电子封装陶瓷基片材料的研究进展

总结微电子封装技术对封装基片材料性能的要求,论述Al2O3、AlN、BeO、SiC和Si3N4陶瓷基片材料的特点及其研究现状,其中AlN陶瓷基片的综合性能最好。分析轧膜、流延和凝胶注模薄片陶瓷成型工艺的优缺点,其中水基凝胶注模成型工艺适用性较强;指出陶瓷基片材料和薄片陶瓷成型工艺的发展趋势。     

熔融石英陶瓷凝胶注模成型及烧结工艺

报道了熔融石英陶瓷的凝胶注模成型及其烧结工艺.对凝胶注模成型工艺的几个主要影响参数对比分析,研究了分散剂、粉体粒径分布和浆料pH值对悬浮体分散效果的影响.并且分别以①苏州土、钾长石、碳酸钙②氟化钙作为烧结助剂,研究了它们对熔融石英陶瓷的烧结性能的影响.本研究工作为非晶态熔融石英陶瓷的凝胶注模成型提供了一定的工艺和理论研究基础.     

PVA-AM体系凝胶流延成型研究

研究了一种新的凝胶体系聚乙烯醇和丙烯酰胺（PVA-AM）的凝胶流延成型。由于空气中的氧阻止了单体的聚合，不能形成胶体，传统丙烯酰胺体系的凝胶注模成型制备的陶瓷坯体的表层出现裂纹甚至脱落。为了避免这个问题，通常都是选择氮气保护下浇注成型，这个过程繁琐且成本较高。通过使用本研究的凝胶体系，在原有体系的基础上添加适量的新组分聚乙烯醇，在自然环境下就可以获得表面完好的陶瓷坯体。研究了氧化铝粉在含有PVA水溶液中的分散情况，PVA-AM体系浆料的流变行为以及固化情况；同时对坯体的性能和显微结构进行了观察。这种新的体系尤其适用于制备陶瓷薄片或陶瓷薄膜，在利用凝胶流延工艺制备固体氧化物燃料电池电解质中有较好的应用。     

Si3N4-SiO2-BN复相陶瓷材料的凝胶注模成型及其性能研究

利用凝胶注模成型法制备在Si3N4和SiO2二元体系的基础上引入BN形成三元体系的陶瓷材料,研究BN的加入量对浆料流变性能的影响,并且选用BN加入量为8%(质量分数,下同)的浆料(在具有优良的流变性能前提下)进行凝胶注模成型,并对含8%BN的浆料制成的生坯和烧结后的复相陶瓷进行性能表征。另外,实验对凝胶注模成型法中的脱模工艺进行了研究,发现按照特定的脱模顺序可保证坯体不会因收缩出现裂缝现象。     

注凝成型技术的研究与进展

注凝成型技术是一种适用于复杂形状、大尺寸部件的近净尺寸成型技术,因其设备简单、工艺过程易控制、坯体密度均匀、强度高等突出优点而受到广泛关注;随着注凝成型技术的不断改进和完善,现已成为复杂形状零部件领域内近净成型的新工艺。本文简要介绍了注凝成型的技术原理和关键工艺,全面阐述了注凝成型技术在现代陶瓷材料、多孔材料、医用材料、复合材料及金属陶瓷等领域上的研究进展,并对注凝成型技术的主要难点以及广阔的应用前景进行了分析与展望,如:高固相含量、低粘度的粉体悬浮液料浆的制备;开发更为有效的分散剂;加强对多孔陶瓷应用的研究;开发新型的凝胶体系;快速推进工业化应用和加强对智能自动化控制设备的开发。     

凝胶注模成型研究进展

凝胶注模成型是20世纪90年代初美国橡树岭国家实验室首创的胶态成型工艺.该工艺利用有机单体聚合反应形成的三维网络凝胶特性,使陶瓷悬浮体注入模具后原位固化成陶瓷坯体.它具有坯体均匀、坯体密度高、坯体强度高、近净尺寸成型等显著优点.本文全面阐述了凝胶注膜成型的近十年来的研究进展,并对其研究前景进行了展望.     

非水基凝胶注模成形高速钢粉末的研究

采用自主开发的非水基凝胶注模工艺,对高速钢粉末进行了凝胶注模的研究。所开发的非水基凝胶注模体系能够为金属粉末的成形开辟一种新型的方法。     

直接凝固注模成型的研究进展

直接凝固注模成型是一种新型的陶瓷净尺寸胶态成型方法。综述直接凝固注模成型的研究状况,阐述直接凝固注模成型的基本原理、工艺流程和实施途径,重点总结3类典型的直接凝固注模成型体系,如酶催化体系、高价离子体系和有机物体系,并介绍该技术的后续处理工艺及应用,探讨直接凝固注模成型存在的主要问题及研究方向。     

凝胶注模成形技术在粉末冶金中的应用

凝胶注模成形最初是用于陶瓷材料近净尺寸成形技术,它适用于成形件尺寸大,复杂形状的部件.随着该技术的发展,凝胶注模成形也应用到粉末冶金领域.本文综述了国内外凝胶注模技术在成形金属粉末的应用研究近况,展望了该技术在粉末冶金中的应用前景,并对凝胶注模成形技术在应用中存在的技术难点及应对策略进行了分析与探讨.     

粉末特性对多孔不锈钢制备工艺和结构的影响

以凝胶注模工艺为基础,结合微波烧结技术,制备了形状和孔隙可控的多孔不锈钢材料。采用扫描电子显微镜、密度仪、抗弯实验等手段研究了粉末粒径、粉末形状、固相含量等特性对多孔不锈钢制备工艺和孔隙形貌、孔隙率的影响。结果表明:粉末粒径越小,形状因子越大,胶体固相含量越高,制备得到的多孔不锈钢的孔隙率越高;粉末形状因子越小,多孔不锈钢的孔隙越不均匀;固相含量越高,虽然坯体强度有所提高,但凝胶体系的粘度也越大,流动性较差,适合不锈钢粉末凝胶注模的最佳固相含量在58%左右。通过控制颗粒直径、颗粒形状、固相含量及采用颗粒级配的方法,可实现对凝胶注模制备多孔不锈钢的孔隙结构和孔隙率的有效控制。     

Titanium with controllable pore fractions by thermoreversible gelcasting of TiH2

Thermoreversible gelcasting, a near-net-shape processing technique, is demonstrated here for titanium. The gelcasting system is composed of TiH₂ particles suspended in a triblock copolymer gel that behaves as a viscous liquid above 56 °C and an elastic solid at room temperature, a temperature-dependent transition that is fully reversible when solvent is present. Organic pyrolysis to remove the gel followed by vacuum sintering to densify the Ti powders (produced by decomposition of the hydride) results in titanium with near full density and low contamination. Incorporation of polypropylene and poly(methyl methacrylate) space-holder particles into the gel results in titanium with controlled porosities up to 44 vol.% and with low contamination. These foams exhibit tailorable stiffness and strength, together with excellent compressive ductility and energy absorption.     

Gelcasting of titanium hydride to fabricate low-cost titanium

In this work, low-cost titanium was fabricated by gelcasting of titanium hydride powder. The effects of morphology and grain composition of powder raw material and solid loading on the rheological behavior of gelcasting slurry were studied. The degreasing, dehydriding and sintering behaviors of gelcasted green body were investigated by differential thermal analysis(DTA) and dilatometer.The results show that the solid loading of titanium hydride slurry reaches 50 vol%. Combination of dehydriding and sintering in one process accelerates the densification, and the relative sintered density of the final part achieves96.5 %. In order to test the ability of gelcasting process for fabricating structural materials, a resin handle produced by3 D printing technology was used as a model and a titanium handle was successfully fabricated. Higher solid loading and better sinterability of titanium hydride powder promote manufacture of bulk titanium with high relative density,complex shape and well-defined microstructure.     

Effect of mould baffle technology on stray grain formation in single crystal blades by integral fabrication based on 3D printing

Stray grains, the most serious casting defect, mainly occur in the platform because of the abrupt transition of the cross-section in the directional solidification of superalloy single-crystal blades. A new mould baffle technology based on 3D printing and gelcasting is proposed herein to reduce the formation of stray grains in the platform. The influence of the proposed mould baffle technology on the temperature field in the platform during solidification was investigated by simulation and experiment. The numerical simulation results indicate that the proposed mould baffle technology can effectively hinder the radiation and heat dissipation at the platform extremities, and therefore, reduce undercooling in the platform and the formation of stray grains during directional solidification. Casting trials of a hollow turbine blade were conducted using CMSX-4 superalloy. The trial results demonstrate the potential of the proposed approach for manufacturing single-crystal superalloy blades.

     

凝胶注模Sialon-SiC材料流变性研究及其性能

70vol.％～78vol.％的Sialon-SiC悬浮体在10～160 s-1范围内显示剪切变稀的幂率特征,突出的“切稀”行为满足凝胶注模成型的要求.建立的悬浮体流变模型与试验值吻合,其流变特征符合Sisko模型.氮化烧结材料的XRD检测和SEM观察显示,材料主要由SiC相和Si4Al2O2N6相组成,显微组织中六方柱状Sialon晶体发育完整,形成了Sialon晶体紧密环绕SiC颗粒的均匀结构.材料的体积密度和抗折强度分别为2.69 g/cm3和56 MPa.     

Comparison of selected inhibitor doped sol–gel coating systems for protection of mild steel

Current legislation around the use of antifouling and anticorrosion coatings has increased the need to find an environment friendly alternative to existing biocide containing pretreatments for steel structures exposed to sea water. Sol–gel technology offers a solution to fouling and corrosion inhibition since sol–gel chemistry lends itself ideally to functionalisation with a variety of components, for example, corrosion inhibitors. In this study, we have utilised the above mentioned approach in order to produce an inhibitor doped sol–gel protective coating on mild steel. The corrosion protection performance of three inhibitors, i.e. SD (Shieldex303), MOLY (Moly-White101ED-PLUS) and ZAPP (Heucophos ZAPP), added individually to a sol–gel, and applied to mild steel Q panels, were evaluated using electrochemical impedance spectroscopy. The inhibitor containing coatings were shown to protect against corrosion of mild steel; the coatings containing the inhibitors Moly and ZAPP were the most effective of the systems tested.

Highlights

? Sol–gel coatings are potential candidate systems for the protection of mild steel substrates.

? Sol–gel chemistry allows a variety of corrosion inhibitors to be incorporated into the sol–gel coating matrix.

? Evaluation of corrosion inhibition efficiency of sol–gel coatings can be assessed using electrochemical impedance spectroscopy (EIS).     

GELCASTING OF NANO-SIZE Y-TZP

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凝胶注模工艺制备医用多孔Ti-Co合金的性能

采用凝胶注模工艺制备含8%和12%Co(质量分数,下同)的多孔Ti-Co合金,研究获得均匀悬浮稳定浆料的分散剂加入量。采用扫描电子显微镜、X射线衍射、压缩和三点弯曲试验分别对多孔Ti-Co合金的显微结构和力学性能进行了测试和分析。结果表明,加入1%分散剂可获得分散效果最佳的悬浮浆料,所制备多孔Ti-Co合金的孔隙率在50%左右,孔隙呈三维通孔结构。与多孔纯钛相比,添加Co元素明显提高了多孔Ti的力学性能,其中压缩强度在68～378MPa之间,抗弯曲强度在53.68～169.17MPa之间,弹性模量在7～21GPa之间。固相体积分数为33%,在1100℃下烧结的多孔Ti-8%Co合金由于与成人骨的力学相容性最好,适合作为医用植入材料。     

精密微塑性成形技术的现状和发展趋势

随着微/纳米科学与技术的不断发展,以形状尺寸微小或操作尺度极小为特征的微型机械系统(MEMS)受到人们高度重视,MEMS技术的发展对微型构件的微细加工技术带来挑战。文章介绍了塑性微成形技术的发展背景及其基本特点,综述了微成形的基本问题、微型零件成形工艺以及成形设备、数值模拟等方面的研究现状,并对其发展趋势进行了展望。     

Fabrication of complex-shaped Y-TZP/Al2O3 nanocomposites

Gelcasting is a very useful technique for producing ceramic green parts with complex shapes. Although it has been successfully applied to ceramic systems consisting of micron size powders, there is little report on gelcasting of ceramics containing nanoparticles. In this work, ceramic system with nano-size ZrO₂–Y₂O₃–A1₂O₃ powders (30–40 nm in size) have been successfully gelcast to form complex-shaped parts. After pressureless-sintering, the Y-TZP/Al₂O₃ nanocomposites with an average grain size of 220 nm are successfully fabricated.