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使用创新的干法复合反应工艺合成了改性淀粉粘接剂,讨论了各因素对改性淀粉及其粘接芯砂性能的影响。结果表明,以此方法对玉米淀粉进行羧甲基化处理,可获得合适取代度范围的CM S颗粒产品。该改性淀粉粘接剂黏度适中,比粘接强度大,且其粘接芯砂具有优良的综合性能,能代替部分合成树脂粘接剂,效果显著。 相似文献
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苯乙烯改性醇酸树脂热变色涂料的研究 总被引:3,自引:1,他引:3
为了克服醇酸树脂涂膜干燥缓慢,硬度低,耐水性、耐候性不佳等缺点,利用苯乙烯对醇酸树脂进行改性,制备出干燥快,硬度高,耐水性、耐腐蚀性、耐候性好的苯乙烯改性醇酸树脂,再将热变色材料分散于苯乙烯改性醇酸树脂中,制备出苯乙烯改性醇酸树脂热变色涂料.结果表明:所得到的苯乙烯改性醇酸树脂热变色涂料的干燥快,硬度高,耐水性、耐腐蚀及耐候性好,热变色效果明显. 相似文献
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目的解决小型铝合金挤压铸件在浇铸过程中,存在的浇铸质量误差大、铸件组织的一致性较差、热节区出现组织缩松的问题,同时提高材料利用率。方法将模具定量精确成形技术引入到实际生产。结论模具定量精确成形技术的应用,能够有效解决小型铝合金挤压铸件在浇铸过程中因浇铸质量误差大的问题,铸件的总体质量误差能够控制在±0.02 kg范围以内,有效解决了因铸件质量误差大造成的铸件壁厚误差大,解决了铸件组织的一致性较差、热节区出现组织缩松的问题,提高了材料的利用率。 相似文献
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为获得磁性能适中的磁体,采用流动温压成型技术制备了各向同性粘结Nd Fe B/锶铁氧体复合磁体.利用振动样品磁强计(VSM)研究了不同粘结剂对粘结Nd Fe B/锶铁氧体复合磁体磁性能的影响.研究表明:环氧值适中的酚醛环氧树脂制备的磁体具有较好的磁性能;当采用环氧值为0.480 mol/100 g酚醛环氧树脂BPANE8200H做粘结剂时,粘结Nd Fe B/锶铁氧体复合磁体获得了最佳的磁性能:Br=0.55 T,Hcj=620.6 k A/m,(BH)max=45.6 k J/m3.在保证磁体磁性能的前提下兼顾力学性能,粘结磁体流动温压成型温度参数的设置必须考虑粘结剂的软化点温度. 相似文献
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燃料电池复合材料双极板的制备与性能研究 总被引:1,自引:0,他引:1
双极板是燃料电池中的重要组成部分,采用模压热固化二步法,以树脂为粘结剂、天然鳞片石墨作导电骨料、碳黑为添加剂制备燃料电池复合材料双极板.系统考察了树脂含量、溶剂比、碳黑含量、成型压力、保压时间以及固化温度等因素对复合材料双极板性能的影响.结果表明,随着粘结剂含量的增加,双极板的电导率减小,抗折强度增大;碳黑的添加可有效地提高其电导率,但强度会有一定程度的减小;增大成型压力和延长保压时间可提高双极板的导电性和强度;最终固化温度主要影响粘结的交联程度.制备天然石墨/聚合物复合材料双极板的最佳条件为:聚合物树脂含量为20%,碳黑含量为4%~5%,溶剂比为1.0,成型压力为10~12MPa,固化温度为180℃. 相似文献
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Carbon composites containing novolac/furfuryl alcohol resins with hexamethylene tetramine (HMTA) as a crosslinker and carbon black or mesophase pitch as an additive, were heated to 1000 °C under Argon atmosphere. Carbonization chemistry was studied including the nitrogen-containing structures in the final carbons. The volatiles released during the heating were furfuryl, phenol-benzene species, methane, ethane and other small molecular species such as moisture, CO2, CO and ammonia. When carbon black was used as an additive in the composite, a considerable amount of furfuryl and phenolic species were “trapped” on the surface of carbon black particles, resulting in a higher carbon yield. Certain carbonization reactions also occurred at lower temperatures, and the dimensional shrinkage was reduced as compared to the resin-only system. On the other hand, the mesophase pitch additive formed homogeneous morphologies with the resin binder, participated in the carbonization process of the resin binder and formed amorphous carbons with porous structures and dimensional expansion. Manipulating the composition and variety of the additives could produce carbon composites with designed performance. 相似文献
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利用高温旋转黏度计,采用梯度降温的方法,研究CBT(环形对苯二甲酸丁二醇酯)树脂与CBT/催化剂混合体系在特定条件下的流变性能。结果表明:采用梯度降温方法可准确获得CBT纯树脂的真实表观黏度。CBT树脂的表观黏度随温度的降低而升高,随转速的加快而降低,在170~180℃下呈现出明显的剪切变稀现象。CBT/催化剂混合体系的反应速率随催化剂浓度的增加而加快。相同浓度下,锡含量较高的CBT/T9体系相对CBT/DBTL体系反应速率更快。较高的温度使催化剂的挥发程度加剧,结晶速率变慢,导致CBT/催化剂混合体系的反应速率随温度升高而变慢。最后研究了催化剂种类、浓度和成型温度对成型窗口时间的影响。 相似文献
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以普通酚醛树脂、硼改性酚醛树脂、三聚氰胺改性酚醛树脂为黏结剂,以陶瓷纤维为增强纤维,制备了3种酚醛树脂陶瓷摩擦材料。对其冲击韧性和硬度进行实验测试,采用摩擦磨损试验机考察其摩擦磨损性能,采用扫描电子显微镜(SEM)和X射线能谱仪分析其磨损表面形貌及其成分,并探讨其磨损机制。结果表明:硼改性酚醛树脂黏结剂能够提高摩擦材料的硬度,三聚氰胺改性酚醛树脂黏结剂能够提高摩擦材料的冲击韧性,降低摩擦材料硬度;在摩擦过程中三聚氰胺改性酚醛树脂在高温下炭化,在摩擦材料表面形成一层致密的摩擦层,摩擦层的存在使摩擦材料的摩擦因数相对比较稳定,降低了摩擦材料的磨损率。 相似文献
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采用自行研制的固化应力测试装置,测量了端羟基聚丁二烯(HTPB)基浇注高聚物黏结炸药(PBX)固化过程的应力变化,计算出固化应力数据,分析了黏结剂相对分子质量对热固性浇注PBX固化应力的影响,并对其在不同固化温度下的黏结强度进行了测试。结果表明:同一固化温度时,随着HTPB相对分子质量的逐渐增大,浇注PBX在固化阶段的最大热应力及收缩应力都逐渐减小。固化温度为100℃时,相对分子质量为1 500、2 800、4 000的HTPB基固化物因固化反应所产生的最大热应力分别为2.14、1.12、1.01 MPa,最大收缩应力分别为0.29、0.22、0.15 MPa。在固化降温阶段,HTPB相对分子质量越大,浇注PBX的收缩应力也越大。HTPB相对分子质量相同时,固化物的黏结强度随着固化温度的升高而降低;而固化温度一定时,HTPB相对分子质量对浇注PBX的黏结强度影响不大。 相似文献
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G. Ya. Gerasimov Yu. M. Pogosbekyan 《Journal of Engineering Physics and Thermophysics》2009,82(1):92-97
A set of experiments on determination of the parameters of the gas release from a mold have been performed. The thickness
of the casting, the thickness of the mold wall, the process time, and the temperature of the charged metal (liquid gray cast
iron) were varied. The investigated molding sands were prepared from quartz sand and organic binders: M19-62 (urea resin),
FF-1S (furanic resin), and PK-104 (phenolic resin). On the basis of the experimental data obtained the kinetic parameters
of the thermal decomposition of the considered resins have been determined.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 92–97, January–February, 2009. 相似文献
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We studied the mechanism of volatile-induced surface porosity formation during the resin transfer molding (RTM) of aerospace composites using a blended benzoxazine/epoxy resin, and identified reduction strategies based on material and processing parameters. First, the influence of viscosity and pressure on resin volatilization were determined. Then, in situ data was collected during molding using a lab-scale RTM system for different cure cycles and catalyst concentrations. Finally, the surface quality of molded samples was evaluated. The results show that surface porosity occurs when cure shrinkage causes a sufficient decrease in cavity pressure prior to resin vitrification. The combination of thermal gradients and rapid gelation can generate large spatial variations in viscosity, rendering the coldest regions of a mold susceptible to porosity formation. However, material and cure cycle modifications can alter the resin cure kinetics, making it possible to delay the pressure drop until higher viscosities are attained to minimize porosity formation. 相似文献