偶联剂KH-550在改性环氧树脂胶粘SiC耐磨涂层中的应用

为了获得改性环氧树脂粘接SiC颗粒钢基表面复合涂层的优异性能,试验采用偶联剂KH-550来改善材料的复合界面.结果表明:一定量的偶联剂KH-550可显著地提高改性环氧树脂胶粘SiC耐磨涂层的粘接强度(包括剪切强度、拉伸强度及弯曲强度)及耐磨性,并确定出了改性环氧树脂胶粘SiC耐磨涂层中KH-550的最佳加入量为3.3%及较好的使用方法为迁移法.     

纳米CaCO3表面性能控制对其在PS中分散的影响

利用钛酸酯NDZ-201调控了纳米碳酸钙的表面性能,用反气相色谱(IGC)和直剪试验表征了纳米碳酸钙表面物理化学性能和粒子团聚性能,并用透射电子显微镜(TEM)观察分析了纳米碳酸钙在聚苯乙烯基体中分散形态.研究结果表明,在NDZ-201用量为2%(以碳酸钙质量分数计)左右时,纳米碳酸钙粒子具有较小的表面吸附能力和团聚强度,纳米碳酸钙具有较好的可分散性.过量的偶联剂NDZ-201会在碳酸钙粒子间起到润滑效果,降低粒子间的内摩擦系数,使粒子在剪切分散过程中的可分散性变差.     

偶联剂对氧化铁红粉体的表面改性

目的研究硅烷偶联剂KH-560与钛酸酯偶联剂对氧化铁红粉体的改性效果。方法采用硅烷偶联剂KH-560与钛酸酯偶联剂对超细氧化铁红粉体进行改性,同时与未改性的粉体进行比较,对比研究粉体的亲油化度、吸油值、粒度分布、疏水性及分散情况。结果改性后,氧化铁红粉体的细化程度、团聚状况都有一定的改善。粉体由改性前的亲水性变为亲油性,在有机体系中的分散性能得到了提高。结论硅烷偶联剂KH-560与钛酸酯偶联剂都能有效改善铁红粉体的表面性能,而钛酸酯偶联剂的改性效果优于KH-560。     

钛酸酯偶联剂NDZ-401对纳米碳酸钙表面性能的影响

利用红外光谱仪(IR)、释放气体分析仪(EGC)、表面分析仪和气相色谱仪等表征和研究了钛酸酯偶联剂NDZ-401对纳米碳酸钙表面物理化学性能的影响.结果表明,钛酸酯偶联剂NDZ-401中的-Ti-(O=PH-(OC8H17)2)2基团以化学键结合在纳米碳酸钙粒子表面.经1.5%(质量分数)左右NDZ-401处理的纳米碳酸钙具有良好的可分散性和较强的表面吸附能力.     

影响纳米碳酸钙在聚苯乙烯中分散因素的研究

利用钛酸酯偶联剂NDZ-401处理纳米碳酸钙,采用熔融法制备了聚苯乙烯基纳米碳酸钙复合材料.利用直剪仪表征了偶联剂NDZ-401对纳米碳酸钙团聚体的团聚强度和内摩擦系数的影响,利用透射电子显微镜(TEM)和图像分析软件观察和统计分析了分散在聚苯乙烯基体中的纳米碳酸钙粒子的粒径,探讨了复合材料制备过程中粒子特征、分散工艺、基体性能等对纳米粒子分散程度的影响.结果表明,经1.5%(质量分数,下同)左右NDZ-401处理的纳米碳酸钙具有良好的可分散性;采用熔体流动速率较高的聚苯乙烯为基体有利于提高纳米碳酸钙在聚苯乙烯中的分散程度;但过度延长分散混炼时间不能显著改善纳米碳酸钙在聚苯乙烯中的分散程度.     

纳米碳酸钙表面特性对PS/纳米CaCO3体系的影响

研究了偶联剂NDZ-101对纳米碳酸钙团聚体性能的影响.采用熔体剪切分散法制备了聚苯乙烯基纳米碳酸钙复合材料,利用粒度分析仪观察并分析了纳米碳酸钙团聚体的特征(包括团聚强度和内摩擦系数)对其在复合材料中分散程度的影响,并进一步研究了纳米碳酸钙表面性能对聚苯乙烯基纳米碳酸钙复合材料性能的影响.结果表明经1%(质量分数,下同)左右的NDZ-101处理的纳米碳酸钙在聚苯乙烯基体中的分散粒径最小,其特征粒径达196 nm.聚苯乙烯基纳米碳酸钙复合材料的玻璃化转变温度、熔体粘度和储能模量等性能都随偶联剂NDZ-101的增加呈先升后降的趋势.     

聚丁烯(PB)/石墨复合材料结晶和力学性能的研究

本文利用钛酸酯偶联剂NDZ-101处理石墨,采用熔融法制备了聚丁烯(PB)/石墨复合材料.利用DSC、XRD等研究了材料晶型、结晶度随结晶时间的变化,同时研究了复合材料结晶性能对其力学性能的影响.研究表明,随着结晶时间的增加,PB/石墨复合材料的晶型由Ⅱ转变为Ⅰ,石墨的加入加速了晶型的转变;随着石墨含量的增加,PB/石墨复合材料的拉伸强度和抗弯强度增加,而冲击强度降低;当PB/石墨复合材料中石墨含量为15%(质量分数)时,随着晶型的转变和结晶时间的增加(从2 h到96 h),复合材料的拉伸强度从17.34 MPa增加到26.59 MPa,弯曲强度也增加了20%,而冲击强度却降低了大约50%.     

先驱体转化法制备2D Cf/SiC材料的力学性能

以聚碳硅烷(PCS)、二乙烯基苯(DVB)和SiC微粉为原料制备碳纤维布增强碳化硅复合材料,考察了分别采用金属模具和石墨模具制备的2D Cf/SiC材料的力学性能.结果表明采用石墨模具可以减少脱模时材料的层间损伤,制备的材料孔隙分布均匀,力学性能较好,材料的弯曲强度和剪切强度分别达到246.4MPa和24.2MPa,弯曲模量达到64.8GPa,断裂韧性达到10.7MPa·m1/2.     

偶联剂对超细氧化铝粉体表面改性的研究

从实验方法、偶联剂用量以及最佳改性时间等几方面对钛酸酯偶联剂JSC表面改性Al2O3超细粉进行了研究.测定活化指数实验结果表明,最佳改性时间为30min,用量为1.6%,小于理论计算用量2.0%.红外光谱图的分析表明,改性后粉体的羟基峰的位置和强度都有变化,出现了有机钛酸酯基中的Ti-O特征振动峰,表明偶联剂在粉体表面产生吸附,键合于填料表面,从而使填料表面有机化.最后浅析了偶联剂对粉体表面改性的作用机理.     

CT136对超细氧化铝粉体的表面改性

表面改性是无机填料由一般增量填料变为功能性填料所必须的加工手段之一,同时也是制备高性能无机/有机复合材料的基础.从实验方法、偶联剂用量、最佳改性时间几方面对偶联剂CT136表面改性超细Al2O3超细粉进行了研究.活化指数的测定确定了偶联剂的最佳改性时间为30min,实际用量为1.8%.红外光谱分析证实改性后粉体的羟基峰的位置和强度都有变化,在1559cm-1,2855cm-1等附近出现了有机钛酸酯基中的Ti-O特征振动峰,表明偶联剂在粉体表面产生吸附,从而使填料表面有机化,改变了填料的表面性质.最后分析了偶联剂对粉体表面改性的作用机理.     

原位生成SiC／TiSi2纳米复合材料的显微结构

采用Ｓｉ和ＴｉＣ为原料,通过反应热压可制得纳米ＳｉＣ粒子复合的ＴｉＳｉ２材料,生成的纳米ＳｉＣ粒子聚集分布在ＴｉＳｉ２基体中,ＳｉＣ粒子与ＴｉＳｉ２的同没有晶界相存在,但由于残余应力的作用,ＴｉＳｉ２晶格发生扭曲并有位错出现。     

CNTs/SiC/Cu复合材料制备及性能

以碳纳米管(CNTs)、碳化硅(SiC)粉体、锌(Zn)粉和CuSO_4·5H_2O为主要原料,用化学镀的方法制备CNTs /Cu复合粉体,再采用非均相沉淀法制备CNTs/SiC/Cu复合粉体.在750 ℃、100 MPa的制度下进行真空热压烧结后制得CNTs/SiC/Cu复合材料,其中Cu的含量(体积分数,下同)为70%,CNTs的含量(体积分数, 下同)分别为0,3%,5%,8%,12%.利用XRD、SEM分析样品的物相组成和显微结构;利用阿基米德排水法、显微硬度计、三点弯曲法测试了复合材料的密度、显微硬度和抗弯强度.结果表明,随着碳纳米管含量的增加,CNTs/SiC/Cu复合材料的密度、显微硬度和抗弯强度等性能发生相应变化,其中,抗弯强度呈现逐渐升高趋势.与未添加碳纳米管的30SiC/70Cu复合材料相比,添加12%CNTs的12CNTs/18SiC/70Cu 样品,抗弯强度提高了21.45 MPa.     

Synthesis of nanosized CuCrO2 porous powders via a self-combustion glycine nitrate process

The glycine nitrate process has been successfully employed to prepare nanosized, porous, stoichiometric, homogeneous CuCrO₂ powders without ambient control. In this method, a precursor solution was prepared by mixing glycine with an aqueous solution of blended (Cu-Cr) metal-nitrates in their stoichiometric ratios. The glycine-mixed precursor solution was first heated in a beaker to evaporate excess water for forming a viscous bluish semi-transparent gel. The beaker was then covered with a metallic mesh, and the temperature increased slowly to 170 °C to auto-ignite the material. The combustion was self-sustaining and very rapid, producing gray colored powders. The as-prepared powders were nanosized (∼20 nm) into a spherical shape and crystallized in a delafossite structure. The powders showed a very large surface area of 30.92 m²/g, as determined by BET surface area measurements. The SEM/TEM studies on these powders confirmed their nanosized nature and porous structure.     

Bulk Al/SiC nanocomposite prepared by ball milling and hot pressing method

Nano-sized Al/SiC powders were prepared by mechanical alloying method. Two sorts of SiC particle, i.e., nano-sized and popular micron-sized SiC were utilized. The particle size and microstructure of the milled powder were characterised. Effects of the particle size and agglomerate state of SiC, as well as the microstructure of Al/SiC nanocomposite were studied by SEM and TEM. The results show that nano-sized SiC particles is dispersed in aluminium uniformly after ball milled for only 2 h, whereas the similar process need about 10 h for popular micron-sized SiC particle. The bulk Al/SiC nanocomposite can be fabricated by hot pressing the nano-sized Al/SiC powders at temperature about 723 K under pressure of 100 MPa.     

热压烧结SiC/CCTO陶瓷电容器的工艺和性能

首先采用固相法合成CaCu_3Ti_4O_(12)(CCTO)粉体,与SiC粉体均匀混合后,采用真空热压制备了SiC/CCTO复合陶瓷电容器.采用DSC-TG技术分析了SiC/CCTO复合粉体的热行为,采用XRD、SEM等手段对样品进行表征,研究了SiC/CCTO复合陶瓷电容器的介电性能,并对其介电机理进行了探讨.结果发现,在950 ℃和 30 MPa的热压条件下制备出的 SiC/CCTO复合陶瓷电容器具有最高的介电常数ε_r≈3×10~8(1 kHz),分析认为其介电机理属于阻挡层机制,载流子在SiC与CCTO界面处聚积,形成空间电荷极化.     

SiC粉体中Fe元素的赋存形态及其提纯工艺

为了探究SiC块体中Fe元素的赋存形态及其粉体纯化机制,分别以冶炼后SiC块体以及经气流磨破碎后的粉体为主要原料,以HCl、HNO3、H2SO4和HF作为酸洗剂,对SiC粉体进行酸洗。通过XRD、SEM和ICP等检测手段对SiC块体和酸洗前后粉体的物相组成、微观结构及Fe元素含量进行表征,重点研究微观状态下SiC中Fe元素的赋存形态及其酸洗提纯工艺。结果表明:Fe元素以FexSiy固溶体的形式赋存于SiC块体的内部,并且微观状态下呈现出被游离Si所包裹的形态;当控制液/固比为5:1时,最佳酸洗的工艺参数为:HF浓度0.15 mol/L,浸出温度70℃,浸出时间2 h,在此工艺下Fe元素的去除率可达94.1%。     

Investigation on reactive diffusion bonding of SiCp/6063 MMC by using mixed powders as interlayers

Mixed Al–Si, Al–Cu and Al–Si–SiC powders were used as interlayers to reactive diffusion bond SiCp/6063 MMC. The microstructure and the effects of bonding parameters on the shear strength of SiCp/6063 MMC joints were investigated. The results show that SiCp/6063 MMC joints bonded by using the interlayers of mixed Al–Si, Al–Cu powders have a dense joining layer of high quality. The mass transfer between the bonded materials and the interlayers during bonding leads to the hypoeutectic microstructure of the joining layers. Using mixed Al–Si–SiC powder as an interlayer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer. This is responsible for the low shear strength of the joints, even lower than those reactive diffusion bonded by using the interlayers of mixed Al–Si and Al–Cu powders. Ti added in the interlayer obviously improves the joint strength reactive diffusion bonded by using the mixed Al–Si–SiC powder.     

Processing of WC/W composites for extreme environments by colloidal dispersion of powders and SPS sintering

Tungsten and tungsten carbide are materials with high thermomechanical response that are used or have been proposed for extreme environment applications such as first plasma face, or cutting tools. The high melting temperature and strong bonding energy of both materials force the use of powder metallurgical processes and non-conventional sintering routes to achieve dense parts. Consequently, a high dispersion and close contacts of the starting powders are required. In this paper tungsten and tungsten carbide powders are colloidally processed and mixed to achieve composite powders that are sintered later by Spark Plasma Sintering. Starting micrometric tungsten carbide and nanosized tungsten powders are dispersed in water at pH 3. By using a cationic dispersant, the surface charge of the nanosized W suspended in water reverses to positive, ensuring its attachment to the carbide surfaces and the good dispersion of the two phases when both slurries are mixed.Composite powders with volumetric rations of 50WC/50W, 80WC/20W and 90WC/10W as well as pure WC and W are sintered by SPS following the dimensional change of the specimens during the process. It has been proved that complete coverage of the micronic WC by the nanosized W powders, achieved with this colloidal approach, makes the tungsten govern the initial sintering stages. The derivative of the sintering curves is used to detect the solid state reactive sintering temperature of W₂C. After sintering, XRD and SEM observations indicate that all the mixture compositions yield to ceramic materials with different W₂C/WC ratios, depending on the initial compositions. Dispersion of the two phases is high and no remaining W is detected. Flexure tests at room temperature show that composite materials present a slightly lower fracture strength than pure WC.     

Influence of additives on oxidation resistance of binderless C/C composite

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液氮球磨制备纳米SiCp/Al基复合材料的研究

利用液氮球磨技术制备了纳米SiC颗粒增强铝基复合材料粉末,对该纳米粉末进行真空热压和热挤压,获得纳米铝基复合材料块体.采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)研究了纳米SiC粉和Al-Zn-Mg-Cu粉在液氮球磨过程中形貌、组织和相组成等.结果表明,液氮球磨可以使复合材料粉末达到纳米级,且纳米SiC可均匀地分布于铝合金中.