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| 1 | Micro-fabrication of ceramics:Additive manufacturing and conventional technologies显示文摘Ceramic materials are increasingly used in micro-electro-mechanical systems(MEMS)as they offer many advantages such as high-temperature resistance,high wear resistance,low density,and favourable mechanical and chemical properties at elevated temperature.However,with the emerging of additive manufacturing,the use of ceramics for functional and structural MEMS raises new opportunities and challenges.This paper provides an extensive review of the manufacturing processes used for ceramic-based MEMS,including additive and conventional manufacturing technologies.The review covers the micro-fabrication techniques of ceramics with the focus on their operating principles,main features,and processed materials.Challenges that need to be addressed in applying additive technologies in MEMS include ceramic printing on wafers,post-processing at the micro-level,resolution,and quality control.The paper also sheds light on the new possibilities of ceramic additive micro-fabrication and their potential applications,which indicates a promising future. | Hany HASSANIN Khamis ESSA Amr ELSHAER Mohamed IMBABY Heba H.EL-MONGY Tamer A.EL-SAYED | 2021 | Journal of Advanced Ceramics2021，10，1： | 1 |
| 2 | The development of a high-performance Ni-superalloy additively manufactured heat pipe显示文摘Additively manufacturing(AM)has been used to manufacture fine structures with structured/engineered porosity in heat management devices.In this study,laser powder bed fusion(LPBF)was used to manufacture a high-performance Ni-superalloy heat pipe,through tailoring LPBF process parameters to fabricate thin wall and micro-channel.By using novel laser scanning strategies,wick structure heat pipes with maximised surface-area-to-volume ratio,fine features size around 100µm,and controlled porosity were successfully fabricated.Microscopy and X-ray microtomography(micro-CT)were used to investigate the 3D structure of the void space within the pipe.Wick test results showed that most of the heat pipes made by LPBF had better performance than the conventionally manufactured pipes.This study also investigated the influences of the process parameters on the porosity volume fraction and the feature size.The results showed that LPBF process could fabricate thin structure due to the change of melt pool contact angle.The relationship between process parameters and bead size reported in this study could help design and manufacture heat pipe with complex fine structure. | Sheng Li Khamis Essa James Carr States Chiwanga Andrew Norton Moataz M.Attallah | 2022 | Advances in Manufacturing2022，10，4： | 0 |
| 3 | Mechanical property and biological behaviour of additive manufactured TiNi functionally graded lattice structure显示文摘Bio-inspired porous metallic scaffolds have tremendous potential to be used as artificial bone substitutes.In this work,a radially graded lattice structure (RGLS),which mimics the structures of natural human bones,was designed and processed by laser powder bed fusion of martensitic Ti-rich TiNi powder.The asymmetric tension-compression behaviour,where the compressive strength is significantly higher than the tensile strength,is observed in this Ti-rich TiNi material,which echoes the mechanical behaviour of bones.The morphologies,mechanical properties,deformation behaviour,and biological compatibility of RGLS samples were characterised and compared with those in the uniform lattice structure.Both the uniform and RGLS samples achieve a relative density higher than 99%.The graded porosities and pore sizes in the RGLS range from 40%-80% and 330-805 µm,respectively,from the centre to the edge.The chemical etching has significantly removed the harmful partially-melted residual powder particles on the lattice struts.The compressive yield strength of RGLS is 71.5 MPa,much higher than that of the uniform sample (46.5 MPa),despite having a similar relative density of about 46%.The calculated Gibson-Ashby equation and the deformation behaviour simulation by finite element suggest that the dense outer regions with high load-bearing capability could sustain high applied stress,improving the overall strength of RGLS significantly.The cell proliferation study suggests better biological compatibility of the RGLS than the uniform structures.The findings highlight a novel strategy to improve the performance of additively manufactured artificial implants by bio-inspiration. | Chaolin Tan Cheng Deng Sheng Li Alessandro Abena Parastoo Jamshidi Khamis Essa Likang Wu Guohua Xu Moataz M Attallah Jia Liu | 2022 | International Journal of Extreme Manufacturing2022，4，4： | 0 |
| 4 | Porosity,cracks,and mechanical properties of additively manufactured tooling alloys:a review显示文摘Additive manufacturing(AM)technologies are currently employed for the manufacturing of completely functional parts and have gained the attention of hightechnology industries such as the aerospace,automotive,and biomedical fields.This is mainly due to their advantages in terms of low material waste and high productivity,particularly owing to the flexibility in the geometries that can be generated.In the tooling industry,specifically the manufacturing of dies and molds,AM technologies enable the generation of complex shapes,internal cooling channels,the repair of damaged dies and molds,and an improved performance of dies and molds employing multipleAMmaterials.Inthepresentpaper,a reviewof AM processes and materials applied in the tooling industry for the generation of dies and molds is addressed.AM technologies used for tooling applications and the characteristics of the materials employed in this industry are first presented.In addition,the most relevant state-of-the-art approaches are analyzed with respect to the process parameters and microstructural and mechanical properties in the processing of high-performance tooling materials used in AM processes.Concretely,studies on the AM of ferrous(maraging steels and H13 steel alloy)and non-ferrous(stellite alloys and WC alloys)tooling alloys are also analyzed. | Prveen Bidare Amaia Jimenez Hany Hassanin Khamis Essa | 2022 | Advances in Manufacturing2022，10，2： | 0 |
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