偶联剂对钛酸钾晶须/双马来酰亚胺树脂摩擦磨损性能的影响

研究了不同偶联剂及钛酸钾晶须添加量对钛酸钾晶须 /双马来酰亚胺树脂复合材料的摩擦磨损性能的影响 .结果发现 ,钛酸钾晶须能明显提高复合材料的耐磨性 ,晶须的加入使材料的磨损率得到显著降低 ;钛酸钾晶须对材料具有一定的润滑性 ,添加晶须后材料的摩擦系数与树脂基体基本相当 ;偶联剂对复合材料的摩擦系数影响不大 ,但是合适的偶联剂对材料耐磨性的提高则具有明显的作用 .晶须添加量较低时 ,复合材料的磨损机理主要为较严重的粘着磨损 ,晶须添加量较高时 ,疲劳磨损占主导地位 .     

稀土/MoSi2复合材料的干摩擦磨损性能

运用M－2型摩擦磨损试验机测定了不同载荷条件下稀土／MoSi2复合材料与45钢配对件的干摩擦磨损性能，采用SEM观察了摩擦副表面的形貌和X射线分析了磨屑相组成，并探讨了其磨损机制。结果表明：稀土／MoSi2和MoSi2与45钢干摩擦时，在负荷不超过150N的范围内，其摩擦系数μ和磨损率W与负荷p间较好地满足关系式：W（或μ）＝a bp cp^2 p^3 ep^4，两种均具有优异的耐磨性能，在80－120N范围，稀土／MoSi2复合材料的磨损率比纯MoSi2材料的至少降低了65％；稀土／MoSi2材料的磨损机制主要是粘着磨损。     

拉伸力场主导作用下硫酸钙晶须(CSW)/PBS复合材料的制备与性能研究

利用基于拉伸力场主导作用下的叶片塑化挤出机分别制备硫酸钙晶须(CSW)含量为0、5%(wt)、10%(wt)、15%(wt)、20%(wt)的硫酸钙晶须(CSW)/PBS复合材料,并讨论了CSW的含量对复合材料力学性能、热稳定性、结晶性能的影响。测试结果表明:当CSW的添加量为PBS的15%(wt)时,复合材料的综合力学性能最优,拉伸模量,弯曲模量和弯曲强度分别提高;随着CSW含量的增加,球晶尺寸减小,成核密度增加,结晶温度也有显著提高;引入CSW对PBS的熔融行为没有影响;热失重分析表明CSW有助于提高复合材料的热稳定性。     

纳米纤维素晶须的表面改性及其在环氧树脂中的应用

以棉纤维素为原料,采用硫酸水解法制备了纳米纤维素晶须.以N,N-二甲基甲酰胺(DMF)为分散介质,二甲基氨基吡啶(DMAP)为催化剂,十二烯基琥珀酸酐为酯化剂对纳米纤维素晶须进行化学改性,得到了一系列取代程度不同的改性产物(记为DCNW).采用红外光谱(FTIR)、X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对DCNW的结构和性能进行了分析和表征.选择表面取代度为0.3的改性产物作为复合材料的增强相.该改性产物能在丙酮中均匀分散和稳定悬浮,并且保持了改性前纳米纤维素晶须的棒状形态和高结晶度.将其分散于环氧单体中,通过浇铸法制备了纳米复合材料,考察了改性纳米纤维素晶须添加量对纳米复合材料拉伸性能、动态力学性能及耐湿热性的影响规律.结果表明,与空白环氧树脂相比,添加了改性纳米纤维素晶须的纳米复合材料的拉伸强度、杨氏模量和断裂伸长率都得到了提高.玻璃化转变温度、耐湿热性也得到了显著改善.其中,当改性纳米纤维素晶须的添加量为3.5%时,拉伸强度从纯环氧的39.85 MPa提高到72.33 MPa,增加了82%;杨氏模量增大了21%;断裂伸长率从纯环氧树脂的2.45%提高到7.29%,增加了198%;Tg值从纯环氧的103.4℃,提高到134.1℃;吸水率从1.9%下降到1.4%.     

W掺杂NbSe2及其Cu基复合材料摩擦学性能研究

本文利用固相合成法制备W掺杂的NbSe2,且以Nb1-xWxSe2为固体润滑相,Cu为基体相,通过粉末冶金的方法制备出不同质量百分比含量的Nb1-xWxSe2/Cu基复合材料。利用XRD、SEM、TEM测试手段分析了样品中的相成分、微观形貌,采用电阻率检测仪、材料试验机和排水法测试块体样品的电阻率、硬度和密度,并用摩擦磨损试验机对其摩擦磨损性能进行评价。结果表明随着W掺杂量的增加,Nb1-xWxSe2的形貌由规则的微米六方片转变为纳米片和纳米带的混合,掺杂对电阻率影响不大。随着Nb1-xWxSe2添加量的增加,Nb1-xWxSe2/Cu基复合材料的电阻率缓慢升高,摩擦系数呈现不同规律变化。当Nb1-xWxSe2中W掺杂量x=0且其添加质量为10%时,NbSe2/Cu基复合材料体系拥有最佳摩擦磨损性能,摩擦系数为0.15,磨痕平滑且宽度较窄。当Nb1-xWxSe2中W掺杂量x=3%且Nb0.97W0.03Se2的添加质量为5%时,Nb0.97W0.03Se2/Cu基复合材料拥有最佳摩擦磨损性能,摩擦系数为0.17,磨痕更加平滑且磨痕浅。这是由于Nb0.97W0.03Se2中同时均匀存在纳米带和纳米片,它们互相缠绕在一起,在复合材料中纳米片起到润滑成膜的作用,纳米带类似于鸟巢中的草屑和树枝,起到了增强增韧的作用,促使材料的力学和摩擦学性能同时提高。     

钛酸钾晶须对热硫化硅橡胶性能的影响

研究了钛酸钾晶须对热硫化硅橡胶复合材料的硫化特性、力学性能及热稳定性的影响,通过扫描电镜观察了复合材料的断面及晶须在基体中的分散性。结果表明:钛酸钾晶须能促进硅橡胶的硫化,提高其最高扭矩;同时,钛酸钾晶须对硅橡胶具有一定的补强作用,拉伸强度、硬度等随晶须用量的增加而增大;钛酸钾晶须的引入,使硅橡胶复合材料的热稳定性明显提高,填充量为9vol%时,与纯硅橡胶相比,复合材料的热分解温度提高了65℃,Kissinger法求出填充量为12vol%的钛酸钾晶须/硅橡胶复合材料的热分解活化能为193.62kJ/mol,高于相同填充量的白炭黑/硅橡胶复合材料,具有较好的热稳定性。     

微米级硫酸钙晶须的制备

为了制备分布均一、具有较好光滑性和长径比的微米结构二水硫酸钙(CaSO4.2H2O)晶须,在室温条件下,以CaCl2和(NH4)2SO4为主要原料,通过一步超声反应制备出具有比较理想结构的微米级二水硫酸钙晶须。研究发现,在硫酸钙晶须生成过程中无水乙醇的量起着非常重要的作用,过多、过少的无水乙醇都不利于生成目标产物。CTAB的量对于二水硫酸钙晶须的长径比大小具有较大的调控作用。当无水乙醇的量为20mL,CTAB的浓度为0.9mmol/L,超声时间为1h时可以制备较理想的目标产物。120℃热处理2h晶须变碎,结果与热重结果相一致。与一般的晶体制备不同的是陈化时间对硫酸钙晶须的长径比无影响。通过X射线粉末衍射和热重分析分别对产物的结构和热稳定性进行了表征。结合实验简单探讨了二水硫酸钙晶须生成的机理,从中发现了制备较高长径比的二水硫酸钙晶须的一些规律。     

多巴胺改性氧化石墨烯对TDE-85环氧树脂的增韧研究

采用多巴胺改性氧化石墨烯(DGO)对TDE-85进行增韧研究.研究发现,与纯TDE-85和TDE-85/GO复合材料相比,DGO的加入在保持TDE-85良好耐热性的同时使其力学性能得到了提高.尤其是当DGO的含量为0.05 wt%时,TDE-85/DGO复合材料的韧性(临界应力强度因子,KIc)提高了284.2%.这可归结为DGO与TDE-85基体树脂的界面结合性较好,当裂纹扩展时在DGO处出现了明显的裂纹阻碍和偏转现象.     

稀土对镁合金AZ91D摩擦磨损性能的影响

研究了不同稀土含量对AZ91D镁合金摩擦磨损性能的影响，结果表明：在所研究的范围内，稀土镁合金的摩擦磨损特性明显优于基体合金，含与不含稀土镁合金的磨损速率都随载荷的增加而增加，磨损机制均发生了由轻微磨损向严重磨损的转变，稀土的加入细化了合金组织，改善了镁合金的综合性能，增强了磨损表面氧化膜的稳定性，提高了稀土镁合金的承载能力，有效地延迟了由轻微磨损向严重磨损的转变过程。     

钛酸钾晶须填充环氧树脂复合材料的摩擦磨损特性

以提高环氧树脂的摩擦磨损性能为目的,研究了钛酸钾晶须(PTW)填充环氧树脂复合材料的滑动干摩擦磨损特性,着重探讨PTW含量、摩擦条件等对复合材料摩擦性能的影响.通过对复合材料磨损表面的形貌分析以及复合材料表面硬度的测定,探讨了复合材料的磨损机理.结果表明:PTW能明显提高环氧树脂耐磨性并降低其摩擦系数,w(PTW)=0.08的环氧树脂复合材料的耐磨性比纯环氧树脂提高近10倍,摩擦系数降低35%.     

Friction and wear properties of combined surface modified carbon fabric reinforced phenolic composites

Carbon fabric (CF) was surface treated with silane-coupling agent modification, HNO₃ oxidation, combined surface treatment, respectively. The friction and wear properties of the carbon fabric reinforced phenolic composites (CFP), sliding against GCr15 steel rings, were investigated on an M-2000 model ring-on-block test rig. Experimental results revealed that combined surface treatment largely reduced the friction and wear of the CFP composites. Scanning electron microscope (SEM) investigation of the worn surfaces of the CFP composites showed that combined surface modified CFP composite had the strongest interfacial adhesion and the smoothest worn surface under given load and sliding rate. SEM and X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the fiber surface became rougher and the oxygen concentration increased greatly after combined surface treatment, which improved the adhesion between the fiber and the phenolic resin matrix and hence to improve the friction-reduction and anti-wear properties of the CFP composite.     

Effects of cellulose whiskers on properties of soy protein thermoplastics

Environmentally-friendly SPI/cellulose whisker composites were successfully prepared using a colloidal suspension of cellulose whiskers, to reinforce soy protein isolate (SPI) plastics. The cellulose whiskers, having an average length of 1.2 microm and diameter of 90 nm, respectively, were prepared from cotton linter pulp by hydrolyzing with sulfuric acid aqueous solution. The effects of the whisker content on the morphology and properties of the glycerol-plasticized SPI composites were investigated by scanning electron microscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, ultraviolet-visible spectroscopy, water-resistivity testing and tensile testing. The results indicated that, with the addition of 0 to 30 wt.-% of cellulose whiskers, strong interactions occurred both between the whiskers and between the filler and the SPI matrix, reinforcing the composites and preserving their biodegradability. Both the tensile strength and Young's modulus of the SPI/cellulose whisker composites increased from 5.8 to 8.1 MPa and from 44.7 to 133.2 MPa, respectively, at a relative humidity of 43%, following an increase of the whisker content from 0 to 30 wt.-%. Furthermore, the incorporation of the cellulose whiskers into the SPI matrix led to an improvement in the water resistance for the SPI-based composites.     

The mechanical and tribological behaviors of PI composite filled with plasma treated UHMWPE fiber

The friction and wear behaviors of ultra‐high molecular weight polyethylene (UHMWPE)/PI composite were investigated in a ring‐on‐block wear tester. Ti6Al4V alloy ring were selected as the counterbody in this study. It was found that the detachment of particles, ripples, and ploughs were observed under higher load. Plasma treatment efficiently improves the interfacial adhesion of UHMWPE/PI composite. Both the friction coefficient and wear increased with load, and the plasma treated one shows lower friction coefficient and wear.     

稀土对玻璃纤维填充金属-塑料多层复合材料抗冲击磨损性能的影响

研究了稀土元素处理玻璃纤维填充金属－塑料多层复合材料在冲击载荷、干摩擦条件下的摩擦和磨损性能，并利用扫描电子显微镜（SEM）对磨损表面进行了观察和分析，结果表明，用稀土表面改性剂处理玻璃纤维表面，可以提高玻璃纤维与聚四氟乙烯之间的界面结合力，改善复合材料的界面性能，并有利于在偶件表面形成分布均匀、结合强度高的转移膜，使复合材料与偶件表面之间的对摩减轻，大幅度地降低了复合材料的磨损，从而使复合材料具有优良的摩擦性能和抗冲击磨损性能。     

Surface modification of calcium sulfate whisker using thiol-ene click reaction and its application in reinforced silicone rubber

The hemihydrate calcium sulfate whisker (HCSW) was modified by γ-(methacryloxy)propyl trimethoxy silane (KH570) and trimethylolpropane tris(3-mercaptopropionate) via wet modification and thiol-ene click reaction, and then the unmodified and modified HCSW were added into α, ω-dihydroxy polysiloxane (DPS) matrix to prepare silicon rubber composites. After the dual-surface modification, the surface of HCSW was transformed to hydrophobic, the hydration of whisker was obviously improved, and the whisker dispersed more evenly in the polymer. The mechanical properties, dynamic mechanical properties, and the medium resistance of the silicone rubber composite were compared. The tensile test shows that the silicone rubber shows better mechanical properties after adding the modified whiskers, among which HCSW-KH570-SH has the most significant reinforcement effect. Moreover, DPS/HCSW-KH570-SH shows the best medium resistance in toluene, gasoline, and water. The addition of modified whiskers can improve the storage modulus of silicone rubber significantly, while DMA and DSC show that the addition of modified whiskers can reduce the glass transition temperature of silicone rubber. The bound rubber indicates that the interface interaction between HCSW-KH570-SH and silicone rubber is the best.     

MECHANICAL PROPERTIES OF SMC WHISKER REINFORCED HIGH DENSITY POLYETHYLENE COMPOSITES

A new type of SiO_2-MgO-CaO (SMC) whisker was used to modify high density polyethylene (HDPE).The melting behavior and crystallinity were investigated by differential scanning calorimetry (DSC).The dispersion of whiskers and interfacial adhesion in the prepared HDPE/SMC whisker composites were investigated by scanning electron microscopy (SEM).The mechanical properties were evaluated by mechanical tests and dynamic mechanical analysis (DMA).DSC data indicated that the melting temperature and the crystall...     

Optimization of tribological behavior of nano clay particle with sisal/jute/glass/epoxy polymer hybrid composites using RSM

The tribological properties are one of the most significant properties in many automobile components such as clutch plate, break shoe, engine liner, piston pin, etc. At present work, attempt on nano clay is loaded with natural fibers (sisal and jute), artificial fiber (E‐glass), and epoxy resin. In this investigation, the specific wear rate and coefficient of friction are analyzed by pin on disc apparatus under dry sliding conditions. The experiment design carried by Box–Behnken design on design of experiment techniques with influence wear parameters, namely, filler content, applied load, sliding distance, and sliding velocity; its responses are analyzed by response surface methodology. The regression mathematical models performed for all the responses, and the most influential factors determined by analysis of variance technique, S/N ratio. The results indicate that the coefficient of friction and specific wear rates are minimized with the addition of filler content to the developed composites and further increasing, the response of composites may be varied. Copyright © 2017 John Wiley & Sons, Ltd.     

Comparative study of the mechanical and wear performance of short carbon fibers and mineral particles (Wollastonite,CaSiO3) filled epoxy composites

To improve the mechanical and tribological performance, two kinds of wollastonite fillers (fine or coarse) and short carbon fibers (5–15 vol %) were, respectively, incorporated into an epoxy resin. Fine wollastonite fillers remarkably enhanced the flexural modulus, strength, and toughness of the resin at some filler contents (i.e., 10 vol %) simultaneously, while coarse wollastonite fillers and short carbon fibers impaired most of mechanical properties except the modulus. The small particle size, low aspect ratio as well as the good adhesion to the epoxy matrix of the fine wollastonite particles are believed to be responsible for the improved strength and toughness. Tribological tests were performed under sliding and low amplitude oscillating wear conditions. All fillers enhanced the wear resistance and reduced the sliding coefficient of friction but to a different extent. Under sliding wear conditions, fine wollastonite particle‐filled epoxy displayed the highest wear resistance because of the formation of an effective transfer film and the low abrasiveness of the fillers. Under low amplitude oscillating wear conditions, both wollastonite fillers showed much higher wear resistance than short carbon fibers regardless of the filler content. The better adhesion between the wollastonite fillers and the epoxy matrix is responsible for the higher wear resistance under oscillating conditions. The wear tracks were inspected by microscopy to analyze the corresponding wear mechanisms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 854–863, 2006     

Surface functionalizing effect of fillers on the tribological properties of MWCNT reinforcement HSGFs/phenolic laminate composites under water lubrication

Multi‐wall carbon nanotubes (MWCNTs) and high strength glass fabrics (HSGFs) were modified by polydopamine and polyethyleneimine, respectively. The aim is to improve the friction and wear performance of the synthesized laminate composites in water environment. In this work, polydopamine was used to improve the dispersibility of MWCNTs in phenolic resin matrix, and polyethyleneimine was utilized to enhance the wettability and reactivity of HSGFs. The modified results showed that the dispersibility of MWCNTs treated by polydopamine in water had a distinct improvement in comparison with that of the pristine MWCNTs. Furthermore, it can be clearly observed that good dispersibility can improve the friction and wear performance of the laminate composites. After functionalizing HSGFs by polyethyleneimine, the laminate composites exhibited excellent interfacial bonding, also greatly enhancing the friction and wear properties of the composites.