Hao Yi

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Verified

Hao verified their affiliation via an institutional email.

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• Doctor of Engineering
• Professor (Associate) at Chongqing University

Ink-jetting printing stands out among various conformal additive manufacturing techniques for its multi-material, digital control, and process flexibility. Ink-jetting-based conformal additive manufacturing is renowned for its adaptability to complex topological surfaces and is emerging as a critical technology for future comprehensive conformal pr...

Multi-material components featuring high performance and design flexibility have attracted considerable attention, providing solutions to meet the performance demands of high-end equipment components. Achieving material diversity in additive manufacturing (AM) is a fundamental step towards manufacturing multi-material components. Wire arc additive...

Symmetric molten pool morphology is essential and fundamental in manufacturing three-dimensional (3D) components by wire-arc directed energy deposition (DED) method. However, when the molten metal droplets are deposited on non-level surfaces, various inclined substrates lead to undesirable molten pool behaviors, asymmetrical weld bead morphologies,...

https://link.springer.com/collections/hcfbdcbced

Wire-arc directed energy deposition (DED), an important branch of additive manufacturing, offers high material utilization and deposition rates for fabricating large-scale components. Although wire-arc DED has many advantages over other additive manufacturing methods, it faces challenges such as low geometric dimensional accuracy, coarse grain stru...

This study investigates the mechanical and tribological performance of nano-graphene (NG) modified polyamide-imide (PAI) composite coatings under different lubrication conditions. PAI/NG coatings with 0, 1, 3, and 5 wt% NG were prepared on 45# steel. Experimental results show that the 3 wt% NG coating achieves optimal performance, with a 59.14 % re...

Porosity is an unavoidable problem in aluminium alloy wire-arc directed energy deposition (DED), becoming even more prominent in aluminium-matrix powder core wires, which significantly limits their performance and application potential. This study combines wire-arc DED technology with Al-matrix powder cored wire for the first time, successfully fab...

The precision and ultra-precision mechanical machining process is accompanied by tool wear, which may also cause cutting chatter and damage the surface quality of the machined parts. The machining quality of the key parts for high-end equipment has a significant effect on its service performance. Monitoring the machining condition is of great signi...

Cored-wire-arc directed energy deposition (DED), as an emerging manufacturing technology, can achieve multi-material additive manufacturing and satisfy the demand for structural-functional integration. However, high-density particles will sink and aggregate at the bottom of molten pool, which will cause defects such as cracks or porosity, decreasin...

Most directed energy deposition (DED) implementations employ a rigid end effector to deposit material layer-by-layer, which is insufficient in cases with space constraints. To enhance the flexibility, this paper proposes a novel soft-robotic gun (SRG) based DED technology. The ideology is to replace the rigid weld gun with a tendon-driven omnidirec...

https://www.tandfonline.com/journals/nvpp20/collections/Wire-based-Additive-Manufacturing

Gas entrapment during droplet deposition may induce pinhole defects in droplet-based 3D printing. However, achieving effective suppression of gas entrapment is challenging given that gas entrapment behavior is the physical essence of droplet impact. Inspired by that charged droplets will be deformed in the electric field, a method of suppressing ga...

To address the issue of low accuracy of directed energy deposition-arc (DED-Arc) and expand its use in producing large-sized components, a novel concept called “in-order stacking of primitives” has been proposed. This concept aims to simplify the additive manufacturing (AM) planning process and improve forming accuracy. Experiments at the weld, lay...

In feedback control systems of wire-arc additive manufacturing (WAAM), timely adjustments before the occurrence of deviations (feedforward control) would reduce excessive requirements on the sensitivity and accuracy of characteristic parameters of control systems. However, the search for characteristic parameters suitable for feedforward control is...

Additive manufacturing (AM) as an advanced manufacturing technology has overturned the traditional concept of subtractive manufacturing. By layering materials in a stack, AM technology enables the manufacturing of metal parts in virtually any shape, offering extensive design flexibility for advanced materials and structures. To propel AM technology...

Wire-arc directed energy deposition (DED), with numerous advantages, is expected to be one of the rapid manufacturing approaches for large Mg-Al alloy components. Nonetheless, this process is prone to fabricating Mg-Al alloy components with coarse columnar grains and is typically accompanied by micro-cracks, which weaken the mechanical properties o...

Energy field-assisted machining technology has the potential to overcome the limitations of machining difficult-to-machine metal materials, such as poor machinability, low cutting efficiency, and high energy consumption. High-speed dry milling has emerged as a typical green processing technology due to its high processing efficiency and avoidance o...

https://www.mdpi.com/journal/materials/special_issues/2KR2MDX81Z

Additive manufacturing (AM) is an emerging and rapidly evolving technology that has revolutionized the way products are developed, fabricated and commercialized [...]

Existing researches on coated tools do not provide predicted data about machining performance while exploring their changing rules. Meanwhile, the traditional cutting process parameters neither guarantees the surface quality of the 30CrMnSiNi2A nor attains high material removal rate (MRR). Accurate control and prediction of workpiece three-dimensio...

Polycaprolactone (PCL) scaffolds have been widely used in biological manufacturing engineering. With the expansion of the PCL application field, the manufacture of high-resolution complex microstructure PCL scaffolds is becoming a technical challenge. In this paper, a novel PCL high-resolution fused deposition 3D printing based on electric field-dr...

Metal droplet deposition is of fundamental importance in many industrial and manufacturing processes. An in‐depth understanding of the fundamental issues of metal droplet deposition is particularly crucial for developing droplet deposition‐based engineering manufacturing technologies. This review systematically introduces the evolution of metal dro...

Se-doped silicon films were fabricated by femtosecond (fs) laser and picosecond (ps) laser irradiating Si–Se bilayer film-coated silicon. The surface morphology, impurity distribution, crystal phase, and near-infrared photocurrent response of fs-laser-processed and ps-laser-processed Si are compared. With the same number of laser pulse irradiation,...

Se-doped silicon with micro-nano structures was designed and fabricated by irradiating Si-Se bilayer films coated crystalline silicon using picosecond laser pulses. In order to explore the evolution of surface morphology carried out by picosecond laser irradiation, four scanning speeds of 100 mm/s, 200 mm/s, 400 mm/s and 600 mm/s were tried in this...

Existing research on coated tools does not predict data while exploring the changing rules. As well as the traditional cutting process parameters neither guarantees the surface quality of the 30CrMnSiNi2A nor attains high material removal rate (MRR). Accurate control and prediction of workpiece three-dimensional surface roughness ( S q ) and specif...

Energy efficiency has been one of the main issues in manufacturing. Rapid energy consumption (EC) calculation is the key to improving the efficiency of EC optimization. In this paper, rapid EC calculation of robot laser processing systems (RLPSs) is studied based on structural decomposition. Firstly, the generalized motion EC models of main functio...

As the radius of carbon fibers and cutting edge are in the same order of magnitude, workpiece self-action, which could not be neglected in machining Carbon Fiber Reinforced Polymer (CFRP) considering size effect, has become a new perspective. Specific Cutting Energy (SCE) is a significant indicator for chip formation, cutting forces, tool wear, and...

Carbon fiber-reinforced polymer (CFRP) composites have been widely used in the aerospace industry due to their excellent mechanical properties. Cutting mechanisms of machining CFRP and its effect on machined surface integrity are still unclear due to inhomogeneity and anisotropy. To this end, this paper studied the cutting mechanisms of CFRP by est...

Magnesium alloys are widely used in industrial fields with excellent comprehensive properties. At the same time, as the lightest structural metal, magnesium alloys are expected to replace aluminum alloys and steels to achieve significant weight reduction in aircraft and automobiles. However, the current mainstream magnesium alloy processing methods...

Projection stereolithography creates 3D structures by projecting patterns onto the surface of a photosensitive material layer by layer. Benefiting from high efficiency and resolution, projection stereolithography 3D printing has been widely used to fabricate microstructures. To improve the geometric accuracy of projection stereolithography 3D print...

Flexible Transparent Electrodes In article number 2105331, Xiaoyang Zhu, Hongbo Lan, and co‐workers develop a fabrication method for flexible transparent electrodes (FTEs) with embedded metal mesh via liquid substrate electric‐fielddriven microscale 3D printing. This method enables the embedded metal mesh with high resolution and high aspect ratio...

Metal droplet-based 3D printing provides unique advantages for fabricating micro complex parts. Especially, assisted by soluble support, structures with high-quality inner surfaces can be directly printed without post-processing, which is very promising for the fabrication of waveguides and antenna horns. Here, a spatially distributed equidistant h...

Transparent Glass Heaters In article number 2107811, Xiaoyang Zhu, Xiaofeng Xu, Hongbo Lan, and co‐workers develop a fabrication method of silver mesh for transparent glass heaters (TGHs) via liquid sacrificial substrate electric‐field‐driven microscale 3D printing thick film silver paste. The fabricated TGHs exhibit excellent comprehensive perform...

Flexible transparent electrodes (FTEs) with embedded metal meshes play an indispensable role in many optoelectronic devices due to their excellent mechanical stability and environmental adaptability. However, low‐cost, simple, efficient, and environmental friendly integrated manufacturing of high‐performance embedded metal meshes remains a huge cha...

Transparent glass with metal mesh is considered a promising strategy for high performance transparent glass heaters (TGHs). However, the realization of simple, low‐cost manufacture of high performance TGHs still faces great challenges. Here, a technique for the fabrication of high performance TGHs is proposed using liquid sacrificial substrate elec...

High-voltage electric field-driven jet deposition technology is a novel high resolution micro scale 3D printing method. In this paper, a novel micro 3D printing method is proposed to fabricate wax micro-structures. The mechanism of the Taylor cone generation and droplet eject deposition was analyzed, and a high-voltage electric field-driven jet pri...

https://www.mdpi.com/journal/crystals/special_issues/additive_manufacturing_green

Bionic Al2O3 nanostructure was successfully prepared by using epipremnum aureum leaf as a bio-template. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Thermogravimetric Analysis (TG) were used to characterize the Bionic Al2O3.The results showed that the optimum temperature is 1200 °C, and the as received bionic Al2O3 was rhombohed...

The properties of chalcogens doped silicon with different atomic structures are systematically investigated using first-principles. The calculated results show that substitutional structure exhibit best thermal stability and hexagonal interstitial is metastable structure. All configurations can introduce intermediate-band (IB) related to the impuri...

Uniform morphology and good metallurgical bonding between neighboring droplets are crucial in metal droplet-based 3D printing. However, this technique is usually accompanied by a heat accumulation effect during the printing process, leading to poor forming accuracy and non-uniform microstructure and properties of the formed parts. Since the heat ac...

Titanium alloys are widely used in aerospace, shipbuilding and some other fields due to their high strength and high heat resistance. However, traditional forging+machining methods are suffering from severe die loss and long manufacturing cycle because of the difficult machining of titanium alloys. Additive manufacturing, as a green manufacturing p...

As the key component of the manufacturing industry, die casting process suffers severe emission problems, which disobeys the prospects of Industry 4.0 and green manufacturing. Environmental emissions prediction of the die casting process is the foundation to optimize the environmental impact factors to achieve lower environmental pollution and heal...

Many liquid metals have a high boiling point, strong electrical conductivity, high thermal conductivity, and nontoxic properties, which make them ideal targets for applications in different fields such as optics, microcircuits, electronic switches, micro-electromechanical System (MEMS) devices and 3D printing manufacturing. However, owing to the ge...

Icing of wind turbine blades seriously affects the efficiency of wind power generation and threatens the safe operation of wind turbines. In order to improve the heat transfer efficiency of wind turbine blade anti-deicing components, a mathematical heat transfer model of graphene oxide (GO) doped reinforced polymer was established based on the ther...

In the field of sculptured surfaces machining, the robot trajectory planning, under high-order complex constraints, aiming at minimizing energy or time, is always a challenge. The complexity of curvature characteristics of sculptured surfaces and the nonlinearity of relevant constraints are the main reasons. This article proposes an efficient plann...

Design change propagation is a primary source of risk and innovation in complex product (CP) development. Soundly predicting and managing the design change propagation have become critical issues. Dynamicity is the non-negligible nature of design change propagation. However, existing specific case studies and static predicting methods are inadequat...

The effect of dopant species on the sintering resistance of zirconia-based ceramics remains a huge challenge in terms of both experiment and theory. As one of the most popular materials for high-temperature protective coatings, it is still urgent to obtain rare earth-doped ZrO2 with high sintering resistance and good phase stability. Here, the sint...

Abstract Inspired by nature, many researchers have noticed that the micro‐ and nano‐structures originated from organism's surfaces which indict unique properties such as superhydrophobicity, drag reduction, structure colour have much use in academic value. However, conventional processing methods for mimicking biomimetic surface need multistep and...

Die casting is a complex process performed in harsh working environments. Driven by cost and environmental pressure, die casting, as one of the most energy-intensive manufacturing processes, has received increasing attention on enhancing energy efficiency toward greener and more sustainable manufacturing. Energy efficiency evaluation is a starting...

Liquid-metal direct writing is a cost-effective and green technology, which is very promising for the customized fabrication of flexible circuits and functional devices. However, owing to the high surface tension of metal ink, the printed circuits are prone to intermittent outflow, large forming size error, and unstable forming. The smooth flowing...

The automated robotic polishing system (ARPS) consisting of several robotic polishing cells (RPCs) is widely adopted in polishing industry to replace manual labor. Recently, energy-saving becomes a hotspot issue in manufacturing industry because of the increase in energy costs and requirement of environmental protection. Traditionally, robot motion...

La2Ce2O7 (LC), La2Zr2O7 (LZ), and yttria stabilized zirconia (YSZ) nanostructured powders with different agglomerate structures were successfully synthesized via wet-chemical method, and their high-temperature sintering resistance was systematically studied in this paper. Experimental results indicate that the synthesized nanostructured YSZ sample...

New special issues in Frontiers in Mechanical Engineering. Scientific articles are welcome to submit! https://www.frontiersin.org/research-topics/16193/advances-in-computational-and-experimental-techniques-for-improvement-in-process-efficiency-and-prod

Requirements for the service performance of aeronautic microelectronic components are increasingly strict. However, sever issues, that the acquisition of the service performance such as micro-mechanical properties is destructive, limit the subsequent application of the tested components. Addressing this issue, this paper proposes a nondestructive a...

Metal micro-droplet 3D printing is an effective additive manufacturing technique to form micro pillar structures. However, the control mechanism of the pillar contour is still unclear. To form a pillar with uniform radius, it is essential to investigate the dependence of processing parameters on pillar contours. In this study, a 3D numerical model...

Droplet-based 3D printing is a promising method to manufacture thin-walled parts with high-quality cavity surfaces of a complex geometry by virtue of dissolvable supports. However, conventional equispaced droplet scanning strategies cannot be used for dissolvable support assisted droplet printing that involves more complex impingement conditions, p...

Droplet-based 3D printing is a promising technique for metal forming in space, owing to the advantages of dispensing without large-scale energy equipment or customized materials. However, the extreme environment in space, for example microgravity, would change the printing mechanisms significantly compared with those on the ground, which hinders th...

La2Ce2O7 (LC) has attracted extensive attention as promising material for thermal barrier coatings (TBCs) in next generation gas turbines due to its outstanding thermophysical properties. To eliminate the reaction between LC and thermal grown oxides (TGO), yttria stabilized zirconia (YSZ) is usually employed as the interlayer to form LC/YSZ double-...

Electric charges are often found in naturally or artificially formed droplets, such as raindrops and those generated by Kelvin’s water dropper. In contrast to the impact of neutral droplets on a flat solid surface upon which a thin convex lens shape layer of gas film is typically formed, we show that the delicate gas thin film can be fundamentally...

3D metal printing involves building a metallic object layer by layer through the deposition of molten metal. This technique is advantageous in that it results in limited material wastage. Moreover, metal 3D printing techniques have shown more benefits when it comes to the direct fabrication of complex 3D structures, particularly, the micro thin-wal...

本发明公开了一种基于均匀金属液滴喷射的多粒径均匀球形粉体批量制备装置与方法，用于解决现有均匀球形金属粉体制备方法生产率低的技术问题。技术方案是通过给压电陶瓷输入电信号使其产生机械振动，产生的机械振动使喷嘴处的金属熔液产生一定的速度，从而使一定量的金属流体喷出，每次喷出的流体形成一颗金属液滴。通过控制装置中金属熔液的压力以及压电陶瓷的振动，可得到尺寸均匀、热履历一致的液滴。该方法制备的液滴飞行速度低，在很短的很行距离内即可完全凝固，液滴的振荡小，球形度高。在装置的纵向和横向安装多个压电陶瓷，同时利用不同尺寸的多喷孔喷嘴，可一次性大量制备多粒径均匀球形金属粉体。

本发明公开了一种均匀金属微滴选域择向沉积3D打印方法，用于解决现有均匀金属微滴沉积3D打印方法打印精度差的技术问题。技术方案是首先以较大间距打印较低温度的金属微滴，使其打印轨迹由一离散的凸点序列组成，然后根据打印件形状要求，在离散凸点间择向沉积高温液滴，利用高温微滴在已锚定凸点间的表面张力毛细扩展机理，实现凸点间隙的完全填充，并保证热应力、热变形及局部沉积缺陷不累积，从而满足高金属件形状尺寸精度以及打印过程的稳定性的要求。

3D printing is one of the latest exciting and revolutionary technologies in the manufacturing industries. It enables the fabrication of complex three-dimensional parts from their computer-aided design drawings. Owing to its flexibility and efficiency, its use has been extended to several other applications for printing structures such as advanced e...

Using droplet-based 3D printing to directly fabricate microwave devices with smooth inner surfaces remains an elusive goal, because of the naturally scalloped shapes of solidified droplets and the staircase effect in 3D printing. In order to address this issue, a novel manufacturing process involving deposition of molten metal droplets on soluble c...

In this paper, the diffusion mechanism of oxygen ions in La2Zr2O7/YSZ (LZ/YSZ) composites was investigated experimentally and numerically. LZ/YSZ composite samples with multiple amounts of LZ were successfully synthesized via a two-step sintering process. The so-obtained samples preserved most of the tetragonal phase (82.2 mol%) in YSZ. Moreover, a...

High temperature stability of potential materials for thermal barrier coatings becomes increasingly important at elevated temperatures. Therefore, high temperature stability, including phase, compositional, structural, and chemical stability of lanthanum cerate (La2Ce2O7, LC) with yttria stabilized zirconia (YSZ) was investigated after heat treatme...

This letter shows the chemical compatibility between LnZ and YSZ after heat treatment at high temperatures. It was found that LnZ would react with YSZ, and a reaction zone with relatively large grains formed after high temperature treatment, which would usually destroy the structural and compositional stability of the composite specimens. The react...

Droplet-based 3D printing is very promising for the fabrication of complex thin-wall microwave devices such as antenna horns and waveguide tubes since it can print a shell by utilizing only several layers of droplets. However, due to the naturally scalloped shape of metal droplets, conventional droplet-based 3D printing methods cannot produce thin-...

In the present study, atmospheric plasma-sprayed yttria-stabilized zirconia coatings were post-remelted by a continuous diode laser to improve the hot corrosion resistance for as-sprayed coatings. The coating surfaces were covered with a salt mixture (V2O5and Na2SO4) and then subjected to a hot corrosion test at 1100 °C in air. The influence of las...

本发明公开了一种航空器损伤金属微滴喷射3D打印原位快速修复方法，用于解决现有航空器损伤修复方法实用性差的技术问题。技术方案是金属熔体在其内部压力作用下，通过喷嘴喷射出单颗均匀的微米级金属熔滴，并基于离散堆积原理，控制均匀金属微熔滴按照指定轨迹的逐点、逐层定向堆积，进而完成受损金属零件的快速修复成型。该修复方法无需大型能源设备，无需专用原材料，可实现包括活泼金属在内的多材质受损件原位修复，且修复设备便携，工序简单，成本低廉，可完成航空器损伤的原位柔性快速修复，实用性强。

In this study, two kinds of La2Zr2O7/YSZ (LZ/YSZ) composite powders, i.e., composite powders (P1) and mechanically mixed powders (P2), were used to fabricate composite thermal barrier coating samples through supersonic air plasma sprayed technology. The microstructure and composition of as-prepared coatings were closely related to the distribution...

The parametric mapping of linear deposition morphology with different droplet spacing is first proposed, which provides a baseline for parameter selection in uniform metal droplet deposition technique. Experiments related to linear deposition are carried out with deviating droplet size and deposition placement. Deposition morphology is first catego...

Good metallurgical bonding between droplets is essential in droplet-based 3D printing. However, although the mechanism of remelting has clearly been mastered, cold laps are still common internal defects of the formed parts in uniform aluminum droplets deposition manufacturing. Here, for the first time, the blocking effect of ripples and solidificat...

This letter presents a method and its mechanism of using Ag coating to inhibit rebound of Al droplets over soluble substrates. Experiments show that Ag coating can eliminate droplet rebound, which makes it possible to print complex parts with high-quality inner surface. Further investigation reveals that Ag coating suppresses the rebound of Al drop...

In order to investigate forming directly complex parts without support materials or structures by uniform micro droplets deposition technique, the present work focus on fabricating the unsupported inclined aluminum pillars through offset deposition. An experimental system is developed to produce and deposit uniform molten aluminum droplets. A model...

Micro metal droplet deposition manufacturing shows great potential applications in many industrial areas such as micro circuits printing, thin-wall metal parts, porous metal parts, and heterogeneous material parts. However, excessive overlapping of metal droplets in corners deteriorates the quality of printed parts. To solve this problem, the dropl...

Solder jet technology is considered as a flexible and low cost method to print bumps directly for flip-chip packaging. However, the height deviation of solder bumps, which decides the quality and reliability of the packaging, is significantly influenced by the fluid dynamics and solidification behaviors during solder droplet impact. Here, an experi...

本发明公开了一种大长径比结构微型金属热沉的制造方法，用于解决现有热沉的制造方法实用性差的技术问题。技术方案是通过外力迫使金属熔液以均匀微滴的形式从喷嘴中喷射出来，并基于离散堆积原理，以微米级的金属微熔滴为制造单元，通过控制金属微滴的堆积轨迹，进行逐点、逐层堆积，直至成型出微小零件。该制造方法工序简单，无需模具的制备，对热沉基座结构、散热片结构和成型材料皆无过多限制，制备出了不同材质的大长径比结构微型热沉。

The impact of molten metal droplets on solid substrates may entrap gas to form pinholes. This letter shows that the detailed pinhole structure is more sophisticated than expected: the void is toroid, which is a result of rapid contact line retraction and subsequent phase change. The substrate surface roughness affects the pinhole size by providing...