放电等离子烧结制备TiAl合金组织和性能

以气雾化工艺制备的Ti43.5 Al5 Nb1 V1 Y(at.％)预合金粉末为原料,采用放电等离子烧结工艺成功制备细晶TiAl合金,研究不同烧结温度(1200～1300℃)对组织和力学性能的影响.通过采用OM,XRD,SEM等方法对烧结试样进行微结构表征,在力学试验机进行室温压缩试验.研究发现,烧结后试样主要有γ-T...     

球磨WC-8Co粉末的放电等离子烧结

对WC-8Co粉末不同球磨时间后进行放电等离子烧结,研究了球磨时间及烧结温度对WC-8Co硬质合金微观结构及性能的影响。结果表明:球磨时间延长,粉末颗粒变细,晶格畸变增加,衍射峰强度降低,并随时间延长,团聚现象严重;采用放电等离子烧结,在1 200℃时,可以得到接近全致密的烧结样品,烧结温度低于传统方法的烧结温度;球磨时间在2 h以下时,样品的致密度、硬度和断裂韧性达到最佳,晶粒较小且分布均匀;延长球磨时间,性能显著下降且出现较多粗晶、空洞、Co池等缺陷。     

原料粉末对碳化硼烧结性能的影响

研究了原料粉末对碳化硼陶瓷常压烧结性能的影响，试验表明增加原料粉末的比表面积和纯度能显著地促进烧结过程，且提高其烧结的质量密度，当比表面积大于16m^2/g时，可使烧结体的相对密度达到98.7%以上，抗弯强度达到456MPa，硬度HV达到为2790。制品的性能接近热压制品的水平。     

放电等离子快速烧结C/BN层状复合材料

采用放电等离子烧结技术（SPS）快速烧结了C／BN层状复合材料，研究了烧结工艺、结构和性能之间的关系。材料的微观结构分析表明，随着温度的升高和保温时间的延长，石墨基体与BN层间的结合逐渐增强；耐热冲击试验表明，在烧结温度1750℃，保温5min左右时，材料可经受40次左右循环；材料的界面结合强度最高可以达到18．2MPa．显示了较好的力学性能。     

3%C-Cu机械球磨复合粉末的烧结

为了给后续的致密化工序（如热挤压）提供较高质量的烧结坯,用扫描电镜和光学显微镜分析了3%C-Cu机械球磨复合粉末所制备烧结坯的显微组织,并研究了工艺参数对其相对致密度的影响规律。结果表明,烧结温度对未机械球磨混合粉烧结行为的影响很大,而机械球磨复合粉对烧结温度不敏感。真空热压烧结可以明显地促进致密化过程。提高烧结温度、延长烧结保温时间或增加热压压强,均有助于提高烧结坯的相对致密度。在相同条件下,烧结坯的相对致密度随着复合粉末机械球磨时间的延长而降低。     

c-BN仿生耐磨复合材料的微观结构和耐磨性能

采用SPS技术制备出多尺度的c-BN仿生耐磨复合材料,应用图像分析仪、SEM和XRD分析c-BN仿生耐磨复合材料的微观组织.研究结果表明,Cu基合金对c-BN单晶颗粒具有良好的润湿性能,界面结合致密,在界面处形成反应层.微观分析表明,Cu基合金中的Ti向c-BN单晶颗粒表面富集,并与N和B元素发生作用,形成TiB2和T...     

球磨对放电等离子烧结TiB2陶瓷的影响

研究了不同球磨处理工艺获得的TiB2粉末的物相及颗粒形貌，不同的原始粉末对SPS烧结效果产生不同的影响。研究结果表明：球料比（5：1)、球磨8h的TiB2粉末具有最好的烧结效果，其SPS烧结温度为1700℃，比热压烧结纯TiB2低100℃左右；烧结体的相对密度达到99％以上，平均粒径约为5μm，与低温液相热压烧结相当。     

高分子粉末材料选区激光烧结性能的研究

为解决以高分子粉末材料为基底的选区激光烧结件力学性能较差的问题，对烧结原型件进行了树脂增强后处理，测试了烧结件和增强件的力学性能，并对两种试件的测试结果进行比较。结果表明，增强处理后的烧结件性能有了大幅度的提高。     

Microstructure of Selective Laser Sintered Polyamide

1　IntroductionSelectivelasersintering (SLS)isanadvancedrapidprototypingtechnologythatcanshortenthedesignandmanufacturingcycle ,hencereducetheproductioncostandincreasethecompetitivenessofnewproducts[1] .SLSisathermalprocess ,creatinglayersbyascanninginfraredla serbeammeltingpowder[2 -4] .Eachlayerisdrawnonthepartcylinderusingthelasertosinterthematerial.Thenthepartbedisloweredandpowder feedingcartridgeraised .Anewcoveringofpowderisnextspreadbyaroll er.Thesinteredmaterialformsthepartwhiletheu…     

Microstructure analysis of microwave sintered ferrous PM alloys

The properties and microstructure of microwave and conventional sintered Fe-2Cu-0.6C powder metallurgy (PM) alloys were investigated. The experimental results show that microwave sintered alloy has the better properties (sintered density 7.20 g/cm³, Rockwell hardness 75 HRB, tensile strength 413.90 MPa and elongation 6.0%), compared with the conventional sintered counterpart. Detailed analyses by using optical microscopy and scanning electron microscopy (SEM) reveal that microwave sintered sample has finer microstructure with small, rounded and uniformly distributed pores, and also demonstrate the presence of more flaky and granular pearlite in the microwave sintered body, both of which account for the property improvement. SEM images on the fracture morphology indicate that a mixed mode containing ductile and brittle fracture is presented in microwave sintered alloy, in contrast with the brittle fracture in conventional sintered counterpart. Funded by the National Science and Technology Development Program (No.2004-09ZD)     

The properties of the sintered copper powder liner

In order to study the properties of sintered copper powder shaped charge liner, the copper powder, whose particle size was below 20 μm, was chosen as the main material. The mixed powders were directly pressed into the desired shape of the shaped charge liner by the top direct-pressure way. The microscopic morphology of the spinning shaped charge liner, the sintered and non-sintered powder liners, and the particle properties of the copper powder were studied with scanning electron microscopy. The experimental results showed that the irregular copper powder could get together effectively and sintering could improve the compactness of the powder liner effectively. The wall thickness and density of the non-sintered and sintered liner were also tested, and it shows that sintering causes the wall thickness thinned and the density improved. The penetration depths of non-sintered powder liner, sintered powder liner and the spinning copper plate liner were tested with different standoff respectively, showing that the penetration properties of sintered powder liner are well.     

多电平变流器多载波PWM技术的研究

针对通常用合金化法提高烧结NdFeB磁体耐蚀性的同时使磁性能严重下降的问题，提出了通过元素
Dy、Nb复合添加的方法，提高磁体耐蚀性和磁性能.结果表明，同时添加Dy、Nb元素，不仅可以大幅增加
磁体矫顽力，而且能削减Dy元素添加对剩磁降低的不利影响，使磁能积增大；当w(Dy)=1.0%，w(Nb)=0.8%
时的磁体显微结构较好、综合磁性能优异.磁体耐蚀性随着Dy、Nb元素添加量的增大而提高.因此通过元素
复合添加，可以提高磁体磁性能及耐腐蚀性，使其能广泛应用于腐蚀环境.     

NdFeBAlDyNb磁性能及抗海水腐蚀研究

针对通常用合金化法提高烧结NdFeB磁体耐蚀性的同时使磁性能严重下降的问题,提出了通过元素Dy、Nb复合添加的方法,提高磁体耐蚀性和磁性能.结果表明,同时添加Dy、Nb元素,不仅可以大幅增加磁体矫顽力,而且能削减Dy元素添加对剩磁降低的不利影响,使磁能积增大;当w(Dy)=1.0%,w(Nb)=0.8%时的磁体显微结构较好、综合磁性能优异.磁体耐蚀性随着Dy、Nb元素添加量的增大而提高.因此通过元素复合添加,可以提高磁体磁性能及耐腐蚀性,使其能广泛应用于腐蚀环境.     

烧结淬冷MnBi合金的相变和磁性

采用密封低温烧结再淬冷的方法制备了高纯度MnBi合金.利用差热分析仪(DTA)分析烧结过程中Mn-Bi的相变.利用X射线衍射仪(XRD)和振动样品磁强计(VSM)分析了烧结样品的物相和磁性.结果 表明:n(Bi)∶n(Mn)为1∶1.3,275℃下烧结20 h后淬冷可获得高纯度的低温相MnBi合金块体材料;温度为50～...     

Microstructure and properties of high emissivity coatings

A new coating on lining in industrial furnace for energy saving has been developed. Properties and microstructure of the coatings were revealed by emissivity instrument,X-ray diffraction (XRD),transmission electron microscope (TEM) and scanning electron microscope (SEM),respectively. The result indicates that the emissivity of coatings is higher than 0.90 and the thickness of coatings is about 200 μm. ZrO2,Cr2O3 and SiC in the coating benefit practical applications of coatings at high temperature with du-ra...     

Microstructure and Properties of Activated Slag Cement

Activation of the slag cement was performed using a composite activator. Experimental results show that the performance of the cement is remarkably improved. The fineness and specific surface area of the cement are increased by 23.7% and 1.4% , and 3d flexural strength and compressive strength are enhanced by 20.9% and 22.9%, respectitely. Microstructure and phase composition of the hydrates were analysed by X-ray diffraction( XRD ) and scanning electron microscopy( SEM ). The results indicate that Ca(OH)2 in the hydrates decrease obvioasly. The morphology of the other hydrates appears to be flocculent, with a dense structure. The improvements of the properties is related to the microstructural changes.     

喷射成形沉积坯组织性能分析

利用金相显微镜和扫描电镜对GCr15喷射成形试样的疏松、显微组织进行了分析,采用能谱分析法对试样中元素含量及分布进行了分析.提出了改进显微组织和性能的方法.     

Microstructure and Properties of CePO4 Ceramic

Cerium phosphate powders were synthesized by direct solid liquid reaction of cerium dioxide and phosphate acid at the Ce ： P ratio of 1 ： 1. Phase-pure and fine grain size CePO4 powers could be obtained by calcining the as received powders at the temperature higher than 600 ℃ . It is demonstrated that the grain size and morphology of the CePO4 powders were calcined at various temperatures. An interesting layered crystal structure and a series of microcracks that cross and occur along the extrusion stress direction on the extruded surface inside CePO4 were observed. The ductility and machinabililty of CePO4 ceramic are attributed to the layered structure. Continuous machining debris was observed on the turned surface.