共查询到18条相似文献,搜索用时 156 毫秒
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工艺参数对316不锈钢粉末激光烧结球化的影响 总被引:5,自引:0,他引:5
采用直接金属激光烧结的方法,对316不锈钢粉末进行了一系列烧结实验.实验发现,在液相粘度较高、表面张力大,熔体材料不浸润固相颗粒和基板等因素的影响下,烧结过程中出现了球化现象.球化的出现妨碍了直接金属激光烧结成形的顺利进行.分析了316不锈钢粉末球化效应产生的原因,讨论了工艺参数(激光功率、扫描速度和粉层厚度)对316不锈钢金属粉末烧结成形的影响.研究表明,适当提高扫描速度或减小激光功率可以在一定程度上减小316不锈钢粉末激光烧结的球化效应. 相似文献
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选择性激光烧结(SLS)中工艺参数和扫描路径对烧结件性能有较大影响,文中研究了激光烧结工艺参数和扫描路径对峰值温度的影响规律。通过建立SLS的温度场模型并开发C++的有限元模拟软件,分析了激光功率、激光扫描速率及预热温度等工艺参数对SLS峰值温度的影响,对比了不同扫描路径下高分子粉末和金属粉末的SLS峰值温度变化规律。数值算例表明,SLS温度场中峰值温度随激光功率和预热温度的升高而升高,随激光扫描速率的升高而降低;扫描路径对高分子粉末SLS峰值温度的影响较小;开发的温度场模型准确合理,能够为实际生产提供理论依据。 相似文献
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金属粉末成形技术若干进展 总被引:3,自引:2,他引:1
金属粉末成形技术是一种高效、近净成形的先进制造技术,在许多领域有着广泛应用.就近几年粉末成形技术的发展,着重评述了几种粉末成形技术的原理和特点,并时其存在问题及发展趋势进行了讨论.同时指出金属注射成形、选区激光烧结及电场活化烧结技术是今后粉末成形技术的发展方向. 相似文献
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通过溶剂沉淀法制备了尼龙12覆膜铜复合粉末材料,并制备了机械混合尼龙12/铜复合粉末材料。通过扫描电子显微镜(SEM)对两种粉末材料的微观形貌进行了观察,对两种粉末的选择性激光烧结(SLS)成形件的强度及翘曲变形行为进行了对比研究。结果表明:尼龙12覆膜铜复合粉末材料中尼龙12包覆均匀,无裸露Cu粉存在,而机械混合尼龙12/铜复合粉末材料中尼龙12颗粒是零散地非均匀性分散在Cu粉颗粒中。在尼龙12含量及烧结工艺参数相同的条件下,尼龙12覆膜铜复合粉末SLS成形件的拉伸强度及弯曲强度是机械混合尼龙12/铜复合粉末SLS成形件的两倍以上,翘曲变形也明显小于机械混合尼龙12/铜复合粉的SLS成形件。 相似文献
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选择性激光烧结用尼龙12覆膜Cu粉的制备 总被引:1,自引:0,他引:1
提出了溶剂沉淀法制备选择性激光烧结(SLS)用尼龙12覆膜Cu粉复合粉末材料,利用扫描电镜(SEM)观察了复合粉末材料的微观形貌,通过差示扫描量热分析(DSC)、热重分析(TGA)对复合粉末材料的熔融、结晶行为,烧结温度窗口及热稳定性进行了研究,并测试了其烧结件的力学性能。结果表明,复合粉末材料的熔点、结晶速度及热稳定性较纯尼龙粉末有所提高,烧结温度窗口变宽,因而烧结性能优于纯尼龙粉。复合粉末材料烧结件的弯曲强度、弯曲模量、硬度均高于纯尼龙粉的烧结件。 相似文献
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本文通过对选择性激光粉末烧结的成型过程的分析,讨论了粉床特性、材料热物性以及激光热载荷对成型件质量的影响,并采用有限元的方法对其三维温度场分布进行了模拟计算, 相似文献
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本文通过对选择性激光粉末烧结的成型过程的分析,讨论了粉床特性、材料热物性以及激光热载荷对成型件质量的影响,并采用有限元的方法对其三维温度场分布进行了模拟计算, 相似文献
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《高分子材料科学与工程》2010,(8)
结合高分子材料的选择性激光烧结(SLS)机理,研究了材料特性对SLS成形的影响,结果表明,表面张力是决定高分子材料烧结速率的重要因素,但不是造成高分子材料之间烧结速率存在差别的主要因素;粉末粒径越小,烧结速率越大,SLS成形件的表面光洁度、精度越高;粉末粒径分布会影响粉床密度;球形粉末成形件的形状精度、铺粉效果好于不规则粉末;材料黏度越小,烧结速率越大;材料本体强度越大,成形件强度越高;非晶态聚合物成形件的致密度低于晶态聚合物,而尺寸精度高于晶态聚合物。为SLS用高分子材料的选择与制备提供理论依据。 相似文献
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In the selective laser sintering (SLS) method, layers of powder are scanned by a laser beam and sintered. The thermal gradients created by laser heating and the subsequent cooling of the sintered sections results in thermal stresses and part warping in the final part. Thermal gradients are dependent on the scanning algorithm, in particular, the scan vector length. In this work, an efficient scanning algorithm for the SLS process is presented with the aim to minimise the part warping in the final part due to thermally induced residual stresses, while maintaining the production time at a minimum. The proposed algorithm is implemented in a finite element simulation and scanning parameters including the number of offsets and scanning length are optimised at constant laser parameters and chamber conditions. The FE model is verified by testing a few samples on SLS machine and comparing the parts made by the proposed algorithm with those made using conventional scan algorithm is the same as parallel-line scan algorithm. It is shown that part warping in the parts made by the proposed algorithm is reduced by up to 35% while the production time, part accuracy and surface properties are improved. 相似文献
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Manufacturing businesses aiming to deliver their new customised products more quickly and gain more consumer markets for their products will increasingly employ selective laser sintering/melting (SLS/SLM) for fabricating high quality, low cost, repeatable, and reliable aluminium alloy powdered parts for automotive, aerospace, and aircraft applications. However, aluminium powder is known to be uniquely bedevilled with the tenacious surface oxide film which is difficult to avoid during SLS/SLM processing. The tenacity of the surface oxide film inhibits metallurgical bonding across the layers during SLS/SLM processing and this consequently leads to initiation of spheroidisation by Marangoni convection. Due to the paucity of publications on SLS/SLM processing of aluminium alloy powders, we review the current state of research and progress from different perspectives of the SLS/SLM, powder metallurgy (P/M) sintering, and pulsed electric current sintering (PECS) of ferrous, non-ferrous alloys, and composite powders as well as laser welding of aluminium alloys in order to provide a basis for follow-on-research that leads to the development of high productivity, SLS/SLM processing of aluminium alloy powders. Moreover, both P/M sintering and PECS of aluminium alloys are evaluated and related to the SLS process with a view to gaining useful insights especially in the aspects of liquid phase sintering (LPS) of aluminium alloys; application of LPS to SLS process; alloying effect in disrupting the surface oxide film of aluminium alloys; and designing of aluminium alloy suitable for the SLS/SLM process. Thereafter, SLS/SLM parameters, powder properties, and different types of lasers with their effects on the processing and densification of aluminium alloys are considered. The microstructure and metallurgical defects associated with SLS/SLM processed parts are also elucidated by highlighting the mechanism of their formation, the main influencing factors, and the remedial measures. Mechanical properties such as hardness, tensile, and fatigue strength of SLS/SLM processed parts are reported. The final part of this paper summarises findings from this review and outlines the trend for future research in the SLS/SLM processing of aluminium alloy powders. 相似文献
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纳米二氧化硅增强尼龙12选择性激光烧结成形件 总被引:1,自引:0,他引:1
使用纳米二氧化硅增强尼龙12选择性激光烧结(SLS)成形件,通过溶剂沉淀法制备SLS用纳米二氧化硅/尼龙12复合粉末材料,研究了纳米二氧化硅对SLS成形件力学性能的影响,结果表明:纳米二氧化硅以纳米尺寸均匀分散在尼龙12基体中:复合粉末的粒径比纯尼龙12的粉末小,因而有利于提高烧结速率及成形件精度;复合粉末比尼龙12的粉末具有更高的热稳定性;复合粉末烧结件的拉伸强度、拉伸模量以及冲击强度比纯尼龙12烧结件分别提高了约20.9%、39.4%和9.5%,说明纳米二氧化硅对尼龙12 SLS成形件的增强效果显著. 相似文献
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Wiria FE Chua CK Leong KF Quah ZY Chandrasekaran M Lee MW 《Journal of materials science. Materials in medicine》2008,19(3):989-996
In scaffold guided tissue engineering (TE), temporary three-dimensional scaffolds are essential to guide and support cell
proliferation. Selective Laser Sintering (SLS) is studied for the development of such scaffolds by eliminating pore spatial
control problems faced in conventional scaffolds fabrication methods. SLS offers good user control over the scaffold’s microstructures
by adjusting its main processing parameters, namely the laser power, scan speed and part bed temperature.
This research focuses on the improvements in the fabrication of TE scaffolds using SLS with powder biomaterials, namely hydroxyapatite
(HA) and poly(vinyl alcohol) (PVA). Grinding of as-received PVA powder to varying particle sizes and two methods of mixing
are investigated as the preparation process to determine a better mixing method that would enhance the mixture homogeneity.
Suitable sintering conditions for the improved biocomposite are then achieved by varying the important process parameters
such as laser power, scan speed and part bed temperature.
SLS fabricated samples are characterized using Fourier Transform Infrared Spectrometer (FTIR) and Scanning Electron Microscope
(SEM). FTIR results show that the grinding and sintering processes neither compromise the chemical composition of the PVA
nor cause undue degradation. Visual analysis of the grinding, powder mixing and sintering effect are carried out with SEM.
The SEM observations show improvements in the sintering effects. The favorable outcome ascertains PVA/HA biocomposite as a
suitable material to be processed by SLS for TE scaffolds. 相似文献
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Study on the reinforcement of nanosilica on the selective laser sintered nylon–12 parts 总被引:1,自引:0,他引:1
使用纳米二氧化硅增强尼龙12选择性激光烧结(SLS)成形件, 通过溶剂沉淀法制备SLS用纳米二氧化硅/尼龙12复合粉末材料, 研究了纳米二氧化硅对SLS成形件力学性能的影响. 结果表明: 纳米二氧化硅以纳米尺寸均匀分散在尼龙12基体中: 复合粉末的粒径比纯尼龙12的粉末小, 因而有利于提高烧结速率及成形件精度; 复合粉末比尼龙12的粉末具有更高的热稳定性; 复合粉末烧结件的拉伸强度、拉伸模量以及冲击强度比纯尼龙12烧结件分别提高了约20.9%、39.4%和9.5%, 说明纳米二氧化硅对尼龙12 SLS成形件的增强效果显著. 相似文献
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《Virtual and Physical Prototyping》2013,8(3):177-188
Selective laser sintering (SLS) is a powder-based rapid prototyping process in which parts are built by sintering of selected areas of layers of powder using laser. Nowadays, SLS is emerging as a rapid manufacturing technique, which produces functional parts in small batches, particularly in aerospace application and rapid tooling. Therefore, SLS prototypes should have sufficient strength to satisfy functional requirements. Apart from the energy density which is the combination of laser power, beam speed and hatch spacing, various other parameters like refresh rate, layer thickness and hatch pattern influence part strength. In the present work, relationship between strength and the various process parameters namely layer thickness, refresh rate, part bed temperature and hatch pattern have been investigated. Experiments are conducted based on Taguchi method using L16 modified orthogonal array. Tensile specimens of polyamide (PA2200) material as per the standard ‘ASTM D638’ are fabricated on SLS machine with constant energy density and tested on a universal testing machine for tensile strength. Optimum strength conditions are obtained by maximising signal to noise (S/N) ratio and analysis of variance (ANOVA) is used to understand the significance of process variables affecting part strength. A regression model to predict part strength has been developed. Confirmation test conducted subsequently has revealed that the results are within the confidence interval. 相似文献
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《材料与设计》2015
This work evaluated the processibility of a low-isotacticity polypropylene (PP) powder by selective laser sintering (SLS), and systematically analyzed and compared the melting and crystallization characteristics, crystalline structure, tensile properties and thermo-mechanical properties of the PP specimens fabricated by SLS and injection molding (IM). The results show that the PP powder has a nearly spherical shape, smooth surfaces, appropriate particle sizes, a wide sintering window and a low degree of crystallinity, consequently indicating good SLS processibility. In SLS, the molten PP continues to maintain at a high part bed temperature until the whole manufacturing process finished, thus demonstrating a low cooling rate. This gives rise to a high degree of crystallinity, formation of γ phase and coarse microstructure. On the contrary, in IM, the fully molten PP is rapidly cooled down to room temperature after injection, and thus show a higher cooling rate and rapid crystallization, leading to a lower degree of crystallinity, absence of γ phase and finer microstructure. Owing to these differences in crystallization characteristics and crystalline structure mentioned above, the SLS PP parts exhibit higher tensile strengths, tensile moduli and storage moduli, but lower elongation at break, toughness and glass transition temperatures, compared with the IM counterparts. 相似文献