选择性激光烧结成形温度场的研究进展

选择性激光烧结技术与传统铸造工艺相结合,为快速制造某些难以用传统方法获得的铸件提供了有利途径.对于各种粉末材料在选择性激光烧结成形过程中温度场的模拟与预测,是合理选择其烧结工艺参数的基础.本文中综述了聚合物粉末、聚合物覆膜金属/陶瓷粉末和金属粉末在选择性激光烧结过程中的热物性参数变化规律及其相应的成形温度场分布,以利于激光选择性烧结各类粉末材料而精确成形零部件.     

激光选区烧结陶瓷粉末材料的研究进展

根据国内外对激光选区烧结使用陶瓷粉末材料的研究成果,分别介绍了四类陶瓷粉末材料的研究现状,并分析了粘结剂直接混合,表面覆膜、表面改性等在陶瓷粉末材料激光烧结机制中的影响,结合陶瓷粉末材料在激光选区烧结应用中存在的问题,讨论了进一步研究陶瓷粉末材料的发展方向.     

纳米材料激光选择性烧结成形的研究

纳米材料由于颗粒尺寸微小，致使其产生一些特异的性能，在应用过程中，把纳米粉末材料成形为大体积的材料及成形纳米零件产生了巨大的困难，激光选择性地成形纳米材料是利用激光烧结能量信号，能迅速加热，剧冷的特性，最大限度地控制纳米材料在烧结过程中颗粒生长的纳米材料成形的方法。本研究中，在激光选择性烧结成形纳米材料Al2O3的基础上，对纳米材料烧结成形过程中产生的问题进行了分析与探讨。     

选择性激光烧结用覆膜砂的研究和发展现状

选择性激光烧结覆膜砂制作砂型具有独特的优势,国内外学者对选择性激光烧结用覆膜砂做了大量研究。本文对覆膜砂的原材料选择及制备工艺过程,选择性激光烧结成型工艺参数对烧结件性能及精度的交互影响及工艺优化,后处理工艺对烧结件质量的影响及优化工艺的研究进行了总结,并简要提出了选择性激光烧结用覆膜砂的发展方向。     

青铜-镍粉末直接选择性激光烧结的研究

简要分析了选择性激光烧结的成形机制及其工艺和材料影响因素。详细分析了青铜一镍粉末直接选择性激光烧结的材料组分以及磷元素对烧结成形质量的影响。具体讨论了粉床温度、粉层厚度、激光功率以及激光扫描速率和方向等工艺参数对烧结件致密度和强度等机械性能的影响     

覆膜砂选择性激光烧结过程的建模研究

建立选择性激光烧结粉末的快速成型工艺过程的数值计算模型,并用于估算热固结宽度和深度.在该计算模型中,综合考虑了材料的热物性参数随温度变化的情况和激光光强分布不均匀的因素,采用Ansys有限元分析软件模拟计算激光点加热过程覆膜砂的热影响区大小,结果与实验吻合较好.     

青铜-镍粉末直接选择性激光烧结的研究

简要分析了选择性激光烧结的成形机制及其工艺和材料影响因素。详细分析了青铜-镍粉末直接选择性激光烧结的材料组分以及磷元素对烧结成形质量的影响。具体讨论了粉床温度、粉层厚度、激光功率以及激光扫描速率和方向等工艺参数对烧结件致密度和强度等机械性能的影响。     

《金属热处理》2005年1~12期总目次

综述期—起页中国热处理和表面工程的现状与展望(潘健生,等)(1—1)※基于选择性激光烧结覆膜金属纳米复合粉末材料的研究进展(曹松,等)(2—20)※相变诱发塑性的影响因素研究进展(景财年,等)(2—26)※高速铁路接触线用时效强化铜合金的发展(雷静果,等)(3—1)※研究强塑性变形过程中第二相回溶现象的现状及发展趋势(许晓嫦,等)(4—1)※体视学与图像分析技术在材料科学中的应用(徐建林,等)(4—7)※刀具材料表面处理的研究现状(郑立允,等)(6—31)泡沫铝的制备方法及应用进展(姜斌,等)(6—36)※激光技术在材料科学中的应用(王赛玉,等)(7—32)※生…     

激光选择性烧结金属粉末快速成形的研究

描述了激光选择性烧结金属粉末快速成形设备的粉末供给和铺平压实系统及动作，探讨了烧结过程参数对烧结质量的影响，粘结剂含量、孔隙率和缺陷尺寸与烧结件压缩强度之间的关系，并指出影响激光选择性烧结的重要因素是烧结粉末的特性、激光参数的设置等。     

激光选择性烧结金属粉末快速成形的研究

描述了激光选择性烧结金属粉末快速成形设备的粉末供给和铺平压实系统及动作,探讨了烧结过程参数对烧结质量的影响,粘结剂含量、孔隙率和缺陷尺寸与烧结件压缩强度之间的关系,并指出影响激光选择性烧结的重要因素是烧结粉末的特性、激光参数的设置等。     

IGNITING SHS BY LASER AND ITS APPLICATION TO SELECTIVE LASER SINTERING OF METALLIC POWDER MATERIAL

1.IntroductionSelective laser sintering (SLS) is one of typical rapid prototyping (RP) technology. SLS adopts the idea of a delamination manufacturing, which is not limited by complicated degree of part shape and not needs any frock & mould, to directly fabricate three dimension (3D) solid parts with powder materials. Theoretically, any powder materials, which can felt each other after they are heated, may be SLS materi-als. Range of SLS materials have covered with polymer powder, cerami…     

IGNITING SHS BY LASER AND ITS APPLICATION TO SELECTIVE LASER SINTERING OF METALLTC POWDER MATERIAL

How to directly fabricate metallic functional parts with selective laser sintering (SLS) process is a potential technique that scientists are researching. Existent problems during directly fabricating metal part by use of SIS are analyzed. For the sake of solving the problems, a new idea of adding self-propagating high-temperature synthesis (SHS) material into metallic powder material to form new type of SIS metallic powder material is put forward. This powder material can release controllable amount of heat during its interaction with the laser beam energy to reduce the requirement to laser power during directly sintering metallic part, to prolong the time of metallic liquid phase existing, and to improve the intensity and accuracy of SIS part. For this reason, SHS material‘s interaction with the CO2 laser beam energy is researched, which proves that CO2 laser beam energy may instantly ignite SHS reaction. On the basis of the above-mentioned researches, the effect of sintering the metal powder material mixing SHS material with CO2 laser is also researched,which shows: there is an optimal blending ratio of various material in the new metallic powder material. Under the optimal blending ratio and SIS process parameters, this new metallic powder material can indeed release amount of heat and SHS reaction may be controlled within the laser sintering. This research result makes it possible that the metallic part is directly sintered with small CO2 laser (less than 50W), which may greatly reduce the volume, cost and running expenditure of SIS machine, be propitious to application.     

Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys

The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion.     

基于选择性激光烧结技术的快速铸造

介绍了用选择性激光烧结（ＳＬＳ）快速成型技术直接制造覆膜砂铸型（芯）的特点及工艺过程。结合铸件生产,分析研究了ＳＬＳ铸型（芯）的工艺设计、三维实体造型及铸型后处理等过程中所遇到的问题。     

Selective laser sintering/melting (SLS/SLM) of pure Al,Al–Mg,and Al–Si powders: Effect of processing conditions and powder properties

Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser–materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al–Mg, and Al–Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps’ boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12–16 J/mm² was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al–12 wt% Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film.     

Characterization of metallic textiles deposited by magnetron sputtering and traditional metallic treatments

In this study, the surface appearance, light reflectivity and low-stress mechanical properties of magnetron sputter coated fabric were compared with traditional metallic treated fabrics. It is found that a layer of fine silver particles distributed evenly on the fabric surface with uniform grains and there were no obvious structural damages to the fabric after the sputtering. The sputter coated fabric has a greater value in reflectance and lightness than metallic powder printed fabric, but is lower than that of metallic foil laminated fabric. The values of surface geometrical smoothness (SMD) increased after metallic powder printing while decreasing slightly after sputter coating and decreasing significantly after metallic foil lamination. The tensile loading curves of both sputter coated and untreated cotton spandex fabrics are similar which indicate that the modification of sputter coating is minimal when compared with the other two metallic treatments. Therefore, sputtering has opened up new possibilities in the modification of textile materials and is an exciting prospect for usage in textile design and technical textiles.     

Fe-Si-Al系合金粉微波吸收特性

采用扁平化工艺以及绝缘包覆工艺对铁硅铝系软磁合金粉末进行改性。对实验样品进行扫描电镜分析,观察颗粒形貌对材料性能的影响;探讨球磨时间以及不同绝缘介质含量对于材料电磁性能的影响规律。根据单层吸波材料(含导电衬底)对电磁波的反射率公式的分析以及对不同样品反射率的计算可知,球磨扁平化工艺以及绝缘包覆工艺可有效地改善铁硅铝金属粉末的微波吸收性能。经改性后的铁硅铝系软磁金属粉末在1.0~3.5 GHz频段具有较好的吸波性能,可应用于抗电磁干扰领域。     

Rapid casting technology based on selective laser sintering

Selective laser sintering (SLS), as a kind of additive manufacturing technology, which uses a laser beam to scan and heat powder material layer by layer to form parts (models), is widely used in the field of casting, mainly for preparing casting coated sand cores, investment casting patterns, etc. The SLS technique facilitates rapid casting and shortens the casting production periods by eliminating mold preparation. In this study, we reached conclusions for the basic principles and characteristics of SLS methods, and focused on the research status, key technology and development trend of SLS in the fields of forming coated sand-casting molds and investment casting patterns.     

木质素磺酸钠对3.5%NaCl溶液中AZ31镁合金的缓蚀作用

采用失重法,极化曲线,电化学阻抗谱和扫描电子显微镜研究木质素磺酸钠(SLS)在质量分数为3.5%NaCl溶液中对AZ31镁合金的缓蚀作用。结果表明:在298 K时SLS可有效抑制AZ31在Na Cl介质中的腐蚀。当SLS为4.0 g·L~(-1)时,缓蚀率可达到最大。提高浓度后,其缓蚀率会下降。SLS是阴极型缓蚀剂,并且SLS在AZ31表面的吸附符合Langmuir吸附模型。由吸附自由能?G~0及Arrhenius活化能E_a可知,SLS在AZ31镁合金表面是化学吸附。