Browsing by Author "Jia, Fanghui"

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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.
Investigation on spark plasma sintering of dissimilar ceramic and steel laminated composite materials
(SCHOLARENA, 2019-11-18) Hasan, Dr. Mahadi; Raza, Hamid; Jia, Fanghui; Jiang, Zhengyi
Spark plasma sintering (SPS) is a powerful technique for consolidating metal and ceramic powders. The key benefits of SPS include rapid sintering capability, achievement of full density at a considerably low temperature and an excellent control over the grain sizes. Such technique can be used to clad dissimilar ceramic and steel materials. In this study, a laminated composite material of nanocrystalline WC-10Co and AISI4340 is fabricated using SPS, which has not been reported so far. The sintering behaviour of 100 nm particle size cemented carbides is analysed, and their bonding characteristics with steel are examined at the temperatures ranging from 1000 to 1150 °C, sintered for 5 min, under 80 MPa of constant pressure. The microstructure of the bonding interface is investigated, and the mechanical properties of the bond are evaluated. The phases formed at the interface are identified and their formation mechanisms are discussed. A novel miniature tensile test system is adopted to determine the tensile strength of the bond, and the fracture characteristics of the bonding interface is illustrated microscopically. It is expected that this research can provide a valuable reference for joining ceramic and steel materials to manufacture dissimilar laminated composite materials using SPS technique.
Micromanufacturing Technology and its Practice
(Transtec Publications, 2022-10-05) Jiang, Zhengyi; Hasan, Mahadi; Raza, Hamid; Jia, Fanghui; Xia, Haibo
In order to make micro composite drills (Fig. 1), 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, pressure and temperature on microstructure and mechanical properties of the sintered carbides and bonding strengths of the bimetallic composites were examined, and a transitional layer was found at the interface as a result of elemental inter-diffusion. The optimal bonding parameters were determined to achieve the maximum bonding strength of 226 MPa of the WC-10Co/AISI 4340 steel joints, which is helpful in producing micro composite drills. Microforming is introduced to produce lighter and more energy effective products. In this study, Magnesium-Lithium (Mg-Li) alloy, new material in microscale, was chosen to superior formed micro-cup due to its ultralight weight with outstanding ductility. The dry and oil lubrication conditions were chosen as benchmarks to investigate effects of a novel oil-based nanoparticle lubricant in micro deep drawing (MDD) process of Mg-Li alloy. Finite Element (FE) modelling was conducted and the simulation results of the drawing force were in a good agreement with the experimental results. The formed cup quality with consideration on the surface roughness has been extensively evaluated and the results illustrated the quality improvement was substantial.
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.