透析硅橡胶的性能特点及其应用领域

硅橡胶是一种分子键兼具无机和有机性质的高分子弹性材料,硅橡胶具有最广的工作温度范围（-100～350℃）,耐高低温性能优异,此外,还具有优良的热稳定性、电绝缘性、耐候性、耐臭氧性、透气性、很高的透明度、撕裂强度,优良的散热性以及优异的粘接性、流动性和脱模性,一些特殊的硅橡胶还具有优异的耐油、耐溶剂、耐辐射及在超高低温下使用等特性。硅橡胶按其硫化温度,可分为高温（加热）硫化型及和室温硫化型两大类,高温胶主要用于制造各种硅橡胶制品,而室温胶则主要是作为粘接剂、灌封材料或模具使用。硅橡胶又是一种由氧和硅交联成的聚合物制成的独特的合成弹性体。它完美地平衡了机械性质和化学性质,因而能满足今天许多苛刻的应用场合要求,因此受到业内的高度关注。     

环氧硬质复合绝缘子的应用研究

针对目前架空输电线路硅橡胶复合绝缘子存在被鸟啄伤、强风损伤的问题,通过对原材料的选取、成型工艺的控制、结构设计的优化,研制出了一种环氧硬质复合绝缘子。经测试,该产品表现出了优异的电气性能和机械性能,从根本上解决了复合绝缘子被鸟类啄伤的问题,提高了输电线路运行的可靠性。     

冷粘接胶带的应用

我国的许多工厂中大量采用皮带机转送物料。而安装和维修时皮带的接头质量是机器正常运行的关键之一。通常安装和维修皮带机时大都采用传统的热硫化法粘接皮带。它要求有专用的蒸气压包，采用碳棒均匀加热，对粘接胶更有很严格的要求（常用保质期在三个月的生胶，放在航空汽油中浸泡）。工艺上温度要求缓升至１４０℃，气压一般在５～１０×１０Ｐａ，保温时间ｔ＝１６＋（ｉ－３）×２分。皮带只有在这种情况下，才能正常硫化。由此可见热硫化法在工器具及操作工艺上都有很严格的要求。热硫化法在皮带的粘接强度及接头的耐久性上是比较可靠…     

一种复合绝缘子全自动底胶喷涂机的研究

针对目前复合绝缘子底胶涂抹工艺存在的缺陷,研发出了一款全自动底胶喷涂机,可减少人工操作因素干扰,严格控制底胶涂抹质量,大大提高了复合绝缘子硅橡胶伞裙护套与中间环氧树脂纤维棒和连接金具的粘接稳定性,减少了因绝缘子粘接性能不稳定导致的电气问题,降低了线路运行事故的发生率。     

注射成型橡胶制品的自动脱模装置

用于输变电线路的硅橡胶绝缘子大多采用注射成型工艺生产。由于注射时的压力较大，成型后的制品与模腔挤压得非常紧，目前尚无法使制品自动脱离模具，一般采用人工脱模。存在这种现状的主要原因是复合绝缘成型技术应用时间较短，目前一次成型的绝缘子产品长度不超过1．5m。由于长度较小，脱模所需的力尚在人力所及范围，因而人工脱模一直沿用至今。     

架空线路新产品在中原油田电网的应用

随着电力技术的不断发展，一些架空线路新产品在中原油田电网逐步推广应用起来，本文针对新架设的柳三力线，对其采用的绝缘导线，有机硅橡胶复合绝缘子等架空线路新元件在中原油田电网的应用与存在的一些问题进行了分析和讨论。     

航空用苯基硅橡胶生胶的合成及性能研究

为探究生胶结构与应用性能之间关系，设计合成不同苯硅比(Ph/Si)的二苯基硅橡胶生胶和甲基苯基硅橡胶生胶。生胶的DSC分析表明：在苯基改性的硅橡胶生胶中，含苯基硅氧链节的摩尔数量是影响硅橡胶低温结晶、熔融的主要因素；同样苯硅比5%的二苯基硅橡胶生胶是结晶橡胶，而甲基苯基硅橡胶生胶则是非结晶橡胶。硅橡胶硫化胶的物理力学性能分析表明：苯基硅橡胶经热空气老化试验后拉伸强度和拉断伸长率得到较显著的提高，苯基硅氧链节结构形式对耐热影响不显著。硫化胶的低温DMTA分析表明：苯基硅橡胶硫化胶的玻璃化转变温度与苯硅比有关，而与苯基硅氧链节的结构形式关系不大，且随苯硅比的增大，玻璃化转变温度向高温方向移动。压缩耐寒系数分析表明：在相同的苯硅比5%下，非结晶的甲基苯基结构硅橡胶具有更优异的低温性能，结晶的二苯基硅橡胶由于低温结晶使其在较长时间压缩状态下失去橡胶弹性。     

DG-1型硅橡胶车顶支持绝缘子

DG-1型硅橡胶车顶支持绝缘子,能解决现国产电力机车车顶绝缘薄弱易发生闪络导致的机破问题。该绝缘子因具有重量轻(10KG),耐污性能好,免清扫等独特优点,将成为电力机车首选车顶支持绝缘子,可以根本消除因车顶绝缘闪络造成机破的现象。该绝缘子为复合结构绝缘子,主结构由玻璃芯棒外装硅橡胶伞盘组成,采用国内先进的芯棒上连续挤包护套新技术和套伞新工艺;在满足安装尺寸不变的前提下,采用4大3小交叉排列伞盘结构,使爬电距离达到900mm以上,绝缘子表面允许盐密度     

±1100kV特高压大吨位压接式复合绝缘子设计及蠕变、强度分散性浅析

由于防污闪需要,我国特高压输电线路大量采用复合绝缘子,同时因特高压线路导线重量较大而对复合绝缘子机械负荷要求不断提高。国家电网计划建设的世界首条±1 100kV特高压直流输电线路已明确提出压接式复合绝缘子的最大额定机械负荷应从目前的550kN提高到840kN,并对1 000kN产品展开研究。为解决大吨位压接式复合绝缘子的长期运行机械可靠性,从压接工艺、芯棒选择、金具设计等方面展开了研究,并通过短时破坏强度试验及"机械强度—时间"特性试验对大吨位压接式复合绝缘子的蠕变及强度分散性进行了分析论证,得出了满足使用要求的840kN大吨位复合绝缘子。     

DG-1型硅橡胶车顶支持绝缘子

ＤＧ 型硅橡胶车顶支持绝缘子 ,能解决现国产电力机车车顶绝缘薄弱易发生闪络导致的机破问题。该绝缘子因具有重量轻 (1 0ＫＧ) ,耐污性能好 ,免清扫等独特优点 ,将成为电力机车首选车顶支持绝缘子 ,可以根本消除因车顶绝缘闪络造成机破现象。该绝缘子为复合结构绝缘子 ,主结构由玻璃钢芯棒外装硅橡胶伞盘组成 ,采用国内先进的芯棒上连续挤包护套新技术和套伞新工艺 ;在满足安装尺寸不变的前提下 ,采用 4大 3小交叉排列伞盘结构 ,使爬电距离达到 90 0ｍｍ以上 ,绝缘子表面允许盐密度比现电瓷瓶绝缘子高 1 0倍以上。允许运行海拔高度 2 5 0 0…     

格构增强型复合材料板材设计与试验研究

复合材料板材有质量轻和结构强的特点,可用于活动房、方舱和厢式车辆,替代传统的铝合金面层及金属骨架的板材。本文设计了一种格构增强型复合材料夹层结构板材,芯材为硬质聚氨酯泡沫,面层为玻璃纤维/不饱和聚酯树脂复合材料,采用整体模压共固化成型工艺。该板材经过拉伸强度、拉伸模量、拉伸延伸率、线膨胀系数、氧指数及其在规定的高、低温条件下的相关力学性能试验表明,保温隔热性能、力学性能和构造要求满足相关应用要求。     

Relationship between liquidity index and stabilized strength of local subgrade materials in a tropical area

This paper presents the effect of soil liquidity index and cement stabilizer on strength properties for the usage of low traffic volume subgrade roads. Three types of soil were used to represent a different soil based on liquid limit value. Standard proctor tests have been conducted to determine the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) of stabilized soils with 0%, 7%, and 13% Ordinary Portland Cement (OPC). In order to study the effect of the soil Liquidity Index, various moisture contents are used based on the OMC value from the compaction test (0.9, 1.0, and 1.1 from OMC). The California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests were conducted to determine the strength of all soil samples at optimum moisture content after 7 days curing period. It has been observed that the CBR and UCS values increased by increasing the percentage of cement content. This study found that 7% of cement content was the optimum percentage of cement content to be added to all tested soils to achieve the minimum required strength of 0.8 MPa and 80% CBR for low traffic volume roads. The presented results could provide a guideline for engineers as regards the property changes of the local subgrade materials in a tropical area due to the addition of cement content.     

Determination of the principal parameter of ultrasonic pulse velocity and compressive strength of lightweight concrete by using variance method

Experiments are usually made to finding maximum ultrasonic pulse velocity and compressive strength of lightweight concrete. In this study, ultrasonic pulse velocity and compressive strength of lightweight concrete made with scoria aggregate, silica fume and fly ash was investigated experimentally and statistically. This article adopts Taguchi approach. The Taguchi method has been used to determine the optimum conditions and to reduce the numbers of experiments. Four control factors (maximum size of aggregate, curing conditions, mineral admixtures and curing time) for this study were used. The level of importance of these parameters on ultrasonic pulse velocity and compressive strength was determined by using analysis of variance (Anova) method. The text was submitted by the authors in English.     

Strength-toughening model of eutectic ceramic composite with inherent defects

Strengthening and toughening mechanisms in composite ceramics is complex. A change in a single parameter induces multiple property variations. The multiple changes in properties are often incompletely represented in theoretical models. This incompleteness in the parameter chosen fails to explain the mechanism of failure in composite ceramics. The exponential toughness function is used to represent the pull-out toughening mechanism, which dominates the crack growth resistance curve（R-curve）. The strengthening-toughening model is established based on the Mori-Tanaka method（M-T method）. The influence of inherent defects on toughness function and strength is analyzed by using this model. The theoretical result is compared with the experiment data. This model exactly reflects the change in strength. The theoretical result indicates that defects change the toughness function. Moreover, micro-cracks increase toughness size ac, and the strength of crack instable extensions acutely decreases as defect content increases. This presented model establishes the relationship among the important mechanical parameters of defect, strength, elastic modulus, and the R-curve.     

碳纤维/玻璃纤维/石墨协同改性PTFE复合材料力学性能

通过机械混合、冷压和烧结成型制备了碳纤维、玻璃纤维和石墨填充协同改性聚四氟乙烯(PTFE)复合材料。对比分析了不同样品的拉伸、冲击和压缩等力学性能。结果表明:玻纤和碳纤维使复合材料冲击强度下降;玻纤使复合材料拉伸强度下降,碳纤维则使复合材料拉伸强度稍有增强;玻纤和碳纤维均使复合材料压缩强度增加,但碳纤维的增强效果更为明显;石墨、玻纤和碳纤维协同增强PTFE复合材料的拉伸强度较高,弹性模量较大,断裂伸长率较高,抗压缩性能明显提高,且材料拉伸时呈塑性断裂,是综合力学性能较好的高性能润滑密封材料。     

Estimation of welded joint strength using genetic algorithm approach

The genetic algorithm approach is extended to the estimation of mechanical properties of the joining of brass materials. The mechanical properties of joint parts can be improved by selecting suitable parameters. The strength of the joint parts is affected by many factors, such as the gap between the parts, the torch angle, the quantity of the shielding gases, the pulse frequencies and the electrode tip angle during welding operations. Since all these factors affect the mechanical properties of the welded joint parts, the effects of these parameters need to be cautiously investigated. The present paper describes the use of the stochastic search process that is the basis of Genetic Algorithms (GA), in developing the strength value of the welded parts. Non-linear estimation models are developed using GAs. Developed models are validated with experimental data. The Genetic Algorithm Welding Strength Estimation Model (GAWSEM) is developed to estimate the mechanical properties of the welded joint for the brass materials. The effects of five welding design parameters on the strength value using the GAWSEM have been examined. The results indicated that the changes of the gap between the joint parts and the torch angle have an important effect on the welded joint strength value and the optimum quantity of the shielding gas and the pulse frequencies exist in the tensile strength of welded joints.     

室温快速固化高性能环氧树脂胶粘剂研究

为了提高胶粘剂在室温条件下的固化速度,并改善其力学性能,研究了固化剂含量、填料含量对环氧树脂胶粘剂固化速度和力学性能的影响.结果表明,当固化剂含量为95～100 phr,填料含量为60～ 80 phr时,胶粘剂的综合性能最好;该新型胶粘剂在室温12 min即可快速固化,剪切强度可达13.8 MPa,拉伸强度和弯曲强度分别达到了43.1MPa和83.2 MPa.     

NiTi超弹性丝复合材料结构强度的监测

研究了NiTi超弹性丝复合材料结构强度的监测方法,设计和制作了埋入NiTi超弹性丝的玻纤环氧层板复合材料试样,对平板及其含孔洞的试样进行了拉伸试验,实时采集结构中传感元件的输出,以试验的方法监测结构宏观力学行为。结果表明：埋入的超弹性传感元件可对结构的裂纹、断裂特性及强度等进行监测。     

复合材料板簧副簧的优化设计

这里建立了轻型车复合材料副簧的力学模型,根据层合板理论,计算出了副簧的危险应力和最大挠度,并以强度和刚度为约束,以质量最小为目标函数,通过有约束最小化优化方法,对复合材料副簧进行了优化设计,得到了最小质量下的副簧的最佳尺寸。     

Tribological Behavior of Acrylic Acid–Modified Date Palm Leaf–Reinforced Polyvinyl Alcohol Composite

Most machine components are frequently exposed to tribological loadings during their service life. Hence, the tribological performance of materials is an essential element to be considered in the design of mechanical parts in addition to mechanical properties. Previously, authors have studied the mechanical properties of date palm leaf–reinforced polyvinyl alcohol composite. In the present investigation, an attempt has been made to investigate the tribological behavior of the composite under a multipass abrasion condition. The composite was prepared by reinforcing randomly oriented acrylic acid–modified date palm leaf fibers with varying weight percentages of 10, 20, 28, and 30%. The performances of the specific wear rate and wear weight loss were investigated as a function of applied loads and abrading distances. It was observed that 28 wt% is the optimum fiber loading to achieve maximum tribological properties similar to mechanical properties obtained from previous work. Scanning electron microscopy was used to understand the wear mechanisms of the composite at optimum fiber loading.