The excess heat generated during the laser additive manufacturing process is prone to cause coating defects; a water-cooled substrate can effectively remove the excess heat and improve the hardness of the coating. In this study, the effects of water-cooled substrate on the microstructure and hardness of laser additive manufactured nickel-based coatings were investigated by experimental and numerical simulations. The results showed that the water-cooled substrate decreased the size of columnar crystals and increased the number as well as the length of secondary dendrite crystals at the bottom of the nickel-based coatings. There was also a noticeable increase in the size of equiaxed grains and the quantity of the solid solution in the middle of the coatings. The hardness value of the coating increased at the water velocity of 200 mL/s and 500 mL/s and finally decreased at 700 mL/s. A finite element model was established by ABAQUS software to numerically simulate the temperature field of the laser additive manufactured nickel-based coating with the water-cooled substrate. The results revealed significant differences in the temperature distribution of the coatings with different velocities. As the water velocity increased, the peak temperature at the center of the coating's molten pool gradually decreased. In addition, the cooling rate of the specimens increased with the application of the water cooling, leading to a more concentrated temperature distribution near the laser heat source.
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http://dx.doi.org/10.3390/ma17235692 | DOI Listing |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11642272 | PMC |
Materials (Basel)
November 2024
School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Narmak, Tehran 13114-16846, Iran.
The excess heat generated during the laser additive manufacturing process is prone to cause coating defects; a water-cooled substrate can effectively remove the excess heat and improve the hardness of the coating. In this study, the effects of water-cooled substrate on the microstructure and hardness of laser additive manufactured nickel-based coatings were investigated by experimental and numerical simulations. The results showed that the water-cooled substrate decreased the size of columnar crystals and increased the number as well as the length of secondary dendrite crystals at the bottom of the nickel-based coatings.
View Article and Find Full Text PDFMaterials (Basel)
July 2023
College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, China.
The brittle failure of ceramic coatings limits their application in many fields. To address this issue, a novel armoured ceramic coating was developed to suppress brittle failure. First, an interconnected frame microstructure was micromachined onto the surface of a mild steel substrate using a nanosecond laser.
View Article and Find Full Text PDFPolymers (Basel)
March 2023
Department of Dentistry, IRCCS San Raffaele Hospital and Dental School, Vita Salute University, 20158 Milan, Italy.
The aim of the study was to compare the translucency of CAD/CAM and printable composite materials for fixed dental prostheses (FDP). Eight A3 composite materials (7 CAD/CAM and 1 printable) for FPD were used to prepare a total of 150 specimens. CAD/CAM materials, all characterized by two different opacity levels, were: Tetric CAD (TEC) HT/MT; Shofu Block HC (SB) HT/LT; Cerasmart (CS) HT/LT; Brilliant Crios (BC) HT/LT; Grandio Bloc (GB) HT/LT; Lava Ultimate (LU) HT/LT, Katana Avencia (KAT) LT/OP.
View Article and Find Full Text PDFMicromachines (Basel)
December 2020
Centre for Advanced Laser Manufacturing (CALM), School of Mechanical Engineering, Shandong University of Technology, Zibo 255000, Shandong, China.
Laser-induced graphene (LIG) is an emerging technique for producing few-layer graphene or graphene-like material that has recently received increasing attention, due to its unique advantages. Subsequently, a variety of lasers and materials have been used to fabricate LIG using this technique. However, there is a lack of understanding of how different lasers (wavelengths) perform differently in the LIG conversion process.
View Article and Find Full Text PDFSci Rep
November 2020
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, 195251, Russian Federation.
In this work, we demonstrate an effective way of deep (30 µm depth), highly oriented (90° sidewall angle) structures formation with sub-nanometer surface roughness (R = 0.7 nm) in silicon carbide (SiC). These structures were obtained by dry etching in SF/O inductively coupled plasma (ICP) at increased substrate holder temperatures.
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