尼龙66纤维混杂刚玉砂对复合纤维型壳性能的影响

为了解决硅溶胶型壳在搬运、脱蜡过程中易开裂的难题,在撒砂材料中混杂尼龙66(PA66)纤维作为常温增强材料和成孔剂,制备不同PA66纤维质量分数的型壳。探究PA66纤维质量分数对型壳抗弯强度、透气性和气孔率的影响规律,并分析PA66纤维对型壳性能的影响机制。研究表明, PA66纤维大幅度提高了型壳的常温抗弯强度和透气性。随着PA66纤维质量分数的增加,型壳的常温抗弯强度和透气性均增大,焙烧后抗弯强度先增大后减小。当PA66纤维质量分数为0.75wt%时,综合性能达到最佳,焙烧后抗弯强度达7.94 MPa,与未混杂纤维的试样相差不大,但其常温抗弯强度达到4.80 MPa,比未混杂纤维的试样提高了32.21%,透气性和气孔率也增加至4.2和22.77%,比未混杂纤维的试样分别提高了90.91%和13.35%。     

复合纤维配比对精铸硅溶胶型壳性能的影响

为了分析复合纤维配比对熔模精铸中硅溶胶型壳的强度和透气性的影响,采用尼龙和陶瓷复合纤维制备硅溶胶型壳试样,在其中加入的尼龙纤维和陶瓷纤维的体积配比为100∶0、82.7∶17.3、61.5∶38.5、34.7∶65.3和0∶100,对获得的复合纤维增强型壳试样的生胚抗弯强度、焙烧后抗弯强度和透气性的变化规律进行研究。结果表明,当尼龙纤维在复合纤维中体积分数从0%~100%变化时,型壳生胚抗弯强度逐渐增大,焙烧后抗弯强度总体变化不明显,透气率先增大后减小。当尼龙纤维的体积分数为82.7%时,透气率达到最大值5.21。根据试样断口形貌及纤维增强行为分析,型壳生胚抗弯强度主要受纤维体积含量的影响;型壳焙烧后抗弯强度和透气性受陶瓷纤维体积含量、涂挂厚度和尼龙纤维烧失后留下孔洞数量的综合影响。     

单向连续竹青纤维填充量对不饱和聚酯树脂力学性能及微观形貌的影响

以单向连续竹青纤维（OBF）和不饱和聚酯树脂（UP）制备了单向OBF/UP复合材料,研究了OBF含量对OBF/UP复合材料纵向静态力学性能及动态力学性能的影响,并采用SEM观察了复合材料拉伸断面处界面结合情况。结果表明:随着OBF含量的增加,OBF/UP复合材料静态力学性能呈先增加后减小趋势,当OBF含量为50wt%时,复合材料拉伸、弯曲性能最优,拉伸强度、拉伸模量、弯曲强度、弯曲模量分别达到285.52 MPa、16.06 GPa、359.80 MPa、27.32 GPa;OBF/UP复合材料存储模量随OBF含量增加呈先增加后减小趋势,当OBF含量为50wt%时,OBF/UP复合材料存储模量最大,且随着OBF含量的增加,OBF/UP复合材料玻璃化转变温度向低温方向移动,损耗峰变宽;断面处微观形貌表明,OBF含量为50wt%时,复合材料界面结合强度较好。制备的OBF/UP复合材料力学性能优良,有潜力取代玻璃纤维增强树脂复合材料在风电叶片材料、公路防护栏材料、船舶材料等领域的应用。      

水分对模具石膏性能及微观结构的影响

本文通过干湿循环试验模拟卫生陶瓷模具石膏的工作环境,探究不同工作周期下水分对模具石膏耐溶蚀性、吸水性能及力学性能的影响规律。结果表明:随着循环周期延长模具石膏耐溶蚀性能大幅降低,循环周期从40次增至50次,溶蚀率由9.03%增至12.41%,增幅达37%;吸水率在循环周期50次内呈抛物线形式增长,30次时达到峰值26.34%,50次之后吸水率大幅增加。模具石膏的饱水抗折强度在干湿循环过程中显著下降,由最初的2.67MPa减小至1.71MPa,降幅高达36%。微观结构分析表明:水分干湿循环作用使模具石膏硬化体孔隙率增加,孔径分布粗化,大于50nm的大孔数量显著增加;二水石膏硬化体内晶体呈针棒状结构,晶体之间搭接紧密,经水分干湿循环后二水石膏硬化体晶体粗化,搭接程度降低,晶体结构的稳定性变差。     

磁控溅射HA（＋YSZ）／Ti6A14V复合涂层的微观形貌和生长方式

采用磁控溅射方法在钛合金（Ti6A14V）基体上制备了HA（4-YSZ）复合涂层。利用X射线衍射仪（XRD）分析涂层的物相组成，扫描电镜（SEM）观察涂层的表面形貌，原子力显微镜（AFM）分析涂层的生长状况，划痕法测定涂层与基体的附着力。结果表明，用磁控溅射法可在Ti6A14V基体上制备HA（＋YSZ）复合涂层，涂层组成与靶材基本相似，涂层呈多孔状，划痕法测量涂层的附着力约为80N，涂层的生长模式为层状生长加岛状生长。     

不同含量钇稳定剂对氧化锆陶瓷性能的影响

在氧化钇含量为8%(摩尔分数)的氧化锆中加入单斜氧化锆,1600℃常压烧结,制得不同含量的氧化钇稳定氧化锆.研究了不同含量的氧化钇对氧化锆陶瓷性能的影响,并对相组成及显微结构进行了分析.当氧化钇的摩尔分数为3%时,材料的相对密度、抗弯强度、硬度等综合力学性能同时达到最大值.超过这个临界点,材料力学性能又会逐渐下降.     

磁控溅射HA(+YSZ)/Ti6Al4V复合涂层的微观形貌和生长方式

采用磁控溅射方法在钛合金(Ti6A14V)基体上制备了HA( YSZ)复合涂层.利用X射线衍射仪(XRD)分析涂层的物相组成,扫描电镜(SEM)观察涂层的表面形貌,原子力显微镜(AFM)分析涂层的生长状况,划痕法测定涂层与基体的附着力.结果表明,用磁控溅射法可在Ti6Al4V基体上制备HA( YSZ)复合涂层,涂层组成与靶材基本相似,涂层呈多孔状,划痕法测量涂层的附着力约为80N,涂层的生长模式为层状生长加岛状生长.     

高效纤维-石膏功能复合吸声材料的研制

以高强石膏为胶凝材料,内掺玻璃纤维,制备出一种新型多孔吸声材料.实验发现,孔隙率、平均孔径大小、玻璃纤维含量、发气剂含量对材料吸声性能有显著影响.采用驻波管法测试材料的吸声系数.结果表明材料的平均吸声系数和降噪系数分别达0.58和0.60,且材料的中低频吸声性能优良.     

高温中和高温后LVL木纤维复合材的抗弯性能

为研究LVL木纤维复合材在高温中和高温后的抗弯性能,对104个试样进行了温度在20~225℃下的三点静态抗弯测试。研究结果表明,随着温度的升高,高温中和高温后的抗弯强度、抗弯弹性模量、延性系数均明显减小;相对于高温中的试样,高温后的抗弯强度和抗弯弹性模量均明显较高,而延性系数则较低。根据回归分析,提出了LVL在高温中和高温后的抗弯强度与温度的关系模型,该模型预测结果与实测值吻合良好。     

316L纤维尺寸和含量对HA-ZrO2(CaO)/316L纤维复合生物材料性能的影响

研究了316L纤维的长度、直径与含量对HA-ZrO_2（CaO）/316L纤维生物复合材料的力学性能的影响规律.结果表明：纤维直径为40μm的复合材料力学性能优于纤维直径为50μm的复合材料;纤维长度为0.8～1.2mm的复合材料力学性能优于纤维长度为2～3mm的复合材料;随着纤维体积分数增大,纤维之间相互接触而导致在复合材料中形成的微孔增多,并成为微裂纹源,导致材料力学性能下降.含20vol%直径为40μm、长度为0.8～1.2mm的316L纤维的HA-ZrO_2（CaO）/316L纤维生物复合材料的综合力学性能最佳,其抗弯强度、杨氏模量、断裂韧性和相对密度分别为140.1MPa、117.8GPa、5.81MPa·m~（1/2）和87.1%.复合材料微观组织随HA粉末和316L纤维成分的变化呈规律性变化,没有出现明显的裂纹或孔隙,316L纤维与HA-ZrO_2（CaO）基体紧紧地咬合在一起,其结合主要靠基体对316L纤维的物理附着力所致.基体中发生微量Fe元素扩散,但在316L纤维中不发生基体Ca、P元素的扩散.含5%316L纤维复合材料表现为脆性断裂,而含10%、20%、40%316L纤维复合材料均表现为韧性断裂,且韧性程度随316L纤维含量的增加而增大.     

稻壳纤维粒径和掺量分数对水泥复合材料性能的影响

以稻壳纤维（Rice husk fiber,RHF）为增强材料,以水泥为基体,制备了RHF/水泥基复合材料。研究了粒径对RHF在水泥基体中分散性能的影响;并以RHF粒径和掺入质量比为考察因素,采用响应曲面法,以RHF/水泥基复合材料的密度、抗折强度、含水率、吸水率和导热系数为响应值,建立数学模型,对RHF/水泥基复合材料的成型工艺进行优化设计。结果表明：RHF的粒径越小,在水泥基体中分散性能越好,粒径为150 μm的RHF分散系数达到最大值,为0.981;响应曲面模型分析表明RHF的粒径为150 μm、掺入质量为水泥质量的3%时,RHF/水泥基复合材料的性能达到最优,此时RHF/水泥基复合材料的密度为1 559.26 kg/m³,抗折强度为9.38 MPa,含水率为7.05%,吸水率为16.71%,导热系数为0.50 W/（m·K）,达到了建筑行业标准JC/T 411-2007的要求。     

植物纤维含量对聚乳酸/玉米秸秆纤维发泡材料(PFFM)性能的影响研究

通过SEM、力学性能测试、TG等方法研究了纤维对聚乳酸/玉米秸秆纤维复合发泡材料(PFFM)微观结构、表观密度、膨胀率、力学性能和热性能的影响。结果表明,玉米秸秆纤维的加入提高了发泡材料的表观密度和力学性能,当纤维含量为15%时,表观密度最小,综合力学性能最好;扫描电镜结果显示,聚乳酸和玉米秸秆纤维之间相容性较好,纤维的加入改变了泡孔成型方式。     

玄武岩纤维含量对玄武岩纤维/聚乳酸-铝合金复合材料连接强度的影响

为了提高聚乳酸（PLA）与铝合金的连接强度,采用在PLA中添加玄武岩纤维（BF）获得BF/PLA复合材料的方式对PLA进行增强。利用转矩流变仪对干燥处理后的PLA及BF进行密炼,利用光纤激光器对铝合金表面进行毛化处理。采用平板硫化机对BF/PLA复合材料和处理后铝合金进行连接成型,测试其拉伸强度,对失效后断面进行分析。结果表明:随着BF质量分数的增加,BF/PLA-铝合金连接强度先增强后降低,BF质量分数的增加影响了BF/PLA复合材料的结晶成核。结合试验获得的结果,建立有限元分析模型进行数值模拟,结果显示所建立的模型能够准确还原BF/PLA-铝合金拉伸过程。      

Effect of fiber surface texture on the mechanical properties of glass fiber reinforced epoxy composite

The effect of fiber sizing and surface texture on the strength and energy absorbing capacity of fiber reinforced composites has been evaluated at two length scales using the macromechanical quasi-static punch shear test and the micromechanical microdroplet test methods. E-Glass/SC-79 epoxy composite laminates with four different fiber sizing formulations with various degrees of chemical bonding and surface texture have been investigated. The failure modes during perforation and different energy dissipating damage mechanisms were identified and quantified. The punch shear strength and the total energy absorption per unit volume of composite with hybrid sizing have increased by 48% and 100% over the incompatible sizing. These results showed linear correlations with the interphase properties reported earlier by the authors (Gao et al., 2011) and provided a methodology for developing new sizing by tailoring chemical bonding and the fiber surface texture at the fiber–matrix interphase for improving both strength and energy absorption of composites.     

Effects of vacuum,mold temperature and cooling rate on mechanical properties of press consolidated glass fiber/PET composite

Glass fiber reinforced polyethylene–terephthalate (PET) matrix composites manufactured by a rapid press consolidation technique were investigated as functions of vacuum, mold temperature, and cooling rate among the many possible processing parameters. Tensile, impact, fracture toughness and short beam shear tests were carried out and these mechanical properties were compared with respect to crystallinity. It was found that the mechanical properties strongly depend on vacuum, mold temperature, and cooling rate. The degree of crystallinity (X_C) in composites affects tensile properties to some degree, but impact properties were affected much more. It also affects the degree of ductility depending mold temperature in consolidation and cooling rate, which determines the impact energy of this material.     

纤维分布均匀性对T300/BMP316复合材料层压板力学性能的影响

采用三点弯曲法和数字化冲击仪, 研究了纤维分布均匀性对T300/BMP316复合材料弯曲和冲击性能的影响, 用有限元方法分析了纤维分布不均匀复合材料弯曲变形时的应力分布, 提出了用纤维分布效应系数R来评价纤维分布不匀复合材料的性能。结果表明, 纤维分布不均使T300/BMP316复合材料的弯曲性能和冲击性能强烈地受到纤维分布方式和载荷方向的影响, 纤维分布效应系数R反映了纤维分布与性能的关系。      

Effect of filler content and size to properties of composite resins on microwave curing

The effect of filler content and size to property of composite resin using high purity spherical silica particles on microwave curing was examined by mechanical means and electron microscope observation to develop microwave-curing composite resin inlay. Increasing filler content in three kinds of filler particles (0.45, 0.96 and 1.46 m) resulted in increasing compressive strength, diametral tensile strength and knoop hardness and indicated the highest values at the operative mixing limit. The effect of particle size was that the mechanical property of the 0.96 m filled resin was highest, followed by 1.46 m and 0.45 m on the same filler content. The 0.96 m filled resin had about the same knoop hardness on both surfaces of the cured sample, which means that uniform polymerization occurred in the cured sample.With electron microscope observation, the bubbles of about 1.0 m and the cracks between the fillers and the matrix were observed in each cured resin. This is caused by the excessive absorption of microwave energy in fillers and surface treatment materials of fillers. Therefore, improvement of the composition of filler and surface treatment material of filler are needed, which makes it harder to absorb the microwave energy. ©©1999©Kluwer Academic Publishers     

纤维含量对VARTM制备竹纤维/环氧树脂复合材料性能影响

纤维含量是影响真空辅助树脂传递模塑成型(VARTM)技术制备高性能纤维复合材料的关键因素之一,通过考察竹纤维(BF)含量对VARTM成型过程中环氧树脂(EP)浸渍BF效果及BF/EP复合材料性能的影响,为竹纤维复合材料实际应用提供理论支撑.利用湿法层铺工艺将竹纤维束制作成竹纤维毡,再利用VARTM成型工艺制备出BF含量...     

Ag颗粒含量对SnCu基复合钎料性能的影响

利用颗粒增强原理研制了新型Ag颗粒增强SnCu基复合钎料,研究了Ag颗粒不同含量对复合钎料性能影响.结果表明:当Ag含量(体积分数)为5%时,复合钎料铺展面积最大,润湿角最小,钎焊接头蠕变寿命最长,比基体钎料提高23倍.     

Design and fabrication of gypsum mold for injection molding

Traditionally, a mold made of gypsum can only be used in a low-pressure molding, e.g. casting, due to the weak strength of gypsum material. This study addresses the potential of gypsum as a candidate for rapid tooling used in injection molding. The ingredients for the gypsum mold were decided upon, and an additional compression with a vibration process was introduced to enhance the mechanical strength of the gypsum mold. Scanning electron microscope (SEM) results show that the amount of void inside the gypsum mold is reduced, and more interlocking of the microstructure of gypsum is formed by increasing the intensity of the compression with a vibration process. A higher degree of interlocking produces a significant enhancement of the compressive strength of the gypsum. Two samples were selected as master designs for testing the replication performance and lifetime of the gypsum mold. The dimensional replication accuracy of the molded part was over 99.9%. The maximum lifetime of the gypsum mold is about 210 cycles of injection shots. This work provides an alternative tooling for injection molding that can allow manufacturers to produce a small quantity of prototypes in an efficient and cost-effective way in the early stages of product development.