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Fused deposition modeling (FDM) technology decreases production time and cost in engineering industry, but with typical low surface quality. In this study, laser polishing was employed to improve surface quality of copper fiber/polylactide acid (Cu/PLA) composite parts fabricated by FDM. Surface roughness, surface morphology, dynamic mechanical analysis (DMA), and tensile properties were studied. The results showed that after laser polishing, the surface roughness was reduced by more than 91% (from 10.52 to 0.87 μm Sa) at the optimized parameters (the laser power of 5 W and the laser beam diameter of 200 μm). Laser polishing can effectively remove surface defects formed during FDM. DMA showed that the storage modulus, loss modulus, and glass transition temperature of Cu/PLA composites were significantly improved, because the Cu fibers and PLA matrix formed a strong interfacial adhesion after treatment. Moreover, the tensile strength and Young's modulus of the Cu/PLA composites sample also improved by laser polishing. The fracture morphologies were observed, and the possible strengthening mechanism was also discussed. [ABSTRACT FROM AUTHOR]

Owing to the layer-by-layer deposition characteristic of fused deposition modeling (FDM) process, parts produced via FDM have typical low surface quality and do not satisfy the requirements for end-use applications. Therefore, it is necessary to improve the surface quality of parts produced via FDM. In this study, laser polishing technology was employed to enhance the surface quality of aluminum fiber/polylactide acid (Al/PLA) composite parts produced via FDM. The surface roughness, surface morphology, dynamic mechanical properties, and tensile properties were investigated. With optimal polishing parameters, the laser polishing process removed the defects formed during the FDM process. The surface roughness was reduced from the initial value of 5.64 μm to 0.32 μm (Ra). The dynamic mechanical analysis (DMA) results showed that there was a remarkable improvement in the storage modulus (E ′), loss modulus (E "), and glass transition temperature of Al/PLA composite specimens after laser polishing. The re-melted and polished surface of the specimens also led to improvement in the tensile strength and Young's modulus. Lastly, the fracture morphologies were observed, and the possible strengthening mechanism was also discussed. These results indicate that laser polishing can be an efficient method for the surface polishing of FDM-printed parts. Unlabelled Image • Laser polished additive manufactured Al/PLA has higher surface quality and many defects are removed. • A maximum reduction in Al/PLA surface roughness of over 93% is achieved at optimized polishing settings. • Laser polishing effectively improves the dynamic mechanical properties and tensile properties of the FMD Al/PLA. • The strengthening mechanism induced by laser polishing is analyzed. [ABSTRACT FROM AUTHOR]

Extreme high-speed laser cladding (EHLA) was used to develop a pore- and crack-free TiC/IN625 coating. The surface roughness of EHLA could be as low as 6.004 µm. A more uniform dendrite size and composition distribution was obtained by EHLA. The mass gain of EHLA was 57.5% lower than that of the conventional laser cladding sample after hot corrosion in a mixed salt of 75%Na 2 SO 4 + 25% NaCl at 900 ℃ for 60 h. High hot corrosion resistance of EHLA was mainly attributed to the lower surface roughness, smaller dendrite size, smaller grain size, and higher amount of low-angle grain boundaries. • Pores- and cracks-free TiC/IN625 coatings over AISI 1045 steel were firstly prepared by EHLA. • EHLA TiC/IN625 coatings possessed much more uniform and finer microstructure. • The uniformly distributed dendrite sizes and compositions contributed to the formation of a dense oxide film. • Superior hot corrosion behavior of EHLA TiC/IN625 coatings was mainly attributed to the lower surface roughness, smaller dendrite size, smaller grain size, and more low-angle grain boundaries. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM) produces parts through layer by layer on the top of each other, making it almost impossible to obtain smooth printed parts. Hence, there is a huge demand for the postprocessing of the FDM‐printed parts. Laser polishing is a novel technique that can be used to polish products to obtain a smoother surface. The aim of this work was to explore the feasibility of surface‐finishing FDM‐printed polylactic acid (PLA) parts by laser polishing. The surface roughness, surface morphology, dynamic mechanical analysis (DMA), and tensile properties were investigated. The results indicated that the lower laser power and the bigger laser beam diameter within a certain range could facilitate the formation of smoother surface. With optimized parameters, the surface roughness was reduced by 90.4%. DMA showed that the storage modulus (E') and glass transition temperature of PLA specimens were significantly improved due to the decrease of molecular mobility of denser structures. Moreover, the tensile strength and Young's modulus of the PLA specimen were also significantly increased after laser polishing. The fracture morphologies were observed, and the possible strengthening mechanism was also discussed. These results indicated that laser polishing could be an efficient method for surface polishing of FDM parts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48288. [ABSTRACT FROM AUTHOR]

Refractory high-entropy alloys (RHEAs) are a new category of high-temperature materials that are high-entropy alloys with refractory metal elements as the major components. SLM technique provides distinct benefits in preparing refractory metals with high melting points. The effects of laser power and scanning speed on the surface morphology and internal defects of VNbMoTaW RHEAs samples were examined using numerical and experimental methods. A DEM-CFD model was created to simulate the process of SLM producing a single-layer, single-track model. The simulation findings show that the melt pool's channel width is 62.31 μm at a scanning speed of 300 mm/s and a laser power of 150 W. The channel width grows to 96.92 μm when the laser power rises to 450 W. When the laser power is increased, the channel becomes flatter. To prepare the VNbMoTaW samples, the process parameters with the highest quality in the numerical simulation were chosen. At a scanning speed of 300 mm/s and a laser power of 450 W, the measured channel width of the high-entropy alloy samples is approximately 104.13 m. Similarly to the numerical simulation results, the channel width of the models generated at the same scanning speed increases as the laser power increases. At low laser power, it was discovered that many unmelted powder particles were dispersed on the surface of the samples. The primary defects found in the samples were pores and fractures. The interlayer non-melting cracks on the sample cross-section vanish at elevated laser power. Whereas the quality of samples created at low scanning speeds is higher at the same laser power, the quality of samples declines as the scanning speed of the laser increases. • The forming process of VNbMoTaW RHEAs by SLM was firstly simulated numerically. • Process parameters such as laser power and scanning speed affected the RHEAs surface morphology. • The experimental results were in good agreement with the simulation rules. • Pores and cracks are the main defects in the RHEAs alloys and cannot be completely avoided. [ABSTRACT FROM AUTHOR]