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Papers - Yan, Jiwang

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Achieving ultra-low wear of Ti6Al4V alloy by introducing a sinusoidal nitriding layer via nanosecond pulsed laser irradiation

Zhang H., Wang C., Huang H., Yan J., Zhang L., Jiang M., Zhang Z.

Tribology International 200 2024.12

ISSN 0301679X

Introducing wear-resistant layers or constructing microtextures is normally employed to improve the wear resistance of materials. However, single role of the wear-resistant layer or microtexture still could not effectively address the wear issue of titanium alloys. In this study, a sinusoidal nitriding layer is directly fabricated on the Ti6Al4V surface by one-step laser irradiation. Chemical composition and microstructure analysis indicate that the nitriding layer contains TiN and α-Ti phases, and it is metallurgically bonded to the heat-affected zone. Friction wear tests show a 96.9 % reduction in wear rate with dry sliding and 99.6 % with oil lubrication, without exhibiting groove orientation dependence. The wear mechanism is discussed by scrutinizing the morphology of the wear scars and their corresponding cross-sections.

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Influence of crystallinity on micro-nano structure response of Zr-based alloys treated by nanosecond laser

Qian Y., Hong J., Jiang M., Zhang Z., Huang H., Yan J.

Optics and Lasers in Engineering 183 2024.12

ISSN 01438166

Understanding the processes and mechanisms of laser-matter interaction is fundamental to the treatment of materials by using laser-based methods, but it is quite challenging because the response of matter to laser irradiation is influenced by many factors, especially the intrinsic properties of the matter. In this study, the influence of crystallinity on micro-nano structure response of Zr-based alloys (Zr41.2Ti13.8Cu12.5Ni10Be22.5) treated by nanosecond laser is investigated. The microscopic topographies and geometrical dimensions of the laser-induced micro-nano structures formed on the surface of Zr-based alloys with different crystallinity have been explored and compared. The experimental results indicate that the microstructural transformation between micro-concave and micro-convex is observed for both amorphous and crystallized Zr-based alloys, i.e., independent of the arrangement of the internal atomic structure. The geometrical dimensions of the laser-induced micro-nano structures and the critical peak laser power intensity required for the microstructural transformation are different, which can be attributed to the difference in thermal conductivity. Inspired by laser-induced micro-convex, a point-by-point laser patterning technique has been proposed for highly efficient and flexible preparation of micro-nano patterns. Importantly, this patterning technique exhibits ultra-high processing efficiency with a material accumulation rate of more than 1012 μm3/s. This work paves an avenue for understanding the laser-matter interaction and is expected to facilitate the advanced functional applications of Zr-based alloys in many fields.

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Surface morphology formation and subsurface microstructure evolution of zirconia in ultrasonic vibration-assisted burnishing

Huang W., Tsuchida T., Yan J.

Journal of Materials Processing Technology 333 2024.12

ISSN 09240136

Yttria-stabilized zirconia (YSZ) is an outstanding ceramic material with applications in dentistry, biomedical, and mechanical device, where a smooth and durable surface is required. This study employed ultrasonic vibration-assisted burnishing (UVB) to enhance the surface hardness of YSZ while simultaneously reducing its roughness. The surface topography formation, subsurface microstructure evolution, and surface hardness change of YSZ were investigated. It was found that a smooth surface with an average roughness (Ra) of 0.12 μm was achieved using UVB, representing 67.6 % reduction in surface roughness from the original sintered surface, which is attributed to the burnishing-to-cutting phenomenon during the processing. The UVB-induced compression and material densification prevented the formation of the monoclinic phase during the processing of YSZ. Grain refinement and crystal lattice distortion occurring in the subsurface layer led to an increase in surface hardness, reaching up to 19.7 % higher than that of the original sintered surface. Moreover, the UVB-processed surface demonstrated a high resistance to mechanical impacts, effectively inhibiting the tetragonal-to-monoclinic phase transformation in indentation testing. These findings demonstrate that UVB is an effective approach for enhancing the surface and subsurface properties of the material.

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Abnormal wetting behavior transformation in RB-SiC composite induced by laser irradiation and annealing treatment

An H., Qian Y., Zhang Z., Huang H., Yan J.

Chemical Engineering Journal 499 2024.11

ISSN 13858947

Multifunctional reaction-bonded silicon carbide (RB-SiC) surfaces with tailored wetting behaviors have garnered notable interest due to their potential applications across various fields. However, the inherent hard-brittle nature of RB-SiC ceramics poses substantial challenges for the facile and controllable preparation of homogeneous and heterogeneous wetting surfaces via conventional techniques. Herein, taking advantage of the fact that laser irradiation of RB-SiC can induce the formation of SiO2 phase and that SiO2 with high surface energy can inhibit the adsorption of organic matter, the surface wetting characteristics of RB-SiC ceramics are flexibly tuned through a hybrid processing technique combining laser irradiation and annealing treatment. The SiO2 content of the laser-irradiated surface can be regulated by varying the laser processing parameters. In the subsequent annealing process, the laser-irradiated surface with low SiO2 content achieves a wettability transition from superhydrophilicity to superhydrophobicity, whereas the laser-irradiated surface with high SiO2 content remains superhydrophilic. Inspired by annealing-induced significant difference in wettability, gradient wetting and extreme wettability contrast surfaces are prepared, enabling the directional transport of droplets. The homogeneous superhydrophobic surfaces produced at different annealing temperatures exhibit distinct anti-icing capabilities and adhesion properties. Importantly, the prepared superhydrophobic surfaces with varying adhesion forces can achieve no-loss droplet transport. This study provides a straightforward, high-efficient, and low-cost method for fabricating RB-SiC surfaces with diverse wetting behaviors, thereby promising to expand their utility spectrum and practical applicability.

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A cross-scale material removal prediction model for magnetorheological shear thickening polishing

Tian Y., Ma Z., Ma X., Li L., Yan J.

Journal of Materials Processing Technology 332 2024.11

ISSN 09240136

Conventional polishing methods face significant challenges for achieving excellent performance on complex surfaces. The magnetorheological shear thickening polishing (MRSTP) method, with its dual-stimulus response of shear thickening and magnetization enhancement, offers an effective solution for polishing complex surfaces. However, existing models fail to elucidate the cross-scale material removal mechanisms in MRSTP owing to the coupling of magnetic and flow fields. In this study, a comprehensive model was proposed to address the the challenge of predicting the cross-scale material removal rate (MRR) in MRSTP for complex surfaces. Analytical and finite difference methods were employed to solve the pressure distribution during the MRSTP process using magnetohydrodynamics. By incorporating the pressure distribution, an MRR predictive model was developed for arbitrary points on the workpiece surface based on the indentation theory for active abrasive grains. The material removal mechanism was explored by considering elastic and plastic deformation under fluid pressure. The experimental validation showed a relative error of 14.9 % between the theoretical and experimental MRR. Experiments on aero-engine blade tenons demonstrated that the established MRR model is well suited for application to complex surfaces. This study ultimately reveals the material removal mechanism of MRSTP with coupled magnetic and flow field, providing a new foundation for predicting MRR on complex surfaces.

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Bridging Data Gaps: A Federated Learning Approach to Heat Emission Prediction in Laser Powder Bed Fusion

Lei R., Guo Y.B., Yan J., Guo W.G.

Journal of Manufacturing Science and Engineering 146 ( 10 ) 2024.10

ISSN 10871357

Deep learning has impacted defect prediction in additive manufacturing (AM), which is important to ensure process stability and part quality. However, its success depends on extensive training, requiring large, homogeneous datasets - remaining a challenge for the AM industry, particularly for small- and medium-sized enterprises (SMEs). The unique and varied characteristics of AM parts, along with the limited resources of SMEs, hamper data collection, posing difficulties in the independent training of deep learning models. Addressing these concerns requires enabling knowledge sharing from the similarities in the physics of the AM process and defect formation mechanisms while carefully handling privacy concerns. Federated learning (FL) offers a solution to allow collaborative model training across multiple entities without sharing local data. This article introduces an FL framework to predict section-wise heat emission during laser powder bed fusion (LPBF), a vital process signature. It incorporates a customized long short-term memory (LSTM) model for each client, capturing the dynamic AM process's time-series properties without sharing sensitive information. Three advanced FL algorithms are integrated - federated averaging (FedAvg), FedProx, and FedAvgM - to aggregate model weights rather than raw datasets. Experiments demonstrate that the FL framework ensures convergence and maintains prediction performance comparable to individually trained models. This work demonstrates the potential of FL-enabled AM modeling and prediction where SMEs can improve their product quality without compromising data privacy.

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On the promotion of serrated flows and shear band behaviors in a Zr-based metallic glass during ultrasonic vibration nanoindentation

Huang H., Su W., Wei D., Jiang M., Qian Y., Yan J.

Intermetallics (Intermetallics) 173 2024.10

ISSN 09669795

Initiation and evolution of flow units and their correlation with mechanical behaviors of metallic glasses (MGs) are well known significant for understanding the rheological behavior of glassy substances. Here, the evolution of plastic deformation behavior of a typical Zr-based MG induced by ultrasonic vibration is investigated by means of nanoindentation, especially focusing on studying structural evolution through analysis of load-displacement curves. Furthermore, the micro-morphologies of residual indentations are characterized by using the scanning electron microscope (SEM) and atomic force microscope (AFM). Compared to quasi-static nanoindentation tests, a significant reduction in the hardness and elastic modulus of the MG by about 15 % and 30 %, respectively, is observed when subjected to ultrasonic vibration nanoindentation with an amplitude of 0.4 μm, accompanied by a pronounced indentation size effect. In addition, higher ultrasonic vibration amplitude induces larger indentation depth, more pronounced serrated flows in the load-displacement curves and more remarkable shear bands around the residual indentations, indicating ultrasonic vibration-promoted plastic flows in MG. This study provides an insight into the structural origin of plastic flows in MG systems under ultrasonic vibration, which will help to facilitate their application in the fields such as ultrasonic vibration assisted forming.

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Experimental investigation on microstructure, mechanical and optical properties of RB-SiC ablated by nanosecond pulsed laser in nitrogen atmosphere

An H., Qian Y., Zhang Z., Huang H., Yan J.

Composites Part A: Applied Science and Manufacturing (Composites Part A: Applied Science and Manufacturing) 185 2024.10

ISSN 1359835X

Reaction-bonded silicon carbide (RB-SiC) has gained significant attention owing to its exceptional physical and chemical properties. Improving the photovoltaic efficiency and mechanical properties of RB-SiC is conducive to further enhancing its applicability. Laser gas nitriding is an effective strategy to simultaneously reduce the surface reflectivity and enhance the surface hardness of materials. Accordingly, the evolution of microstructure, mechanical and optical properties of RB-SiC composite ablated by nanosecond pulsed laser in nitrogen atmosphere was comprehensively investigated. After laser gas nitriding, the surface hardness of RB-SiC composite was increased by 10.6–44.6 %. The chemical composition analysis indicated that Si-based nitride was formed on the laser-ablated surface, which was mainly responsible for the hardness enhancement. Additionally, the reflectivity of the laser-ablated surface was reduced by up to 95.2 % compared to the original RB-SiC composite. This study provides a straightforward and effective method to simultaneously improve the mechanical and optical properties of RB-SiC composites.

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Improving the surface characteristics of metallic glass thin ribbons by laser gas nitriding

Huang H., Guo H., Wang J., Jiang M., Qian Y., Yan J.

Surfaces and Interfaces 53 2024.10

ISSN 24680230

The single-roll cooling method excels in producing metallic glass ribbons (MGRs), offering rapid cooling rates and exceptional thickness consistency. Nevertheless, a large number of defects including micro-pits and micro-gaps usually appear on the surface of MGRs after the roll forming process, significantly impacting their service life and performance. Laser gas nitriding is a cutting-edge surface modification technology that has been extensively used to improve the comprehensive performance of various metal components. Herein, an attempt was made to simultaneously improve the surface quality and mechanical properties of Zr41.2Ti13.8Cu12.5Ni10Be22.5 MGRs by nanosecond pulsed laser irradiation in a flowing nitrogen atmosphere. The effects of laser irradiation parameters on the surface characteristics of the laser gas nitrided regions were systematically investigated. The experimental results showed that the surface quality of MGRs after laser gas nitriding was enhanced, accompanied by a simultaneous improvement in hardness and scratch resistance. This study underscores laser gas nitriding as a potent strategy to augment the comprehensive surface characteristics of MGRs. This enhancement is poised to significantly extend their service life and reinforce their reliability when utilized as structural and functional materials in sectors such as machinery, national defense, and aerospace.

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A nonlinear dynamic analysis of skidding behavior in rolling bearings using lubricant traction coefficients and cage flexibility

Atef M.M., Khair-Eldeen W., Yan J., Nassef M.G.A.

Tribology International (Tribology International) 197 2024.09

ISSN 0301679X

Skidding is a primary cause of rolling element bearing (REB) failure, which is influenced by operating conditions, lubricant properties, and bearing design. This paper presents an improved nonlinear dynamic model of REBs to analyze the impact of lubricant characteristics on REB skidding at different speed states. The model considers time-varying traction coefficient, cage flexibility, and cage pocket clearance. The selected tested lubricants include lithium grease (LGT2), compound calcium sulfonate (CCS) grease, and 4109 Chinese aviation oil. Simulation results show that CCS grease effectively reduces cage skidding, with the lowest load limits (300 N at 2000 RPM) under constant speed conditions and the highest stable limit (2932 RPM) during acceleration. LGT2 grease exhibits minimal sensitivity to acceleration and fluctuation speed parameters change.

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Significant improvement in surface hardness of CrMnFeCoNi high entropy alloy via nanosecond pulse laser grain refinement

Huang H., Tian X., Wang C., Yan J.

Vacuum (Vacuum) 226 2024.08

ISSN 0042207X

The CrMnFeCoNi alloy with a stable single face-centered cubic (FCC) phase, representing a typical class of high-entropy alloys (HEAs), has garnered considerable attention owing to their exceptional mechanical properties. However, the inherent low hardness has impeded their utilization in structural or contact components. This study attempted to improve the surface hardness of CrMnFeCoNi HEA via grain refinement realized by nanosecond pulse laser irradiation. The effects of laser parameters on the surface microstructures, chemical composition, and mechanical properties were investigated, and the mechanism for grain refinement was analyzed. The experimental results showed that the hardness of the laser-irradiated surface was significantly improved without altering the chemical composition. This study provides a simple but effective method to refine the grain of HEAs and improve their surface hardness.

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Bending Forming Characteristics of CoCrFeMnNi High-Entropy Alloy Sheets Induced by Nanosecond Pulse Laser Irradiation

Tian X., Wang C., Zhang H., Gao J., Huang H., Yan J.

Materials 17 ( 15 ) 2024.07

Laser bending forming, as a flexible and die-less forming approach, facilitates the three-dimensional shaping of sheets through the generation of thermal stress via laser-material interaction. In this study, the bending forming characteristics of CoCrFeMnNi high-entropy alloy sheets induced by nanosecond pulse laser irradiation were systematically investigated. The effects of parameters including laser power, scanning speed, number of scans, scanning interval, and sheet size on the bending angle, cross-sectional morphology, and hardness were studied in detail under both the laser single-line and multi-line scanning modes. The experimental results confirmed the effectiveness of nanosecond pulse laser irradiation for achieving accurate formation of CoCrFeMnNi sheets, with the successful fabrication of J, L, and U-shaped metal components. Apart from the forming ability, the cross-sectional hardness was significantly increased due to the grain refinement effect of nanosecond pulse laser irradiation. Furthermore, employing the laser single-line scanning mode enabled the effective rectification of overbending parts, showcasing complete recovery for small-angle overbending, and a remarkable 91% recovery for larger-angle overbending. This study provides an important basis for the bendability of CoCrFeMnNi sheets by laser forming and elucidates the evolution of the microstructure and mechanical properties in the bending region.

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Surface quality and mechanical property evolution of laser nitrided Zr-based metallic glass induced by laser shock flattening

Huang H., Xu P., Liu B., An H., Qian Y., Yan J.

Vacuum (Vacuum) 224 2024.06

ISSN 0042207X

Laser nitriding is an effective modification technique to improve the comprehensive mechanical properties of metallic glasses (MGs). However, numerous micro-defects, such as pores and humps, usually appear on the laser-nitriding-treated (LNed) MG surface, and therefore additional post-treatment is required. Herein, laser shock processing was implemented to flatten the LNed MG and as well modify its surface mechanical property. The dependence of the laser shock flattening process on the laser energy density was investigated. The results revealed that the surface micro-defects on the LNed MG were significantly reduced after laser shock flattening, and accordingly, the surface roughness (Sa) was decreased, with a maximum reduction of 61.87% (from 0.48 to 0.183 μm) achieved at a relatively high laser energy density of 178.3 J/cm2. Furthermore, nanoindentation measurements indicated that although the surface hardness of the LNed MG was decreased after laser shock flattening, it was still higher than that of the as-cast MG.

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Investigation of failure modes and material structural responses of nanographite coatings on single-crystal silicon by nanoscratching

Brüssel F., Huang W., Yan J.

Tribology International (Tribology International) 193 2024.05

ISSN 0301679X

The failure modes of a nanographite-on-silicon system and the effects of the coating on the load-induced phase transformation of the silicon substrate were investigated using a series of nanoscratching tests with a spherical diamond indenter. The critical normal load for the failure of the nanographite coating was determined based on the thickness of the coating. When the load increased beyond the critical point, cracks, press spallation, and lift spallation were observed, and the silicon substrate underwent a phase transformation from the original crystalline phase to a mixture of amorphous, Si-III and Si-XII phases. For a thin coating, the silicon substrate was free of phase transformation owing to the coating protection. These findings provide guidance for glass molding and other applications.

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Simultaneous flattening and hardening of laser shock peened Zr-based metallic glass surface by nanosecond laser irradiation in a flowing nitrogen atmosphere

Qian Y., Liu B., Hong J., Jiang M., Zhang Z., Zhang L., Huang H., Yan J.

Journal of Materials Processing Technology (Journal of Materials Processing Technology) 326 2024.05

ISSN 09240136

Laser shock peening (LSP) is an ideal surface modification technique which has been extensively applied to improve the room-temperature plasticity of metallic glasses (MGs) by generating extra-deep compressive residual stress region and increasing the free volume content. Nevertheless, after LSP treatment, the surface quality and hardness of MGs are usually impaired simultaneously, which hinders their applications as structural and functional materials. In the current study, an attempt was made to achieve simultaneous flattening and hardening of LSP treated (LSPed) Zr-based MG by nanosecond laser irradiation in a flowing nitrogen atmosphere. The effects of laser power level on the macro- and micro-morphology, chemical composition, surface hardness, and surface roughness (Sa) of the laser-irradiated LSPed MG were comprehensively investigated. It was found that the minor surface defects of the LSPed MGs could be effectively reduced by nanosecond laser irradiation under appropriate laser irradiation parameters, and accordingly, the surface quality was improved (with a maximum reduction in surface roughness (Sa) by 86.3%). Furthermore, the nanoindentation test results indicated that nanosecond laser irradiation at a relatively high laser power of 15.6 W resulted in an impressive improvement (173.9%) in surface hardness of the LSPed MG, which could be attributed to the introduction of hard nitrided phases mainly consisting of Zr3N4. This study provides an insightful understanding of the microstructure changes and surface characteristics of the LSPed MGs after nanosecond laser irradiation in a flowing nitrogen atmosphere, which paves the way for improving the applicability of MGs as structural and functional materials.

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Surface conditioning in cutting and abrasive processes

Schulze V., Aurich J., Jawahir I.S., Karpuschewski B., Yan J.

CIRP Annals (CIRP Annals) 73 ( 2 ) 667 - 693 2024.05

ISSN 00078506

Cutting and abrasive processes affect the surface layer state of the components treated. This determines their performance in service. An adjustment of the surface layer properties would allow for enhanced performance. This paper introduces the influences of named processes on the surface layer state and their systematics. Models and sensor concepts for surface conditioning are described and combined to soft sensors which are the basis for active control within the processes. A validation study and actual applications of the conditioning concept are shown, allowing for further technological and scientific understanding of surface conditioning and its contribution to material and energy efficiency.

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Effect of dopant concentration on femtosecond pulsed laser irradiation of yttria-stabilized zirconia for generating nanopores

Yamamuro Y., Shimoyama T., Nagata H., Yan J.

Journal of Alloys and Compounds (Journal of Alloys and Compounds) 980 2024.04

ISSN 09258388

Yttria-stabilized zirconia (YSZ) is a fine ceramics material that has been applied to dental implants and mechanical components. As YSZ is a hard, brittle, and chemically stable material, that undergoes phase transformation during mechanical loading, it is difficult to fabricate nanostructures using mechanical processing methods. In this study, a surface structuring method using a femtosecond pulsed laser was proposed, which is effective in suppressing the mechanical loading-induced phase transformation. As the material properties of YSZ vary with the concentration of yttria dopant, polycrystalline zirconia samples with different yttria concentrations (2, 3, 5, and 8 mol%) were used to investigate the effect of yttria concentrations on laser processing characteristics for nanostructuring. At all concentrations, nanopore generation in the surface grain was achieved by laser irradiation near the ablation threshold. In addition, there was no significant change in the crystal structure before and after laser irradiation, and no damage to the bulk occurred. At 2 mol%, intergranular cracks were generated around the pores. By increasing the dopant level to 5 mol%, the lens effect of the crystal grains became stronger due to enhanced grain growth, and the diameter and number of pores increased. In addition, pores formed preferentially on smaller grains at 5 mol%. However, for YSZ with 8 mol%, the pore formation phenomenon was different from that in the lower dopant level, as the area near the grain boundary was preferentially ablated, and microcracks formation and exfoliation of the surface also occurred. These results contribute to a deeper understanding of the laser ablation characteristics of zirconia with different dopant levels and to the development of surface structuring methods for fine ceramics materials.

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Enhancing object detection and classification using deep learning: A novel approach with annotated dataset and YOLO-C3GTR architecture

Usman, RM; Yan, JH; Mehmood, S; Jamil, M

MEHRAN UNIVERSITY RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY 43 ( 2 ) 205 - 219 2024.04

ISSN 0254-7821

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Change in Material Structure upon Laser Irradiation of Mixed Target of Si Grinding Waste and Graphite Powder

Kanon MINAMI, Kyosuke KOBINATA and Jiwang YAN

Journal of The Japan Scoiety of Electrical Machining Engineers 58 ( 147 ) 3 - 11 2024.03

Research paper (scientific journal), Joint Work, Last author, Accepted

On the surface characteristics and removability of RB-SiC composite processed by nanosecond pulsed laser

An H., Qian Y., Zhang L., Zhang Z., Huang H., Yan J.

Composites Part A: Applied Science and Manufacturing (Composites Part A: Applied Science and Manufacturing) 180 2024.02

ISSN 1359835X

The inherent hard-brittle nature of RB-SiC composite poses significant challenges for efficient machining, hindering its application and promotion. Laser processing is a non-contact treatment technique that can effectively modify the mechanical properties of the material surface, thereby altering its removability. Accordingly, the change in surface characteristics of RB-SiC composite induced by nanosecond laser irradiation was investigated. It was found that laser irradiation could effectively soften the RB-SiC composite (with a maximum reduction in hardness by 40.7%), and the softening degree was strongly dependent on the laser parameters. The chemical composition analysis showed that the SiC content was decreased while the Si content was increased after laser irradiation, which was mainly responsible for the hardness reduction of RB-SiC composite. In addition, compared to the original RB-SiC composite, the laser-irradiated samples exhibited enhanced weight loss during the polishing process. This work gives a feasible route to improve the removability of RB-SiC composite.

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