Thermal and strain-stress transient fields during laser cladding of bioactive glass coatings on the Ti6Al4V alloy basement were numerically calculated and analysed. Conditions leading to micro-cracking susceptibility of the coating have been investigated using the finite element based modelling supported by experimental results of microscopic investigation of the sample coatings. Consecutive temperature and stress peaks are developed within the cladded material as a result of the laser beam moving along the complex trajectory, which can lead to micro-cracking. The preheated to 500°C base plate allowed for decrease of the laser power and lowering of the cooling speed between the consecutive temperature peaks contributing in such way to achievement of lower cracking susceptibility. The cooling rate during cladding of the second and the third layer was lower than during cladding of the first one, in such way, contributing towards improvement of cracking resistance of the subsequent layers due to progressive accumulation of heat over the process.
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http://dx.doi.org/10.1016/j.jmbbm.2016.02.023 | DOI Listing |
Nanomaterials (Basel)
January 2025
Key Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China.
Antimonide laser diodes, with their high performance above room temperature, exhibit significant potential for widespread applications in the mid-infrared spectral region. However, the laser's performance significantly degrades as the emission wavelength increases, primarily due to severe quantum-well hole leakage and significant non-radiative recombination. In this paper, we put up an active region with a high valence band offset and excellent crystalline quality with high luminescence to improve the laser's performance.
View Article and Find Full Text PDFDynamic transverse mode instability (TMI) has become one of the primary limitations for power scaling of high-power fiber lasers. Experimental evidence has shown that static mode degradation can suppress the dynamic TMI effect. This study reveals the physical mechanisms behind the mitigation of dynamic TMI in two-mode fiber lasers through static mode degradation.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China.
In this study, FeCoNiCrSi (x = 0, 4, and 8) powders were successfully prepared using the aerosol method and employed to produce high-entropy coatings on Q235 steel via laser cladding. The microstructure and phase composition of the coatings were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Corrosion resistance and potential were evaluated through electrochemical analysis and Kelvin probe force microscopy.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
School of Mechanical and Electrical Engineering, Soochow University, Suzhou 215137, China.
Composite coatings reinforced with varying mass fractions of SiC particles were successfully fabricated on 316 stainless steel substrates via laser cladding. The phase compositions, elemental distribution, microstructural characteristics, hardness, wear resistance and corrosion resistance of the composite coatings were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Vickers hardness testing, friction-wear testing and electrochemical methods. The coatings have no obvious pores, cracks or other defects.
View Article and Find Full Text PDFMicromachines (Basel)
November 2024
College of Aeronautical Engineering, Civil Aviation University of China, Tianjin 300300, China.
To enhance the tribological properties of the coatings and to inhibit cracking, sandwich-structured composite coatings were fabricated, consisting of a Ni60CuMo/IN718 transition layer and a Ni60CuMo/Ni-coated Cu wear-resistant layer with four different Ni-coated Cu contents. The results indicate that the transition layer inhibits the crack formation in the coating, and the refined grain structure stabilizes its average hardness at approximately 485 HV. Increasing the Cu content in the wear-resistant layer exacerbates the segregation of the Cu-rich solid solution phases and refines the in situ-generated CrC, TiC, and NbC phases.
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