PVD涂层阶梯杆的磁粒研磨加工研究

为了改善PVD(Physical Vapor Deposition)涂层阶梯杆的表面质量,实验中采用磁粒研磨的方法对阶梯杆进行磨削加工,并对实验参数进行优化,得出最佳磨削加工参数。结果表明,优化后的实验参数为:磁性磨粒的粒径大小为250μm,车床主轴转速为750 r/min,加工间隙为3 mm。用优化后的参数对阶梯杆进行磨削加工40 min,阶梯杆表面粗糙度从原始的Ra 1.35μm降低到Ra 0.26μm,阶梯杆表面光洁度有明显提高。     

The use of fire‐retardant intumescent mats for fire and heat protection of glass fibre‐reinforced polyester composites: Thermal barrier properties

This study investigates the use of integral, hybrid intumescent thermal barriers (mats) to provide surface protection to the core fibre‐reinforced polyester composite structural integrity when exposed to a fire or heat source. Glass fibre‐reinforced composites protected by intumescent mats/fabrics containing silicate fibres, expandable graphite and in some cases borosilicate glass bounded together by an organic matrix have been evaluated for fire performance under a constant heat flux of 50kW/m². The effect of insulative fabric thickness as well as chemical composition on the flammability of the resultant hybrid composites is evaluated. Glass fibre‐reinforced polyester (GRP) composites without any surface protection have a relatively higher time‐to‐ignition and peak heat release rate values when compared with core composites protected by insulative fabrics. Thermograms representing the variation of temperature on the reverse side of the hybrid composites with time when exposed to a constant heat flux show that the inclusion of intumescent surface barriers results in retarded temperature increments within the core GRP composites. Copyright © 2009 John Wiley & Sons, Ltd.     

Composite machining damage quantification using thermoelastic stress analysis

A new experimental method is presented for quantifying machining damage in polymer matrix composites. The method consists of capturing infrared images of machined samples and using thermoelastic stress analysis to quantify damage from the machining event. A modified stress concentration factor is presented as an easily measured and useful damage parameter. Circular holes were drilled into the center of plate specimens fabricated from a commercially available glass fiber reinforced composite. A standard drill bit, brad point drill bit, and abrasive water jet machining were the three machine tools investigated. Infrared images were used to quantify the machining damage by assigning a thermoelastic stress analysis based stress concentration factor (mSCF) to each machined hole. The mSCF was then used to rank the damage inherent to each machining method. Optical and electron microscopy were utilized to identify the types of damage associated with the three machining methods. Finally, each sample was fatigued to failure to substantiate the IR results. The ranking of damage based upon the mSCF was in good agreement with the fatigue lifetime rankings: higher mSCF is associated with shorter fatigue lifetimes.     

Modeling and optimization of operating parameters for abrasive waterjet turning alumina ceramics using response surface methodology combined with Box–Behnken design

Abrasive waterjet turning is a newly emerging non-traditional technology for machining ceramics. In the present study, an attempt has been made to investigate the effect of operating parameters on depth of penetration and surface roughness (Ra) in turning of alumina ceramics using abrasive waterjet. The quadratic regression models were developed to predict the depth of penetration and Ra by experiments using Response Surface Methodology. The influence of each operating factors has been studied through analysis of variance technique. Key parameters and their interactive effects on depth of penetration and surface roughness have also been presented in graphical contours which are useful for choosing operating parameter preciously. The operating parameters for depth of penetration and surface roughness were simultaneously optimized by RSM with desirability function. The absolute average error between the experimental and predicted values at the optimal combination of parameter settings for depth of penetration and surface roughness were calculated as within 5%. Thus the developed model can be effectively used to predict the depth of penetration and surface roughness in the machining of alumina ceramics.     

燃气流作用时间对玻璃钢层间剪切强度的影响

研究了不同燃气流作用时间对玻璃钢层间剪切强度的影响。研究结果表明:随着燃气流作用时间的延长,玻璃钢表面碳化失效层数呈增加趋势;未烧蚀部分复合材料层间剪切强度虽有降低,但是降低幅度不大,说明表面的玻璃布层碳化失效对深层复合材料层间剪切强度影响不大;烧蚀后复合材料断裂模式由韧性转变为脆性。该研究结果为玻璃钢在燃气流环境中的应用提供了重要的数据支撑。     

Mechanical and three‐body abrasive wear behaviour of SiC filled glass‐epoxy composites

Fiber/filler reinforced polymer composites are known to possess high strength and attractive wear resistance in dry sliding conditions. How these composites perform in abrasive wear situations needs a proper understanding. Hence, in this research article the mechanical and three‐body abrasive wear behaviour of E‐glass fabric reinforced epoxy (G‐E) and silicon carbide filled E‐glass fabric reinforced epoxy (SiC‐G‐E) composites are investigated. The mechanical properties were evaluated using Universal testing machine. Three‐body abrasive wear tests are conducted using rubber wheel abrasion tester wherein two different loads and four varying abrading distances are employed. The results showed that the wear volume loss is increased with increase in abrading distance and the specific wear rate decreased with increase in abrading distance/load. However, the presence of SiC particulate fillers in the G‐E composites showed a promising trend. The worn surface features, when examined through scanning electron microscopy, show higher levels of broken glass fiber in G‐E system compared to SiC‐ filled G‐E composites. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Abrasive water jet machining and mechanical behavior of banyan tree saw dust powder loaded polypropylene green composites

Banyan tree saw dust powder (BSD) filled Polypropylene (PP) green composites have been fabricated with varying amounts viz., 0%, 20%, and 40% of BSD particulate filler by using a co‐rotating twin screw extruder followed by injection molding. The mechanical properties such as surface hardness, tensile behavior, and impact strength of the fabricated PP/BSD green composites have been studied in order to standardize the composites. Abrasive water jet (AWJ) machining has been reported mainly for ceramics, concrete, and glass but not much literature is available on AWJ machining of polymer composites. This research is aimed at examining the AWJ machining of green polymer composites. The effect of BSD loading on the AWJ machining behavior of the PP/BSD green composites has been investigated. Furthermore, the effect of addition of 4% maleic anhydride grafted PP (coupling agent) and 4% talc (mineral filler) on the machining behavior of PP/BSD composites has also been evaluated. Surface roughness and optical micrographs of the AWJ cut composite specimens were examined to assess the effect of BSD content, AWJ traverse speed and pressure on the machining behavior of the composites. In order to probe the mechanism of AWJ machining behavior of PP/BSD composites, the kerf width and taper have been measured and results are correlated. POLYM. COMPOS., 37:1754–1764, 2016. © 2014 Society of Plastics Engineers     

Flame retardant synergy between interfacial and bulk carbonation in glass fiber reinforced polypropylene

Glass fiber reinforced polypropylene (GF-PP) composites have high flammability on account of wick effect which leads to accelerated flow of the polymer melt along the glass fibers (GF) surface to the flame zone. In this study, dipentaerythritol (DPER), a charring agent, was adsorbed on the GF surface through the hydrogen bond between silane coupling agent and DPER. DPER has a synergistic effect with the intumescent flame retardants (IFR) added in the composites, which can induce interfacial carbonization on the surface of GF, thus transforming the intrinsic smooth GF surface into roughness one. In this way, the negative effect of the wick effect in flame retardancy is weakened. Moreover, the char residues remained on the surface of GF can bring an improved adhesion between GF and char residues formed in the resin so that a more stable barrier char layer is formed. The PP composites with 20 wt% modified glass fiber (M-GF) and 30 wt% IFR can achieve the UL-94V-0, and its limiting oxygen index (LOI) value increased from 16.5% to 29.5%. Simultaneously, the heat release rate (HRR), total heat release (THR) and total smoke release (TSR) decreased significantly, and the peak of heat release rate (PHRR) reduced 60.6% compared with GF-PP.     

Effect of Nanoclay on the Impact Properties of Glass Fiber-Reinforced Polymer Composites

This paper presents the influence of nanoclay and E-glass fibre reinforcement on impact response in polymer composite laminates under low velocity impact loading conditions. Glass fibre reinforced epoxy/nanoclay composites were prepared by hand lay-up techniques. Morphological studies using SEM and XRD revealed that fully intercalation of nanoclay in epoxy system. The result showed that the energy absorption became more efficient and also increased by 21% for CSM fibre composites at the velocity of 4.42 m/s, when 3% nanoclay was added. The fracture surface of the nanocomposites was analyzed using the Scanning electron microscopy (SEM) to characterize the damage progression.     

Adhesion of polymers to reinforcing fibres

A single fibre pull out technique is presented which makes it possible to measure the strength in the interface between fibre and polymer with high precision even if the embedded length of the fibre is short. The method allows measurements for all kinds of fibres in thermoplastic or thermosetting polymers. The effect of fibre surface treatment can be investigated as well as the effect of morphology or internal stresses in the polymer. Examples are given. The shear strength results are compared with results of tensile shear tests performed on symmetrically notched unidirectional reinforced composite samples. The correlation is good and it is shown that the new single fibre pull out method is able to give a better discrimination between the composites than other methods. An analysis of mechanical stress induced during the pull out demonstrates the use and limitation of this method.     

等离子体射流载气流量大小对玻璃纤维改性效果影响的研究

通过大气压等离子体射流在玻璃纤维（GF）表面沉积氧化硅（SiOx）纳米颗粒的方法改善玻璃纤维增强聚丙烯（GFRP）复合材料的界面结合性能,利用扫描电子显微镜、原子力显微镜和X射线光电子能谱等表征分析了改性纤维的表面形貌、化学成分、润湿性能和复合材料的界面结合性能,并考察了等离子体射流载气流量大小对GF改性效果的影响。结果表明,当载气流量为40 mL/min时,GF的改性效果最好,且此时GF的表面能相比对照组提高了43.18%,GFRP复合材料的层间剪切强度提高了30.79%;经过等离子体处理后,GF的表面粗糙度增大,极性官能团增多,复合材料的界面结合性能提升。     

玻璃纤维布/苎麻纤维布混杂增强不饱和聚酯树脂的研究

采用玻璃纤维布与苎麻纤维布混杂增强不饱和聚酯(UP)树脂制备复合材料,研究玻纤布与苎麻布的相对比例及偶联剂处理对复合材料力学性能的影响,研究了不同复合材料的吸水性并与玻璃纤维复合材料和苎麻纤维复合材料二者进行了比较。结果表明,混杂纤维增强复合材料的拉伸强度、拉伸模量随混杂纤维中苎麻布含量的增加而下降,弯曲强度及弯曲模量在混杂纤维中苎麻布与玻纤布的比例为10∶20和15∶15时分别达到最大值188.09 MPa和1.56 GPa;所有偶联剂处理均可明显改善复合材料的拉伸模量及弯曲模量,硅烷类偶联剂的效果更佳,NDZ401可使复合材料的拉伸强度得到最大幅度(37.66%)的提高,而KH570及NDZ401对改善弯曲强度效果最佳;复合材料吸水后,厚度变化率大于宽度变化率,温度升高,复合材料吸水后尺寸变化率及吸水率均增大,混杂纤维复合材料的吸水率与玻纤布复合材料的吸水率相近,远低于苎麻布复合材料的吸水率。     

离子交换器的玻璃钢衬里

介绍了锅炉给水处理用的离子交换器传统村里方法的缺点。本文推荐用玻璃钢衬里。介绍了本法的施工方法、工艺及其优点。     

Tensile properties of plant fibre‐polymer composites in fire

The structural performance of polymer composites reinforced with plant fibres when exposed to fire was experimentally evaluated and compared against an E‐glass fibre laminate. Fire testing under combined one‐sided radiant heating and static tensile loading revealed that flax, jute, or hemp fibre composites experience more rapid thermal softening and fail within much shorter times than the fibreglass laminate, which is indicative of vastly inferior structural performance in fire. The plant fibre composites soften and fail before the onset of thermal decomposition of the plant fibres and polymer matrix, whereas the E‐glass fibres provide the composite with superior tensile properties to higher temperatures and higher applied tensile stresses. The tensile performance of the three types of plant fibre composites in fire was not identical. When exposed to the same radiant heat flux, the flax fibre composite could withstand higher tensile stresses for longer times than the hemp and jute laminates, which showed similar performance.     

Development of magnetic nanoparticle based nanoabrasives for magnetorheological finishing process and all their variants

Efficacy and the outcome of the magnetorheological finishing (MRF) related processes depends on two crucial factors, (i) a finishing abrasive and (ii) a magnetic particle. However, the magnetic particles although necessary, become a hindrance for non-magnetic abrasive particles in directly reaching the surface to be finished. This study relates to the development of SPION-based smart material for MRF and all their variant processes. The SPION particles possess dual nature such as nanoabrasives and magnetic nanoparticle. The superparamagnetic property of the developed SPION particle has been confirmed by alternating gradient magnetometer with the saturation magnetization value of 82.23 emu/g. The polishing performance of the developed SPION-based particle as abrasive has been investigated on a BK-7 optical glass and the polishing is done via a 5-axes automated ball end magnetorheological finishing (BEMRF). The developed SPION abrasive enhanced the finishing process of the BEMRF technique and provided surface finishing on the BK-7 substrate up to the surface roughness (Ra) values of 22.3 nm with the Ra improvement of 88.14%.     

Pretreatments of natural fibers and their application as reinforcing material in polymer composites—A review

In recent years, natural fibers reinforced composites have received much attention because of their lightweight, nonabrasive, combustible, nontoxic, low cost and biodegradable properties. Among the various natural fibers; flax, bamboo, sisal, hemp, ramie, jute, and wood fibers are of particular interest. A lot of research work has been performed all over the world on the use of natural fibers as a reinforcing material for the preparation of various types of composites. However, lack of good interfacial adhesion, low melting point, and poor resistance towards moisture make the use of natural fiber reinforced composites less attractive. Pretreatments of the natural fiber can clean the fiber surface, chemically modify the surface, stop the moisture absorption process, and increase the surface roughness. Among the various pretreatment techniques, graft copolymerization and plasma treatment are the best methods for surface modification of natural fibers. Graft copolymers of natural fibers with vinyl monomers provide better adhesion between matrix and fiber. In the present article, the use of pretreated natural fibers in polymer matrix‐based composites has been reviewed. Effect of surface modification of natural fibers on the properties of fibers and fiber reinforced polymer composites has also been discussed. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

复合材料/玻璃钢在煤矿中的应用研究

玻璃纤维增强聚合物基复合材料简称为玻璃钢,其优异的物理、力学、化学性能而得到广泛关注并在国民经济的诸多领域得到应用。文章对玻璃钢的优异性能及其在煤矿领域的应用研究工作做了简要论述,展望了玻璃钢在煤矿的广阔应用前景。     

Enhancing ductile removal of Cf/SiC composites during abrasive belt grinding using low-hardness rubber contact wheels

C_f/SiC composites are used as advanced thermal protection and friction materials. However, machining these materials is difficult because of their hard, brittle, anisotropic, and heterogeneous characteristics. This study investigated the removal behavior and surface integrity of C_f/SiC composites during abrasive belt grinding using rubber contact wheels of various hardness. Additionally, detailed analysis was performed on their thermal-mechanical coupling characteristics, surface integrity (that is, surface roughness, surface micro morphology, and subsurface damages), and the grinding chips produced. Results revealed that with decreasing hardness of the contact wheel, the surface roughness in all directions, grinding force, and temperature decreased significantly. Moreover, the surface removal morphology of the C_f/SiC composites changed from macro-fracture to micro-fracture, and the subsurface morphology changed from SiC matrix cracking and carbon fibers pull-out to matrix plastic flow and fiber micro-fracture, respectively. Furthermore, strip chips with plastically squeezed and cut surfaces were visible in the grinding chips obtained under the 40-HA contact wheel. Therefore, the ductile removal behavior of the C_f/SiC composites was enhanced, and the surface quality in abrasive belt grinding with low-hardness contact wheels was markedly improved.     

Numerical and experimental investigations on NANO-SIO2 jet polishing efficiency by different nozzle structures

This paper focuses on the fused silica material removal efficiency with different nozzle structures during nano-SiO₂ jet polishing. The removal function and flow field distribution are with different nozzle structures obtained from the numerical and experimental investigations. The results show that under the same conditions, the removal efficiency of single-slit nozzle is 2.55 times that of single-hole nozzle, and the removal efficiency of multi-slit nozzle is 1.65 times that of the single-slit nozzle. The optimal length and width of a single slit is 5 mm and 0.6 mm, respectively. Finally, the variation of surface roughness is obtained with slit nozzle structure. With the increase of removal depth, the surface roughness of fused silica decreased from 1.86 nm to 0.491 nm, which further verified that the slit nozzle can quickly achieve super-smooth machining of fused silica surface during nano-SiO₂ jet polishing.     

Influence of cenosphere filler additions on the three‐body abrasive wear behavior of glass fiber‐reinforced epoxy composites

The dry three‐body abrasive wear behavior of bi‐directional glass fabric reinforced epoxy composites with and without cenosphere filler have been studied using dry sand/rubber wheel abrasion tester. The angular silica sand particle sizes in the range 200–250 μm were used as dry and loose abrasives. The wear experiments have been conducted at two different loads viz., 22 and 32 N and different abrading distances viz. 270, 540, 810, and 1,080 m. The wear volume increases with an increase in load/abrading distance for all composites. From the experimental wear data it was observed that the abrasive wear of the composites dependent on the applied load and abrading distance. Further, the cenospheres filler inclusion in glass fiber reinforced epoxy (G‐E) composite showed poor abrasive wear performance. Scanning electron microscopy was used to study the morphology of the worn surface features of composites and to understand the mechanisms involved in the wear analysis. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers