一种新型材料3D打印性能及应用研究

本文提出了一种用于激光选区烧结(Selective Laser Sintering,SLS)成形的新型粉末材料KZF。研究了其适合进行SLS成形的粉末制备工艺,基于不同的激光加工工艺参数,得出了最优工艺参数。在最优工艺参数下SLS成形KZF粉生坯体具有较高的初始强度,得出了成形KZF生坯所需粘接剂的最低含量,和具有的强度值。研发了SLS成形的KZF生坯件的后处理材料、配方及工艺规范,研究了经确定最佳后处理规范后的KZF SLS成形件的力学性能以及微观组织的影响,确定了提高KZF生坯强度的材料及含量,经后处理后的KZF粉SLS成形件的弯曲强度提升幅度最大达273倍。本文为制造复杂形状的KZF成形件提供了一种新的思路与方法,并扩大了SLS成形材料的应用范围。     

一种新型材料3D打印性能及应用研究

本文提出了一种用于激光选区烧结(Selective Laser Sintering,SLS)成形的新型粉末材料KZF。研究了其适合进行SLS成形的粉末制备工艺,基于不同的激光加工工艺参数,得出了最优工艺参数。在最优工艺参数下SLS成形KZF粉生坯体具有较高的初始强度,得出了成形KZF生坯所需粘接剂的最低含量,和具有的强度值。研发了SLS成形的KZF生坯件的后处理材料、配方及工艺规范,研究了经确定最佳后处理规范后的KZF-SLS成形件的力学性能以及微观组织的影响,确定了提高KZF生坯强度的材料及含量,经后处理后的KZF-SLS成形件的弯曲强度提升幅度最大达273倍。本文为制造复杂形状的KZF成形件提供了一种新的思路与方法,并扩大了SLS成形材料的应用范围。     

氧化锆零件激光选区烧结/冷等静压复合成形技术

氧化锆陶瓷材料以其优异的性能在工业生产中具有极大的应用前景,但由于脆性大、硬度高等原因,复杂形状氧化锆零件往往难以成形和加工。为了获得复杂形状氧化锆陶瓷零件,通过溶剂沉淀法将粘接剂尼龙12覆膜至纳米氧化锆粉末的表面,然后对覆膜后的粉体进行激光选区烧结(Selective laser sintering, SLS)成形,并通过传统的冷等静压(Cold isostatic pressing, CIP)技术对SLS零件进行致密化处理,同时满足氧化锆初坯成形时形状复杂度和密度的要求。通过试验得出在激光能量密度为0.415 J/mm2时,获得的SLS陶瓷件密度较大,对不同激光能量密度制备的SLS陶瓷件进行保压压力为200 MPa的冷等静压致密化处理,根据热脱脂机理以及粘接剂的TG曲线,分别制定了SLS/CIP试样的热脱脂工艺,最后对脱脂试样进行高温烧结,在后续处理的各环节,氧化锆零件的密度仍受SLS成形的影响,但该影响逐渐减弱,SLS/CIP/FS成形件最大相对密度和维氏硬度分别达到了97%和1180 HV1,已接近“模压-烧结”的致密氧化锆陶瓷的性能,在试样断口的扫描电子显微镜(SEM)分析基础上,对氧化锆复合成形的微观演变进行了研究。虽然最终烧结件密度和硬度仍有待提高,但是提出了一种极具潜力的氧化锆零件近净成形工艺方法,为制造高性能复杂形状的陶瓷零件奠定了基础。     

激光诱导等离子体加工蓝宝石微结构及其润湿性

激光诱导等离子体刻蚀技术在蓝宝石表面微结构制作方面具有独特的优势。通过控制变量法研究了激光能量密度、靶材和蓝宝石之间的距离和扫描速度对激光诱导等离子体加工蓝宝石微槽的微观形貌和几何尺寸的影响规律。通过正交试验研究了激光诱导等离子体工艺参数对蓝宝石表面微结构接触角的影响,发现扫描线间距对接触角的影响最大,靶材和蓝宝石之间的距离和激光能量密度次之,扫描速度的影响最小。当激光能量密度为6.3 J/cm²,扫描线间距为200μm,靶材和蓝宝石之间的距离为150μm,扫描速度为10 mm/s时,蓝宝石表面微结构的接触角为136°,表现出良好的疏水性;当激光能量密度为7.4 J/cm²,扫描线间距为50μm,靶材和蓝宝石之间的距离为100μm,扫描速度为5 mm/s时,蓝宝石表面微结构的接触角为29°,具有较好的亲水性,并且长时间放置后表面接触角基本保持不变。通过扫描电镜观察发现,蓝宝石表面的微结构上分布着许多纳米颗粒,这些微纳结构共同影响蓝宝石的润湿性。     

选区激光熔化成形碳纳米管增强铝基复合材料成形机制及力学性能研究

铸造铝合金具有优良的铸造焊接性能等优点,但是低硬度和较差的耐磨性能限制了其应用的范围,成形铝基复合材料构件是一种有效途径。采用选区激光熔化(Selectivelasermelting,SLM)增材制造技术成形碳纳米管增强铝基纳米复合材料(CNT/Al)构件,通过设置不同的激光参数,研究不同激光能量密度(η)下试样的致密化行为、物相和显微组织及其力学性能。研究表明:随着η从150J/m增加至187.5J/m,致密度从94.49%上升至99.83%。高能量密度增大了熔池的尺寸和温度,导致液相的黏度下降和润湿性能提高,使得液相均匀铺展,熔池间搭接程度上升以及孔洞等冶金缺陷减少,致密化程度上升。成形试样的主要物相为Al9Si和Si,碳纳米管(CNTs)外壁与基体发生原位反应生成了Al_4C_3,提高了界面稳定性。成形试样的硬度和耐磨性能与致密度变化表现为正相关。当η=187.5 J/m时,成形试样的平均显微硬度为164.3 HV_(0.2),摩擦因数下降至0.21,强度和延伸率分别为452 MPa和9.0%,表现出优良的力学性能。     

SUS304不锈钢超薄片脉冲激光焊接工艺及接头的显微组织和力学性能

在不同激光功率(140～420 W)和焊接速度(10～30 mm·s~(-1))(即不同热输入)下对SUS304不锈钢超薄片(厚度0.2mm)进行脉冲激光搭接焊,研究了热输入对焊缝成形的影响,并分析了最优成形接头的显微组织和力学性能。结果表明:当热输入在9～20J·mm~(-1)时可获得成形良好的焊缝,其中在激光功率320 W、焊接速度20mm·s~(-1)(热输入16J·mm~(-1))条件下的成形性能最优;最优成形接头焊缝中心为等轴晶组织,熔合线处为细小柱状晶组织,近熔合线的焊缝中形成了胞状树枝晶;最优成形接头熔合线处的硬度最高,其次为焊缝区;不同激光功率和焊接速度所得接头均在热影响区发生断裂,最优成形接头的抗拉强度最高,达到790.1MPa,接近于母材的,其拉伸断裂方式为韧性断裂。     

激光能量密度对激光选区熔化Cu-Al-Ni-Ti合金相对密度、微观组织和力学性能的影响

采用激光选区熔化技术(Selective laser melting,SLM)成形制备了不同工艺参数下Cu-Al-Ni-Ti铜基形状记忆合金试样。用排水法测试了块体试样的相对密度,对试样进行了显微组织分析和热分析,测试了拉伸试样在不同温度下的力学性能和测试试样的形状记忆性能,研究了激光能量密度对相对密度、显微组织和常温力学性能的影响规律。结果表明:块体试样的相对密度随激光能量密度的增大先增大再减小,试样的相对密度最大值达99.9%;当激光能量密度适中时(107J/mm3),熔化道连续且无明显缺陷,激光能量密度过低或者过高,试样会产生熔化道不连续或者球化等缺陷;拉伸试样的常温拉伸性能随激光能量密度的增大先增大再减小,常温下试样最大抗拉强度和延伸率分别为541MPa和7.63%。在300℃下试样的抗拉强度提升至最大为611MPa,延伸率提升至10.78%。试样的马氏体相变开始温度Ms约为83℃,结束温度Mf约为40℃,形变回复率接近90%。     

4D打印热塑性聚氨酯/钕铁硼磁性复合材料成形工艺与性能研究

传统的3D打印技术逐渐无法满足高端制造领域对构件的要求,材料-结构-功能一体化增材制造即4D打印技术将是新的发展方向。为此,选取热塑性聚氨酯(TPU)/钕铁硼(NdFeB)磁性复合材料体系,采用激光选区烧结(Selective laser sintering,SLS)工艺成形具有不同Nd FeB含量的复合材料成形件,研究了复合粉末的粒度及其分布、微观形貌、成形前后化学基团演变,成形件晶体结构、力学性能及变形行为,结果表明Nd Fe B含量会影响复合材料成形件的力学性能和变形行为,增加Nd Fe B含量能够增大成形件在磁场中受到的作用力;当Nd Fe B含量在复合材料中质量分数为30%时,复合材料成形件拥有最佳的拉伸强度。本研究将TPU/NdFeB复合材料体系作为一种创新的4D打印材料,成形的磁性智能构件在磁场中发生变形,实现了磁场驱动的4D打印,对4D打印磁性智能构件的发展具有指导意义。     

纳米Al2O3/PS复合材料选区激光烧结成形域及力学性能

在前期研究确认激光功率P和扫描速度v对成形粉末NH1的选区激光烧结(Selective laser sintering,SLS)成形性具有显著性影响的基础上,重点研究P和v对NH1粉末的SLS成形性的影响,研究发现当P较小、v较快时,SLS烧结件结构不致密,强度较低;当P较高、v较慢时,SLS试件容易着火和翘曲变形;只有合理匹配P和v(即处在成形区内),才能直接制备出变形较小、密度较高的烧结件.同时对相同工艺条件下的Al2O3/PS纳米复合材料与纯聚苯乙烯SLS试件的缺口冲击吸收功进行比较,结果表明纳米复合材料的缺口冲击吸收功提高20%～50%,其最大值达到10.5 kJ/m2.利用场发射扫描式电子显微镜(FE-SEM)对NH1和纯PS(Polystyrene)粉SLS试件的断面进行微观结构分析,结果表明核壳式纳米Al2O3/PS复合粒子改善纳米氧化铝表面与聚苯乙烯极性的差异,纳米Al2O3在基体中分散性良好,且很好地起着增强增韧的效果.     

激光能量密度对SLM成形316L不锈钢表面完整性的影响

采用激光选区熔化(Selective Laser Melting, SLM)技术成形制备316L不锈钢试样,探索了不同激光能量密度对金属增材制造成形质量的影响规律。选取激光功率、扫描间距、扫描速度和铺粉厚度等工艺参数,设计了正交试验,分析了激光能量密度对试件侧表面的表面粗糙度、维氏硬度、致密度、残余应力及表面形貌的影响规律。结果表明,随着激光能量密度的增大,试件侧表面的表面粗糙度与维氏硬度呈现先减小后增大的趋势,致密度和残余应力呈现先增大后减小的趋势,在激光能量密度为70.37 J/mm³时试件表面质量最佳,即最优工艺参数为激光功率P=190 W,扫描速度v=750 mm/s,铺粉厚度h=0.03 mm,扫描间距d=0.12 mm。     

Functional graded scaffold of HDPE/HA prepared by selective laser sintering: microstructure and mechanical properties

This paper presents a study on the effect of hydroxyapatite (HA) content on the microstructure and mechanical properties of high-density polyethylene (HDPE)/HA composites and the fabrication of functional graded scaffold of HDPE/HA by selective laser sintering (SLS). The microstructure of the sintered composite scaffolds had interconnected pores with diameters of 30–180 μm and porosity of 45–48 %. The HDPE/HA composite scaffolds had a flexural modulus of 36–161 MPa and ultimate strength of 4.5–33 MPa. The maximum loss modulus peak tended toward lower temperature values for HDPE/HA composites with 10 and 20 % of HA content, indicating that the α_χ relaxation was slightly affected by higher quantities of HA. The HA particles reinforced the matrix and minimized the plastic and definitive deformation under the test conditions. HDPE/HA functional graded scaffold fabricated using SLS with controlled microstructure and properties showed considerable potential for biomedical applications, being suitable for bone and cartilage tissue engineering.     

碳化硅零件的激光选区烧结及反应烧结工艺

为了获得高密度、高性能、复杂结构的碳化硅陶瓷件,提出采用机械混合法制备含有黏结剂和乌洛托品固化剂的碳化硅复合粉体,对复合粉体进行激光选区烧结（SLS）形成陶瓷素坯,并对素坯进行气氛烧结和渗硅处理,使其与基体发生反应烧结,最终形成复杂陶瓷异形件。实验证明：若激光功率为8.0 W、扫描速率为2 000 mm/s、扫描间距为0.1 mm、单层厚度为0.15 mm,获得的 SLS 陶瓷样品密度和强度最好。对SLS试样进行合理的中温碳化和高温渗硅,所得碳化硅陶瓷烧结体的抗弯强度最高可达 81 MPa,相对密度大于86%。     

激光选区烧结超高分子量聚乙烯工艺及性能

研究了激光选区烧结(SLS)成型工艺中不同工艺参数以及后续热处理工艺对超高分子量聚乙烯(UHMWPE)材料成型性能的影响。通过调整扫描间距、激光功率、扫描速度等不同工艺参数,描述了SLS成型UHMWPE零件的致密度、拉伸强度以及断裂伸长率,并对热处理前后的SLS成型UHMWPE零件的力学性能进行了比较。结果显示,致密度、拉伸强度、断裂伸长率总体上与激光功率呈正相关关系,与扫描间距、扫描速度呈负相关关系。经热处理后,SLS成型UHMWPE零件的力学性能有明显提高,致密度达到95.12%,抗拉强度达到24.08 MPa,断裂伸长率达到334.82 MPa。实验结果表明:SLS成型UHMWPE零件与模塑成型UHMWPE零件性能尚有差距,仅优化成型工艺不足以得到理想性能,但经热处理后,零件性能基本满足使用要求。     

Selective laser sintering of hydroxyapatite reinforced polyethylene composites for bioactive implants and tissue scaffold development

Selective laser sintering (SLS) has been investigated for the production of bioactive implants and tissue scaffolds using composites of high-density polyethylene (HDPE) reinforced with hydroxyapatite (HA) with the aim of achieving the rapid manufacturing of customized implants. Single-layer and multilayer block specimens made of HA-HDPE composites with 30 and 40 vol % HA were sintered successfully using a CO2 laser sintering system. Laser power and scanning speed had a significant effect on the sintering behaviour. The degree of particle fusion and porosity were influenced by the laser processing parameters, hence control can be attained by varying these parameters. Moreover, the SLS processing allowed exposure of HA particles on the surface of the composites and thereby should provide bioactive products. Pores existed in the SLS-fabricated composite parts and at certain processing parameters a significant fraction of the pores were within the optimal sizes for tissue regeneration. The results indicate that the SLS technique has the potential not only to fabricate HA-HDPE composite products but also to produce appropriate features for their application as bioactive implants and tissue scaffolds.     

Effects of manufacturing process and surface treatments on mechanical properties of PLA/SCF composites using extrusion printing

Short carbon fiber (SCF) reinforced polylactic acid (PLA) composites were fabricated by extrusion printing, and the effects of process parameters and surface treatments on the mechanical properties of composites were studied. Based on the rheological properties of composites and the extrusion process simulation, pure PLA specimens and PLA/SCF specimens were manufactured under different printing parameters. Three kinds of surface treatment were adopted to improve the mechanical properties. The experimental results show that SCF can effectively improve the tensile strength and bending strength, but the compressive strength decreased. The specimen had the best mechanical properties when the layer height was 0.1 mm and the nozzle diameter was 0.6 mm. The mechanical properties can be further improved by coupling agent coating method, and the compressive strength was even higher than that of pure PLA specimen. The research in this paper can provide a reference for the fabrication of thermoplastic composites with excellent mechanical properties by extrusion printing.

     

载荷对激光选区烧结Cf/SiC复合材料摩擦磨损性能的影响

通过激光选区烧结技术和液相渗硅工艺制备了碳纤维增强碳化硅（Cf/SiC）复合材料。试样组织由C、SiC和Si三相组成,其密度和弯曲强度分别为2.89±0.01 g/cm3和237±9.8 MPa。采用UMT TriboLab多功能摩擦磨损试验机研究了Cf/SiC复合材料在不同载荷(10 N, 30 N, 50 N和70 N)条件下的摩擦学特性。研究结果表明：载荷较小(10 N)时,Cf/SiC复合材料的磨损由微凸起和SiC硬质点造成,磨损机制为磨粒磨损;载荷为30 N时,复合材料的摩擦磨损综合性能最好,其平均摩擦因数为0.564,磨损率低(5.24×10-7 cm3/（N·m）),主要磨损机制为犁削形成的磨粒磨损和黏结磨损。载荷增大到70N时,材料磨损严重,磨粒脱落形成凹坑,产生裂纹,其磨损率(8.68×10-7 cm3/（N·m）)高,磨损机制主要为脆性剥落。     

氮化碳基陶瓷刀具材料的制备与力学性能研究

采用热压烧结工艺,以Ti(C, N)为添加相,以Mo、Ni和Co为金属相,成功制备了氮化碳(C₃N₄)基陶瓷刀具材料,测量了其断裂韧度、抗弯强度和维氏硬度,分析了其微观组织。结果表明,在烧结温度为1600℃、保温时间为45 min和烧结压力为32 MPa的工艺条件下,Ti(C, N)质量分数为35%、Ni-Co质量分数为8%的C₃N₄基陶瓷刀具材料力学性能最优。合适的Ti(C, N)含量能细化C₃N₄晶粒、提高烧结密度、改善力学性能,合适的Ni-Co含量能使微观组织细小均匀。     

Research on manufacturing Cu matrix Fe-Cu-Ni-C alloy composite parts by indirect selective laser sintering

The property of alloy parts can be adjusted conveniently if alloy element powders are used for manufacturing alloy parts by indirect selective laser sintering (SLS), but there have been no reports in this field. Fe, Cu, Ni, C composite powders of two compositions were obtained through a 3D blending way in this paper. Green parts of above composite powder were manufactured by indirect SLS. Then, Cu matrix Fe-Cu-Ni-C alloy composites were produced after green parts had been depolymerized, high temperature sintered and infiltrated by molten Cu. The post-processing of green parts, microstructure and mechanical properties of alloy composites were investigated. The results show: Ni, Cu and C diffuse into γ-Fe when green parts are being sintered at high temperature and the distributing non-uniformity of alloy elements is eliminated basically; at room temperature, alloy composite microstructures are composed of lower bainite, α-Cu precipitated out of γ-Fe and Fe-Ni after they have been solution treated at 930°C and held at 350°C for 1 h later; the yield strength of alloy composites is near to 400 MPa and the elongation is under 3%. It can be used for manufacturing injection mold or other functional parts by indirect SLS.     

能量密度对激光选区熔化成形AlSi10Mg合金缺陷及力学性能的影响

分析了能量密度对激光选区熔化成形AlSi10Mg合金致密度的影响规律，并采用微纳CT检测结合EDS能谱分析的方法，统计了试样内部缺陷的类型和尺寸，分析了缺陷在试样三维层面上的分布规律及产生原因，得出了影响激光选区熔化成形AlSi10Mg合金致密度和内部缺陷的主要因素。结果表明，合适的激光能量输入是获得高致密度的关键，当激光能量密度处于47.62~50.00 J/mm³区间时，试样致密度最高，此时试样中夹杂缺陷消失，孔洞缺陷最大尺寸降至0.056 mm。孔洞缺陷产生原因主要与未熔粉体、空心粉及氧化物有关。在优选激光能量密度区间内成形的AlSi10Mg合金试样，其平均抗拉强度和伸长率分别在294 MPa和8.0%以上，优于铸造AlSi10Mg合金。