Layer Deposition Research Articles

Luminescence and radiocarbon chronology of Bhagatrav: A Sorath Harappan camp site in South Gujarat

Abstract Excavation at the site of Bhagatrav yielded four layers of cultural deposits: the lowermost being the Sorath Harappan, the upper two are medieval, and layer three caps the Sorath Harappan layer. A horn-deity painted dish was found in a stratified context at the lowest level. The medieval deposit includes turquoise glazed and celadon wares, followed by an abundance of Monochrome Glazed Ware, which is otherwise known as Khambhat ware. The date of the Sorath Harappan layer of the site, the time and space of the horn-deity motif in the Harappan world, and the date of Khambhat ware have long been subjects of discussion. With the help of a series of absolute dating (radiocarbon and luminescence), this paper attempts to place the site, horn-deity motif, and the Khambhat ware in the cultural chronology of Gujarat.

Parameters of graphite shock compression at the initial stages of Popigai astrobleme formation

A numerical modeling of the process of a high-speed impact of a massive asteroid with the Earth’s surface was carried out to study the hypothesis of the meteoritic origin of the impact diamond deposit located in the Popigai River basin. A normal collision of a chondritic asteroid with a layered structure of the Earth’s soil at a speed of 25 km/s is simulated in 2D axisymmetric formulation. The natural carbon deposit layer is located in the near-surface zone of the loaded area. The calculations were carried out using a multidimensional parallel implementation of the finite-size particle-in-cell method. Models of the equations of state of chondrite, quartz and carbon are used to describe the properties of the meteorite and soil material. Thermodynamic parameters of impact compression of soil materials at the initial stages of loading and crater formation processes are obtained.

Investigation of thermal and fluid dynamics behaviors of melt pool during laser direct metal deposition on inclined substrates

The laser direct metal deposition (DMD) technique offers an efficient solution for repairing and manufacturing structures with variable curvatures, such as impeller blades. However, how the non-vertical laser irradiation on curved surfaces impacts the thermal and fluid dynamics of the melt pool still remains unclear. In the current research, a high-fidelity multi-physics numerical model is developed to explore the mechanisms of melt pool development and the effects of inclined angle and laser spot diameter on morphological evolution of deposition layers during DMD under non-vertical irradiation on inclined substrates. Results indicate that as the inclination angle increases, deposited track fluctuations become evident, with a critical angle from 40° to 42.5° identified for hump formation. A smaller laser spot diameter increases the likelihood of humps and irregularities, while a larger spot diameter expands the deposition layer and enhances melt pool wettability. This study is expected to provide significant theoretical guidance for selecting and applying process parameters for the fabrication of curved structures by DMD.

An experimental study on laser cleaning of the soot deposition layer on a white marble surface

A coordinated application of the image binarization, area extrapolation, and laser-induced breakdown spectroscopy (LIBS) detection for monitoring and controlling the laser cleaning soot deposition layer process on a white marble surface was reported. The laser cleaning process used a fiber pulsed laser beam with a fixed wavelength of 1064 nm, a pulse repetition frequency of 100 kHz, and a focal spot diameter of 95 μm. Image binarization was conducted to determine 150 ns as the appropriate fixed pulse width for laser cleaning of the soot deposition layers from four discrete values of 50 ns, 100 ns, 150 ns, and 200 ns. The optimal laser energy density of 2.82 J·cm-2 was obtained through area extrapolation, while the optimal spot overlap rate of 20 % was determined to maximize the effective laser cleaning speed. The optimal number of cleanings for a soot deposition layer with a thickness of 77μm was determined to be 5 using LIBS detection and to monitor the laser cleaning process in real time for each small area of the soot deposition layer. Image binarization was used to evaluate the overall cleaning quality of large marble surfaces. By dynamically adjusting the optimal number of cleanings, the cleaning efficiency of the soot deposition layers on half of the surface area of a 20 cm diameter white marble artifact exceeded 95 %. The results indicate that the synergistic use of various online monitoring methods can optimize multiple laser parameters, enabling precise removal of the soot deposition layer on the white marble surfaces caused by anthropic factors, without damaging its surface.

Potentiostatic electrolysis of fluoride melts with zirconium oxide additives

Currently, the demand for zirconium-based alloys and materials is growing significantly due to their high thermal and corrosion resistance combined with mechanical strength. Existing technologies for producing zirconium and its alloys are complicated by the high temperature of the process, or labor intensity and multi-stage nature, which significantly increases the cost of the target material up to the loss of profitability of the process. Electrochemical synthesis of zirconium and its alloys in fluoride-based melts, using zirconium oxides as the main metal-containing consumable component, seems more profitable. In this work, a series of electrolysis tests were carried out to deposit Al-Zr alloy at a potential of 1.6 V on graphite and molybdenum cathodes. According to the previously obtained results, in the presence of ZrO2 in the KF-AlF3-Al2O3 melt, a plateau and a discharge peak of electroactive ions appear on the cathode branch of the voltammograms at potentials of -1.4 and -1.7 V, ZrI and ZrII, respectively. Similar responses appear on tungsten at potentials of -1.3 and -1.6 V, respectively, and in the potential region of -1.9 V there is a clear peak (Al) of electroreduction of aluminum ions. As a result of electrolysis, it was found that the graphite anode was consumed, and a fairly well-bonded deposit was formed on the cathode. Part of the cathode deposit was mechanically separated from the cathode for analysis of its chemical and phase composition. Based on the results of X-ray phase analysis, it was found that the cathode deposit mainly consists of Al3Zr and aluminum compounds with molybdenum impurities, with the composition Al12Mo, which is consistent with known ideas about the formation of intermetallic compounds during the interaction of aluminum with other metals. Electrolysis of the melt on the graphite cathode was carried out under similar conditions. Based on a microphotograph of the cathode cross section, it was found that during electrolysis, a layer of deposit containing both zirconium and aluminum was formed at the electrode-electrolyte phase boundary.

Additive Manufacturing of Tungsten Carbide (WC)-Based Cemented Carbides and Niobium Carbide (NbC)-Based Cermets with High Binder Content via Laser Powder Bed Fusion

The additive manufacturing technique performed via laser powder bed fusion has matured as a technology for manufacturing cemented carbide parts. The parts are built by additive consolidation of thin layers of a WC and Co mixture using a laser, depending on the power and scanning speed, making it possible to create small, complex parts with different geometries. NbC-based cermets, as the main phase, can replace WC-based cemented carbides for some applications. Issues related to the high costs and dependence on imports have made WC and Co powders emerge as critical raw materials. Furthermore, avoiding manufacturing workers’ health problems and occupational diseases is a positive advantage of replacing WC with NbC and alternative binder phases. This work used WC and NbC as the main carbides and three binders: 100% Ni, 100% Co, and 50Ni/50Co wt.%. For the flowability and spreadability of the powders of WC- and NbC-based alloy mixtures in the powder bed with high cohesiveness, it was necessary to build a vibrating container with a pneumatic turbine ranging from 460 to 520 Hz. Concurrently, compaction was promoted by a compacting system. The thin deposition layers of the mixtures were applied uniformly and were well distributed in the powder bed to minimize the defects and cracks during the direct sintering of the samples. The parameters of the L-PBF process varied, with laser scanning speeds from 25 to 125 mm.s─1 and laser power from 50 to 125 W. Microstructural aspects and the properties obtained are presented and discussed, seeking to establish the relationships between the L-PBF process variables and compare them with the liquid phase sintering technique.

Investigation of three-dimensional forces during additive friction stir deposition — How could force signals reveal the deposition quality?

Additive friction stir deposition (AFSD) is a solid-phase forming technology based on microzone forging, which is essentially a force-driven additive manufacturing process. This work focuses on the effects of the AFSD parameters on the force signals and forming quality, which is highly important for optimizing the process parameters and controlling the forming quality. By analyzing the force features in the time‒frequency domain, the evolution mechanism of three-dimensional forces during AFSD was explored. A 3D scanner, scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) were used to clarify the surface morphology and microstructures of the deposition layers. It was found that deposition defects were accompanied by a lack of plasticization or nonuniform deformation between the advancing side (AS) and the retreating side (RS). Moreover, the relationships among the process parameters, three-dimensional forces and deposition quality were investigated. It is proved that force signal can effectively reflect the deposition quality. A comprehensive prediction model based on three-dimensional force features was developed, achieving an accurate prediction of deposition quality. Furthermore, this work demonstrated the feasibility of AFSD quality control on the basis of force signals. The currently employed control strategies can be further extended to address the AFSD of large components in the future.

(Invited) In Situ Measurements during ALD/ALE Processes

Atomic layer deposition (ALD) and atomic layer etching (ALE) provide exquisite control over the addition and removal of thin film materials and are invaluable tools for semiconductor manufacturing and a wide range of other applications. However, it is not always clear why some ALD/ALE processes succeed while others fail. Performing in situ measurements during ALD/ALE can unravel the detailed surface chemistries underlying these processes to elucidate the reaction mechanisms and ultimately yield more robust and reliable processes. In this presentation, I will motivate the need for in situ measurements during ALD/ALE and provide detailed examples of the techniques used under typical ALD conditions including quartz crystal microbalance, mass spectrometry, infrared spectroscopy, spectroscopic ellipsometry, and optical emission spectroscopy for plasma-based processes. I will also describe some of the high vacuum in situ methods that have been exploited such as X-ray photoelectron spectroscopy and scanning probe microscopy. In addition, I will discuss synchrotron X-ray based methods for in situ study of ALD/ALE reactions.

A hybrid approach: Box–Behnken design and COPRAS on the investigation of biocompatible polylactic acid via material extrusion

This study investigates the performance of biocompatible polylactic acid (PLA) processed through material extrusion/fused filament fabrication (FFF). In this study, the significant FFF input parameters, such as layer deposition, infill angle (degree), and infill percentage (%), were designated to process the PLA based on the screening design experiments. Following Box–Behnken design (BBD), the different input conditions were analyzed to evaluate the performance by assessing the characteristics such as ultimate tensile strength (UTS) and relative density (RD). Printing speed (30 mm/s), nozzle temperature (200°C), and bed temperature (70°C) are considered as fixed input parameters. The novel combination of BBD approach with the Complex Proportional Assessment (COPRAS) technique was employed to obtain the appropriate input conditions. It was beneficial to attain the individual parameter's contribution to the PLA characteristics through analysis of variance and best alternative condition through degree of utility. The combined approach was validated with a composite desirability index “D.” Finally, the hybrid approach yielded better results, such as a maximum ultimate tensile strength (UTS) of 37.43 MPa, relative density (RD) 99.12%, and microhardness 52 HRB under the layer deposition: 0.12 mm, infill angle: 0°, and infill percentage: 100% in the printed biocompatible PLA.

Laser-Induced Nanostructured Si and SiGe Layers for Enhanced Optical and Thermoelectric Performance.

We investigate a method for fabricating layers that exhibit both high optical absorption and promising thermoelectric properties. Using plasma-enhanced chemical vapor deposition (PECVD), amorphous Si and Si72Ge28 layers are deposited on glass substrates and subsequently processed via laser annealing to achieve nanostructured layers. Our results show that a single laser annealing pulse at 40 mJ yields the highest power factor, approximately 90 μW/m·K2. Additionally, we observe a maximum absorbance enhancement factor of 60 times in the spectral region near 880 nm for samples treated with a single pulse of 60 mJ compared to untreated samples. The effects of laser energy, the number of pulses, and material choice are further discussed.

Corrosion Inhibition of PAAS/ZnO Complex Additive in Alkaline Al-Air Battery with SLM-Manufactured Anode

In order to improve the electrochemical activity and discharge performance of aluminum–air batteries and to reduce self-corrosion of the anode, an SLM-manufactured aluminum alloy was employed as the anode of the Al-air battery, and the influence of PAAS and ZnO inhibitors taken separately or together on the self-corrosion rate and discharge performance of the Al-air battery in a 4 M NaOH solution were investigated. The experimental result indicated that the effect of a composite corrosion inhibitor was stronger than that of a single corrosion inhibitor. The addition of the compound inhibitor not only promoted the activation of the anode but also formed a more stable composite protective film on the surface of the anode, which effectively slowed down the self-corrosion and improved the utilization rate of the anode. In NaOH/PAAS/ZnO electrolytes, the dissolution of the Al6061 alloy was mainly controlled by the diffusion of the electric charge in the corrosion products or the zinc salt deposition layer. Meanwhile, for the Al-air battery, the discharge voltage, specific capacity, and specific energy increased by 21.74%, 26.72%, and 54.20%, respectively. In addition, the inhibition mechanism of the composite corrosion inhibitor was also expounded. The excellent discharge performance was due to the addition of the composite corrosion inhibitor, which promoted the charge transfer of the anode reaction, improved the anode’s activity, and promoted the uniform corrosion of the anode. This study provides ideas for the application of aluminum–air batteries in the field of new energy.

Additive friction stir deposition of an Al-Cu-Mg alloy: Microstructure evolution and mechanical properties

Additive Friction Stir Deposition (AFSD), an emerging solid-based additive manufacturing technology, has demonstrated significant potential in the fabrication of high-strength aluminum alloys. In this study, a 22 mm thick 2024 aluminum alloy deposit having ten layers was for the first time successfully fabricated using the AFSD technique. The correlation between the microstructure evolution and mechanical properties within the deposit was revealed. The results indicated that the deposit exhibited very fine recrystallized microstructure and excellent mechanical properties. Dynamic recrystallization occurred with the average grain sizes at the top, center, and bottom of the deposit being 3.0 μm, 4.7 μm, and 4.8 μm, respectively. The Al2CuMg (S phase) at grain boundaries of the deposit was observed to fracture due to the plastic deformation of the feedstock during the deposition process. The Vickers hardness of the deposit cross-section along the build direction (BD) changed from 125 HV of the top to 85 HV of the bottom. Better tensile properties in the TD compared to the BD were observed with the excellent tensile strength of 532 MPa and 473 MPa, and the elongation of 31.2 % and 15.2 %, respectively. The synergistically improvement of the tensile strength and elongation in the TD was attributed to the uniform microstructure and mechanical properties exhibited by each deposit layer.

Constructing interfacial molecular layer coupled with Zn2+ transfer/deposition kinetics modulation toward deeply reversible Zn anodes

Irreversible Zn dendrite formation and hydrogen evolution reactions (HER) have significantly impeded the large-scale commercial deployment of aqueous zinc-metal batteries (AZMBs). Herein, we proposed an innovative interfacial strategy activated by the biomacromolecule Pullulan (Pul) on the surface of zinc metal anodes (ZMAs) within the electrolyte system. The combination of comprehensive experimental results and simulation calculations demonstrated that the spontaneous assembly of the interfacial molecular layer (IML), facilitated by the adaptive adsorption of Pul molecules, not only triggers the formation of a Zn²⁺-concentrated region and effectively balances ionic flux, but also simultaneously transforms the nucleation growth pattern of Zn2+ into an instantaneous and progressive hybridized mechanism, reconfiguring the Zn2+ transfer/deposition kinetics at the heterogeneous electrode/electrolyte interface. Moreover, the IML provides a stable shielding effect for hydrated hydrogen with high thermodynamic activity and SO42− at the solid-liquid interface. Therefore, a smooth and compact Zn deposition layer devoid of dendritic growth is achieved during subsequent plating processes. As a result, Zn||Zn symmetric cells utilizing modified electrolytes exhibit remarkable plating/stripping performance exceeding 1800 h without significant voltage fluctuations, which contributes to the exceptional long-term durability observed in Zn||CNTs@MnO2 batteries.

The diversity of evolution behavior between stoichiometric and non-stoichiometric AlTM intermetallics in Mg melt

In this study, Al-5Ti, Al-18Si-5Ti, Al-12Si-2Sc and Al-12Si-1Sc-1Zr alloys, containing the Al3Ti, Ti7Al5Si12, AlSi2Sc2 and AlSi2(Sc, Zr)2 particles, respectively, were introduced into a Mg melt to understand the morphological and structural evolution behaviors of AlTM intermetallic compounds. Deposition layers at the bottom of the Mg melt were obtained due to the particle settlement. Scanning electron microscope and X-ray diffraction were employed to analyze the phase morphologies and structures of the AlTM intermetallic compounds in the deposition layers. A morphological transformation, characterized by the cracking of particles into fine clusters, was observed in all these AlTM intermetallic compounds, which is promoted by the inward diffusion of Mg atoms. The phase structures of the final particles remained Al3Ti and AlSi2Sc2 when Al-5Ti and Al-12Si-2Sc alloys were introduced into the Mg melt, indicating no structural evolution. However, structural evolutions were detected from Ti7Al5Si12 to Ti5Si4 and from AlSi2(Sc, Zr)2 to SiScZr when they were introduced in the Mg melt. It is hypothesized that the crystal structure, whether stoichiometric or non-stoichiometric, is closely related to the structural evolution behavior of AlTM intermetallic compounds. This work may provide new insights into phase control by introducing one type of metal matrix master alloy into another metal melt.

Effect of Composite Scanning Strategy on Forming Quality, Microstructure, and Tensile Properties of Laser Powder Bed Fusion Titanium Alloy

Laser powder bed fusion (LPBF) technology offers significant advantages in manufacturing complex‐shaped titanium alloy components. Traditional scanning strategies, such as zigzag and island scanning, however, often fall short in fabricating parts with variable cross sections. To enhance the forming quality of components featuring combined thin‐walled and bulk structures, a composite scanning strategy is proposed that adapts to the local characteristics of parts. This novel approach is designed to employ both island and zigzag scanning within the same deposition layer, aiming to optimize the balance between porosity and stress distribution. Notably, with a feature transition distance of 4 mm and a scan line offset of 0.67 mm, the specimens achieve a tensile strength of 1311.0 MPa, a yield strength of 1103.0 MPa, and an elongation of 8.8%. This strategy leads to the optimization of defects and a transition in microstructure for combined structural features. These promising outcomes lay the foundation for the intelligent allocation of scanning strategies and the high‐quality formation of complex‐shaped, high‐strength titanium alloy parts.

Study on Mitigation of Interfacial Intermetallic Compounds by Applying Alternating Magnetic Field in Laser-Directed Energy Deposition of Ti6Al4V/AA2024 Dissimilar Materials

Brittle intermetallic compounds (IMCs) at the interface of dissimilar materials can seriously affect the mechanical properties of the dissimilar components. Introducing external assisted fields in the fabrication of dissimilar components is a potential solution to this problem. In this study, an alternating magnetic field (AMF) was introduced for the first time in the additive manufacturing of Ti6Al4V/AA2024 dissimilar alloy components by laser-directed energy deposition (L-DED). The effect of the AMF on the interfacial IMCs’ distribution was studied. The results indicate that the contents of the IMCs were different for different magnetic flux densities and frequencies, and the lowest content was obtained with a magnetic flux density of 10 mT at a frequency of 40 Hz. When an appropriate AMF was applied, the IMC layer was no longer continuous at the interface, and the thickness was notably decreased. In addition, the influence of the AMF on the temperature distribution and fluid flow in the melt pool was analyzed through numerical simulation. The simulation results indicate that the effect of the AMF on the temperature of the melt pool was not significant, but it changed the flow pattern inside the melt pool. The two vortices inside the cross-section that formed when the AMF was applied caused different orientations of club-shaped IMCs inside the deposition layer. A sudden change in the streamline direction at the bottom of the longitudinal cross-section of the melt pool can affect the formation of the IMC layer at the interface of dissimilar materials, resulting in inconsistent thickness and even gaps. This work provides a useful guidance for regulating IMCs at dissimilar material interfaces.

Machine Learning-Enhanced Fabrication of Three-Dimensional Co-Pt Microstructures via Localized Electrochemical Deposition

This paper presents a novel method for fabricating three-dimensional (3D) microstructures of cobalt–platinum (Co-Pt) permanent magnets using a localized electrochemical deposition (LECD) technique. The method involves the use of an electrolyte and a micro-nozzle to control the deposition process. However, traditional methods face significant challenges in controlling the thickness and uniformity of deposition layers, particularly in the manufacturing of magnetic materials. To address these challenges, this paper proposes a method that integrates machine learning algorithms to optimize the electrochemical deposition parameters, achieving a Co:Pt atomic ratio of 50:50. This optimized ratio is crucial for enhancing the material’s magnetic properties. The Co-Pt microstructures fabricated exhibit high coercivity and remanence magnetization comparable to those of bulk Co-Pt magnets. Our machine learning framework provides a robust approach for optimizing complex material synthesis processes, enhancing control over deposition conditions, and achieving superior material properties. This method opens up new possibilities for the fabrication of 3D microstructures with complex shapes and structures, which could be useful in a variety of applications, including micro-electromechanical systems (MEMSs), micro-robots, and data storage devices.

Microstructure and friction properties of NiTi2-based composite layer prepared by ultrasonic assisted underwater wet laser deposition

An in situ TiC-enhanced NiTi2-based composite deposition layer was prepared by ultrasonic assisted underwater wet laser deposition. The evolution of the microstructure and interface state, and the friction properties in the air and brine solution environments of the deposition layer were analyzed and researched. The results demonstrated that the thermal and steady-state cavitation from ultrasound effects increase the total energy of the melt pool and promote mixing. The dilution rate of the ultrasonic assisted underwater laser deposition layer increases to 86.72 % compared with that of the underwater laser deposition layer (78.75 %). Ultrasonic reduced underwater laser deposition defects such as lack of fusion and weld slag, and enhanced the wettability between the deposition layer and substrate. The contact angle of the UWNT layer (24.40°, in average) is smaller than the WNT layer (29.80°, in average). Ultrasonic shortened the contact time between the deposition layer surface and the solution, which reduced the reaction of the Ni element with the brine solution. It also transformed the deposition layer from hypereutectoid microstructure to hypoeutectic microstructure and from planar interface to cellular interface. With the effect of the ultrasonic field, the elements in the deposition layer become more uniformly distributed and the secondary phases undergo spheroidization. In the ultrasonic assisted deposition layer, stress-induced FCC-Ti was discovered. Ultrasonic field also reduced the dispersion of the microhardness and increased the average microhardness to 863.3 ± 45.1 HV0.3. Tribology properties show that ultrasonic field effectively improved the wear resistance and friction stability of the ultrasonic assisted deposition layer. The COF of the ultrasonic assisted deposition layer was less affected by the environment, with values of 0.25 and 0.24 observed in air and brine solution, respectively. Overall, the research results in this paper can provide a new insight to improve the surface properties of NiTi2-based alloy underwater laser deposition.

Crystallization of antimony sulfide films on stainless steel substrates obtained by sequential chemical bath deposition

Antimony sulfide (Sb2S3) films have been typically deposited on glass substrates, however, there are a few reports about its deposition on stainless steel substrates. In this work, Sb2S3 was successfully deposited on stainless steel substrates for the first time using sequential chemical bath deposition (CBD) at 2 °C and thermally treated at 300 °C by 5 min in air. XRD and Raman spectroscopy analysis revealed that the as deposited Sb2S3 films exhibits an amorphous phase while the thermally treated has a polycrystalline nature with an orthorhombic structure. An increase in (002) crystalline plane was favored with the increases in deposition layers and was not observed an increase in the oxide phases. The optical band gap was calculated directly on stainless steel substrates by diffuse reflectance and Kubelka-Munk function, and was found a band gap of 2.36, 1.78, 1.71 and 1.75 eV for amorphous, 1 layer, 2 layers, and 3 layers, respectively. The SEM analysis revealed that the sequential deposition improves the surfaces of the Sb2S3 films on stainless steel substrates, and the atomic ratio measured by EDS is near to 1, however the properties of Sb2S3 films were not strongly affected. Our results suggest that the properties of Sb2S3 films on stainless steel substrates can be used for the development of flexible solar cells.

Quaternary transgression process controlled by tectonic subsidence over the last 1.35 Ma: New insights from the eastern Bohai Sea

The Quaternary sedimentary history of the Yellow Sea and Bohai Sea offers significant insights into global sea-level changes. This history is intricately linked to tectonic subsidence. However, the process of the Quaternary transgressions of these areas remains controversial due to the lack of cores with comprehensive sedimentary sequences and reliable chronological frameworks in representative sites. This study evaluated the grain size, benthic foraminifera assemblages, quartz optically stimulated luminescence (OSL) dates, and magnetostratigraphy of Core CSH05 (102.4 m) from the eastern boundary of the Bohai Sea. By comparing these results with previous research, new insights were gained into sea-level changes and tectonic events in the Bohai Sea. The paleomagnetic analysis revealed the existence of Brunhes and Matuyama chrons in the core, including the Jaramillo and Cobb Mountain subchrons and Blake excursion. The boundary between the Brunhes and Matuyama chrons was determined at 57.2 m in the core, aligning with adjacent cores. The basal age of the core is estimated to be ~1.35 Ma. Thirteen sedimentary units (U1-U13), consisting of seven neritic deposits and six terrestrial/littoral deposit layers, were identified in the core through sedimentology and environmental proxies (grain size and benthic foraminifera), indicating alternating transgression-regression cycles. OSL samples suggest that the neritic deposits layer (16.2–20.6 m) probably originated during the early Marine Isotope Stage 3 (MIS3), exhibiting a weaker transgression than MIS5 and MIS1. The initial transgression (U13) dates back to no later than 1.35 Ma, representing the earliest documentation in the Bohai Sea. U11 shows a transgression to 1 Ma, aligning with results from adjacent cores, indicating that the Miaodao Island uplift experienced further subsidence between 1 and 0.83 Ma, allowing seawater to inundate the central basin of the Bohai Sea during high sea level periods. The current sea-land configuration structure emerged after 0.3 Ma due to the complete subsidence of the Miaodao Islands Uplift. The Quaternary transgressions in the Bohai Sea demonstrate a coupling relationship with the uplift of the Qinghai Tibet Plateau, glacial-interglacial cycles, and integration of the Yellow River. This study traces the initial transgression in the Bohai Sea to 1.35 Ma and provides a new detailed evolutionary model of the timing and routes for the Quaternary transgression of the Bohai Sea and Yellow Sea, thereby enhancing our understanding of sedimentary evolution and paleoenvironmental changes in the region.