钒铁炉渣对矾土基自流浇注料性能的影响

以矾土、钒铁炉渣、硅灰为主要原料,铝酸盐水泥为结合剂,制备了矾土基自流浇注料.测试了试样的常温抗折强度、耐压强度、烧后线变化率,利用X射线衍射(XRD)分析了烧后试样的物相组成,采用扫描电子显微镜(SEM)观察和分析了烧后试样的显微结构.结果表明:随着矾铁炉渣加入量的增加,1 10℃烘后试样强度逐渐降低,1350℃烧后试样强度先增大后减小,试样的体积密度略有降低,形成的镁铝尖晶石相逐渐增多,试样烧后线变化率由收缩转为膨胀;引入适量的矾铁炉渣,有益于矾土基浇注料烧结强度的提高,同时能够有效保持材料的体积稳定性,其最佳加入量为40％.     

蓝晶石粒度对刚玉-莫来石材料性能的影响

以粒度为2～1mm和1～0.5mm的M60莫来石为骨料,以电熔白刚玉粉以及粒度分别为0.8～0.355mm、0.355～0.088mm和<0.088mm的蓝晶石为基质料,以少量二氧化硅微粉和苏州土为结合剂,制成36mm×36mm的试样,在110℃干燥24h后,分别在1200℃、1300℃、1400℃和1500℃保温3h煅烧,然后测定烧后试样的线变化率、显气孔率、体积密度和耐压强度。结果表明:(1)对于在各温度下煅烧后的试样,添加粒度<0.088mm蓝晶石的试样烧后线变化率和显气孔率较添加粒度>0.088mm蓝晶石的小,体积密度和耐压强度较添加粒度>0.088mm蓝晶石的大;(2)当添加粒度<0.088mm的蓝晶石时,随着煅烧温度的升高,试样的烧后线变化率、显气孔率、体积密度和耐压强度变化较小;当添加粒度>0.088mm的蓝晶石时,随着煅烧温度的升高,试样的烧后线变化率和显气孔率迅速增大,体积密度和耐压强度迅速减小。     

添加Ti-Si-Fe合金粉对埋碳反应烧结法制备Si_3N_4结合SiC材料性能的影响

以碳化硅颗粒、碳化硅细粉、硅粉、炭黑和Ti-Si-Fe合金粉为主要原料,以热固性酚醛树脂作为结合剂,在埋碳气氛下采用反应烧结法制备Si_3N_4结合Si C材料,研究了Ti-Si-Fe合金粉加入量对材料体积密度、显气孔率、常温耐压强度、烧后线变化率、物相组成和显微结构等的影响。结果表明:1)随着Ti-Si-Fe合金粉添加量从0增加至9%(w),烧后试样的显气孔率逐渐降低,体积密度和常温耐压强度逐渐增大,烧后线变化率从-0. 10%逐渐增大至0. 12%。2)各试样的SiC含量均比配料高;但随着Ti-Si-Fe合金粉添加量的增加,烧后试样的Si C含量逐渐减少,氮化产物含量逐渐增多,表明Ti-Si-Fe合金粉的加入促进了氮化物结合相的形成。3)因Ti-Si-Fe合金粉中的TiSi_2、Ti_5Si_3在氮化过程中的体积膨胀比Si粉的大,以Ti-Si-Fe合金粉部分取代Si粉促进了试样的致密化,提高了试样的力学性能。     

发泡法制备轻质莫来石结合氧化铝空心球制品的性能研究

为了改善莫来石结合氧化铝空心球制品的隔热性能,以氧化铝微粉、二氧化硅微粉和≤3 mm的氧化铝空心球为主要原料,采用发泡法结合凝胶注模工艺制备了轻质莫来石结合氧化铝空心球制品,并研究了发泡时间(5、10、15和20 min)对试样的体积密度、气孔率、耐压强度、显微结构和热导率的影响。结果表明:合成试样的基质部分为气孔孔径50~100μm的多孔结构,与氧化铝空心球结合紧密;随着发泡时间增加,试样的气孔率增加,而体积密度、耐压强度和热导率降低;当发泡时间为20 min时,试样体积密度为0. 71 g·cm-3,气孔率为80. 2%,常温耐压强度为1. 81 MPa,600℃热导率为0. 467 W·m~(-1)·K~(-1)。     

泡沫注凝法制备刚玉-莫来石多孔陶瓷

以T60板状刚玉粉(d50=10.74μm)、ZTP-200氧化铝微粉(d50=4.96μm)、RG4000煅烧氧化铝微粉(d50=1.46μm)和NS-30型硅溶胶为原料,采用泡沫注凝法制备了刚玉-莫来石多孔陶瓷,主要研究了粉料粒度级配(d50分别为1.46、4.96、10.74μm的三种氧化铝粉料的质量分数分别为44%、26%、30%,36%、28%、36%,30%、29%、41%,21%、29%、50%)和浆料中硅溶胶加入量(质量分数分别为0、2%、4%)对坯体的烧后收缩及烧后试样的致密度、常温耐压强度、热导率、相组成和显微结构的影响。结果表明:1)d50=10.74μm的粗颗粒加入量增加,试样的烧后线收缩率、致密度和常温耐压强度减小;2)硅溶胶加入量增加,试样的烧后线收缩率和体积密度减小,但由于SiO2与Al2O3反应生成莫来石,试样的常温耐压强度变化较复杂;3)泡沫注凝法制备的刚玉-莫来石复相多孔陶瓷具有球形孔结构,平均孔径约为140μm,其性能如下:烧后线收缩率9.29%,体积密度0.78 g·cm-3,显气孔率79.8%,常温耐压强度25.3 MPa,1 000℃(热面温度)下的热导率为0.481W·m-1·K-1。     

采用微孔CA6-MA骨料的Al2O3-CaO-MgO轻质浇注料的性能

以自合成的微孔CA6-MA颗粒(8～5、5～3、3～1 mm)为骨料,以速烧刚玉粉(≤0.074、≤0.043 mm)、α-Al2O3微粉、纯铝酸钙水泥为粉料,经配料、混练、振动成型、养护、烘干后,分别在1 000、1 200、1 400、1 600℃保温3 h热处理,检测热处理后试样的永久线变化、显气孔率、体积密度、常温抗折强度、常温耐压强度、热态抗折强度和热导率,并分析其显微结构。结果表明:1)试样在1 600℃热处理后的永久线变化为1.14%,1 600℃热处理后试样的显气孔率为59.84%,体积密度为1.51 g.cm-3,常温抗折强度为2.7 MPa,常温耐压强度为7.3 MPa,1 400℃的热态抗折强度为1.4 MPa,1 000℃的热导率为0.219 W.m-1.K-1;2)1 600℃热处理后试样基质中有大量片状CA6,骨料和基质之间结合很好。     

硅线石含量对轻质莫来石-刚玉耐火材料的显微结构与性能的影响

以多孔球形莫来石为骨料,板状刚玉细粉、硅线石和粘土为基质,经1400 ℃、1500 ℃和1600 ℃保温3 h烧成,制备了四组轻质莫来石-刚玉耐火材料.采用X-射线衍射仪(XRD)和扫描电子显微镜(SEM)对试样的物相组成和显微结构进行表征,研究了烧成温度及硅线石含量(4%、6%、8%和10%)对试样常温物理性能和显微结构的影响.结果表明:(1)当硅线石含量不变时,随着烧成温度的升高,试样的显气孔率逐渐减小,体积密度逐渐增大,线收缩率逐渐增加,常温耐压强度先降低后升高;(2)当硅线石的含量从4%增加到8%时,经1400 ℃烧后,试样的显气孔率和体积密度变化不大,当硅线石含量超过8%时耐压强度显著下降;经1600 ℃烧后,随硅线石含量的增加,试样的体积密度减小,强度降低,线收缩率也由2.5%减小到1.5%;(3)当硅线石含量为6%、烧成温度为1400 ℃时,试样的线收缩率为0.86%,耐压强度为36.1 MPa,热导率为0.249 W/(m·K)(300 ℃),试样基质中气孔的d50为46.7 μm.     

骨料对氧化铝质不烧砖性能的影响研究

以板刚玉、棕刚玉、88高铝矾土等为骨料,加入铝镁结合剂和水,制备了不同骨料的氧化铝质不烧砖。研究了骨料对氧化铝质不烧砖气孔率、体积密度、抗折强度、耐压强度、抗渣性能以及高温抗折强度的影响。实验结果表明:骨料组成为棕刚玉或88高铝矾土和棕刚玉时,试样体积密度较大,气孔率较小,不烧砖制品结构致密;骨料组成为88高铝矾土、棕刚玉和板状刚玉时,试样的重烧线变化率最小,不烧砖制品在高温时体积变化率小,稳定性强;骨料组成为棕刚玉时试样高温耐压强度最高;骨料组成为88高铝矾土和棕刚玉时,试样的常温及中温耐压强度最高,不烧砖制品抗渣性能好。     

不同造孔剂对方镁石-镁橄榄石隔热材料性能的影响

为了利用辽宁地区丰富的镁资源制备方镁石-镁橄榄石质隔热材料,以高纯镁砂(≤3 mm)、镁橄榄石(≤1 mm)、SiO_2粉(≤0.044 mm)为主要原料,在以菱镁矿粉(≤0.074 mm)为主要造孔剂的基础上,分别添加石墨(≤0.149 mm)、炭黑(≤0.044 mm)、聚苯乙烯球(1 mm)、聚丙烯塑料颗粒(1 mm)和木屑(1~2 mm)作为造孔剂,以亚硫酸纸浆废液作为结合剂,在2 MPa压力下压制成型,在110℃保温24 h干燥后,在1 550℃保温3 h烧成,然后检测烧后试样的显气孔率、体积密度、烧后线变化率、常温耐压强度和常温抗折强度,并分析典型试样的物相组成和显微结构。结果表明:1)添加上述造孔剂后,烧后试样的显气孔率增大,体积密度、常温耐压强度和常温抗折强度均减小;试样烧成后均发生收缩,其中,添加石墨的试样的收缩率最小(0.26%),添加木屑的试样的收缩率最大(1.47%);综合比较,添加炭黑的试样的综合性能最优。2)烧后试样的主晶相为方镁石、镁橄榄石及少量的钙镁橄榄石。3)添加粒径较大(1 mm)的聚丙烯塑料颗粒的试样烧后产生了较大的气孔,并且气孔分布不均均;添加炭黑的试样在显气孔率增大的同时仍具有较高的强度。     

Carbores P加入量对硅溶胶结合铁沟浇注料性能的影响

为了获得更加环保的Al2O3-Si C-C铁沟浇注料,在w(电熔棕刚玉颗粒)为60%、w(Si C颗粒和细粉)为21%、w(硅灰)为3%、w(α-Al2O3微粉)为3%、w(白刚玉微粉)为10.5%、w(Si粉)为2.5%的基础配方中,分别以质量分数为0、1%、2%、3%和4%的环保型含碳材料Carbores P等量替代白刚玉微粉,外加质量分数为7%的硅溶胶为结合剂,制成Al2O3-Si C-C浇注料,研究了Carbores P加入量对110℃干燥后及1 100和1 500℃烧后试样显气孔率、体积密度、烧后线变化率、常温耐压强度、常温抗折强度和高温抗折强度的影响。结果表明:随着Carbores P加入量的增加,干燥及烧后试样的显气孔率逐渐增大,干燥后试样的体积密度逐渐减小,1 100℃烧后试样的线膨胀率逐渐增大,干燥后试样的常温抗折强度和常温耐压强度以及1 100和1 500℃烧后试样的常温抗折强度变化均不大;1 100和1 500℃烧后试样的体积密度、1 500℃烧后试样的线膨胀率、1 100和1 500℃烧后试样的常温耐压强度、干燥后试样的高温抗折强度等均呈先增大后减小的变化趋势,均在Carbores P加入量为2%(w)时达到了最大。     

Identification of fiber misalignment in continuous fiber composites

Misaligned fibers are invariably present in nominally unidirectional high‐performance composites. Such misaligned fibers are known to affect key mechanical properties of the composite, such as the longitudinal compressive strength, longitudinal tensile modulus, fatigue endurance, shear strength, and delamination resistance (1). In this paper we present a method for the automated detection of large angle fiber misalignment (θ > 40°) in continuous fiber‐reinforced composite materials. The method relies on the application of a series of geometrical criteria based upon measurements routinely obtained during optical scanning of polished sample cross‐sections. As such, the technique is ideal for the automated identification of highly misaligned fibers in large‐area (∼ cm²) specimens that may contain several millions of individual fiber images. The criteria applied take into account the fact that prepared cross‐sections of such materials contain many damaged fibers as a result of attrition during polishing. Data obtained from three pultruded unidirectional rods reinforced with continuous carbon filaments are used to illustrate the effectiveness of this method in identifying regions where large angle misalignment occurs.     

Direct fiber formation and fiber properties of aromatic polyoxadiazoles

A novel and simple fiber formation process has been developed to fabricate aromatic polyoxadiazoles. The aromatic copolyoxadiazole solution prepared from terephthalic acid, isophthalic acid, and hydrazine sulfate in fuming sulfuric acid was utilized directly as spinning solution and was successfully wet-spun to form fiber into a coagulating bath containing sulfuric acid. In the wet-spinning process, selection of the coagulating bath was the most important factor, and the best results were obtained by the use of approximately 50 wt-% aqueous sulfuric acid. It was easy to prepare a polyoxadiazole fiber having a tenacity of more than 4 g/den. and an elongation of more than 10%. In addition, the fiber properties reached to a tenacity of 6 g/den. and an elongation of 12% under optimum spinning conditions. The wet-spun polyoxadiazole fiber showed an almost round cross section and a clear skin-core structure by microscopic observation. The fiber had a high level of thermal and dimensional stability and a high proportion of property retention at elevated temperatures, as well as all-round general fiber properties.     

锦纶纤维特性及纤维骨架材料的发展

一、锦纶骨架材料世界应用概况 锦纶66的合成及纺丝技术于1935～1937年由美国杜邦公司的Carothers发明，并于1938年实现了中试规模，第二次世界大战期间美国开始使用锦纶66帘布制造军用飞机轮胎，1947年后用于载重胎，到50年代后期，美国的载重胎用骨架材料几乎完全由锦纶66取代了人造丝。德国于1941年实现锦纶66工业化生产。日本1958年发明用锦纶6做轮胎骨架材料制造轮胎。     

Interpretation of fiber fragmentation in carbon/epoxy single fiber composites: Possible fiber pre-tension effects

The fiber straightening pre-tension applied during the sample preparation of single fiber composites is suggested here to significantly affect the number of fragments as well as the value of the Kelly-Tyson interface shear strength obtained from single filament composite tests. This implies that fragmentation tests performed under seemingly identical conditions, but in which the fiber pre-tension is not accurately controlled during sample preparation, might yield widely differing experimental results. We present and discuss a new set of experimental results dealing with fiber pre-tension effects in carbon/epoxy single fiber composites.     

Effect of polypropylene fiber processing conditions on fiber mechanical behavior

An investigation into the mechanical behavior of melt‐spun isotactic polypropylene (iPP) fibers is reported. Two different iPP formulations, PH835 and Exxon3854, synthesized using Ziegler–Natta and metallocene catalysts, respectively, and spun at take‐up velocities ranging from 1000 to 3000 m min^?1 were subjected to uniaxial tensile loading, cyclic loading and creep tests. The strain rate sensitivity was determined by performing strain rate jumps. Injection molded specimens from the same iPP formulations were tested under the same conditions. The fiber birefringence increases slightly with increasing take‐up velocity, while the crystallinity is approximately insensitive to this process parameter in this range of velocities. Fibers from the two iPP samples behave differently at large plastic strains despite having the same birefringence and crystallinity. Differences are also seen in creep. The behavior of fibers is significantly different from that of the injection molded samples of the same iPP and same crystallinity. These have lower strain hardening rate, smaller failure strains, close to zero strain rate sensitivity and exhibit a yield point phenomenon. The difference is associated with the different nature and spatial organization of the crystals and inter‐crystalline amorphous and mesomorphic phases. © 2014 Society of Chemical Industry     

P84纤维和普抗纤维性能介绍及应用

1前言 随着国家对大气治理力度的加大,对排放浓度要求越来越严,其它一些除尘器已不能满足新标准的要求,唯有袋式除尘器能实现这一点.滤袋作为袋式除尘器的关键部件,其性能直接影响着排放浓度和使用寿命,滤袋器的发展,远远跟不上滤袋本身的发展,新的滤材不断出现,下面仅对两种性能较突出的P4纤维和普抗纤维的性能及应用进行初步探讨.     

The viscosity of fiber suspensions at low fiber volume fractions

The viscosities of suspensions of glass fibers in an aqueous solution of sucrose have been studied by use of a capillary viscometer. In the aligned condition in the capillary, the viscosity depends little on shear rate within the range studied or on fiber length, but increases with increasing volume fraction of the fibers. The entrance effect was found to depend strongly on fiber volume fraction and fiber length: this indicates that the suspensions are relatively resistant to flow during the initial stages while alignment takes place.     

工程用聚丙烯腈纤维为基体的羧酸纤维的制备

采用断裂强度为12.26 cN/dtex、玻璃化转变温度高于250℃的工程用聚丙烯腈纤维(PAN-EF)为基体纤维,通过二甲基亚砜(DMSO)和氢氧化钠(NaOH)混合水解制备羧基含量(M_COOH)高且力学性能好的PAN-EF基羧酸纤维(PAN-EF-COOH),探讨了DMSO浓度、反应温度和反应时间对纤维水解效果的影响。结果表明:加入溶胀剂DMSO,可以降低PAN-EF在碱性条件下的水解难度;随着DMSO浓度增加、反应温度提高、反应时间延长,PAN-EF-COOH的M_COOH显著增大,但断裂强度逐渐降低;PAN-EF在NaOH质量分数0.1%、DMSO体积分数50%、反应温度120℃、反应时间2.5 h条件下水解,可以获得M_COOH较高且力学性能好的羧酸型纤维PAN-EF-COOH,纤维M_COOH为2.00 mmol/g、断裂强度为9.92 cN/dtex。     

Pineapple leaf fiber reinforced thermoplastic composites: Effects of fiber length and fiber content on their characteristics

Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and low‐density polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0–25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Impact behavior of carbon fiber/polyethylene fiber hybrid composite: The effect of surface treatment of polyethylene fiber

Hybrid composites were prepared by adding one or two plies of polyethylene (PE) fabric to the bottom side of four-ply carbon fiber/vinylester composites. The effect of the surface treatment of PE fiber on the impact properties of carbon fiber/PE fiber hybrid composites was investigated using oxygen plasma, γ-MPS, and γ-MPS-modified polybutadiene (PB/γ-MPS) as surface modifiers. Carbon fiber/vinylester composite exhibited brittle failure with cross-shaped crack at the back side. The addition of PE fabric on the bottom side resulted in a change of the impact behavior of hybrid composites. After hybridization, the absorption of much impact energy was attributed to a considerable degree of plastic deformation in PE plies and the delamination at the interface between carbon and PE layer. However, the surface treatment of PE fiber reduced the impact energy of composites with restriction of deformation at the interface between the carbon and the PE layer. Moreover, the addition of a treated PE layer decreased the degree of deformation with a dagger-shaped deformation zone at the back side. The extent of the deformation area had a significant effect on the impact energy of the hybrid composites.