Fabrication and Life Prediction of SSiC Ceramic Joint Joined with Silicon Resin YR3370

Joints between sintered silicon carbide （SSiC） were produced using a polysiloxane silicon resin YR3370 （GE Toshiba Silicones） as joining material. Samples were heat treated in a 99.99% nitrogen flux at temperatures ranging from 1 100 ℃ to 1 300 ℃. Three point bending strength of the joint reached the maximum of 179 MPa as joined at 1 200℃. The joining layer is continuous, homogeneous and densified and has a thickness of 2 μm -5μm. The joining mechanism is that the amorphous silicon oxycarbide （SixOyCz） ceramic pyrolyzed from silicon resin YR3370 acts as an inorganic adhesive to SSiC substrate, which means the formation of the continuous Si-C bond structure between SixOyCz structure and SSiC substrate. Life prediction of the ceramic joint can be realized through the measurement of the critical time of the joint after the cyclic loading test.

Preparation, Curing Reactivity and Thermal Properties of Titanium-doped Silicone Resins

Novel titanium-doped silicone resins were synthesized from low-cost silane monomers and tetrabutyl titanate as raw materials and hydrochloric acid as catalyst, with titanium element as dopant into principal chain of Si-O-Si. The resins were characterized by means of FTIR, IH NMR and 13C NMR spectra, their thermal properties and curing properties were investigated and their corresponding films were determined. The results show that the thermal stability and storage stability of the resins were influenced by the types of silane monomers containing dif- ferent carbon atomicities of organic group. The thermal stability of the titanium-doped silicone resin with a molar ratio of silane monomer B（n-propyl triethoxysilane） to silane monomer C（n-octyl triethoxysilane） being 1：1 is superior to that of the resin with a molar ratio of silane monomer B to silane monomer C being 1：3. However, the storage stability of the former is inferior to that of the latter. This work also showed that the synthesized titanium-doped silicone resins have the highest thermal stability up to 450--500℃ with an atomicity molar ratio of 1：4 of titanium to silicon in the reactants. But the best storage stability of the resin prepared from the reactants with an atomicity molar ratio of 1：6[n（Ti）：n（Si）] was obtained. The effect of the type and content of curing agent on the curing properties of the resin was also studied. Moreover, thermal mechanism and curing mechanism were proposed in this work.

THE EFFECT OF THE ACID CATALYST ON THE PREPARATION OF MQ SILICONE RESINS

MQ silicone resins were prepared through hydrolytic condensation of ethyl polysilicate or tetraethoxysilane and hexamethyl disiloxane. The unit ratio of the MQ resins was determined by Si-29-NMR. The relationship of the unit ratio of the product resins with that in the feed was studied. When the reaction was catalyzed by aqueous hydrochloric acid, and the unit ratio of M to Q in the feed was more than 1, the unit ratio of the product was usually lower than that of the feed. The MQ silicon with an unit ratio of M/Q > 2 could not be obtained. However, if the reaction was catalyzed by concentrated sulfuric acid and the reverse hydrolysis process was employed, MQ silicone resin with very high M/Q ratio was successfully prepared.

Development of Siliconized Epoxy Resins and Their Application as Anticorrosive Coatings

The present work involves the development of siliconized epoxy resin to overcome the drawback of epoxy resin like poor impact strength, high rigidity and moisture absorbing nature because of which they are not applied as corrosion resistant coating. By embedding silicone into the back bone of polymeric resin the above drawback can be reduced to substantial level. For achieving this, siliconised epoxy resins were prepared by reacting amine terminated silicone resin with novolac epoxy resin and meta-phenylenediamine was used as curing agent. The applied films of coating were baked at 150oC. Cured films were evaluated for their thermal, mechanical, chemical and corrosion resistance properties to ascertain the commercial utility of these eco-friendly resin for use in anti corrosive formulations. The siliconized epoxy resins system was found to exhibit good thermal and anticorrosive properties.

Effects of pyrolysis temperature and fillers on joining of ceramics via silicone resin

The joining of graphite, ceramic SiC and C_f/SiC composites via preceramic silicone resin(SR) at high temperature (8001400℃) was studied. The curing and pyrolysis process of SR, pyrolysis temperature, inert and active fillers were especially discussed. The results show that the curing process of SR was accomplished by consuming Si—OH. The temperature of 1200℃ is the appropriate treating temperature for graphite and SiC ceramic, and the temperature of 1400℃ is suitable for C_f/SiC composites. Inert filler SiC powder(5%, mass fraction) has much positive influence on the shear strength of the joints. Active filler nano Ai, Si powder can greatly improve the properties of the joints treated at high temperature. The improvement is over 700%.

Synthesis and Properties of Perfluorinated Alkyl Silicone Oil Modified Epoxy Resin

Perfluorinated alkyl silicone oil （PFASO） was successfully synthesized from N-ethyl-N- hydroxylethyl perfluorinated octane sulfonamide, succinie anhydride and amino silicone oil by esterification and amide reaction at moderate temperature in the presence of different catalysts. The chemical structure of the synthesized samples was characterized by Fourier transform infrared spectroscopy （FT-IR）, the relative molecular mass（MM） and molecular mass distribution（MMD） of PFASO were tested by gel filtration chromatography（GFC）. A commercial epoxy resin （DGEBA） was modified with PFASO, with the content of PFASO 1-5 phr. Thermo-gravimetric analysis （TGA）, impact tests, scanning electron microscope （SEM） and water contact angle test were applied to provide accurate results on the thermal stability, toughness and hydrophobicity of PFASO/epoxy complex. The experimental results reveal that epoxy resins can be successfully modified by adding a small amount of as-synthesized modifiers via simple direct mixing, and verify that the as-synthesized modifier can improve the toughness and hydrophobicity of epoxy resin without sacrificing its thermal properties.

TRIMETHYLSILYLATED SILICA AS RHEOLOGY MODIFIER FOR SILICONE RESINS

Trimethylsilylated silica was synthesized. through hydrolytic condensation of tetraethoxysilane followed by trimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. It turned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylated silica of medium particle size shows the strongest tendency of forming physical network in the resin.

Protective Performance of Fiberglass Fabrics Coated by Silicone Resin Mixed with Nature Filler Powders

The coated fiberglass fabric was prepared to protect personnel and equipment from sparks, heat, and molten metals during hot work projects. Ferric oxide powder 2%,mica powder6%,wollastonite powder 4%,and white carbon black 8% were added in the phenyl methyl silicone to prepare the composite silicone solution. The french chalk and coupling agent can effectively solve the deposition of fillers in the coating solution. Compared with the original fiberglass fabric,heat resistance of the coated fabric under high temperature was greatly improved, and the temperature limitation in short period was higher than 900℃. Horizontal flammability tests showed that the coated fabric was non-combustible with no melting and no fragments. The temperature for long period usage of coated fabric was lower than 500 ℃. Welding drop test showed that the coating could prevent the molten metals,sparks and heat from transferring in the fabric. Test for toxic gas release showed that the toxic gases such as HCN,SO_2,HCl,and HF were not detected,only CO( 100 mg / m^3) and NO( 12 mg /m^3) were detected,and their concentrations were far lower than the limitation values CO( 4 375 mg / m^3) and NO( 134 mg /m^3). The breaking strength of coated fabric was almost twice the strength of the original fabric,and the coated surface had good water and oil repellency.

Nanocomposites of a Silicon-containing Arylacetylene Resin with Octakis(dimethylsiloxy)octasilsesquoixane

Nanocomposites（PMSEPE/Q8M8^H） were prepared via solution blending of octakis（dimethylsiloxy）octasilsesquoixane（Q8M8^H） into poly（dimethylsilyleneethynylenephenyleneethynyle ne）（PMSEPE）. PMSEPE/Q8M8^H nanocomposites were characterized by Fourier transform infrared（FT-IR） spectroscopy, rheological measurement, differential scanning calorimetry（DSC）, scanning electron microscopy（SEM） and thermal gravimetric analysis（TGA）. The experimental results show that the hydrosilylation reaction in PMSEPE/Q8M8^H nanocomposites occurs slowly exceeding 180 ℃. PMSEPE/Q8M8^H nanocomposites can be cured at temperatures less than 260 ℃ and the cube structure of Q8M8^H keeps stable during the curing process. POSS domains are evenly dispersed in the cured nanocomposite. However, serious aggregation of POSS occurs at 15% Q8M8^H content. The thermal and thermooxidative stabilities of PMSEPE/Q8M8^H nanocomposites obviously depend on the content of Q8M8^H. The incorporation of Q8M8^H can effectively enhance the thermal and thermooxidative stabilities of cured PMSEPE. PMSEPE/Q8M8^H nanocomposites can be the candidates for applications in high temperature environment.

Preparation of Porous Silicone Resin Sheet with Phase Inversion in Parallel with Non Solvent Induced Phase Separation and Application to Hollow Particle Formation

We have tried to prepare the porous silicone resin sheet with the phase inversion method in parallel with the non solvent induced phase separation method. In the experiment, ethyl acetate and water were adopted as a good solvent and a poor solvent for silicone resin, respectively and ethyl alcohol as an amphiphilic solvent was used to increase the solubility of ethyl acetate in water and decrease the interfacial tension by mass transfer from water to ethyl acetate. The concentration of silicone resin in ethyl acetate and the oil soluble surfactant species were changed. Increasing the concentration of silicone resin could depress coalescence between the water droplets in the (W/O) dispersion and increase the porosity and pore number density of silicone resin sheet. Span 80 among the oil soluble surfactant species made the porosity and pore number density larger. The effect of physical proparties of liquids concerned on the porosity and pore number density was discussed on the basis of dispersing behavior of liquid droplets in the liquid-liquid dispersion. The hollow silicone resin particles could be prepared by applying the preparation method presented here.

互穿网络结构的二氧化硅/环氧树脂复合材料的制备及介电性能研究

环氧树脂(EP)具有较高的电绝缘性能和较低的介电损耗,因此被广泛应用于电气设备和电子封装等绝缘材料领域。由于传统EP耐热性能较差、韧性不足,极大限制了其作为微电子元器件在高频电场下的使用。本工作以硅烷偶联剂(3-环氧乙基甲氧基丙基)三甲氧基硅烷(KH-560)和正硅酸乙酯(TEOS)为原料,通过溶胶-凝胶法合成末端含有环氧基团的新型端环氧基纳米SiO_(2)(E-SiO_(2)),用其对E-51型EP进行改性,在固化剂作用下使E-SiO_(2)和EP上的环氧基团发生开环反应,通过有机EP与无机E-SiO_(2)填料之间的化学键结合,制备出具有互穿网络结构的E-SiO_(2)/EP复合材料。本工作研究了添加E-SiO_(2)对EP固化反应工艺和综合性能的影响,以期在保证EP低介电常数和低介电损耗的同时,赋予其良好的韧性和耐热性能,为EP在高频电路下的应用奠定基础。

有机玻璃表面硅树脂耐磨涂层的制备与表征

以纳米SiO_(2)溶胶、甲基三乙氧基硅烷(MTES)和γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH-560)为原料,采用溶胶-凝胶法制备了一系列环氧烃基硅树脂;添加1-苄基-2-甲基咪唑(BMI)、乙酰丙酮铝、混合溶剂等,配成用于改善聚甲基丙烯酸甲酯(PMMA)表面抗划伤性的有机硅涂料。研究了SiO_(2)溶胶与KH-560的配比、乙酰丙酮铝的用量等参数对涂层耐磨性、硬度、附着力及光学透光性等性能的影响。结果表明,制备的硅树脂涂层可以有效提高PMMA表面的硬度和耐磨性,当涂层原料SiO_(2)和KH-560的质量比为2∶1、乙酰丙酮铝用量为涂层液质量的0.4%时,涂层的铅笔硬度和附着力分别为4H和1级,耐磨性和透光性均较未涂覆的PMMA基材有所提高。

硅树脂/EPDM绝热材料的性能及陶瓷化机理

采用SEM、TG、DSC、拉伸试验和氧-乙炔烧蚀试验,研究了硅树脂对EPDM绝热材料力学性能、热稳定性以及耐烧蚀性能的影响,并分析了硅树脂/EPDM绝热材料在烧蚀过程中炭化层的陶瓷化机理。结果表明:随着硅树脂含量的增加,绝热层的抗拉强度和断裂伸长率均有所降低;在硅树脂含量为35 phr时,绝热层的热稳定性以及耐烧蚀性能最好,残炭率能达到30%左右,线烧蚀率最小为0.048 mm/s;观察形貌发现,含硅树脂绝热层烧蚀后形成的炭化层更致密坚硬,孔洞更小,耐冲刷性能更好。添加硅树脂能够有效提高EPDM绝热层的耐烧蚀性能,其作用机理主要是通过高温下分解产生的硅氧化物与碳进行碳热还原反应形成碳化硅和其熔融态将炭化层粘结在一起,最终形成一种类陶瓷结构的炭化层。

有机硅树脂乳液的制备方法及应用研究进展

有机硅树脂乳液是将主链含SiOSi的高度交联聚硅氧烷在外加乳化剂或亲水基团的作用下,经过机械分散后形成的聚合物乳液,具有环境友好特性,可用于水性耐高温涂料、防水涂料、水性胶黏剂、日化和纺织品、纸张及皮革整理等。本文详细综述了有机硅树脂乳液的3种常用制备方法,重点介绍了其应用进展,并对未来发展方向进行了展望。

水性有机硅改性环氧树脂的制备与性能

利用二甲基二氯硅烷(DMDCS)与环氧树脂E51中-OH缩合反应合成有机硅改性环氧树脂,并采用相反转法制备水性有机硅改性环氧树脂,以疏水性优选有机硅改性环氧树脂合成条件,分析了乳化工艺对乳液平均粒径的影响,并考察了固化膜性能。结果表明,在环氧树脂40 g、DMDCS 1.6 g、溶剂用量20 mL、50℃反应8 h的条件下,有机硅改性环氧树脂与水的接触角为106.8°;当乳化剂用量为25%、乳化温度为65℃、剪切机转速为3000 r/min时,乳液平均粒径为1.011μm,储存稳定性(30 d)和离心稳定性(3000 r/min,30 min)良好;水性有机硅改性环氧固化膜固化时间短,具有优良的疏水性、力学性能、耐腐蚀性能。

水性丙烯酸涂层改性研究进展

简单阐述了水性丙烯酸树脂的单体结构、聚合方法以及应用现状;较为系统地总结了根据不同材料改性水性丙烯酸树脂的研究进展,改性材料可归纳为纳米材料、有机硅、有机氟、聚氨酯和环氧树脂以及一些新型材料等。重点论述了改性材料对水性丙烯酸树脂进行改性的反应机理、相应的微观结构及性能提高情况。展望了水性丙烯酸涂料发展的方向。

有机硅树脂改性蓖麻油基聚氨酯的制备与性能分析

为提高蓖麻油基聚氨酯(Castor oil-based polyurethane,CO-PU)的耐高温性能,选用五种有机硅树脂对CO-PU进行改性,制备得到有机硅改性蓖麻油基聚氨酯(Silicon-modified castor oil-based polyurethane,Si-CO-PU)并探究不同有机硅树脂种类及质量比对聚合物各种性能的影响。对Si-CO-PU的拉伸性能、水接触角、光泽度、耐液体介质性能等进行测试,并结合傅里叶变换红外光谱仪和同步热分析仪进行表征。研究结果表明,当有机硅树脂质量比为12.5%时,环氧有机硅树脂(SH-023-4)改性CO-PU的综合性能相对较好,耐高温性能达到最佳,这为扩展聚氨酯的应用途径提供了研究思路和方法。

新型有机硼防污剂在自抛光防污涂料中的匹配稳定性和防污性能研究

本工作探究了一种新型有机硼防污剂——4-异丙基吡啶甲基二苯基硼烷(4-IPDMB)在防污涂料中的稳定性和防污性能。以稳定水解的丙烯酸硅树脂为自抛光基体树脂,以4-IPDMB为主防污剂,以吡啶硫酮锌、溴代吡咯腈或异噻唑啉酮等作为辅助防污剂,制备了多种防污涂料,并进行性能表征。首先采用一步自由基聚合法成功制备了一种具有稳定抛光速率的丙烯酸硅树脂,抛光速率测试结果表明该丙烯酸硅树脂的抛光速率为4μm/month。按配方将如上组分配制成涂料后,通过附着力试验、储存稳定性试验和浅海静态挂板试验对4-IPDMB在防污涂料中的配方匹配稳定性和防污能力进行了表征。结果表明,含有4-IPDMB的防污涂料具有良好的防污性能,当与其他辅助防污剂混合后,附着力、防污性能和储存稳定性均产生一定程度的变化,需进一步探究4-IPDMB与辅助防污剂之间的潜在化学反应,指导配方优化。

改性MPSA树脂的合成及在耐高温胶粘剂制备中的应用

以间二乙炔基苯和甲基苯基二氯硅烷采用格氏试剂法合成了甲基苯基含硅芳炔(MPSA)树脂,进行了红外(FT-IR)、核磁(^(1)H-NMR)、热性能和流变特性分析表征,通过MPSA与聚酰亚胺树脂共混制备胶粘剂,以差示扫描量热法(DSC)、热失重分析(TGA)研究胶粘剂的固化性能、耐热性能,测试了胶粘剂室温和高温剪切强度。结果表明,制备的MPSA树脂显示出优异的耐热性和加工性,室温到210℃黏度在10Pa·s以下,5%热失重温度(T_(d5))为583℃,800℃残碳率(Y_(r800))为88%。聚酰亚胺树脂改性的MPSA胶粘剂显示出较高的高温粘接性能和良好的高温热稳定性,T_(d5)在564~573℃,Y_(r800)在80%~85%,其中AtPI:MPSA=5:5胶粘剂的室温和450℃剪切强度分别达到10.7MPa和7.5MPa。

六钛酸钾晶须改性环氧有机硅树脂的抗烧蚀性能

制备了六钛酸钾晶须(PHW)改性的环氧有机硅树脂复合材料,研究了PHW含量对复合材料在氧-乙炔烧蚀环境中抗烧蚀性能的影响。结果表明:添加PHW能够有效提高环氧有机硅树脂烧蚀产物层的抗剥落能力和耐高温烧蚀性能,其中PHW添加量为20wt%时,复合材料的线烧蚀率和质量烧蚀率均最低,分别为0.136 mm/s和1.143 g/s,与环氧有机硅树脂相比分别低约53.74%和47.04%;当PHW含量超过20wt%后,进一步增加其含量对复合材料耐烧蚀性能的改善效果不再明显。TG分析结果表明:添加PHW能大幅降低环氧有机硅树脂的失重率,其中PHW添加量为20wt%时,复合材料的失重率约为38.57%,较环氧有机硅树脂低约19.89%;当PHW含量高于20wt%后,进一步增加其在复合材料中的含量对失重率的改善效果不再明显。