六方氮化硼的合成及表征

以硼酸、三聚氰胺为原料,通过高温反应,在氮气气氛下制备出六方氮化硼（h-BN）样品。考察了硼酸与三聚氰胺物质的量比、焙烧温度对h-BN产率、纯度及形貌的影响。制备h-BN最佳工艺条件:硼酸与三聚氰胺物质的量比为4.0:1,1 000 ℃焙烧2 h,1 400 ℃焙烧2 h。在此条件下h-BN产率为25%、纯度为97%、粒度约为250 nm。     

连续合成六方氮化硼的新工艺

着重介绍连续合成六方BN的创新工艺，该工艺既有效地提高了产品的产量和质量，又大大降低了生产成本，使氨氮法制备BN的生产方法向前推进了一步，提高到一个新水平。     

影响立方氮化硼单晶合成效果的工艺探讨

通过对立方氮化硼单晶生产工艺的改进,六方氮化硼的转化率提高了一倍,单产有了较大幅度的提高,合成电流较为平稳,较好地保护了导电钢圈,因而顶锤消耗明显降低,达到了高产低成本的效果.     

六方氮化硼的制备与应用综述

主要综述了六方氮化硼的基本结构和性能,介绍了其常用制备方法,并对其应用前景进行了展望。     

利用真空氮化炉制备六方氮化硼粉体工艺研究与表征

本研究用一种操作简单、适合规模化、低成本的方法制备六方氮化硼粉末.研究了硼、氮元素的物质的量比值,烧成制度,助熔剂的添加量对产物物相成份和颗粒形貌的影响,并对酸洗和碱洗对产物中杂质的去除效果进行了比较.用X-射线衍射仪(XRD)、扫描电镜(SEM)对制备的产物样品进行了分析表征,发现用该工艺制得的六方氮化硼纯度可达95.6%,去杂后纯度可达99%以上,晶粒直径约为0.2～0.5 μm,厚度在60～70 nm,晶粒尺寸比较均匀.     

改性六方氮化硼/水性聚氨酯防腐涂料制备与性能

以聚甘油-10(PG)作为稳定剂，在超声条件下对六方氮化硼(h-BN)进行剥离和改性。通过红外光谱(FT-IR)、热重分析(TG)、原子力显微镜(AFM)和透射电镜(TEM)对PG改性的h-BN纳米片(GB)进行了表征。将制备的PG纳米粒子用作水性聚氨酯(WPU)涂层的防腐填料，制备了GB质量分数分别0，0.5%，1.0%，2.0%的为复合涂层(PU/GB)。考察了不同涂层的水接触角、吸水率、附着力损失、热稳定性和机械性能。最后，通过电化学工作站研究了WPU、PU/GB0.5、 PU/GB1.0 和PU/GB2.0复合涂层在3.5%NaCl水溶液中的腐蚀行为。结果表明，GB纳米粒子可以显著增强水性聚氨酯涂层的耐水性、热稳定性、机械性能和耐腐蚀性能。     

化学气相沉积六方氮化硼涂层的制备及应用

六方氮化硼(h-BN)涂层是一种性能优异的功能陶瓷材料,介绍了化学气相沉积( CVD)六方氮化硼涂层的制备工艺,综述了h-BN涂层的优异性能和应用现状,并对其研究发展趋势进行了展望.认为先驱体性能存在缺陷、沉积机理复杂、工艺可控性差、生产成本高是目前CVD制备h-BN涂层存在的主要工艺问题,指出今后还需在新型先驱体的研发和使用、沉积机理的深入探究、工艺优化和放大等方面开展深入研究,以实现h-BN涂层的大规模工业化生产和应用.     

固态润滑剂六方氮化硼在陶瓷摩擦材料中的应用研究

利用层状结构六方ＢＮ优良的润滑特性,将其引入Ａｌ２Ｏ３陶瓷基体之中,制备了陶瓷摩擦材料,通过销－盘对磨方式的摩擦磨损研究了材料的摩擦学特性,结果表明,摩擦过程中由于ＢＮ的润滑作用使得陶瓷摩擦材料的摩擦平稳性得到明显提高。与粉末冶金摩擦材料相比,陶瓷摩擦材料具有较高的摩擦系数、较低的磨损率以及良好的摩擦系数稳定性。     

硼砂尿素复合改性聚乙烯醇制备可降解包装材料

硼砂、尿素复合改性聚乙烯醇实验表明:在6%聚乙烯醇溶液中加硼砂、尿素、甘油分别为聚乙烯醇质量的1.2%、5%、0.16%,在反应温度为80℃、pH=8的条件下制得糊状材料。再用聚四氟乙烯模具制成膜,膜经100℃烘干1.5~2 h,得到厚度为0.050 mm可降解包装膜,该膜经测定:拉力强度7.8 N/mm2,拉伸强度1.2 N/mm2,断裂强度1.3 N/mm2,断裂伸长率247.9%。膜在4%乙酸中溶出度2.09 mg/L,乙醇溶出度1.17 mg/L,高锰酸钾指数38.14 mg/L。包装膜降解实验表明:膜累计降解150 d后,降解率达88%。膜封口试验表明:封口部位断裂强度55.6 N/mm2,符合生产使用要求。     

以三乙醇胺硼酸酯为前驱体制备大颗粒六方氮化硼

以三乙醇胺和硼酸为原料,甲苯为带水剂,合成了三乙醇胺硼酸酯,在最佳工艺条件下以三乙醇胺硼酸酯为前驱体在氨气气氛中烧结制得六方氮化硼颗粒。采用IR、XRD、SEM、NMR等测试方法对中间物和产物进行了表征,确定了中间物及产物的组成、物相、粒度及形貌。研究结果表明：以三乙醇胺硼酸酯为前驱体在1200℃烧结4h,可制得高纯度、晶型良好,粒径在20μm左右的六方氮化硼颗粒。经过高温精制后的六方氮化硼颗粒具有较高的结晶度和致密度,其粒径可以达到30μm以上,纯度为98.5%。     

改性h-BN/聚氨酯丙烯酸酯涂料的制备与性能

利用水热法制备羟基化六方氮化硼（BNNSs）,采用异佛尔酮二异氰酸酯（IPDI）和丙烯酸羟乙酯（HEA）在其表面进行接枝得到功能化六方氮化硼（Fh-BN）。然后将得到的Fh-BN掺入有机硅改性的聚氨酯丙烯酸酯（PUA）涂料中,成功制备出改性h-BN/聚氨酯丙烯酸酯涂料。研究了水热时间、温度对BNNSs硼羟基含量的影响,利用XPS分析得出水热反应最佳反应条件为180℃、12h,B—OH质量分数达到5.97%。通过机械性能、综合热分析、耐水性、涂层交流阻抗和Tafel极化曲线进行测试分析,掺杂0.75%Fh-BN涂膜硬度达到3H,耐冲击性50cm,柔韧性0.5mm;与未掺杂前涂层相比,吸水率降低4.96%;涂层耐热性提高,T_50%提升了6℃;耐水测试浸泡168h后涂膜无变化;电化学测试表明：0.75%Fh-BN涂层阻抗R₁达到1.818×10⁹Ω·cm²,比原有涂层提升了两个数量级,E_corr由-0.4886V正移至-0.32124V,I_corr由2.5552×10^-7A/cm²降低至1.5555×10^-8A/cm²。Fh-BN的引入显著提升了涂层的机械性能、热稳定性和耐腐蚀性。     

氟化钙对常压烧结Si3N4/BN复相陶瓷结构与性能的影响

以微米级Si3N4和h-BN粉末为原料,CaF2–Al2O3–Y2O3为烧结助剂,采用常压烧结工艺制备了BN体积含量为25%的Si3N4/BN复相陶瓷。研究了CaF2添加量对Si3N4/BN复相陶瓷材料力学性能的影响,并通过X射线衍射和场发射扫描电镜分析了复相陶瓷的物相组成和显微组织。结果表明：随着CaF2添加量增加,制备的Si3N4/BN复相陶瓷材料气孔率逐渐增大,收缩率变小,相对密度减小。添加量为2%（质量分数）时,Si3N4/BN复相陶瓷的室温抗弯强度达145.5MPa。添加适量的CaF2可在Si3N4/BN复相陶瓷材料常压烧结过程中较大程度地破坏h-BN的卡片房式结构,将微米级的h-BN颗粒变成纳米级颗粒。     

Synthesis of highly purified and crystallized h-BN using calcium-assisted carbothermal reduction nitridation

Highly purified and crystallized hexagonal boron nitride (h-BN) powder is suitable as thermally conductive filler in resins. To obtain h-BN powder with large particle size, as well as high purity and crystallinity, high-temperature heat treatment over 1800°C in a N₂ gas atmosphere is effective. The carbothermal reduction nitridation (CRN) involves the carbothermic reduction of boric oxide in a N₂ gas atmosphere. In CRN using a CaO promoter, h-BN particles with high crystallinity can be obtained by a simple heat treatment process. CaO prevents the evaporation of boron oxide and aids in h-BN particle growth at high temperatures. However, CaB₆ is formed as byproduct or impurity when CRN using the CaO promoter is performed at temperatures higher than 1800°C. In this study, the relationship between the products and the reaction temperature was clarified via thermodynamic considerations and experimentation. The results clarified the ideal reaction process of CRN using a CaO promoter to obtain highly purified and crystallized h-BN powder.     

浸渍及热处理对常压烧结AlN/h-BN复相陶瓷微观结构及性能的影响

采用常压烧结方法在1 700℃保温2 h制备出AlN/20%(体积分数)h-BN复相陶瓷,对烧结后的样品分别采用A10铝溶胶和硅溶胶/酚醛树脂进行浸渍处理,随后在1 450℃氮气气氛下热处理2 h。对比研究了浸渍及热处理前后复相陶瓷的致密度、抗弯强度、Vickers硬度、微观结构和物相组成,并分析了复相陶瓷的强化机理。结果表明:A10铝溶胶浸渍处理后样品的抗弯强度和Vickers硬度略有提高;经过硅溶胶/酚醛树脂处理的样品抗弯强度和Vickers硬度大幅提高,抗弯强度和Vickers硬度分别从81.5MPa和1.99 GPa提高到130.1 MPa和3.58GPa;硅溶胶/酚醛树脂处理后的样品在孔隙界面处生成的碳化硅及氮氧化铝是样品抗弯强度和Vickers硬度显著提高的主要原因。     

Characterization of cordierite based h-BN doped ceramics as an electronic substrate/circuit board material

In this study, h-BN was added to the cordierite composition obtained from zeolite, which was prepared by the determined stoichiometry to facilitate machinability and increase thermal conductivity. Sintering behavior, hardness, machinability, and thermal/electrical properties of the samples obtained by sintering the compounds at different times were investigated. Thanks to these features, it is aimed to use cordierite as an alternative material to integrated circuit substrates and electronic packaging materials. The produced samples were analyzed by X-ray diffraction analysis, examined by scanning electron microscopy, and field emission scanning electron microscopy. Afterward, thermal properties such as thermal diffusivity, thermal conductivity, and electrical properties such as electrical conductivity and dielectric permittivity were measured. The hardness and machinability of samples were investigated. Cordierite, spinel, glassy phase, and h-BN phase were detected, and it was observed that the blocky cordierite grains turned into equiaxed grains with the increase of the h-BN. According to the results obtained from the thermal conductivity test, it was seen that the h-BN additive increased the thermal conductivity value in general. In addition, it was determined that with the increase of h-BN, the hardness decreased, and the machinability properties of the samples improved.     

Cr–C/h-BN 自润滑复合镀层的制备与摩擦学性能

在三价铬Cr–C镀液中添加1~5 g/L的h-BN自润滑微粒,运用直流电沉积技术在Q235碳素结构钢基体上制备了Cr–C/h-BN复合镀层。利用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机等设备分析了h-BN微粒添加量、电流密度等工艺参数对镀层组织和性能的影响。结果表明:在电流密度20 A/dm2,h-BN添加量3 g/L的条件下,可获得h-BN微粒体积分数为6.15%的复合镀层。h-BN微粒的添加改善了Cr–C合金镀层的耐磨性,Cr–C/h-BN复合镀层在室温干摩擦条件下的磨损率减少了22%,平均摩擦因数由原先的0.49降低至0.31。     

Synthesis,characterization and adsorption studies of h-BN crystal for efficient removal of Cd2+ from aqueous solution

In the present study, hexagonal boron nitride (h-BN) was synthesized from boric acid and melamine by thermal annealing method in a nitrogen atmosphere. The pure h-BN was used as an efficient sorbent for the uptake of Cd²⁺ ions from the solution phase. The kinetics and sorption studies of metal ions onto the h-BN were carried out in batch adsorption experiments at different temperature, time, pH, sorbent dosage, and concentration of metal ions. The optimum pH for the removal of the Cd²⁺ ions was found to be pH 7. The effect of temperature showed that the process of Cd²⁺ sorption remained endothermic in the range of 298 K–328 K. The Lagergren's first and Ho's second kinetic models were tested to interpret the adsorption kinetic data, however the present data was explained well by Ho's model for kinetics. The thermodynamic perameters ΔG, ΔS and ΔH were determined using the available adsorption data at different temperatures. The physicochemical properties of the synthesized product were also characterized before and after adsorption by different analytical techniques like FT-IR, TGA, XRD and Point of Zero Charge (PZC). The morphology of the surface was analyzed with the help of Scanning Electron Microscopy. The h-BN proved to be an efficient adsorbent for the uptake of the Cd²⁺ ions from aqueous media.