选择性激光烧结用复合尼龙粉的制备与性能

采用溶剂沉析法制备了低熔点复合尼龙12基料,对其改性处理后获得适合于选择性激光烧结用的复合尼龙粉末。通过正交实验的方法对复合尼龙粉末的烧结工艺进行研究,得到优化的烧结工艺参数,探讨了烧结工艺参数对成型件烧结成型性能的影响,对复合尼龙粉及其烧结成型件进行了SEM分析,发现尼龙12烧结件的烧结精度和力学性能都得到了很大的改善。     

真空净化处理工艺参数对PDC耐磨性的影响

研究了真空净化处理工艺中氢气还原条件、烧结温度、烧结时间等工艺参数对不同粒度PDC耐磨性的影响,并对不同真空工艺条件下生产的PDC耐磨性进行检测与分析,发现金属粘结剂氧含量越小,真空还原效果越显著;金刚石原料粒度越细所需真空烧结的温度越高、时间越长。试验得出了不同粒度的PDC复合体坯料试样氢气还原、烧结温度、烧结时间等最佳工艺参数,在此真空工艺条件下, PDC磨耗比数值最高。     

聚苯乙烯/玻璃纤维复合粉末SLS烧结件收缩率实验研究

针对选择性激光烧结(SLS)制件尺寸精度差的问题,对聚苯乙烯/玻璃纤维复合粉末进行烧结实验研究。在激光功率25 W、扫描间距0.30 mm等工艺条件下,研究了预热温度、分层厚度和扫描速度对正八面体烧结件尺寸收缩率的影响。为了得到最优工艺参数,采用正交实验设计法对三种影响因素进行研究。结果表明,在同一工艺参数组合下,制件竖直方向的尺寸收缩率比水平方向的收缩率变化幅度大;最优的工艺参数为:预热温度85℃、扫描速度2 000 mm/s和分层厚度0.20 mm;最优工艺参数下制件水平方向修正系数为1.014 7,竖直方向的修正系数为1.024 1。经过修正的模型在最优工艺参数下烧结达到了PS/GF复合粉末烧结件的精度要求。     

石墨/聚醚砜树脂复合粉末的激光烧结工艺参数优化试验

采用鳞片状石墨和聚醚砜树脂(PES)作为选择性激光烧结原材料,制备复合材料烧结制件。通过正交试验法,对石墨/聚醚砜树脂复合粉末激光烧结成型件的烧结工艺参数进行优化。采用四因素三水平的设计方案,以成型件弯曲强度和密度作为评价指标,得到最佳工艺参数组合,并将优化的工艺参数应用于石墨/聚醚砜树脂复合材料成型件的制作中。     

PS/PET/GF三元复合材料SLS工艺参数耦合实验研究

为了研究选择性激光烧结工艺参数对聚苯乙烯（PS）/聚酯纤维（PET）/玻璃纤维(GF)三元复合材料烧结件质量的影响,选取分层厚度、扫描速度和扫描间距3个工艺参数进行耦合实验,分析总结了尺寸精度和弯曲强度的变化规律和原因。其中,x和y方向对PS/PET/GF复合粉末烧结件尺寸精度的工艺参数变化影响较小,而z向对其影响较大,弯曲强度主要受成型过程中激光能量密度的影响。结果表明烧结件的弯曲强度和精度呈此消彼长的变化规律,这对选择合适的工艺参数来提高烧结件的质量提供了实验依据。     

陶瓷材料的热等静压

这是一篇关于热等静压工艺的述评。文章介绍了由热等静压烧结陶瓷材料的必要性、热等静压的装置、工艺过程及某些参数、主要优缺点和发展趋势。由热等静压可烧结陶瓷粉末或素坯、进行烧结体的后处理及使烧结体扩散结合。该工艺具有降低烧结温度、减少或取消烧结助剂、提高材料性能、制造复杂形状制品、降低成本等优点,是一种前景广阔的烧成工艺。     

选择性激光烧结聚丙烯工艺-结构-性能的研究

系统地评价了商用选择性激光烧结（SLS）聚丙烯（PP）的加工性能和力学性能，并比较了它和注射成型（IM）样品的差异。结果表明，预热温度、激光功率和能量密度作为选择性激光烧结的3个重要工艺参数，对最终产品的性能有很大影响。在选择工艺参数时，必须同时兼顾制品的力学性能和尺寸精度。本文的独特之处在于定量分析了不同工艺条件下选择性烧结带的结晶形态，建立了工艺条件、结晶晶型和力学性能之间的关系。通过调整选择性激光烧结的工艺参数，可获得不同晶型含量的样品，以便调控制品的力学性能。     

聚苯乙烯粉选择性激光烧结工艺参数优化

对聚苯乙烯(PS)粉在激光功率20 W、预热温度70℃、扫描间隔0.30 mm等工艺参数下,研究了扫描速度和层厚对烧结试样长度、宽度、高度相对误差及孔隙率等的影响,并在电镜下观察了烧结试样微观组织,对工艺参数进行优化。结果表明:PS粉烧结时,在不同工艺参数下会分为熔融区和微熔区,熔融区和微熔区烧结件长和宽均由于收缩变形而小于理论值;在熔融区,随着扫描速度和层厚的增大,长、宽尺寸精度越来越高;在微熔区,长、宽尺寸精度变化不大,同时试样由过深烧结到烧结不足,高度值由大变小,试样孔隙率逐渐增大。扫描速度对孔隙率影响较大,分层厚度对孔隙率影响较小,确定层厚在0.20~0.22 mm、扫描速度在2 100 mm/s为最佳烧结工艺参数。     

树脂基复合成型材料的选择性激光烧结

介绍选择性激光烧结及烧结技术的基本原理,探讨了树脂基复合成型材料选择性激光烧结工艺及参数。     

选择性激光烧结PS/PET/GF复合粉末工艺参数的研究

在选择经激光烧结工艺下,通过对聚苯乙烯(PS)粉末基体材料中添加聚酯纤维和玻璃纤维(GF)进行改性实验,分析总结了不同工艺参数下PS/聚酯纤维(PET)/GF烧结件尺寸精度及弯曲强度的变化规律及成因。选取扫描间距、扫描速度与分层厚度三种工艺参数进行三因素三水平正交实验,以烧结件Z向尺寸精度和弯曲强度为实验指标,通过方差分析法得到一组最佳工艺参数组合。结果表明,在工艺参数范围内,弯曲强度和精度呈现此消彼长的规律;最优参数组合为分层厚度0.19 mm,扫描速度1 700 mm/s,扫描间距0.21 mm,此时PS/PET/GF复合粉末烧结件的弯曲强度为9.75 MPa,Z向尺寸误差为10.45%。     

Powder metallurgical processing of Co-28%Cr-6%Mo for dental implants: Physical, mechanical and electrochemical properties

The parameters for conventional powder-metallurgical production of a CoCrMo alloy for dental implants were determined. With the application of these parameters an alloy with sufficient green density, low porosity after sintering, considerable hardness and spontaneously passive behavior in the Ringer solution can be achieved. The comparison of samples with different sintering temperatures revealed that a slight variation of the sintering temperature can have a considerable effect on the physical, mechanical and electrochemical properties of the alloy.     

Fabrication of high-density quartz ceramics: Research and practical aspects. Part 3. Sintering of quartz ceramics

Results of a study of the sintering of quartz ceramics are presented and problems inherent in the production of densely sintered minimally crystallized materials are outlined. The effective energy of activation of ceramic sintering is closely controlled by the quality parameters of raw materials and process parameters. The activation of sintering process is discussed and agents aiding in the preparation of densely sintered quartz ceramics are recommended. __________ Translated from Novye Ogneupory, No. 10, pp. 60–67, October, 2005.     

浅谈彩釉玻璃的生产

针对彩釉玻璃生产的车间环境要求,对网版选择、印刷中相关工艺参数的设置及烘干烧结等方面进行了阐述,并根据实际工作经验给出了建议,以更好地控制彩釉玻璃的质量。     

粉料参数对罐形磁心开裂的影响

由于罐形磁心结构复杂,在其制作过程中,粉料参数以及在成型、烧结过程中都可能使罐形磁心产生裂纹,甚至形成开裂。本文分析了罐形磁心裂纹产生的原因,实验研究了粉料粒度分布和含水量对罐形磁心开裂的影响。实验获得了具有良好成型性和较高效率的粉体参数。     

A parameter for the evaluation of sintering of ceramic materials

A method for analyzing the sintering process in ceramic materials in an isothermal regime using a multifactor evaluation parametern, which can be one of the main control parameters of the sintered system, is suggested. The results of experimental investigations of sintering processes in clays and mixtures used in the production of various ceramic pieces are presented. The method is simple and can be used in laboratory and industrial conditions.     

逆反应烧结制备碳化硅/氮化硅复合材料的工艺

制备Si3N4／SiC复合材料的常规反应烧结是以Si和SiC为原料进行氮化烧结,而逆反应烧结是以Si3N4和SiC为原料,首先使Si3N4反向反应为活性氧化物后再进行烧结。建立逆反应烧结工艺制备Si3N4／SiC复合材料的热力学基础。确定了Si3N4先于SiC氧化;氧化产物可以是SiO2,也可以是Si2N2O;形成的SiO2氧化膜不会与基体材料反应;在膜与基体之间可能生成Si2N2O。论证了逆反应烧结的热力学可行性。通过6个烧结实验,证实了其热力学分析的正确性,并从工艺参数与密度变化、残氮率和比强度等关系筛选出最佳的烧结工艺参数。     

Experimental based full process simulation of alumina selective laser processed parts densified by cold isostatic pressing and solid state sintering

The compound process of cold isostatic pressing (CIP) of alumina selective laser processed (SLP) parts and solid state sintering (SSS) and its full process simulation were realized in this paper, focusing on studying the overall deformation, relative density distribution, grain growth and sintering stress variation during the process. Especially, correlation was established between the macroscopic deformation and microscopic evolution. Model parameters for alumina are presented, which were optimized in accordance with the experimental results. CIPed part still exhibited density inhomogeneity, of which SSS tended to increase the overall density and homogenize density distribution. The sintering behavior was studied with the employment of dilatometer experiments. Furthermore, compared with conventional heating strategy, fast firing turned out to decrease sintering production time as well as drive the matter diffusion and densification process. The master sintering curve (MSC) moves upward a little under the condition of fast firing.     

Influencing factors on the performance of tubular ceramic membrane supports prepared by extrusion

Inorganic ceramic membrane has the advantages of excellent thermal stability, mechanical strength, chemical resistance and fouling resistance. And it has been widely studied and applied in flue gas moisture recovery, gas purification and wastewater treatment. The support is the basis of preparation and application of inorganic ceramic membrane, and its performance determines the performance of the ceramic membrane to a certain extent. At present, extrusion is a common method used in the ceramic industry to prepare supports, which has the advantages of high production efficiency and good product uniformity. In this paper, the processes of preparing support by extrusion including mixing, vacuum pugging, aging, extruding and sintering are introduced in detail. In preparing support by extrusion, the product performance is easily affected by many factors, including the type of raw materials, raw material particles, extrusion parameters, pore-forming agents, sintering temperature, and sintering aids. Therefore, this paper also conducts a comparative and comprehensive study on the process parameters and influencing factors in the process of preparing ceramic membrane support by extrusion to obtain the support with the best performance. The main influencing factors that this paper focuses on are the types of raw materials, powder particles, water content, pore-forming agents, binders, sintering temperature, and sintering aids. The trends and mechanisms of these factors affecting the performance of the support are analyzed in detail.     

先进陶瓷材料快速烧结技术发展现状及趋势

快速烧结技术在节省时间和能源方面的巨大优势使其成为一直以来的研究热点。近几十年来,快速烧结技术(如火花等离子烧结、闪电烧结、选区激光烧结、感应烧结、微波烧结和传统烧结装置中的快速烧结等)的发展,使陶瓷材料的快速烧结成为可能。本文综述了近20年来先进陶瓷领域中的快速烧结技术和烧结机理,并对火花等离子烧结中直流脉冲电流和机械压力对微观结构、材料性能和烧结机理的影响进行了深入分析和总结。同时指出,快速烧结技术今后的发展一方面是对烧结机理的进一步研究并应用到先进陶瓷材料的制备中,另一方面是解决快速烧结技术工业化生产中大尺寸、大批量生产的难题。     

Critical analysis of aqueous tape casting,sintering, and characterization of planar Yttria‐Stabilized Zirconia electrolytes for SOFC

Tape casting is an established forming technique for several industries, however, researches focus more on slurry composition. In this work, the combined use of design of experiment and materials characterization techniques showed tape casting process parameters have great influence on the microstructure and mechanical properties of green tapes. Formulation and processing optimization allowed obtaining YSZ green tapes with good mechanical characteristics and homogeneous microstructure without laminating step. The optimized sintering schedule and sintering load allowed obtaining planar electrolytes with high density, tensile strength, and electrical conductivity. This work provides an environmental friendly procedure for large‐scale production of SOFCs planar electrolytes.