Al(H2PO2)3/聚氨酯弹性体复合材料的制备及阻燃性能

采用熔融共混技术,将Al（H₂PO₂）₃引入聚氨酯热塑性弹性体,制备了一系列次磷酸铝/聚氨酯弹性体复合材料（Al（H₂PO₂）₃/TPU）。采用极限氧指数（LOI）、垂直燃烧（UL-94）、锥形量热测试、TG和SEM研究了Al（H₂PO₂）₃对Al（H₂PO₂）₃/TPU复合材料阻燃性能及热稳定性的影响,采用力学测试研究Al（H₂PO₂）₃对其力学性能的影响。阻燃测试表明,Al（H₂PO₂）₃可以有效提高Al（H₂PO₂）₃/TPU复合材料的阻燃性能。当Al（H₂PO₂）₃添加量为20wt%时,Al（H₂PO₂）₃/TPU复合材料UL-94级别达到V-0级,LOI达到30.5vol%。热重测试表明,Al（H₂PO₂）₃的加入会导致复合材料热分解温度降低,但其残炭率有明显升高。锥形量热测试表明,Al（H₂PO₂）₃的加入有效降低复合材料热释放速率峰值（pHRR）和总热释放（THR）,并明显提高其火灾安全性能,其中20wt% Al（H₂PO₂）₃/TPU的pHRR和THR相对纯TPU分别下降65.7%和20.2%。SEM表明,Al（H₂PO₂）₃/TPU复合材料炭渣致密性有明显提高。在此基础上,采用TGA-FTIR联用分析Al（H₂PO₂）₃/TPU复合材料阻燃机制,研究发现,Al（H₂PO₂）₃在燃烧过程中可以有效促进TPU裂解产物成炭,降低可燃性气体生成量,从而提高复合材料阻燃性能。     

基于铁粉还原的LiFePO4/C合成路径及其电化学性能研究

使用还原铁粉作为铁源, 通过超细球磨与喷雾干燥、高温煅烧技术制备了球形微纳米LiFePO₄/C复合材料。使用DSC/TG以及XRD对LiFePO₄/C复合材料的形成过程进行了分析; 使用SEM、穆斯堡谱仪等手段对复合材料进行分析; 使用电化学工作站、容量测试仪对其充放电行为进行分析。研究发现, 使用该合成技术路线, 在500~700℃下能够合成LiFePO₄/C复合材料。获得的LiFePO₄/C复合材料具有规则的球形外貌, 平均尺寸4~5 μm。该微米颗粒由200 nm左右细小颗粒组成, 颗粒间具有纳米尺寸微孔。穆斯堡谱仪测试结果表明, 复合材料中Fe处于+2价的价态。复合材料在1C倍率下表现出稳定的充放电行为, 平均比容量在156 mAh/g, 300次循环后, 容量保持率为92.8%。该技术制备的LiFePO₄/C复合材料具有潜在的应用价值。     

聚吡咯/磷酸铁锂复合正极材料的制备与表征

采用化学氧化法, 以吡咯为单体、 三氯化铁为氧化剂、 苯磺酸钠为掺杂剂在磷酸铁锂颗粒表面进行原位聚合, 制备了聚吡咯/磷酸铁锂(PPy/LiFePO₄)复合材料。用FTIR、 XRD和SEM对PPy/LiFePO₄复合材料进行了结构与形貌表征。用电化学工作站和充放电测试系统对复合材料的电化学性能进行了表征。结果表明: PPy/LiFePO₄复合材料作锂二次电池正极具有良好的充放电循环性能。当PPy质量分数为17%, 充放电电流为0.1 mA时, PPy/LiFePO₄复合材料最高放电比容量达163 mAh·g^-1, 50次循环之后放电比容量仍为初始时的94.9%; 与LiFePO₄相比, 当PPy的含量适当时, PPy/LiFePO₄复合正极材料的放电比容量会有明显提高。PPy的加入提高了LiFePO₄的电子电导率, 从而提高了活性物质有效利用率, 因此PPy/LiFePO₄复合材料的比容量和循环性能均得到了提升。     

高倍率性能磷酸亚铁锂/碳正极材料的制备与表征

以水溶性酚醛树脂为碳源, Li₂CO₃为锂源, 纳米FePO₄前躯体为铁源和磷源, 以水为介质, 采用湿法研磨混合均匀, 然后通过高温固相法制备出纳米磷酸亚铁锂/碳(LiFePO₄/C)复合材料。采用XRD、SEM、TEM、TG和拉曼光谱对该复合材料进行了表征, 并研究了其电化学性能。结果表明, 制备的LiFePO₄/C纳米颗粒为类球形, 表面均匀地包覆了一层约5 nm厚的碳层, 作为锂离子电池正极材料表现出良好的倍率性能和循环性能, 在0.2 C(1 C=170 mAh·g^-1)、0.5 C、1 C、2 C、5 C、10 C下首次放电容量分别为151、150、146、142、132、119 mAh·g^-1, 20 C下的首次放电容量也达105 mAh·g^-1, 且循环50次几乎无衰减。     

BNmf-Si3N4w/Si3N4复合材料的制备与性能

为制备一种介电性能和力学性能优异的高温透波材料,采用凝胶注模(GC)结合先驱体浸渍裂解(PIP)工艺制备了BN_mf-Si₃N_4w/Si₃N₄复合材料。研究了浸渍裂解次数及BN_mf含量对复合材料的力学性能与介电性能的影响。结果表明：(1)随着PIP循环次数增加,复合材料的密度增大,气孔率降低,氮化硅基体逐渐形成三维网络结构包裹在复相微米增强体周围,复合材料力学性能提升;(2)当BN_mf含量从4vol%增加到12vol%时,弯曲强度从175.5 MPa降低到139.3 MPa,断裂韧性从2.36 MPa·m^1/2增加到2.73 MPa·m^1/2,介电常数从3.62下降到3.25,介电损耗角正切从0.012下降到0.007;(3) BN_mf-Si₃N_4w/Si₃N₄复合材料的强韧化机制主要...     

纳米LiFePO4/C复合正极材料的溶剂热合成

采用乙二醇溶剂热法,以蔗糖为碳源,制备了橄榄石型纳米级LiFePO₄/C复合正极材料,对其物相、形貌、结构、成分和性能进行了表征。结果表明,所制备的纳米LiFePO₄/C的形貌为棒状,直径约为100 nm,结晶度高、分散性好。LiFePO₄的粒径细化和掺碳有利于提高LiFePO₄正极材料的电化学性能,其首次充放电比容量（0.1 C）分别为166 mAh·g^-1和164 mAh·g^-1,充放电电压平台分别为3.45 V和3.40 V;在5 C大倍率放电下,经过20次循环,其比容量保持率为95.4%。     

聚丙烯酰胺改性LiFePO4/C正极材料的研究

以聚丙烯酰胺(PAM)作为分散剂, 采用液相控制结晶-碳热还原法制备LiFePO₄/C正极材料, 考察了PAM对LiFePO₄/C正极材料性能的影响, 采用热化学分析、X射线衍射、扫描电镜、碳含量分析和充放电测试等分析测试手段对材料进行表征。结果表明, 将PAM溶于酸液中且添加量为1.5wt%时制备的LiFePO₄平均粒径约为100 nm, 颗粒分散较为均匀; 该材料在0.1C、1C、2C、5C和10C倍率下首次放电比容量分别为153.8、142.5、138.4、128.7和124.3 mAh/g, 1C倍率下循环100次后容量保持率仍在99%以上; 交流阻抗分析表明: 1.5wt%PAM改性后的材料的各种阻抗值均降低, 锂离子的导电速率提高了28倍。PAM改性后的LiFePO₄/C正极材料的离子及电子导电性提高了, 具有优良的倍率性能与循环性能, 有利于大规模推广应用。     

石墨烯掺杂的纳米金属复合材料的制备及其电化学性能研究

选择改进的Hummers法制备了氧化石墨烯(GO),将GO进行高温热还原处理，形成还原氧化石墨烯(RGO),再以油酸作为表面活性剂，通过球磨法与金属氧化物正极材料LiFePO₄通过复合生成了LiFePO₄/RGO正极材料。采用XRD、TEM和电化学性能测试等手段对复合材料进行了表征。结果表明，RGO的掺杂没有影响LiFePO₄材料的晶体结构，没有产生新的产物，当RGO的掺杂量为6%(质量分数)时，复合材料中RGO和LiFePO₄分散较为均匀，形貌结构较好。随着RGO掺杂量的增加，复合材料的首次充放电比容量均先增大后减小，当RGO的掺杂量为6%(质量分数)时，复合材料的首次放电、充电比容量均达到最大值，分别为137.5和139.5 mAh/g。在0.2 C的倍率下循环30次后，6%(质量分数) RGO掺杂的复合材料的放电比容量的保持率最高可达86.1%,电荷转移电阻最小为512.70Ω,电化学性能最佳。因此可知，RGO的最佳掺杂量为6%(质量分数)。     

活性炭/高密度聚乙烯复合材料的力学性能

以稻壳为原料,以H₃PO₄、KOH、ZnCl₂为活化剂在600℃条件下制备三种活性炭,以生物炭、三种活性炭为填料填充高密度聚乙烯(HDPE)制备生物炭/HDPE复合材料和活性炭/HDPE复合材料,并对其力学性能进行测试和分析。结果表明,活性炭比生物炭具有更高的比表面积和发达的孔隙结构,其中经H₃PO₄活化制备的活性炭比表面积最高,为714.27 m2/g;活性炭/HDPE复合材料比生物炭/HDPE复合材料具有更佳的力学性能,相对于其他材料而言,经H₃PO₄活化制备的活性炭/HDPE复合材料具有较佳的弯曲性能、拉伸性能、刚性、弹性、抗蠕变性能及抗应力松弛能力,其弯曲强度、弯曲模量、拉伸强度、拉伸模量分别为38.66 MPa、2.46 GPa、32.17 MPa、1.95 GPa。本研究可为活性炭的材料化利用提供有益的借鉴经验。      

CTAB辅助水热合成球状纳米花MoS2/C复合材料及其电化学性能研究

以钼酸钠(Na₂MoO₄·2H₂O)、硫脲(NH₂CSNH₂)、CTAB为原料, 利用水热法合成了MoS₂/C球状纳米花复合材料。通过XRD、SEM、TEM、TG等分析测试方法, 研究了不同CTAB添加量对MoS₂/C复合材料的微观结构、表面形貌的影响规律, 结果显示, 有部分无定形碳嵌入了MoS₂层间, 并抑制了MoS₂(002)面的堆积。电化学测试表明: 与纯MoS₂相比, MoS₂/C复合材料具有更好的电化学性能, 当加入0.025 g CTAB时首次放电比容量达到730 mAh/g, 在100 mA/g的电流密度下经过100次循环比容量稳定在415 mAh/g。在此基础上讨论了MoS₂/C球状纳米花复合材料的可能生长机理以及对材料电化学性能的影响规律。     

Effect of hydrogen radical on growth of μc-Si in hetero-structured SiCx alloy films

The changes of the crystallinity of μc-Si phase are studied in samples deposited with hydrogen dilution ratio, H₂/SiH₄, from 9.0 to 19.0 by hot-wire CVD (Cat-CVD). In the samples deposited at filament temperature, T_f, of 1850 °C, the crystalline fraction and the crystallite size of μc-Si phase increased with increasing the H₂/SiH₄. The carbon content, C/(Si+C), was almost constant. In the XRD patterns, the intensity of Si(1 1 1) peak decreased and that of Si(2 2 0) peak increased with increasing the H₂/SiH₄. In the samples deposited at T_f of 2100 °C with H₂/SiH₄ over 11.4, the μc-Si phase was not formed and the C/(Si+C) increased. The growth mechanism of μc-Si in hetero-structured SiC_x alloy films is discussed.     

Preparation of (Ti1−xAlx)N films from mixed alkoxide solutions by plasma CVD

(Ti_1−xAl_x)N films were prepared on a Si wafer at 700°C from toluene solution of alkoxides (titanium tetraetoxide and aluminum tri-butoxide) in an Ar/N₂/H₂ plasma by the thermal plasma chemical vapor deposition (CVD) method. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electrical resistivity, and Vickers micro-hardness. Single phase TiN formed at an Al atomic fraction of 0–0.2, with a mixed TiN and AlN phase occurring up to 0.6 and single phase AlN forming above 0.8. The films had relatively sooth surfaces, 0.4 μm thick at an Al atomic fraction of 0.2, and thickened with increasing Al fraction. The atomic concentration of Ti, Al, N, O, and C determined from their respective XPS areas showed that the Ti and Al contents of the films changes with the solution composition in a complementary way. The impurities were about 10 at.% oxygen and carbon. The electrical resistivity was almost unchanged from the value of 10³ μΩ cm at 0–0.6 Al but then suddenly increased to 10⁴ μΩ cm at higher Al contents. The hardness showed a synergic maximum of about 20 GPa at an Al fraction of 0.6–0.8.     

Preparation of nanocrystalline SnO2 thin film coated Al2O3 ultrafine particles by fluidized chemical vapor deposition

Fluidized chemical vapor deposition (FCVD) technology was developed for coating SnO₂ thin film on Al₂O₃ ultrafine particles. TEM and HREM analysis found that SnO₂ films with different structures were deposited by controlling the coating temperature, reactant concentration, etc. Nanocrystalline SnO₂ film was coated at 573.15 K by gas phase reaction of SnCl₄ with H₂O. EPMA and EDS studies indicated that the distribution of SnO₂ inner and outer of the agglomerates was uniform. Nucleation and film deposition were coexisted mechanism during the FCVD coating process. The fraction of SnO₂ in the composite particles increased with increasing coating temperature, SnCl₄ concentration, and coating time. The mass fraction of SnO₂ in the composite particles increased strongly with the ratio of P_H2O and P_SnCl4 at low mole ratio of H₂O with SnCl₄, but increased little under the conditions of excess H₂O with respect to SnCl₄.     

Carburization performance of Incoloy 800HT in CH4/H2 gas mixtures

Carburization performance of Incoloy 800HT has been studied after cyclic and isothermal exposures to CH₄/H₂ carburizing gas mixtures at high temperatures for 500 h. At 800 °C in 2% CH₄/H₂, Incoloy 800HT suffered external oxidation and carburization, the external continuous layer of reaction products consists primarily of Cr₇C₃, Mn_1.5Cr_1.5O₄, and FeCr₂O₄ with Fe(Cr, Al)₂O₄ as a minor phase. At 1100 °C in 10% CH₄/H₂, external carburization did not occur likely due to high carbon dissolution in the alloy substrate at this temperature. A thermodynamic analysis indicated that 1000 °C was an approximate critical temperature, below which the environment should result in mixed oxidizing/carburizing behavior, while above this temperature reducing carburizing behavior should occur. The experimental results approximately agree with the thermodynamic analysis. Metal dusting was not observed under highly carburizing conditions (a_C>1). The size and morphology of Cr-rich phases (or Cr-carbides) are both temperature- and time-dependent, while the external continuity is more temperature-dependent rather than time-dependent.     

(H4N)2S对电合成CoO/聚苯胺复合膜腐蚀性能的影响

在CoSO₄-C₆H₇N-H₂SO₄混合液中,采用恒电位法合成了CoO/聚苯胺（PANI）复合膜,研究了添加剂（H₄N）₂S对CoO/PANI复合膜的影响。通过电化学测试技术、SEM、XRD和加速腐蚀试验等方法对CoO/PANI复合膜的微观形貌及耐腐蚀性能进行分析。结果表明,合成的CoO/PANI复合膜中,CoO以晶体形式存在,（H₄N）₂S的加入改变了CoO/PANI复合膜膜层的微观形貌,由不致密不规则的片状结构转变为均匀致密规则的片状一体结构,（H₄N）₂S加入量过大导致（H₄N）₂S-CoO/PANI复合膜表面出现少量孔洞;未添加（H₄N）₂S的CoO/PANI复合膜自腐蚀电流密度为7.079×10-6 A/cm2,自腐蚀电位为-0.545 V,添加0.3 g/L的（H₄N）₂S后,（H₄N）₂S-CoO/PANI复合膜自腐蚀电流密度达到7.943×10-7 A/cm2,自腐蚀电位达到-0.314 V,极化电阻为6 426.8 Ωcm2,经过10% HCl点滴腐蚀时间达478 s,中性盐雾实验56 h未见锈蚀,（H₄N）₂S显著提高了CoO/PANI复合膜的耐腐蚀性能。      

Sensitivity enhancement for H2 gas detection using a SnO2–Ag2O–PdOx nanocrystalline system

Thick film H₂ sensors were fabricated using SnO₂ loaded with Ag₂O and PdO_x. The composition that gave highest sensitivity for H₂ was in the wt.% ratio of SnO₂:Ag₂O:PdO_x as 93:5:2. The nano-crystalline powders of SnO₂–Ag₂O–PdO_x composites synthesized by sol–gel method were screen printed on alumina substrates. Fabricated sensors were tested against gases like H₂, CH₄, C₃H₈, C₂H₅OH and SO₂. The composite material was found sensitive against H₂ at the working temperature 125 °C, with minor interference of other gases. H₂ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on SnO₂–Ag₂O–PdO_x nanocrystalline system exhibited high performance, high selectivity and very short response time to H₂ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of H₂.     

稀土氧化物(La2O3或CeO2)对搅拌摩擦加工制备Ni/Al复合材料组织和性能的影响

采用搅拌摩擦加工（FSP）的方法制备Ni/Al复合材料,并在此基础上添加不同种类稀土氧化物（La₂O₃或CeO₂）,通过SEM、EDS、XRD、电子探针（EPMA）和室温拉伸试验研究稀土氧化物对FSP制备Ni/Al复合材料组织和性能的影响。结果表明：Ni/Al复合材料复合区有较明显的Ni粉团聚物存在,Ni-La₂O₃/Al、Ni-CeO₂/Al复合材料中Ni粉团聚物数量减少,尺寸减小。La₂O₃和CeO₂均对Al-Ni原位反应有较大影响,能够促进Al-Ni原位反应的进行,生成更多增强相。Ni-CeO₂/Al复合材料与Ni-La₂O₃/Al复合材料相比,复合区组织更加均匀,增强颗粒Al₃Ni含量更多。La₂O₃和CeO₂均能显著提高FSP制备Ni/Al原位复合材料的抗拉强度。Ni-La₂O₃/Al复合材料的抗拉强度达到221 MPa,Ni-CeO₂/Al复合材料的抗拉强度达到238 MPa,两者相比于Ni/Al的复合材料抗拉强度（166 MPa）分别提高了33.1%和43.4%。