at intervals of 50 °C. This study shows that the properties of sintered powder and the bonding quality with the steel improve with an increase in sintering temperature. A bonding beneficiary reaction layer was observed to grow at the joining interface by mutual diffusion of the alloying elements, which increases with the increasing temperature. The maximum width of the reaction layer observed was 4.13 μm and consists mainly of intermetallic ternary carbides. The bonding shear strength of the interface is found to be slightly higher than claimed in previous studies. The developed bimetal composite could be used in applications where a combination of high strength and hardness is required
Analysis of sintering and bonding of ultrafine WC powder and stainless steel by hot compaction diffusion bonding
(Anhui University of Technology, Anhui, China, 2018-05-20) Hasan, Dr. Mahadi; Zhao, Jingwei; Jiang, Zhengyi
Bonding between tungsten carbide and steel is a challenging task due to their large difference of physical properties. Previous reports were based on solid state bonding. In this study, a powder-solid mechanism was employed for analysing the sintering and bonding process of ultrafine WC (with 8% Co added as binder) powder and solid stainless steel (SS 304). A novel manufacturing mechanism of hot compaction diffusion bonding (HCDB) was implemented to facilitate the bonding process. The influence of temperature varying from 1160 to 1220 °C was investigated with an interval of 20 °C. The experiment is conducted in a vacuum environment at constant pressure of 160 MPa. Under simultaneous effects of temperature and pressure, WC powder was solidified and a diffusion bonding was realised with SS 304. The bonding interface is characterised by three distinctive features, namely properly bonded area, crack appearance and formation of diffusion layer. Generation of micro cracks are examined in the form of single long micro crack, cluster of micro cracks and crack in WC region. An average hardness of 1971 HV was found at 1220 °C, and the maximum mechanical bonding shear strength achieved was 172 MPa. The microstructure morphology, composition distribution, bonding characteristics and crack formation, diffusion mechanism and mechanical properties of the composite bimetal were examined. The fabricated composite bimetal has the potentials in the applications where high hardness and high strength are required simultaneously.
"Effect of annealing temperature on the microstructure and tensile properties of copper/aluminum composite thin strip"
(Science Direct, 2023-02-01) WANG, Chen; MA, Li-nan; Ma, Xiaoguang; Hasan, Mahadi; Zhao, Jingwei
The effect of annealing temperature on the microstructure and tensile properties of copper/aluminum (Cu/Al) composite thin strips was studied to improve the mechanical properties of materials. The change of interface layer, the diffusion of interface elements, and the microstructural evolution of each matrix of Cu and Al were observed and analyzed using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and electron back-scatter diffraction (EBSD) techniques. The tensile properties of the Cu/Al composite thin strip were studied by static uniaxial tensile tests. The results show that recrystallization occurs in the Cu/Al matrix during annealing process, and the grains of the Al matrix grow into coarse grains after annealing at 400 °C. The thickness of diffusion layer increases with the increase of annealing temperature, and the thickness of the diffusion layer reaches 12 μm after annealing at 500 °C. The original typical rolling texture is transformed into the typical annealing texture components {001}〈100〉 and {001}〈110〉 after annealing treatment. In general, the annealing treatment reduces the tensile strength and improves the overall plasticity of the material, and the diffusion layer plays a significant role in transmitting tensile stress.
Effects of holding time on the sintering of cemented tungsten carbide powder and bonding with high strength steel wire
(Springer Link, 2019-07-15) Hasan, Mahadi; Zhao, Jingwei; Huang, Zhenyi; Wu, Hui; Jia, Fanghui; Jiang, Zhengyi
Cemented tungsten carbide (WC-10Co) and high-strength (AISI 4340) steel were successfully bonded by hot compaction diffusion bonding at a low temperature. The effects of holding time (5-50 min) on microstructure and mechanical properties of the sintered carbides and bonding strengths of the dissimilar bilayered composite materials were examined. The results show that the mechanical properties of the carbides increase, but the bonding strength increases firstly and then decreases with the increase in holding time. The maximum density and hardness achieved are 95.92 and 99.5%, respectively. A transitional layer forms at the interface as a result of elemental interdiffusion. The depth of the layer increases with the increase in holding time. The optimal bonding time is determined to be 40 min at a temperature of 1200C and a pressure 160 MPa, by which the maximum bonding strength of 204 MPa of the WC-10Co/4340 steel joints can be achieved.
Influence of dwelling time on the bonding of cemented carbides and high strength steel by SPS
(Chinamet, 2022-02-16) Hasan, Mahadi; Ningfei, Zhang; Huang, Zhenyi; Zhao, Jingwei; Jiang, Zhengyi
The effects of dwelling time (5,10,15 and 20 min) on the microstructure, phase formation and mechanical properties of cemented carbide and high strength steel composites were investigated by SPS. The results showed that with the increase of the dwelling time, the sintering quality was gradually improved, and the bonding interface was smooth and continuous, and there was no obvious crack and delamination. The XRD results showed that WC, Fe and Fe, Co phases existed in the microstructure of the composites when the dwelling time was 5 min. When the dwelling time increased to 20 min, a new W2 C phase was clearly formed. With the increase in dwelling time, micro- hardness and tensile strength showed an increasing trend. When holding time was 20 min, the strain when the maxi- mum tensile strength is 152 MPa was only 0.22, and the maximum micro-hardness was 1 763 MPa.
Influence of sintering time on diffusion bonding of WC-10Co and AISI4340 by spark plasma sintering
(Taylor and Francis, 2022-10-16) Hasan, Mahadi; Islam, Md. Ashraful; Huang, Zhenyi; Zhao, Jingwei; Jiang, Zhengyi
It is challenging to obtain successful bonding between cemented tungsten carbide and steel due to the large differences in their physical and mechanical properties. We used spark plasma sintering (SPS) technique and successfully bonded WC-10Co and AISI4340 high-strength steel at a low temperature. The effects of sintering time (5–20 min with a gap of 5 min) on their diffusion bonding were examined. The microstructure of the bonded composite materials was evaluated, and formed phases were identified. The mechanical properties were investigated, and the importance of processing parameters of SPS was discussed. The results show a crackfree continuous metallurgical bonding achieved at 1000°C, and the bonding strength increased with increasing holding times of 5, 10, 15, and 20 min. The sintered WC-10Co powders obtained nearly full density (99.07%) with an average maximum hardness of 1763 HV5. A special arrangement was used to determine the tensile bonding-strength with maximum average of 152 MPa at 20 min.
Micromanufacturing of composite materials: a review
(IOP Publishing, 2019-04-15) Hasan, Mahadi; Zhao, Jingwei; Jiang, Zhengyi
Composite materials exhibit advantages from the combination of multiple properties, which cannot be achieved by a monolithic material. At present, the use of composite materials in miniaturized scale is receiving much attention in the fields of medicine, electronics, aerospace, and microtooling. A common method for producing miniaturized composite parts is micromanufacturing. There has been, however, no comprehensive literature published that reviews, compares, and discusses the ongoing micromanufacturing methods for producing miniaturized composite components. This study identifies the major micromanufacturing methods used with composite materials, categorizes their subclasses, and highlights the latest developments, new trends, and effects of key factors on the productivity, quality, and cost of manufacturing composite materials. A comparative study is presented that shows the potential and versatility associated with producing composite materials along with possible future applications. This review will be helpful in promoting micromanufacturing technology for fabricating miniaturized products made of composite materials to meet the growing industrial demand.
Microstructural evaluation of WC and steel dissimilar bilayered composite obtained by spark plasma sintering
(Springer, 2020-10-13) Hasan, Mahadi; Huang, Zhenyi; Zhao, Jingwei; Jumlat, Al; Jia, Fanghui; Wu, Hui; Jiang, Zhengyi
Spark plasma sintering (SPS) is a powerful technique for consolidating metal powders at a remarkably shorter time with excellent quality. We used this technique for sintering nanocrystalline WC10Co powders and simultaneously bonding with high-strength steel. A series of experiments were conducted in order to find out the optimised set of SPS controlling parameters. The effects of temperatures (1000 to 1150 °C, with a 50 °C interval) in sintering nanocrystalline WC10Co powders and their bonding phenomena with AISI4340 steel were examined at a constant pressure of 80 MPa and a holding time of 5 min. The full density of the carbide powders was achieved at a lower temperature compared with that of conventional techniques. A number of techniques were employed to evaluate the microstructural characteristics of WC and steel bilayered composite and their mechanical properties. For determining the bonding strength of the joint, a novel micro-tensile testing system was adopted. Since such investigation is the first of its kind, to the best knowledge of the authors, where SPS is used to join the tungsten carbide with the steel, this research is expected to provide a valuable future reference for fabricating dissimilar bilayered composite materials.
Optimisation of sintering parameters for bonding nanocrystalline cemented tungsten carbide powder and solid high strength steel
(Taylor & Francis, 2020-07-07) Hasan, Mahadi; Zhao, Jingwei; Jia, Fanghui; Wu, Hui; Ahmad, Farooq; Huang, Zhenyi; Wei, Dongbin; Ma, Lifeng; Jiang, Zhengyi
In this study we examined the effects of compaction pressure for bonding nanocrystalline cemented tungsten carbide (WC-10Co) and high-strength steel (AISI4340) and successfully fabricated a bilayered composite of ceramic and steel. The obtained results were compared with our previous studies, and then the optimized sintering conditions were suggested. The compaction pressure examined varied from 120–200 MPa at 1150°C for 20 min. The study shows that the change in experimental parameters has significant effects on both the sintering properties of nanocrystalline WC-10Co powders and their bonding with AISI4340 steel. The microstructure reveals a successful metallurgical bonding between ceramic and steel. Bonding temperature determines, to a great extent, the diffusion processes across the bonding interface and has found to be the most influential variable compared to sintering time and compaction pressure. The obtained average maximum bonding strength of the bimetal composite is 226 MPa, which is higher than that of previous studies.