水溶性环氧树脂体系的氧化锆凝胶浇注成型

研究了氧化锆凝胶浇注成型工艺中,水溶性环氧树脂凝胶剂对浆料的流变性和固化过程的影响.结果表明:环氧树脂的加入增加了浆料的黏度,但可制备固体含量为53.7%(体积分数),黏度为0.60Pa·s(剪切速率为100 s-1),适合浇注的浆料;为得到较高弹性模量的凝胶,固化剂(二丙三胺)最佳加入量为3.4%(质量分数);环氧树脂溶液的聚合过程和氧化锆浆料的固化过程对温度都具有较大的依赖性,利用这些依赖性可控制浆料的制备、浇注和固化过程.30℃时,浆料中环氧树脂的聚合反应在8min后开始,20min后浆料失去流动性,1 h后浆料完全固化,湿坯弹性模量达到1.96MPa.固化温度越高,浆料固化越快,固化后湿坯的弹性模量就越高.     

SiC陶瓷的浇注成型初探

从Ｚｅｔａ电位的角度出发，对泥浆粘度、泥浆稳定性以及素坯密度进行了调整和比较，解决了ＳｉＣ泥浆制备及其浇注中的一些问题。用３种ＳｉＣ原料，浇注成型后素坯密度、无压烧结后烧结密度和烧结样品的抗弯强度分别达１．６６ｇ／ｃｍ＾３（５１．７％），２．９３ｇ／ｃｍ＾３（９１．３％）和２６８ＭＰａ。     

环氧树脂浇注成型工艺及模具设计

环氧树脂浇注成型工艺及模具设计是一门综合性的技术。浇注工艺、模具设计制造技术等都能给浇注件的质量产生很大的影响,因此必须进行系统的研究以得到符合要求的制件。提出了相关工艺方法、模具设计关键技术。     

适用于RTM成型的高性能环氧树脂体系的研制

通过优化实验得到了具有室温粘度小于1000 mPa·s,凝胶化和固化时间短,固化时放热量少,有足够的适用时间(室温下适用期大于48 h)等满足RTM成型要求的树脂体系。经拉伸强度、弯曲强度、剪切强度及模量的测试表明该体系具有较好的强韧性。通过扫描电镜照片,表明微观结构均匀致密,树脂基体的湿润性良好,断裂形式为韧性破坏。     

自动压力凝胶成型工艺及环氧树脂触头盒注射模设计

介绍环氧树脂自动压力凝胶（APG）成型工艺的原理，设计了带内外裙触头盒环氧树脂注射模，提出了分型面、浇注系统、排气、嵌件安放、内裙型芯等的设计要点，重点分析了内裙型芯的分块方法及抽芯顺序，并展望了环氧树脂APG工艺的发展前景。     

用于挤拉成型的高性能无MDA环氧树脂体系

目前,90％以上的挤拉成型制品是用玻璃纤维增强的热固性聚酯树脂生产的。在许多工业市场上,该体系成本低、生产速度快、性能良好。树脂增强纤维和工艺控制方面的新发展为先进的高性能结构部件提供了更多的机会。例如添加玻纤、碳纤或芳纶纤维的环氧树脂体系,工艺条件合适能生产出航天等级的复合材料部件。     

SiC部件泥浆浇注工艺

本文论述了影响SiC泥浆性能的几个主要因素,运用SiC粉料Zeta电位随PH值变化曲线作指导,通过PH值调整和改变分散介质,着重研究了SiC泥浆稳定性、泥浆浇注样品的性能和显微结构,获得了浇注性能好、长时间稳定不沉淀的泥浆。分析了浇注过程中的各种影响因素,讨论了泥浆性状对浇注性能及样品烧结后力学性能的影响,最终浇注出大尺寸SiC陶瓷部件。     

关于陶瓷成型工艺的讨论

陶瓷制造经历数千年历史,直到20世纪中叶因为烧结理论的创立获得了飞速发展,上世纪七八十年代关于超细粉体制备和表征的发展,促使陶瓷工艺第二次大发展,当前阻碍陶瓷材料进一步发展的关键之一是成型工艺技术没有突破,压力成型不能满足形状复杂性和密度均匀性的要求,传统的湿法成型工艺可以获得复杂形状,但不能保证坯体的均匀性,90年代以来发展起来的多种胶体原位成型工艺和气相成型工艺有望促使成型工艺获得突破。     

浅析意大利浇注成型设备

本文介绍了意大利西蒂公司、娜塞提公司的浇注成型设备性能及作业指标,值得同行业人员参考。     

Gelcasting of Alumina Using Epoxy Resin as a Gelling Agent

A water-soluble epoxy resin and hardener system for gelcasting of ceramics was developed. Polymerization of the system is a nucleophilic addition reaction, and not affected by oxygen. Therefore, this gelcasting system can be carried out in an air atmosphere. The ceramic slurries were prepared by mixing the aqueous premix solution of epoxy resin with alumina powder and dispersant. For cross-linking, a polyamine hardener was added. Both the rheological properties of the slurries and the gelling behaviors of the aqueous premix solutions were evaluated. The slurry with a solid loading of 80 wt% is optimized for gelcasting. The flexural strength of the sintered ceramics is 335±47 MPa with 98% of theoretical density.     

Effects of Epoxy Resin on Gelcasting Process and Mechanical Properties of Alumina Ceramics

A gelling system based on the polymerization of epoxy resin ethylene glycol diglycidyl ether (EGDGE) and 3,3′‐Diaminodipropylamine (DPTA) was developed for gelcasting alumina ceramics. The gelation process of 50 vol% alumina‐epoxy resin suspensions were investigated in accordance with the change in temperature and epoxy resin concentration. The activation energy E_a of polymerization reaction was 63.76 kJ/mol and no significant gelation was observed at 25°C during the test for 50 vol% Al₂O₃ suspensions with 10 wt% EGDGE. With the increase in EGDGE concentration, Al₂O₃ green bodies exhibited higher relative density, flexural strength, and Weibull modulus, reaching 64.4%, 41.03 MPa, and 12.51, respectively, when EGDGE concentration was 20 wt%. However, for sintered Al₂O₃ bodies, the highest characteristic strength and Weibull modulus were obtained for 15 wt% EGDGE concentration, reaching 367.57 MPa and 14.52, respectively.     

周期性孪晶结构碳化硅纳米线改性环氧树脂的性能

通过超声分散和模具浇注成型法制备了周期性孪晶结构碳化硅(SiC)纳米线改性环氧树脂,探讨了SiC纳米线的周期性孪晶结构及含量对环氧树脂复合材料力学性能的影响。结果表明,周期性孪晶结构SiC纳米线的加入明显改善了环氧树脂基体的力学性能,孪晶结构有助于提高SiC纳米线与基体树脂之间的相互结合程度。随着孪晶SiC纳米线含量的增加,复合材料的拉伸性能和弯曲性能都呈现出先增加后减小的趋势。当SiC纳米线的含量为2%时,复合材料的拉伸强度、拉伸弹性模量、断裂伸长率、弯曲强度和弯曲弹性模量均达到最大值,相比于纯环氧树脂分别提高了90.6%,37.8%,38.3%,53.4%和24.5%。当SiC纳米线含量为3%时,弯曲应变达到最大值(6.72%),相比于环氧树脂提高了32.0%。     

Gelcasting of SiC using epoxy resin as gel former

Epoxy resin was used as gel former in SiC gelcasting. A hardener as cross-linker causes a nucleophilic addition reaction of epoxy resin instead of free radical reaction of the acrylamide-based gel former system to avoid oxygen and mould materials (plastic and rubber) inhibition. The gelling behavior of premix solution and slurry was investigated by the change of elastic modulus (G′) changing during gelling. Data show 3.4 wt% hardener in 15 wt% epoxy resin solution to be the optimized content to obtain gel with high-G′. Both the polymerization process and the gelation process depend greatly on temperature, which is beneficial for mixing and casting. Green bodies fabricated with epoxy resin show that rubber do not inhibit in the process.     

Modified Cyclohexanone-Formaldehyde Resin as an Epoxy Resin Curing Agent

Cyclohexanone-formaldehyde (CHF) resin was brominated and the brominated CHF (BCHF) was then reacted with excess aromatic diamines. The aminated CHF resins designated as ACHFs (modified ketone resin) were characterized and then applied as epoxy resin curing agents. Thus, the curing of the commercial epoxy resin diglycidil ether of bisphenol-A (DGEBA) by ACHFs was monitored by differential scanning calorimetric (DSC), based on the the DSC scans, the glass fiber-reinforced composites of DGEBA-ACHF systems were prepared and characterized by chemical resistivity and mechanical properties.     

SiC陶瓷表面增韧用环氧树脂基增韧剂的制备与性能研究

碳化硅陶瓷在磨削加工中极易产生崩碎损伤,在碳化硅陶瓷磨削层实时涂覆增韧剂是降低崩碎损伤的新方法。以E51双酚A型环氧树脂、无水乙醇、651型低相对分子质量聚酰胺树脂和1,8-二氮杂二环十一碳-7-烯(DBU)为主要成分制备了一种增韧剂,通过测量增韧剂在碳化硅陶瓷表层的接触角、浸润深度与固化时间,探究了增韧剂各组分的添加量与碳化硅陶瓷表面粗糙度对增韧剂润湿性能与固化速率的影响规律,优化出一种润湿性能好、固化速率快的增韧剂。结果表明:增韧剂的最佳质量配比为m(E51双酚A型环氧树脂)∶m(无水乙醇)∶m(651型低相对分子质量聚酰胺树脂)∶m(DBU)=1∶0.9∶0.5∶0.02,该增韧剂在碳化硅陶瓷表层的浸润时间约为160 s,浸润深度约为40 μm,可使碳化硅陶瓷的表层硬度降低约25%;增韧剂的润湿性能随着溶剂的增加或碳化硅表面粗糙度的增大而提高,促进剂添加量的改变对增韧剂的润湿性能几乎无影响;增韧剂的固化速率随溶剂的增加而降低,随促进剂的增加而提高,但当促进剂达到饱和时,固化速率不再提高。     

A Comparison of Gel Permeation Chromatography and Liquid Chromatography for Epoxy Resin Analysis

Gel permeation chromatography and liquid Chromatography are used for analyzing various epoxy resins. The chromatograms are compared with related information available from each. Because the separation is based on different principles, each method gives unique and different information about the same sample. For a complete analysis of epoxy resins, both techniques seem to be required.     

环氧树脂固化剂

本文比较详细地介绍了环氧树脂两类固化剂。     

含联苯结构环氧树脂材料

引入高刚性联苯结构可有效改善环氧树脂耐热(湿)性、熔融黏度等性能,环氧值和熔程有较大提高,关于它的合成研究已较深入。制备含联苯结构环氧树脂/粘土纳米复合材料成为新的热点,研究表明:粘土的质量分数对拉伸强度、弯曲模量、冲击强度等力学性能影响显著,当质量分数小于10%时性能较优,具有较高的玻璃化转变温度。     

聚硅氮烷/环氧树脂固化体系的研究

研究了聚硅氮烷(PSN-1)/双酚A型环氧树脂固化体系的固化温度、PSN-1用量对固化速度的影响;并利用热重分析(TGA)研究了PSN-1用量对固化树脂高温残余质量分数的影响,对固化机理进行了初步探讨.结果表明,PSN-1可作为双酚A型环氧树脂的高温固化剂,在170～180℃范围内、PSN-1用量为20～50份时,均可有效固化双酚A型环氧树脂;采用PSN-1固化的环氧树脂的初始失重温度略低于采用三乙烯四胺(TETA)固化的环氧树脂,但在800℃时的残余质量分数均远远高于采用TETA固化的环氧树脂;且随着PSN-1用量的增加,环氧树脂的高温残余质量分数也增加.