Search

Ceramic oxides, renowned for their exceptional combination of mechanical, thermal, and chemical properties, are indispensable in numerous crucial applications across diverse engineering fields. However, conventional manufacturing methods frequently grapple with limitations, such as challenges in shaping intricate geometries, extended processing durations, elevated porosity, and substantial shrinkage deformations. Direct additive manufacturing (dAM) technology stands out as a state-of-the-art solution for ceramic oxides production. It facilitates the one-step fabrication of high-performance, intricately designed components characterized by dense structures. Importantly, dAM eliminates the necessity for post-heat treatments, streamlining the manufacturing process and enhancing overall efficiency. This study undertakes a comprehensive review of recent developments in dAM for ceramic oxides, with a specific emphasis on the laser powder bed fusion and laser directed energy deposition techniques. A thorough investigation is conducted into the shaping quality, microstructure, and properties of diverse ceramic oxides produced through dAM. Critical examination is given to key aspects including feedstock preparation, laser-material coupling, formation and control of defects, in-situmonitoring and simulation. This paper concludes by outlining future trends and potential breakthrough directions, taking into account current gaps in this rapidly evolving field.

This study aims to establish the relationship between material removal characteristics and various surface features on selective laser melted 316L stainless steel after electropolishing (EP). Morphology and roughness were characterized on top, face up, side and face down surfaces of 316L stainless steel samples prepared by selective laser melting (SLM). Three types of un-sintered powders and two types of sintered area were categorized and further investigated based on the differences of morphology, microstructure and location. Material removal mechanism of each surface feature was also studied based on experimental and simulation results. Impacts of these surface features on the reduction of roughness during EP were thus discussed. The study reveals that different microstructures and feature locations lead to diverse material removal behaviors during EP process. Understanding the characteristics of un-sintered powders and sintered area on SLM surfaces is crucial in achieving satisfactory surface finish in EP.

•A novel method for analyzing diffractive optical characteristics of diamond-turned surfaces is proposed.•The height and spacing of nanometric topographical features exert different influences on diffraction spots.•A laser beam with a smaller wavelength and incident angle would induce more prominent high-order diffraction spots.•The intensity of high-order diffraction spots may increase by nearly 5 times due to the roughness change of 2 nm.•Diffraction spot observation is a promising method for the rapid evaluation of diamond-turned surfaces.

•A general smooth tool path planning method on NURBS surface is developed.•There are little influences of surface complexity on the computation efficiency of tool path planning.•Tool path interval can be determined easily to restrict the scallop height based on the difference of SBG.•Effectiveness and superiorities of the proposed method are verified by typical case studies and experiments.

Rotary ultrasonic-assisted machining (RUAM) processes have been recognized as leading, non-traditional, high-precision machining processes that have been recently developed to machine a vast range of advanced, hard-to-machine, brittle materials like reinforced composites, ceramics, and metallic alloys to a very high surface finish in an efficient and cost-effective manner. As the field of materials engineering further progresses in search of materials with very high hardness and resistance to wear for use in the biomedical, energy, aerospace, automobile, and optical industries, so too must the machining processes progress in order to fulfill the demand for manufacturing the components. RUAM processes have been shown to reduce cutting forces and improve tool life during machining of very hard and brittle materials so far. Therefore, from the very first implementation of ultrasonic energy for higher-quality machining in the late 1920s to today’s advanced computer numerical control RUAM 5-axis machining centers, this review examines the development history, the working mechanisms, and the critical performance of each RUAM process, which influence the process outputs. The advancements, applications, limitations, and future perspective of RUAM processes are also discussed in detail with the aim of providing clear insight into the future of RUAM, for further development and to extend the range of its applications.