选择性激光熔化快速成形技术与装备

介绍了华中科技大学基于粉末材料选择性激光熔化（Selective laser melting，SLM）成形技术的一些最新研究成果，主要包括设备与软件，以及该技术的主要应用领域。由于SLM成形过程是一个复杂的物理化学冶金过程，金属粉末熔化快，熔池存在时间短，凝固成形时存在较大的温度梯度与热应力，液态金属表面张力大，因而容易产生翘曲变形、裂纹与球化现象三个国际性难题，针对这些难题，提出了相应的研究方案。     

选择性激光烧结技术在医学上的应用

简述了选择性激光烧结技术(SLS)和熔化技术(SLM)的成型原理及其在生物医学领域的应用,重点介绍了SLS在医学模型、植入体和赝复体、组织工程支架及药物传送装置等方面的应用,并对SLS和SLM技术的研究与发展方向进行展望。     

选择性激光熔化快速成形技术与装备

介绍了华中科技大学基于粉末材料选择性激光熔化(Selective laser melting,SLM)成形技术的一些最新研究成果,主要包括设备与软件,以及该技术的主要应用领域.由于SLM成形过程是一个复杂的物理化学冶金过程,金属粉末熔化快,熔池存在时间短,凝固成形时存在较大的温度梯度与热应力,液态金属表面张力大,因而容易产生翘曲变形、裂纹与球化现象三个国际性难题,针对这些难题,提出了相应的研究方案.     

选择性激光熔化快速成型工艺研究

利用IPG200W光纤激光器和自主研发的SLM(Selective Laser Melting)快速成型设备,采用不同工艺参数组合,在25mm厚Q235钢板上进行不锈钢粉末单道熔覆实验。研究了激光功率、扫描速度对单道熔覆形貌和宽度、高度的影响规律;分析了选择性激光熔化球化现象产生机理及避免产生球化的途径;论述了最佳工艺参数的获取方法。结果表明:能量密度越高,熔覆形貌越好,球化现象越不明显;激光功率增大,单道熔覆宽度和高度也增加;扫描速度增大,单道熔覆高度和宽度减小。最后给出了几组最佳加工工艺参数和加工实例。     

选择性激光烧结成型材料研究现状及展望

选择性激光烧结(Selective Laser Sintering,SLS)是增材制造技术的一个重要分支。选择性激光烧结所用原材料是决定SLS工艺成功与否的最基本因素,影响着成型件的致密度、气孔率、显微组织性能、尺寸精度及表面粗糙度等。原材料的开发是制约SLS技术发展的决定性因素。现在,国内外已成功研发出SLS原料主要有金属基粉末、陶瓷基粉末、高分子基粉末材料等。本文对几种主要的粉末材料进行比较和分析,阐述了成型材料的特点及国内外研究现状,并对SLS材料的发展前景进行展望。     

激光重熔对选区激光熔化成形4Cr5MoSiV1钢组织和性能的影响

目的 优化选区激光熔化(Selective Laser Melting, SLM)成形4Cr5MoSiV1钢的激光重熔工艺，综合提升SLM成形4Cr5MoSiV1钢的力学性能。方法 通过调整SLM成形过程中的激光重熔工艺参数成形4Cr5MoSiV1钢试样，采用扫描电镜、显微硬度计、万能材料试验机和摩擦磨损试验机测试分析试样的表面形貌、显微组织、显微硬度、抗拉强度、断后伸长率和耐磨性。结果 SLM成形4Cr5MoSiV1钢试样表面的飞溅颗粒、杂质颗粒和弧形波纹数量较多，其显微硬度为599HV，抗拉强度为1050.2 MPa，断后伸长率为9.5%，磨损率为1.309´10^?10 kg/(N.m)。4Cr5MoSiV1钢试样经激光重熔后，其冶金质量明显改善，显微硬度、抗拉强度、断后伸长率和耐磨性均提高，且各项力学性能间呈正相关关系。冶金质量和细晶强化作用共同决定4Cr5MoSiV1钢试样的力学性能水平，且随激光重熔线能量密度增加，试样的力学性能均表现为先升高后降低的趋势。当激光重熔线能量密度为238 J/m时，试样的力学性能最高，其显微硬度为645HV，抗拉强度为1430.7 MPa，断后伸长率为16.9%，磨损率为0.354×10^?10 kg/(N.m)。SLM成形4Cr5MoSiV1钢试样的断裂机理为脆性解理断裂，激光重熔试样的断裂机理为准解理断裂。SLM成形4Cr5MoSiV1钢试样及激光重熔试样的磨损机制均以粘着磨损和氧化磨损为主。结论 SLM成形4Cr5MoSiV1钢试样的最优激光重熔线能量密度为238 J/m，经激光重熔后，试样的冶金质量和力学性能明显提高。     

选择性激光烧结法制备SiC颗粒预制体

介绍了一种新的制备颗粒预制体的方法，即采用选择性激光烧结（SLS）法制备SiC颗粒预制体。结果表明，用表面已预处理的SiC与粘结剂混合粉料作为SLS用粉，在一定的激光烧结工艺条件下，可将其烧结成SiC颗粒均匀分散的预制体；并可通过控制烧结粉末的配比获得不同孔隙率的SiC颗粒预制体。     

316L不锈钢SLM件与锻件的激光焊接头微观组织与性能

文中采用激光焊接技术连接316L不锈钢SLM成形件与锻件,进行工艺优化并对其接头微观组织与性能进行研究。结果表明,该接头具有良好的激光焊接性能,无明显缺陷。激光焊接接头和SLM成形件的显微组织为柱状晶粒内的奥氏体基体中的胞状枝晶。与SLM成形件相比,接头表现出较粗的枝晶结构、较低的显微硬度、拉伸性能。该接头的力学性能满足实际应用的要求。各向异性对激光焊接接头的组织和力学性能的影响可以忽略不计。平行于打印方向的SLM成形件与锻件焊接得到的接头,可以得到较细的树枝状结构和较高的拉伸性能。     

高效选择性激光烧结系统的研究

选择性激光烧结(Selective Laser Sintering,SLS)是快速成形技术的一种,其成形效率是需要考虑的重要指标之一。为了提高成形效率,我们从机械和工艺两方面着手研究和改进,并在华中科技大学研制的HRPS-III型SLS快速成形系统中应用,取得了良好的效果。     

选择性激光烧结快速成形制件翘曲变形的研究

翘曲变形对选择性激光烧结(SLS)成形精度的影响很大.通过在HRPS-ⅢA型成型机上进行快速成型试验,找出产生翘曲变形的根本原因;得到了激光扫描速度和激光功率、粉末预热温度等工艺参数对翘曲变形的影响规律;并提出了减小翘曲变形的有效措施.     

Manufacturing by combining Selective Laser Melting and Selective Laser Erosion/laser re-melting

This study presents an experimental investigation to improve Selective Laser Melting (SLM) regarding aspects such as surface roughness, density, precision and micro machining capability by employing secondary processes such as Selective Laser Erosion (SLE) and laser re-melting. SLM is a layered additive manufacturing technique for the direct fabrication of functional parts by fusing together metal powder particles. Laser re-melting, applied after each layer or only on the top surfaces, is used to improve the roughness and density while SLE, a subtractive process, is combined with SLM to improve the precision and micro machining capability.     

Selective Laser Sintering of PEEK

Polyetheretherketone (PEEK) is a good choice especially for manufacturing medical instruments or implants. These parts are typically produced by conventional manufacturing methods, like injection moulding. Selective Laser Sintering (SLS) could offer more flexibility. It enables the direct manufacturing of products with complex geometries. Although SLS of polymers like polyamide or polystyrene is a standard industrial process already, laser sintering of PEEK remains a challenge.This article will show for SLS of PEEK the necessary adaptations in systems technology and material modifications and discuss a step-by-step process implementation. Process boundaries are shown concerning temperature and energy input. The high influence of porosity, which could be varied from zero to 15%, on mechanical properties is shown.     

Quantifying the degree of particle melt in Selective Laser Sintering

This research highlights the fact that individual particles are melted to different degrees during Selective Laser Sintering^® (SLS) of Nylon 12. Many particles comprise an un-melted core, surrounded by a melted and crystallised mass that bonds with other particles. Methods to quantify the Degree of Particle Melt (DPM), including Differential Scanning Calorimetry (DSC) analysis and optical microscopy analysis, are compared against each other and against mechanical properties of parts manufactured under different conditions. The results show that the derived DPM has a close correlation with mechanical properties. This represents a new depth of understanding of the SLS process.     

金属粉末选区激光熔化技术的研究现状及其发展趋势

选区激光熔化(SLM)技术是近年来出现的一种新型的快速成型(RP)技术。该技术的优点是:工艺简单、成型件尺寸精度高、表面粗糙度好、致密度几乎能达到100%、力学性能优良、应用前景广阔。本文描述了该技术的基本原理;详细介绍了国内外选区激光熔化技术相关设备、工艺以及成型用金属粉末材料等的研究成果;并进一步讨论了选区激光熔化技术的应用及其发展方向。     

激光重熔技术在选区激光熔化中的研究进展

激光重熔使得材料表面的固化层再次快速熔化、凝固，从而提高了材料的致密度和表面质量。作为一种表面改性技术，激光重熔已经在传统制造工艺中得到了广泛的应用。近期研究表明，激光重熔技术也可以应用到选区激光熔化（SLM）中，实现消除缺陷并优化组织结构。激光重熔技术还可以提高零件的硬度和延展性等力学性能。本文主要总结了激光重熔对于常见SLM成形金属材料的质量提升作用，激光重熔工艺手段以及重熔参数（重熔激光功率、重熔扫描速度、重熔扫描间距和重熔次数）对于缺陷消除、组织结构优化的作用规律。     

选区激光熔化金属表面成形质量控制的研究进展

选区激光熔化是目前应用广泛的金属增材制造方法，能够实现复杂精密金属件的成形。但是，由于技术原理的限制，选区激光熔化金属表面与切削加工表面相比，成形质量仍然存在较大差距，影响了这一方法的进一步应用。如何提高表面成形质量，是目前选区激光熔化金属成形领域重要的研究方向。介绍了选区激光熔化成形原理，分析了影响选区激光熔化金属表面成形质量的因素，总结了目前选区激光熔化金属表面成形质量的控制方法及相关研究进展。指出合理地布置成形件位置、避免将成形质量要求高的轮廓面设置为第三类表面、优化扫描工艺参数，是控制和提高选区激光熔化金属表面成形质量的主要途径。     

选择性激光烧结铸造覆膜砂的实验研究

通过对铸造用覆膜砂烧结实验,激光功率、扫描速度、预热温度、光斑直径工艺参数对烧结试样成型精度和烧结质量的影响,总结出了制件尺寸随各工艺参数变化的趋势。并提出烧结制件后处理的合理温度范围。     

Effects of the Selective Laser Melting manufacturing process on the properties of CoCrMo single tracks

Selective Laser Melting (SLM) is an additive technology that produces solid parts by selectively melting thin layers of metallic powder. SLM can produce significant differences in the final properties due to the melting-consolidation phenomena of the process, which can be controlled by the appropriate parameters. Therefore, the objective of this study was to create a link between the process conditions and the resulting properties by experimenting in an own-developed SLM machine using CoCrMo powder as material. The fabricated samples were characterized by density, hardness and microstructural properties. The experimental results proved the capability of the SLM technique to build high dense samples. The hardness results gave evidence of a superior outcome compared to conventional processes. Finally, it was found that grain size was defined by scanning speed. Based on the results, a better understanding of the processing principles given by the parameters was achieved and improved fabrication quality was promoted.     

The use of off-line part production to predict the tensile properties of parts produced by Selective Laser Sintering

Rapid Manufacturing, and specifically Selective Laser Sintering, has the potential to become one of the most useful manufacturing techniques of the future, largely as a result of the extremely high levels of geometric complexity which can be produced. As the use of these technologies becomes more widespread, so the amount, and variety, of materials available for use in these processes also increases. However, the Selective Laser Sintering process can be both expensive and time-consuming when testing new materials. A method of off-line casting has been proposed here, and the tensile properties of parts produced using this method are compared with the properties achieved in Selective Laser Sintered parts produced in the same materials. For the materials tested it has been shown that the casting method provided an acceptable correlation with the properties of the Selective Laser Sintered parts, rendering this a suitable method of assessing the properties of a Selective Laser Sintering material without the requirement to produce a full build.     

Interface interactions between porous titanium/tantalum coatings, produced by Selective Laser Melting (SLM), on a cobalt-chromium alloy

Porous titanium and tantalum coatings were produced on cast cobalt-chromium alloy substrate plates (Co-28 Cr-6 Mo ASTM designation F75)) using the additive manufacturing process Selective Laser Melting (SLM). Both tantalum and titanium coatings where successfully produced, however, a poor interface bond was observed with the titanium coatings on the cobalt-chrome alloy. This was due to a eutectic reaction leading to the formation of a low melting point phase βTi(CoCr) which cracks during cooling, rather than the formation of titanium carbide, as previously reported. This cracking makes titanium an unsuitable material to coat cobalt-chromium alloys using SLM.Tantalum coatings, however, showed considerably improved performance in terms of interface compatibility when compared to titanium and therefore a Co-Cr/Ta system would seem feasible for the manufacture of porous structured devices when a bi-material approach is required. This would allow the advantages of a highly biocompatible structured coating to be combined with the mechanical performance of a less biocompatible substrate.