Materials & Design最新文献_第3页

Metal additive manufacturing of damage-controlled elements for structural protection of steel members 用于钢构件结构保护的损伤控制元件的金属快速成型技术

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113428

Hamdy Farhoud , Islam Mantawy

This paper develops hybrid steel members by integrating additively manufactured, ultra-lightweight, damage-controlled elements (DCEs) into hot-rolled structural steel members. This approach relies on segmenting a structural member into distinct sections; one or two segments are enlarged to be capacity protected; however, another end or middle DCE segment is optimized to emulate the conventional member’s strength and stiffness. A small-scale DCE was topologically optimized and then additively manufactured using a powder bed fusion technique through a direct metal laser sintering process of 17-4PH stainless steel and then was experimentally tested to study the buckling behavior under compression. The experimental testing of the optimized DCE shows a compressive strength of 81,000 times the specimen’s weight with stable post-peak buckling behavior. Numerical simulation confirms experimental results, showing a good correlation in fracture energy. A parametric study on four DCE specimens, scaled up by three, four, five, and six times, was performed and compared to hollow structural sections (HSS) of A500 Gr. C in tensile and compression strengths. The numerical simulation shows a linear relation between the weight ratio and HSS length. Additionally, numerical simulation of conventional member, DCE (scaled by three), and three hybrid members revealed that failure occurred in DCE as intended.

本文通过将快速成型、超轻、损伤控制元件（DCE）集成到热轧结构钢构件中，开发出混合钢构件。这种方法依赖于将结构构件分割成不同的部分；一个或两个部分被放大以保护承载能力；然而，另一个末端或中间 DCE 部分被优化以模拟传统构件的强度和刚度。对小型 DCE 进行了拓扑优化，然后采用粉末床熔融技术，通过直接金属激光烧结工艺对 17-4PH 不锈钢进行了加成制造，并进行了实验测试，以研究其在压缩条件下的屈曲行为。对优化后的 DCE 进行的实验测试表明，其抗压强度为试样重量的 81,000 倍，并具有稳定的峰值后屈曲行为。数值模拟证实了实验结果，显示出断裂能的良好相关性。对四个 DCE 试样进行了参数研究，分别放大了三倍、四倍、五倍和六倍，并与 A500 Gr. C 的空心结构截面 (HSS) 在拉伸和压缩方面进行了比较。C 的空心结构截面 (HSS) 的拉伸和压缩强度进行了比较。数值模拟结果表明，重量比与 HSS 长度之间存在线性关系。此外，对传统构件、DCE（按三倍缩放）和三种混合构件进行的数值模拟显示，DCE 按预期发生了破坏。

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引用次数: 0

Assessing the fracture toughness in Tungsten-based nanocomposites: A micro-mechanical approach 评估钨基纳米复合材料的断裂韧性：微机械方法

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113433

K. Schmuck, M. Burtscher, M. Alfreider, D. Kiener

Nanocrystalline tungsten-copper composites can favorably combine the outstanding material properties of both elements. This work investigates tungsten-copper composites fabricated from elemental powders with 80 wt.% tungsten and either copper or

α

-brass containing 20 wt.% zinc, respectively. Moreover, high-pressure torsion is used to compact the powders, strengthen the resulting composite by grain refinement, and tailor the grain-size in the nanocrystalline regime by varying the deformation temperature between RT, 400°C and 550°C, resulting in grain-sizes of 9 nm 14 nm and 28 nm, respectively. Hardness measurements revealed a transition from normal to inverse Hall-Petch behavior for grain-sizes below 11 nm. To examine the fracture properties, micro-cantilever bending beams with a cross-section of 10x10 µm² were fabricated. Evaluation of these experiments indicated a fracture toughness of 3 MPa

\sqrt{m}

. The slight decrease of fracture toughness between a grain-size of 9 nm to 14 nm indicates a reduction of the grain boundary cohesion strength. The grain-size increase to 28 nm reversed the trend in fracture toughness and raised it to 3.4 MPa

\sqrt{m}

, which points to activating additional deformation mechanisms, such as dislocation-accumulation and twinning. Additionally, alloying with zinc raised the composites strength and retained the composites fracture toughness, benefiting the damage tolerance.

纳米结晶钨铜复合材料能很好地结合两种元素的优异材料特性。这项工作研究的钨铜复合材料是由钨含量为 80 wt.%、铜含量为 20 wt.%、锌含量为 20 wt.%的元素粉末或 α-黄铜制成的。此外，还利用高压扭转来压实粉末，通过晶粒细化来强化所产生的复合材料，并通过在 RT、400°C 和 550°C 之间改变变形温度来定制纳米晶体系中的晶粒大小，从而分别获得 9 nm、14 nm 和 28 nm 的晶粒大小。硬度测量结果表明，当晶粒大小低于 11 纳米时，硬度行为从正态过渡到反霍尔-佩奇态。为了检查断裂特性，制作了横截面为 10x10 µm2 的微型悬臂弯曲梁。对这些实验的评估表明，其断裂韧性为 3 MPam。在晶粒尺寸为 9 纳米到 14 纳米之间，断裂韧性略有下降，这表明晶界内聚强度有所降低。晶粒大小增加到 28 纳米时，断裂韧性的趋势发生了逆转，上升到 3.4 MPam，这表明激活了其他变形机制，如位错累积和孪生。此外，锌合金提高了复合材料的强度，并保持了复合材料的断裂韧性，有利于提高耐损伤性。

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引用次数: 0

Hybrid manufacturing and performance evaluation of β Ti-alloy stents β钛合金支架的混合制造和性能评估

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113420

Peter Ibrahim , Rebecca Garrard , Pavel Penchev , Kenny Man , Sophie C. Cox , Stefan Dimov , Moataz M. Attallah

Biomedical β Ti-alloys possess an interesting combination of mechanical properties, including an elastic modulus lower than 60 GPa. In this study, a hybrid manufacturing route for Ti-34Nb-13Ta-5Zr-0.3O (TNTZO) alloy stents was developed and assessed. The route involves using Laser Powder Bed Fusion (L-PBF) to manufacture thin-walled tubes, which are then laser micro-machined to directly produce customised stents, cutting short the laborious process and overcome the design limitations for stents manufacturing. Different post processing techniques were used to improve the surface finish and cell attachment properties of the tubes. Finite Element (FE) modelling was used to simulate stent crimping and deployment. The study identified the key parameters that control the performance of the final product, including the optimum laser scanning strategies during L-PBF to achieve smooth thin-walled tubes, and the use of electropolishing to improve the surface finish and cell attachment. FE simulations showed that TNTZO can achieve crimping ranges up to 74% following the optimisation of the strut diameter, which brings us one step closer to a Ni-free alternative to nitinol in manufacturing stents that require significant deformation.

生物医学 β Ti-合金具有有趣的机械性能组合，包括低于 60 GPa 的弹性模量。本研究开发并评估了 Ti-34Nb-13Ta-5Zr-0.3O (TNTZO) 合金支架的混合制造工艺。该工艺包括使用激光粉末床熔融（L-PBF）制造薄壁管，然后通过激光微加工直接生产定制支架，缩短了费力的工艺流程，克服了支架制造的设计限制。不同的后处理技术可改善管材的表面光洁度和细胞附着特性。有限元（FE）建模用于模拟支架的卷曲和展开。研究确定了控制最终产品性能的关键参数，包括在 L-PBF 过程中实现光滑薄壁管的最佳激光扫描策略，以及使用电抛光来改善表面光洁度和细胞附着性。FE 模拟显示，在优化支杆直径后，TNTZO 的压接范围可达 74%，这使我们在制造需要显著变形的支架时，离无镍替代品镍钛诺更近了一步。

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引用次数: 0

Direct imaging of gas atomization process accompanying surface oxidation of tin droplets 伴随锡滴表面氧化的气体雾化过程的直接成像

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113413

Taiko Tanimoto , Nao Uchida , Mengjia Ren , Zhenying Wang , Chihiro Inoue , Jun Horiuchi , Takuya Takashita , Kazutoyo Yamada , Noriharu Yodoshi

Fine metal particles produced by gas atomization are recognized as an essential material for additive manufacturing. However, spatio-temporally resolved images for the atomization process are still lacking. In the present study, we apply a high-speed Schlieren optical system synchronized with a pulse light source with flashing period of 30 ns to a simple atomization setup, consisting of a single supersonic

jet at Mach number of 1.5 and free-falling tin droplets. Covering the tin droplets by Ar gas, we generate spherical droplets by minimizing the initial oxidation from the ambient. Impinging on the large-momentum gas jet, the tin droplet largely deforms to be shaved the bottom end and bounced above the jet with partially penetrating inside the gas core. The spreading ligaments above the jet thins at first along with the capillary timescale. As the surface oxidation proceeds, the neck transitionally shrinks according to the viscous-capillary timescale, which evidences the direct observation of gas atomization process superposed by the molecular diffusion across the interface. Statistics of collected metal particles demonstrate a bimodal distribution for the diameter, originated from the distinct atomization mechanisms of aerodynamic dominant breakup inside the gas jet and of capillary dominant breakup spreading above the jet.

通过气体雾化产生的细小金属颗粒被认为是增材制造的重要材料。然而，雾化过程的时空分辨图像仍然缺乏。在本研究中，我们将与闪烁周期为 30 ns 的脉冲光源同步的高速 Schlieren 光学系统应用于简单的雾化装置，该装置由马赫数为 1.5 的单个超音速射流和自由下落的锡滴组成。我们用氩气覆盖锡滴，通过尽量减少环境中的初始氧化作用生成球形锡滴。锡滴撞击到大动量气体射流上，锡滴在很大程度上发生形变，底端被削去，并在射流上方反弹，部分穿透气体核心。射流上方的扩张韧带最初会随着毛细管时间尺度的变化而变薄。随着表面氧化的进行，颈部根据粘性-毛细管时间尺度过渡收缩，这证明了气体雾化过程与分子在界面上的扩散相叠加的直接观测结果。收集到的金属颗粒的统计数据显示出直径的双峰分布，这源于不同的雾化机制：气体射流内部的空气动力学主导破裂和射流上方扩散的毛细管主导破裂。

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引用次数: 0

Screen-printing high/low resistance using only a single silver nanowire ink: Resistance-gradient metasurface application for broadband microwave absorption and optical transparency 仅使用单一银纳米线油墨就能丝网印刷出高/低电阻：用于宽带微波吸收和光学透明的电阻梯度元表面应用

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113451

Junghyeon Kim , Prabhakar Jepiti , Minjae Lee , Eiyong Park , Ratanak Phon , Sungjoon Lim

Transparent metasurface absorbers are highly sought after for their diverse applications, but achieving broad absorption bandwidths without sacrificing optical transparency remains a challenge. Traditionally, enhancing absorption involves increasing substrate thickness, which reduces transmittance. We address this by introducing a resistance-gradient metasurface (RGM) that combines broad absorption with high optical transparency. Unlike conventional methods requiring various inks for different resistances, our approach uses a single silver nanowire ink and screen-printing to create multiple resistances. This technique allows for flexible design and multiple resonances within the metasurface, achieving broad absorption even with a thin substrate. The RGM demonstrates an absorption bandwidth from 8.68 to 11.48 GHz with a substrate thickness of just 0.045 λ₀, and optical transmittance of 66.3 % at 550 nm. This innovation promises to enhance both substrate efficiency and bandwidth in transparent metasurface absorbers, broadening their application potential in advanced devices.

透明超表面吸收器因其用途广泛而备受追捧，但在不牺牲光学透明度的前提下实现宽吸收带宽仍然是一项挑战。传统上，增强吸收能力需要增加基底厚度，这就会降低透射率。为了解决这个问题，我们引入了一种电阻梯度元表面 (RGM)，它兼具宽吸收带宽和高光学透明度。与需要用不同油墨来产生不同电阻的传统方法不同，我们的方法使用单一银纳米线油墨和丝网印刷来产生多个电阻。这种技术可以在元表面内实现灵活的设计和多重共振，即使在基底很薄的情况下也能实现宽吸收。RGM 的吸收带宽从 8.68 GHz 到 11.48 GHz，基底厚度仅为 0.045 λ0，在 550 纳米波长处的光学透过率为 66.3%。这项创新有望提高透明超表面吸收器的衬底效率和带宽，扩大其在先进设备中的应用潜力。

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引用次数: 0

Ply-ply friction behavior between unidirectional thermoplastic prepreg plies during thermoforming: Characterization and modeling 热成型过程中单向热塑性预浸料层间的摩擦行为：表征和建模

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113426

Wenwu Zhang , Lidong Wang , Xiongqi Peng

The ply-ply friction behavior of unidirectional carbon fiber reinforced polyphenylene sulfide (UD CF/PPS) prepreg in thermoforming was investigated through an improved pull-through testing system. The effects of temperature, normal force and slipping velocity were considered in testing. The results indicated the existence of three key mechanisms underlying slipping: namely the resin shear, fiber–fiber contact and fiber-resin interaction. A three-stage division of the experimental curve was proposed, and several factors were defined to establish a quantitative definition of the ply-ply friction behavior. The results showed that the influence of slipping velocity is particularly evident. Its post-yield stress (12.8 kPa), steady-state CoF (0.118) and residual stress (0.705 kPa) were the highest, exhibiting the largest changes of 957.9 %, 736.9 % and 47.2 %, respectively. This indicated the strong contribution of resin in ply-ply friction. In addition, the Stribeck analysis also suggested the dominance of hydrodynamic lubrication condition in slipping. Based on the experimental results, a simple phenomenological model was proposed based on experimental curves to accurately describe the effects of processing parameters. This work presents a comprehensive characterization of the ply-ply friction behavior of UD CF/PPS prepreg in thermoforming, providing a substantial experimental foundation for the subsequent simulation research.

通过改进的拉通测试系统，研究了单向碳纤维增强聚苯硫醚（UD CF/PPS）预浸料在热成型过程中的层间摩擦行为。测试中考虑了温度、法向力和滑动速度的影响。结果表明存在三种关键的滑动机制：即树脂剪切、纤维-纤维接触和纤维-树脂相互作用。提出了实验曲线的三阶段划分，并定义了几个因素，从而建立了层间摩擦行为的定量定义。结果表明，滑动速度的影响尤为明显。其屈服后应力（12.8 kPa）、稳态 CoF（0.118）和残余应力（0.705 kPa）最高，分别出现了 957.9 %、736.9 % 和 47.2 % 的最大变化。这表明树脂在层间摩擦中的作用很大。此外，Stribeck 分析还表明流体动力润滑条件在滑动中占主导地位。根据实验结果，提出了一个基于实验曲线的简单现象学模型，以准确描述加工参数的影响。这项研究全面描述了 UD CF/PPS 预浸料在热成型过程中的层间摩擦行为，为后续的模拟研究提供了坚实的实验基础。

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引用次数: 0

Electrophoretic deposition of LiFePO4 and carbon black: A numerical study to explore longitudinal trends using Taguchi design 磷酸铁锂和炭黑的电泳沉积：利用田口设计探索纵向趋势的数值研究

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113446

Stefano Russo , Marzio Grasso , Jian Huang , Stevin S. Pramana , Francesco Gucci , Christopher Shaw , Glenn J. Leighton

Developing Electrophoretic Deposition (EPD) for Composite Structural Batteries (CSBs) could revolutionise energy storage technology. CSBs offer an innovative solution by seamlessly integrating batteries into structures and effectively reducing weight and space constraints. Despite its successful implementation across various fields, EPD method still lacks comprehensive understanding of the underlying physical and chemical processes due to the number of variables involved. In this study the effects of key parameters associated with the process are investigated with a coupled FEM and analytical approach to find correlations with the deposition process. A Taguchi Design of Experiment with five parameters, namely voltage, concentration, relative weight ratio of LiFePO₄ – carbon black particles, length and perimeter of the electrodes is implemented to identify the correlations with mass deposited, thickness of the coating and yield rate when LiFePO₄ and Carbon Black particles in ethanol suspension are used. In order to capture the variation over time, each parameter is studied at six different time of deposition. A concentration that optimises yield rate resulting in thickness and mass deposition is identified. The resistivity of the suspension dictates the yield rate dynamics, allowing it to be designed within a specific range to meet requirements of different applications.

开发用于复合结构电池（CSB）的电泳沉积（EPD）技术可彻底改变能源存储技术。CSB 将电池无缝集成到结构中，有效减轻了重量，减少了空间限制，从而提供了一种创新的解决方案。尽管 EPD 方法在各个领域得到了成功应用，但由于涉及的变量较多，人们对其背后的物理和化学过程仍然缺乏全面的了解。本研究采用有限元和分析耦合方法研究了与工艺相关的关键参数的影响，以找到与沉积工艺的相关性。在使用乙醇悬浮液中的磷酸铁锂和炭黑颗粒时，采用了包含五个参数（即电压、浓度、磷酸铁锂和炭黑颗粒的相对重量比、电极的长度和周长）的田口实验设计，以确定与沉积质量、涂层厚度和成品率之间的相关性。为了捕捉随时间的变化，在六个不同的沉积时间对每个参数进行了研究。最终确定了一种浓度，该浓度可优化厚度和质量沉积的产出率。悬浮液的电阻率决定了产率的动态变化，因此可以在特定范围内进行设计，以满足不同应用的要求。

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引用次数: 0

Microstructural evolution and strengthening mechanism of U71Mn steel joints fabricated by friction-flash hybrid welding 摩擦闪光混合焊接 U71Mn 钢接头的微结构演变和强化机理

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113403

Jiaqing You , Jinhong Tan , Xingping Liu , Kai Du , Jiarui Li , Chengyang Yi , Yunqiang Zhao

The softening layer formed by the ferrite in the welding interface can significantly reduce the mechanical properties of traditional flash butt welding joints. This study proposed a flash-friction hybrid welding method to address the issue of the ferrite softening layer and comprehensively investigated the impact of vibration friction speed on joint performance. The results showed that increasing the vibration friction speed could effectively inhibit the formation of the ferrite softening layer in the weld center zone (WCZ) and enhance the mechanical properties of the joint. When the vibration friction speed was 3 mm/s, the tensile strength of the joint reached its maximum value of 982.9 MPa, approximately equal to 97.3 % of that of the base material (BM). The fracture occurred in the heat-affected zone (HAZ) and was characterized by a ductile fracture mechanism. Moreover, the microstructural analysis revealed that dynamic recrystallization (DRX) occurred in the WCZ, thermo-mechanically affected zone (TMAZ), and fine-grained zone (FGZ)-HAZ of the joint. Compared to the BM, the grain size significantly decreased, and the thickness and spacing of lamellar cementite also reduced. These microstructural evolutions also contributed to the enhanced mechanical properties of the joints. This study provided new insights for welding in the rail transportation field.

铁素体在焊接界面形成的软化层会显著降低传统闪光对焊接头的机械性能。本研究针对铁素体软化层问题提出了一种闪光摩擦混合焊接方法，并全面研究了振动摩擦速度对接头性能的影响。结果表明，提高振动摩擦速度可有效抑制焊接中心区（WCZ）铁素体软化层的形成，提高接头的力学性能。当振动摩擦速度为 3 mm/s 时，接头的抗拉强度达到最大值 982.9 MPa，约等于母材（BM）抗拉强度的 97.3%。断裂发生在热影响区（HAZ），断裂机理为韧性断裂。此外，微观结构分析表明，动态再结晶（DRX）发生在接头的WCZ、热机械影响区（TMAZ）和细晶粒区（FGZ）-HAZ。与 BM 相比，晶粒尺寸明显减小，片状水泥土的厚度和间距也有所减少。这些微结构演变也有助于提高接头的机械性能。这项研究为轨道交通领域的焊接提供了新的见解。

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引用次数: 0

Machine learning in additive manufacturing——NiTi alloy’s transformation behavior 机器学习在快速成型制造中的应用--镍钛合金的转化行为

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113443

Lidong Gu , Kongyuan Yang , Hongchang Ding , Zezhou Xu , Chunling Mao , Panpan Li , Zhenglei Yu , Yunting Guo , Luquan Ren

The laser powder bed fused NiTi alloys (LPBF-NiTi) demonstrate shape memory functionality and superelasticity as a result of their distinctive phase transition characteristics. Nevertheless, achieving precise control and regulation of the phase transition temperature poses a challenge, influenced by factors like powder composition and process parameter. In this study, a feature screening strategy and machine learning (ML) method were employed to predict and regulate the phase transition temperature of LPBF-NiTi alloy, offering a more efficient and cost-effective alternative to traditional experimental methods of regulation and control. Specifically, accuracy analysis was performed on LPBF-NiTi phase transition datasets with varying compositions and process conditions utilizing generalized regression neural network (GRNN), and other methods. The findings indicate that the interpretable features extracted through the selection strategy outlined in this study when combined with the GRNN model, demonstrate a high level of prediction accuracy (R² = 0.97). To investigate the accuracy of the model, this study utilized various process parameters to fabricate NiTi alloys with different compositions from Ni_50.8Ti_49.2 alloy powder. Using this model, the study identified a novel, larger window of optimal LPBF processing that allows for controllable complex phase transitions.

激光粉末床熔融镍钛合金（LPBF-NiTi）因其独特的相变特性而具有形状记忆功能和超弹性。然而，受粉末成分和工艺参数等因素的影响，实现相变温度的精确控制和调节是一项挑战。本研究采用特征筛选策略和机器学习（ML）方法来预测和调节 LPBF-NiTi 合金的相变温度，为传统的调节和控制实验方法提供了一种更高效、更经济的替代方法。具体而言，利用广义回归神经网络（GRNN）和其他方法对不同成分和工艺条件下的 LPBF-NiTi 相变数据集进行了精度分析。研究结果表明，通过本研究中概述的选择策略提取的可解释特征与 GRNN 模型相结合，显示出较高的预测精度（R2 = 0.97）。为了研究该模型的准确性，本研究利用各种工艺参数从 Ni50.8Ti49.2 合金粉末中制造出不同成分的镍钛合金。利用该模型，研究确定了一个新的、更大的 LPBF 最佳加工窗口，可实现可控的复杂相变。

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引用次数: 0

Effects of firing process on the composition, structure, and properties of near stoichiometric SiC fiber 焙烧工艺对接近化学计量的碳化硅纤维的成分、结构和性能的影响

IF 7.6 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials & Design

Pub Date : 2024-11-01 DOI: 10.1016/j.matdes.2024.113427

Wenxing Zhao, Yuanfeng Gan, Xiaozhou Wang

Two kinds of near-stoichiometric SiC fibers were prepared through the pyrolysis of oxygen-free cured polycarbosilane fibers at 1,000 °C within a controlled hydrogen atmosphere, followed by sintering at 1,500 °C under a nitrogen atmosphere by one-step and two-step firing processes. The compositions, structures, and properties of the obtained SiC fibers were characterized using elemental analysis, mechanical performance testing, X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Silicon radicals were generated in the process of hydrogen firing, which readily reacted with oxygen to form SiO₂ or SiC_xO_y phases on the fiber surface, resulting in the obtained fibers exhibited a gradient in compositional distribution across the radial direction, with higher oxygen content at their surfaces and higher carbon content at their cores. The strength of one-step-fired SiC fiber exceeded 1 GPa after treatment at 1,800℃ in argon and 1,500℃ in air for 1 h.

通过一步法和两步法烧结工艺，将无氧固化聚碳硅烷纤维在受控氢气气氛下于 1,000 ℃ 高温分解，然后在氮气气氛下于 1,500 ℃ 烧结，制备了两种近全度碳化硅纤维。利用元素分析、机械性能测试、X 射线衍射分析、X 射线光电子能谱、扫描电子显微镜和透射电子显微镜对获得的碳化硅纤维的成分、结构和性能进行了表征。氢气焙烧过程中产生了硅自由基，硅自由基很容易与氧气反应，在纤维表面形成SiO2或SiCxOy相，从而使所获得的纤维在径向上呈现出成分梯度分布，表面氧含量较高，芯部碳含量较高。在氩气中 1,800℃ 和空气中 1,500℃ 处理 1 小时后，一步法烧结碳化硅纤维的强度超过 1 GPa。

引用次数: 0