聚合物/BN导热复合材料研究进展

与其他导热无机粒子相比,氮化硼粒子具有的独特结构及良好的热、电综合性能,是制备高导热、高绝缘聚合物的一类重要导热绝缘填料。综述了微、纳米氮化硼粒子填充导热聚合物的研究进展,重点讨论了氮化硼粒子的物理性能、表面改性、结构及用量等对聚合物导热、绝缘及力学性能的影响。与微米氮化硼相比,氮化硼纳米管及纳米片增强的聚合物具有高导热、高电击穿强度、高绝缘电阻、低介电常数及介电损耗、良好的力学性能。解决导热聚合物高导热与高电击穿强度间的矛盾是聚合物/氮化硼导热复合材料未来发展的方向。     

基于氮化硼取向结构的高导热聚合物基复合材料研究进展

简要介绍了氮化硼的分类、结构特点以及其导热特性。重点概述了近几年基于在聚合物基体中形成氮化硼取向结构制备高导热复合材料的研究进展,分析了磁场诱导法、电场诱导法、剪切诱导法、冰晶诱导法以及热压取向等方法的特点。对氮化硼取向填充的导热聚合物基复合材料的未来发展趋势进行了分析与展望,为低填充、高导热绝缘聚合物基复合材料的开发及应用提供借鉴。     

氮化硼填充导热绝缘塑料的研究及应用

六方氮化硼(h-BN)由于其高的导热系数和良好的电绝缘性能在学术界和工业界都受到了广泛的关注。以其作为导热填料制备导热绝缘塑料是近年来研究者的重点研究方向。介绍了氮化硼填充的聚合物基复合材料导热性能的影响因素,包括氮化硼的表面功能化、填料混杂、塑料基体以及填料在基体中的取向。此外,还介绍了氮化硼/聚合物复合材料在电子领域的应用情况。     

氮化硼对硅橡胶复合材料导热性能和力学性能的影响

研究了氮化硼微观结构(团聚体和片状微观结构)和用量对硅橡胶复合材料导热性能、力学性能、基体中分散形态结构的影响。结果表明,随着氮化硼用量的增加,硅橡胶复合材料的拉伸强度和导热系数提高;当硅橡胶复合材料填料用量相同时,氮化硼团聚体比片状氮化硼的导热系数高,但拉伸强度低;当球状结构的氮化硼团聚体用量为100份时,硅橡胶复合材料的导热系数可从0.18 W/m·K提高到1.72 W/m·K;氮化硼团聚体和片状氮化硼填充硅橡胶表现出不同的应力松弛行为,其中高密度氮化硼团聚体表现出了良好的抗压缩性能。     

氮化硼/蚕丝导热复合材料的制备及其性能研究

针对传统导热材料基体难以自然降解的问题,选择更加环保的蚕丝蛋白为基体材料,采用球磨共混-热压成型制备了氮化硼/蚕丝蛋白导热复合材料,考察了复合材料的形貌结构和导热性能。结果表明,氮化硼在复合材料中沿水平方向分布,导致复合材料表现出明显的导热各向异性。复合材料的导热系数随着氮化硼质量分数的增加而提高。当氮化硼质量分数为50%时,复合材料的水平方向导热系数为12.42 W/(m·K),垂直方向导热系数为0.41 W/(m·K)。红外热成像结果表明,氮化硼/蚕丝蛋白复合材料具有优异的传热性能。     

氮化硼填充MVQ制备导热橡胶的研究

以甲基乙烯基硅橡胶（MVQ）为主体材料，用氮化硼填充MVQ制备导热橡胶，研究氮化硼用量、粒径等对MVQ导热性能、物理性能和工艺性能的影响。结果表明。随着氮化硼用量的增大。MVQ的热导率增大而工艺性能变差;氮化硼最大适宜用量为150份。小粒径氮化硼填充MVQ的物理性能较好，工艺性能稍差。氮化硼用量小于70份时，粒径为20μm的氮化硼填充MVQ的导热性能较好;氮化硼用量为70～180份时，粒径为6μm的氮化硼填充MVQ的导热性能较好。不同粒径氮化硼按适当比例配合填充MVQ的导热性能优于单一粒径氮化硼填充MVQ．且物理性能改善。     

碳纳米管/氮化硼配比对聚乙烯复合材料性能的影响

以高密度聚乙烯为基体材料,以碳纳米管和氮化硼颗粒为导热填料,通过熔融共混法制备了导热聚乙烯复合材料;研究了碳纳米管和氮化硼颗粒的配比和添加量时复合材料力学性能、导热率、流动性、耐热性的影响。结果表明:当碳纳米管和氮化硼的质量比为1:1时,复合材料导热率最高;当碳纳米管和氮化硼含量均为10%时,复合材料的导热率提高了62.64%(100℃)。     

导热PA6复合材料导热性能的研究

将氮化硼和氧化铝等助剂混合后,经过平行双螺杆挤出机制备了导热PA6复合材料,研究了将不同粒径的氮化硼和氧化铝复配对尼龙6复合材料导热系数的影响。结果表明:采用不同粒径的氮化硼和氧化铝复配,添加60%的含量可得到导热系数为1.869的导热PA6复合材料。     

聚合物/氮化硼填充型导热界面材料研究进展

电子电气等行业的发展更趋向于密集化和微型化。电子器件在工作时会释放出大量热量,能及时将其传导移除,导热界面材料(TIM)在生、散热器件间起到重要作用。氮化硼作为导热填料,优异导热性能、低膨胀率、低电阻系数和化学稳定性,在制备高性能TIM方面越来越受到重视。本文重点介绍了氮化硼的结构以及影响氮化硼/聚合物复合材料导热性能的关键因素,并展望了今后以氮化硼作为填充材料的导热界面材料研究重点和方向。     

氮化硼/碳纳米管对乙烯基聚二甲基硅氧烷导热性能影响的研究

分别采用氮化硼和氮化硼/碳纳米管(CNTs)复配物制备导热乙烯基聚二甲基硅氧烷(PDMS)材料,并对其导热性能进行研究。结果表明:随着氮化硼和CNTs用量的增大,材料的热导率和热扩散系数逐渐增大;氮化硼用量足够大时,能够形成导热通路进而促进填料网络的形成;CNTs在填料中将氮化硼粒子之间形成的平面结构连接起来,从而形成三维网络结构;填料越多,形成的导热网络结构越强;氮化硼在网络中起主要作用,CNTs起到辅助增强的作用。     

可加工氮化硼系复相陶瓷的研究发展现状和发展趋势以及应用现状分析

先进陶瓷材料具有较高的力学性能,以及较高的抗高温氧化性能等。但是先进陶瓷材料由于硬度较高、可加工性能较差,导致陶瓷材料的机械加工成本较高,所以限制了陶瓷材料的广泛应用。为了改善和提高陶瓷材料的可加工性能,向陶瓷基体中加入六方氮化硼形成可加工氮化硼系复相陶瓷。可加工氮化硼系复相陶瓷具有较高的力学性能和优良的可加工性能,氮化硼系复相陶瓷可以进行机械加工。目前研究和开发的可加工氮化硼系复相陶瓷主要包括:Al_2O_3/BN复相陶瓷,ZrO_2/BN复相陶瓷,SiC/BN复相陶瓷,Si_3N_4/BN复相陶瓷,AlN/BN复相陶瓷等。目前可加工氮化硼系复相陶瓷的研究主要集中在氮化硼系复相陶瓷的制备工艺,力学性能,可加工性能,抗热震性能,抗高温氧化性能等。本文主要叙述可加工氮化硼系复相陶瓷的制备工艺,力学性能和可加工性能,抗热震性能,抗高温氧化性能等。并叙述可加工氮化硼系复相陶瓷的研究发展现状和发展趋势,并对可加工氮化硼系复相陶瓷的未来发展趋势进行分析和预测。     

Role of the particle size of graphite-like boron nitride in nucleation of cubic boron nitride

The influence of the reduced radius of grains of the graphite-like hexagonal boron nitride (h-BN) on the nucleation of the cubic boron nitride (c-BN) during synthesis from an initiator solution at a high pressure is analyzed. The colloidal mechanism of nucleation is confirmed experimentally. It is shown that there is a correlation between the nucleus sizes of the hexagonal boron nitride and the pressure of the onset of nucleation of the cubic boron nitride. The effect of these sizes of the hexagonal boron nitride on the concentration of crystal nuclei of the cubic boron nitride is studied. The kinetic nucleation curves are obtained. It is demonstrated that the concentration of crystallization centers depends on the thermodynamic and kinetic parameters, as well as on the particle size of the graphite-like hexagonal boron nitride. Original Russian Text ? S.P. Bogdanov, 2008, published in Fizika i Khimiya Stekla.     

Combustion synthesis of hexagonal boron nitride nanoplates with high aspect ratio

High crystalline hexagonal boron nitride nanoplates with high aspect ratio of ~400 have been synthesized by combustion synthesis method through magnesiothermic reduction reaction between B₂O₃ and Mg in N₂ pressure. The synthesized hexagonal boron nitride nanoplates were about 50 nm in thickness and larger than 20 μm in lateral size. The six-fold symmetric spots electron diffraction pattern of transmission electron microscopy shows that the nanoplate is well crystallized. Hexagonal boron nitride nanoplates grow via an Oswald ripening process and have larger lateral size when it was prepared with larger magnesium particles. High temperature liquid magnesium provides an important environment for the growth and crystallization of boron nitride. This work provides an effective way to achieve low-cost and large-scale preparation of high-quality boron nitride nanoplates.     

Effect of Interfacial Interaction on Morphology and Properties of Polyethylene/Boron Nitride Thermally Conductive Composites

In this study, polyethylene-g-maleic anhydride was utilized to enhance interfacial interaction between boron nitride and polyethylene. Moreover, KH550 was used as a surface treatment agent to improve interfacial interaction between boron nitride and polyethylene. It was found that surface functionalization of boron nitride particles and the addition of polyethylene-g-maleic anhydride can promote dispersion of boron nitride particles with reduced aggregation, resulting in the improvement of both tensile and impact strength of polyethylene/boron nitride composites. Compared to surface functionalization of boron nitride particles, the addition of polyethylene-g-maleic anhydride was much effective to enhance thermal conductivity of polyethylene/boron nitride composites and drop effectively rheological percolation threshold and gel point of polyethylene/boron nitride composites.     

有机先驱体法制备氮化硼涂层改性玻璃纤维织物

以三乙醇胺和硼酸为原料,合成了硼酸氨基三乙酯。研究了原料配比、反应温度及反应时间对产率的影响,在原料摩尔比1：1、温度160℃的条件下反应180rain,硼酸氨基三乙酯的产率达到87％。由于N元素的引入,硼酸氨基三乙酯的水解稳定性良好,且在无水乙醇溶液中水解缓慢,能够满足工业上制备硼酸氨基三乙酯涂层的工艺要求。以硼酸氨基三乙酯为先驱体在氮气气氛中于400℃和800℃条件下热解,其热解产物为氮化硼和碳化硼的混合物。400℃时氮化硼的结晶程度较低,800℃时结晶程度提高。氮化硼涂层对高硅氧、无碱玻璃纤维织物具有显著的增强作用并可明显改善其耐温性能。     

On the polymorphism in carbon and baron nitride systems

Formation of different forms of carbon and its analog, boron nitride, is examined under low and high pressures. It is found that practically all known carbon modifications are present on the surface of diamond and boron nitride crystals.     

Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demonstrate a typical semiconductor characteristic which were studied on a new scanning tunneling microscope-transmission electron microscope holder. Since this property changes from an insulator to a semiconductor of the boron nitride, these nanosheets will be able to extend their applications in designing and fabricating electronic nanodevices.     

Nano boron nitride/polyurethane adhesives in flexible laminated food packaging: Peeling resistance and permeability properties

Polymeric multilayer films are widely used in food packaging due to their versatility. However, there are still some properties that might be improved, such as gas and vapor barrier behaviors. The incorporation of boron nitride into polymer matrixes is emerging as a potential method for the improvement of barrier properties due to its lamellar structure. In this context, our work investigates the addition of boron nitride into a bicomponent reactive polyurethane (PU), which could be used as an adhesive and improve the barrier layer. This material could be used as an alternative to aluminum foil in food packaging. Different concentrations of two different sizes of boron nitride (BN) particles were added to the PU adhesive: micro-structured boron nitride (BNm) and nano-structured boron nitride (BNn). The aim was to investigate the influence on the barrier properties against moisture and the peeling resistance. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) were performed to characterize the boron nitride samples. The effect of BNm or BNn addition on the glass transition of the nanocomposites was investigated by differential scanning calorimetry (DSC). Barrier properties were measured by a water vapor permeation test and the practical adhesion of laminates with BN/PU adhesives was characterized using peeling tests. The nanocomposites achieved reduction in water vapor permeance of up to 50% and a 37% increase in mechanical adhesion properties compared to the PU adhesive. The results revealed the high potential of boron nitride/PU adhesives for food packaging applications.     

High density carbon fiber/boron nitride matrix composites: Fabrication of composites with exceptional wear resistance

This paper describes the fabrication of high density (ρ ∼ 1.75 g/cc) composites containing a hybrid (carbon and boron nitride), or complete boron nitride matrix. The composites were reinforced with either chopped or 3D needled carbon fibers. The boron nitride was introduced via liquid infiltration of a borazine oligomer that can exhibit liquid crystallinity. The processing scheme was developed for the chopped carbon fiber/boron nitride matrix composites (C/BN) and later applied to the 3D carbon fiber reinforced/boron nitride matrix composites (3D C/BN). The hybrid matrix composites were produced by infiltrating the borazine oligomer into a low density 3D needled C/C composite to yield 3D C/C-BN. In addition to achieving high densities, the processing scheme yielded d₀₀₂ spacings of 3.35 Å, which afforded boron nitride with excellent hydrolytic stability. The friction and wear properties of the composites were explored over the entire energy spectrum for aircraft braking using an inertial brake dynamometer. The C/BN composites outperformed both the previously reported C/C-BN and chopped fiber reinforced C/C. The high density 3D C/BN performed as well as both the 3D C/C and the C/BN. The 3D C/C-BN provided outstanding wear resistance, incurring nearly zero wear across the entire testing spectrum. The coefficient of friction was relatively stable with respect to energy level, varying from 0.2 to 0.3.     

Formation of cBN nanocrystals by He+ implantation into hBN

The structural modifications of polycrystalline hexagonal boron nitride implanted with He⁺ beams at energies between 200 keV and 1.2 MeV to fluences of 1.0 × 10¹⁷ ions cm^? 2 were investigated using micro-Raman spectroscopy. The measured Raman spectra show evidence of implantation-induced structural transformations from the hexagonal phase to nanocrystalline cubic boron nitride, rhombohedral boron nitride and amorphous boron nitride phases. The first-order Longitudinal-Optical cubic boron nitride phonon was observed to be downshifted and asymmetrically broadened and this was explained using the spatial correlation model coupled with the high ion implantation-induced defect density.