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Investigation of melt-growth alumina/aluminum titanate composite ceramics prepared by directed energy deposition

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International Journal of Extreme Manufacturing 2021年第3期3卷 49-62页

作者： Yunfei Huang Dongjiang Wu Dake Zhao fangyong niu Guangyi Ma Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalianLiaoning Province 116024People’s Republic of China

Al_(2)O_(3)/Al_(6)Ti_(2)O_(13) composite ceramics with low thermal expansion properties are promising for the rapid preparation of large-scale and complex components by directed energy deposition-laser based(DED-LB)***,the wider application of DED-LB technology is limited due to the inadequate understanding of process *** shaping quality,microstructure,and mechanical properties of Al_(2)O_(3)/Al_(6)Ti_(2)O_(13)(6 mol%TiO_(2))composite ceramics were systematically investigated as a function of energy input in an extensive process *** this basis,the formation mechanism of solidification defects and the evolution process of microstructure were revealed,and the optimized process parameters were *** show that high energy input improves the fluidity of the molten pool and promotes the uniform distribution and full growth of constituent phases,thus,facilitating the elimination of solidification defects,such as pores and strip *** addition,the microstructure size is strongly dependent on the energy input,increasing when the energy input ***,the morphology of theα-Al_(2)O_(3) phase gradually transforms from cellular into cellular dendrite with increasing energy input due to changing solidification *** the comprehensive influence of solidification defects and microstructure size,the fracture toughness and flexural strength of Al_(2)O_(3)/Al_(6)Ti_(2)O_(13) composite ceramics present a parabolic law behavior as the energy input *** shaping quality and excellent mechanical properties are achieved at an energy input range of 0.36-0.54 W*min^(2) g^(-1) mm^(-1).Within this process window,the average microhardness,fracture toughness,and flexural strength of Al_(2)O_(3)/Al_(6)Ti_(2)O_(13) composite ceramics are up to 1640 Hv,3.87 MPa m^(1/2),and 227 MPa,*** study provides practical guidance for determining the process parameters of DED-LB of melt growth Al_(2)O_(3)/Al_(6)Ti_(2)

关键词： additive manufacturing Al_(2)O_(3) composite ceramics microstructure mechanical properties

Microstructure and mechanical properties of melt-grown alumina-mullite/glass composites fabricated by directed laser deposition

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Journal of Advanced Ceramics 2022年第1期11卷 75-93页

作者： Dake ZHAO Dongjiang WU Jing SHI fangyong niu Guangyi MA Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China

Melt-grown alumina-based composites are receiving increasing attention due to their potential for aerospace applications;however,the rapid preparation of high-performance components remains a ***,a novel route for 3D printing dense(<99.4%)high-performance melt-grown alumina-mullite/glass composites using directed laser deposition(DLD)is *** issues on the composites,including phase composition,microstructure formation/evolution,densification,and mechanical properties,are systematically *** toughening and strengthening mechanisms are analyzed using classical fracture mechanics,Griffith strength theory,and solid/glass interface infiltration *** is demonstrated that the composites are composed of corundum,mullite,and glass,or corundum and *** the increase of alumina content in the initial powder,corundum grains gradually evolve from near-equiaxed dendrite to columnar dendrite and cellular structures due to the weakening of constitutional undercooling and small nucleation *** microhardness and fracture toughness are the highest at 92.5 mol%alumina,with 18.39±0.38 GPa and 3.07±0.13 MPa-m1/2,*** maximum strength is 310.1±36.5 MPa at 95 mol%*** enhancement is attributed to the improved densification due to the trace silica doping and the relief of residual *** method unravels the potential of preparing dense high-performance melt-grown alumina-based composites by the DLD technology.

关键词： laser additive manufacturing alumina mullite microstructure mechanical properties

A critical review of direct laser additive manufacturing ceramics

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International Journal of Minerals,Metallurgy and Materials 2024年第12期31卷 2607-2626页

作者： Dake Zhao Guijun Bi Jie Chen WaiMeng Quach Ran Feng Antti Salminen fangyong niu Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou 510070China Guangdong Key Laboratory of Modern Control Technology Guangzhou 510070China Department of Civil and Environmental Engineering University of MacaoMacao 310058China School of Civil and Environmental Engineering Harbin Institute of TechnologyShenzhen 518055China Department of Mechanical and Materials Engineering Faculty of TechnologyUniversity of TurkuFI-20014 Turun yliopistoFinland Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116000China

The urgent need for integrated molding and sintering across various industries has inspired the development of additive manu-facturing(AM)*** the different AM technologies,direct laser additive manufacturing(DLAM)stands out as a group of highly promising technology for flexibly manufacturing ceramics without molds and adhesives in a single *** the last decade,sig-nificant and encouraging progress has been accomplished in DLAM of high-performance ceramics,including Al_(2)O_(3),ZrO_(2),Al_(2)O_(3)/ZrO_(2),SiC,and ***,high-performance ceramics fabricated by DLAM face challenges such as formation of pores and cracks and resultant low mechanical properties,hindering their practical application in high-end *** improvements are necessary be-fore they can be widely *** such as field-assisted techniques and post-processing can be employed to address these chal-lenges,but a more systematic review is *** work aims to critically review the advancements in direct selective laser sintering/melting(SLS/SLM)and laser directed energy deposition(LDED)for various ceramic material ***,it provides an overview of the current challenges,future research opportunities,and potential applications associated with DLAM of high-perform-ance ceramics.

关键词： 3D printing laser additive manufacturing ceramics quality microstructure mechanical properties

Enhanced high-temperature mechanical properties of laser-arc hybrid additive manufacturing of Al-Zn-Mg-Cu alloy via microstructure control

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Journal of Materials Science & Technology 2024年第2期169卷 220-234页

作者： Dehua Liu Dongjiang Wu Yunsong Wang Zhuo Chen Changrong Ge Qingyu Zhao fangyong niu Guangyi Ma State Key Laboratory of High-performance Precision Manufacturing Dalian University of TechnologyDalian 116024China

Recently,rapid and cost-effective additive manufacturing solutions for lightweight aluminum alloys with excellent high-temperature mechanical properties have been increasingly in *** this study,we combined laser-arc hybrid additive manufacturing with solution and artificial aging treatments to achieve Al-Zn-Mg-Cu alloy with favorable high-temperature strength via microstructure *** pores became the major defect in the as-deposited and heat-treated *** continuous distribution of eutectics with hard-brittle characteristics at the grain boundaries was destructed following heat ***-densityηprecipitates were uniformly dispersed in the heat-treated Al-Zn-Mg-Cu alloy,whereas appeared coarsened and dissolved at 473 K,owing to the rapid diffusion of Zn and *** average 0.2%yield strength(318±16 MPa)and ultimate tensile strength(362±20 MPa)at 473 K af-ter heat treatment were enhanced by approximately 58%and 51%,respectively,compared to those of the as-deposited *** addition,theηprecipitates contributed to lattice distortions and strain fields,which prevented dislocation motion and increased slip deformation resistance at high *** as-deposited specimen exhibited intergranular fracture at 473 K,with cracks preferring to propagate along the aggregated ***,crack propagation proceeded in the sections with more pores in the heat-treated *** approach may provide a valid option for achieving alu-minum alloys with excellent high-temperature mechanical properties.

关键词： Laser-arc hybrid additive manufacturing Al-Zn-Mg-Cu alloy High-temperature strength Heat treatment,Microstructure evolution

Laser-assisted grinding of RB-SiC composites:Laser ablation behavior and mechanism

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Chinese Journal of Aeronautics 2024年第1期37卷 362-376页

作者： Zhigang DONG Wenchao SUN Xintong CAI Feng YANG Yan BAO Renke KANG Dongjiang WU Guangyi MA fangyong niu Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Laser ablation is an important process during Laser-Assisted Grinding(LAG)of hard and brittle *** realize controllable material removal during laser ablation of RB-SiC composites,ablation experiments under different Laser Energy Density(LAED)and LAG experiments are *** rules and mechanism of physical phase,ablation morphology and crack characteristics caused by laser irradiation are *** forces of LAG and Conventional Grinding(CG)are *** results show that ablation surface changes from slight oxidation to obvious material removal with LAED increasing,and ablation depth increases *** ablation products change from submicron SiO_(2)particles to nanoscale particles and *** LAED promotes SiC decomposition and sublimation,which leads to the increase of C *** SiC phase forms corrugated shape in recast layer and columnar shape in Heat Affected Zone(HAZ)at 56 J/mm^(2).The cold and heat cycle leads to formation of fishbone *** ablation specimen under 30 J/mm^(2),the grinding force can be reduced by a maximum of 39%and brittle damage region is *** material removal and microcrack generated will significantly reduce the hardness and improve machinability,which can promote grinding efficiency.

关键词： RB-SiC Laser Ceramic Composites Grinding

Investigation on the Cracking Mechanism of Melt Growth Alumina/Aluminum Titanate Ceramics Prepared by Laser Directed Energy Deposition

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Chinese Journal of Mechanical Engineering(Additive Manufacturing Frontiers) 2023年第4期2卷 23-32页

作者： Yunfei Huang Dongjiang Wu Chengxin Li Weijie Lv Guangyi Ma Cong Zhou fangyong niu State Key Laboratory of High-performance Precision Manufacturing Dalian University of TechnologyDalian116024China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen518055China

Oxide melt growth ceramics(OMGCs)exhibit excellent performance and microstructure stability near their melt-ing point and are expected to become a new structural material for long-term stable service in extremely high-temperature water-oxygen *** to its unique advantages of high efficiency,flexible manufac-turing,and near-net shaping,laser directed energy deposition(LDED)has become a promising technology for the rapid preparation of high-performance ***,owing to the limited understanding of the crack-ing mechanism,the severe cracking problem that hinders OMGCs-LDED towards engineering applications has not been ***/aluminum titanate(Al_(2)O_(3)/Al_(x)Ti_(y)O_(z),A/AT)ceramics are prepared using an LDED system and their cracking characteristics are ***,numerical simulations are conducted to reveal the dominant factors and influencing mechanisms of the cracking *** results demonstrate that the cracking nucleation process is mainly controlled by solidification defects,whereas the cracking propagation process is determined primarily by both the microstructure and stress *** study provides a theoretical basis for the development of appropriate cracking suppression methods for OMGCs-LDED.

关键词： Additive manufacturing Laser directed energy deposition Composite ceramics Alumina/aluminum titanate Cracking mechanism

激光能量输入对直接激光沉积莫来石陶瓷组织性能的影响

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稀有金属材料与工程 2021年第3期50卷 1007-1015页

作者：赵大可吴东江牛方勇马广义大连理工大学精密与特种加工教育部重点实验室辽宁大连116024

研究了激光能量密度对直接激光沉积熔体自生莫来石陶瓷孔隙/密度、微观组织和力学性能的影响。结果表明,较低激光能量密度(15 J/mm^(2))所制备的陶瓷样件边缘分布有尺寸较大的气孔,使得样件整体孔隙率较高,且表面粘粉严重,这与成形扫描... 详细信息

研究了激光能量密度对直接激光沉积熔体自生莫来石陶瓷孔隙/密度、微观组织和力学性能的影响。结果表明,较低激光能量密度(15 J/mm^(2))所制备的陶瓷样件边缘分布有尺寸较大的气孔,使得样件整体孔隙率较高,且表面粘粉严重,这与成形扫描速度大和硅酸盐熔体粘度高有关。而较高激光能量密度(90 J/mm^(2))虽然可以获得表面光滑、莫来石晶粒尺寸较小的陶瓷样件,但由于单位时间内输入熔池能量高,粉末蒸发产生的气孔来不及逃逸出熔池,使得样件心部形成较大的气孔,影响样件的力学性能。在激光能量密度为45J/mm^(2)时,获得了表面相对光洁、孔隙率较低和力学性能较好的莫来石陶瓷样件。本研究结果为直接激光沉积增材制造高性能陶瓷过程中合理选定工艺条件提供了理论指导及技术支撑。

关键词：增材制造陶瓷激光能量密度孔隙力学性能

TC4/ZrO_2复合材料激光近净成形微观组织分析

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稀有金属材料与工程 2018年第8期47卷 2465-2471页

作者：沈忱马广义闫帅牛方勇吴东江大连理工大学精密与特种加工教育部重点实验室辽宁大连116024

采用激光近净成形系统成形了不同ZrO_2掺入量的TC4/ZrO_2薄壁,研究了扫描速率对金属基陶瓷材料成形热应力的影响,利用X射线衍射仪(XRD)、扫描电镜(SEM)、X射线能量色散谱仪(EDS)对薄壁样件进行相组成分析、微观组织观察以及元素分布检... 详细信息

采用激光近净成形系统成形了不同ZrO_2掺入量的TC4/ZrO_2薄壁,研究了扫描速率对金属基陶瓷材料成形热应力的影响,利用X射线衍射仪(XRD)、扫描电镜(SEM)、X射线能量色散谱仪(EDS)对薄壁样件进行相组成分析、微观组织观察以及元素分布检测。研究表明,相对较低的扫描速度可以减小薄壁件的残余应力,抑制样件的宏观裂纹;XRD结果显示当ZrO_2含量达到30%以上时,生成了TiO.325的Ti的非化学计量氧化物;TC4基体的微观组织随着ZrO_2掺入量的增多晶粒逐渐从针状过渡到板条状、块状;EDS结果显示当Ti晶粒为板条状,晶界间有ZrO_2富集;随着ZrO_2含量增多,Ti固溶体中固溶的Zr增多。本研究为最终成形TC4/ZrO_2梯度材料提供了可靠的技术支持。

关键词：激光近净成形 TC4/ZrO2复合材料掺杂比例微观组织元素分布

激光近净成形Al_2O_3–YAG复合陶瓷薄壁件微观组织与力学性能分析

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硅酸盐学报 2015年第6期43卷 741-746页

作者：吴东江王江田牛方勇马广义大连理工大学精密与特种加工教育部重点实验室辽宁大连116024

采用同轴输送Al2O3–Y2O3粉末激光近净成形方法进行复合陶瓷薄壁件成形实验,使用扫描电子显微镜,X射线衍射及电子探针显微分析仪对成形薄壁样件微观组织、物相组成及元素含量进行检测,通过压痕法测量样件显微硬度与断裂韧性。结果表明:... 详细信息

采用同轴输送Al2O3–Y2O3粉末激光近净成形方法进行复合陶瓷薄壁件成形实验,使用扫描电子显微镜,X射线衍射及电子探针显微分析仪对成形薄壁样件微观组织、物相组成及元素含量进行检测,通过压痕法测量样件显微硬度与断裂韧性。结果表明:同轴输送Al2O3–Y2O3粉末激光近净成形可得到Al2O3–YAG复合陶瓷件,主要由α-Al2O3和YAG两相组成,但同时存少量亚稳态YAP或YAM相;薄壁样件内部主要由粗大的富YAG初生相和Al2O3/YAG交错生长的网状共晶组织组成,成形过程中Al2O3较易挥发,不同高度位置重熔次数影响Al相对挥发量,导致两相比例不同,由顶部到底部,富YAG初生相尺寸和比例增大,成形过程中,高温促使亚稳相向YAG转化加剧这一现象;压痕法测量样件显微硬度为16 GPa,断裂韧性为2.89 MPa·m1/2,说明该方法可得到性能较好的陶瓷件。

关键词：激光近净成形氧化铝-钇铝柘榴石复合陶瓷微观组织力学性能