钡铁氧体的表面改性与红外隐身性能的研究

以硝酸铁、硝酸钡和柠檬酸为原料，采用溶胶．凝胶自蔓延法制得钡铁氧体。为使钡铁氧体具有红外隐身性能，利用化学镀工艺对其表面进行金属化改性可以得到表面完整包覆的导电粉末。借助于XRD、SEM等测试手段，对材料的晶体结构及表面形貌进行了观察和分析表征，利用FT-IR的漫反射系统对钡铁氧体及钡铁氧体表面改性材料的红外隐身性能进行测试，结果表明：所制得的钡铁氧体为M型钡铁氧体，在8～14μm的平均红外发射率为0．8542；而经过表面改性后的钡铁氧体，在8～14μm的平均红外发射率为0．5910，具有良好的红外隐身性能。     

Ni-P化学镀制备钡铁氧体基红外-微波一体化隐身材料

为使钡铁氧体粉末具有红外隐身性能,采用化学镀工艺在钡铁氧体表面镀Ni-P合金,系统研究了化学镀制备工艺对钡铁氧体复合粒子红外发射率的影响.得出了镀Ni-P合金的最佳工艺条件为:硫酸镍30g/L,次亚磷酸钠20g/L,柠檬酸钠70g/L,硫酸铵50g/L,反应温度85℃,pH值为10.0.借助于XRD、SEM等分析测试手段对样品的晶体结构、粒径及表面形貌进行了表征,利用FT-IR的漫反射系统以及矢量网络分析仪对材料的红外发射率和微波吸收性能进行了测试,结果表明:钡铁氧体表面包覆了完整的Ni-P合金镀层;钡铁氧体复合粒子在8～14μm的红外发射率最低降至0.5910,在2～18GHz频段内最大反射率为-24.3dB,大于-10dB的吸收频带宽约2.8GHz,具有良好的红外和微波隐身性能;钡铁氧体复合粒子有望实现红外-微波一体化隐身.     

聚氨酯基低红外发射率涂层的力学性能研究

以铝粉为主要填料,聚氨酯为粘合剂,制备了8~14μm波段发射率低至0.10的低红外发射率涂层。研究了基板处理、涂层厚度和固化温度对涂层力学性能的影响,并对其在涂料中的作用机理进行了探讨。结果表明,当基板用偶联剂处理、涂层厚度为30μm、热处理温度为80℃时,制得的涂层能在保持低红外发射率的同时具有最佳的力学性能。     

Ge/ZnS一维光子晶体的设计、制备及低红外发射率性能

通过从理论上分析介质层厚度、不同介质材料的折射率差及周期数对一维光子晶体红外发射率的影响规律,设计得到了可实现8~14μm波段低红外发射率性能的Ge/ZnS一维光子晶体。随后采用光学镀膜技术在石英基片上通过交替沉积Ge层和ZnS层的方法制得所设计的一维光子晶体,并采用扫描电镜(SEM)及傅里叶变换红外光谱(FTIR)分别对其微结构及光谱发射率进行了系统研究。结果表明,所制备一维光子晶体在8~14μm波段具有低红外发射率性能,其平均发射率可低至0.195。采用Ge、ZnS等无机半导体材料,通过合理的一维光子晶体设计同样可以获得低至0.2以下的红外发射率。     

制备工艺对锌铝氧化物(ZAO)粉末红外发射率的影响

采用液相共沉淀法制备了ZAO掺杂半导体粉末材料,系统研究了制备工艺对ZAO粉末红外发射率的影响.借助于TG-DTA、XRD、SEM对材料的热处理温度,晶体结构及表面形貌进行了考察,利用IR-2双波段发射率测量仪对ZAO粉末材料的红外发射率进行了测试.研究结果表明:当反应物终点pH值为8.5、反应时间为2.5h、煅烧温度为800℃,煅烧时间为2h、Al2O3的掺杂量为3%时所得的ZAO粉末的红外发射率最低;ZAO掺杂半导体粉末的晶体结构为ZnO的铅锌矿结构;粒子形状近似为椭圆形,平均粒径为5～10μm;在中红外(3～5μm)和远红外(8～14μm)波段均具有较低的红外发射率.     

溶胶-凝胶法制备ZnO:Al(ZAO)薄膜的红外发射率研究

用溶胶-凝胶法在石英玻璃基底上制备了ZnO:Al(ZAO)薄膜,研究了热处理温度和Al掺杂含量对薄膜红外发射率的影响.通过XRD和SEM分析了薄膜的微观结构和表面形貌,用光谱辐射计测量了薄膜在8～14μm波段的光谱发射率.结果表明,制备的ZAO薄膜都具有ZnO六角形纤锌矿结构,没有生成杂质相.热处理温度是影响薄膜在8～14μm波段平均红外发射率(ε)的主要因素.随热处理温度的升高和Al掺杂含量的增加,薄膜的ε值有降低的趋势.     

核-壳结构粒子SiO_2@Bi_2O_3的制备及红外发射率研究

为了研究制备复合隐身粒子的方法,采用溶胶-凝胶法制备了核-壳结构SiO2@Bi2O3粒子.通过XRD、TEM及发射率测试仪对制备的材料的结构、形貌和性能进行了表征.XRD表明在700℃可以得到Bi2O3纯相;红外发射率测试表明,Bi2O3具有较低的红外发射率,在SiO2表面包覆Bi2O3后,在3～5μm和8～14μm两个测试波段都能降低SiO2的红外发射率.通过核-壳结构的形式,在较高发射率的样品表面涂覆红外发射率较低的样品,可以提高红外隐身效果.     

石墨烯包覆的MUF石蜡微胶囊的制备及在红外隐身领域的应用

研究了石墨烯包覆对于三聚氰胺-尿素-甲醛树脂(MUF)微胶囊红外发射率以及热性能的影响。研究表明,MUF@石墨烯复合材料粒径分布均匀,石墨烯成功包覆在了微胶囊表面,MUF@石墨烯复合材料的微胶囊化效率为80.4%。在1~14μm波段,MUF微胶囊的红外发射率为0.95,MUF@石墨烯复合材料的红外发射率为0.69,下降27.3%。MUF@石墨烯复合材料的热导率为0.5037W/(m·K),相对于MUF微胶囊提高159%。     

红外高发射率ZnO∶Al粉末的制备

基于红外高发射率材料的应用,用固相法制备了Zn1-xAlxO(x=0.01,0.02,0.05,0.07)粉末,并研究预煅烧和二次煅烧后样品的红外发射率.X射线衍射和扫描电镜分析结果表明,当Al掺杂浓度达到2％(原子比)时,出现了尖晶石相ZnAl2O4.预煅烧和二次煅烧后的样品结晶质量差,有尖晶石相ZnAl2O4形成.红外发射率分析表明,1200℃时,随着掺杂浓度的增大,样品在3～5μm,8～ 14μm,1～ 22 μm三个波段内的发射率都降低了.随着煅烧温度的升高,在8～14μm波段内,Zn0.99Al0.01O发射率先升高后降低,在0.984 ～ 0.987之间.Zn0.99Al0.01O经过预煅烧和二次煅烧后,在这三个波段内的发射率都升高了.二次煅烧温度为1200℃时,得到的8～ 14μm内的发射率最高,为0.989.二次煅烧温度为1300℃的样品在三个波段内的整体发射率大于0.95.     

AZO@C柔性纳米纤维的制备与性能

以聚乙烯醇(PVA)为原料,成功制备了新型掺铝氧化锌包覆碳结构(AZO@C)的柔性纳米纤维。首先通过静电纺丝制备PVA初生纳米纤维,经过热处理工艺提高纳米纤维的耐水性,然后采用水热合成法在其表面包覆一层锌铝氢氧化物,再经过在500℃高温条件下烧结,PVA表面包覆的锌铝氢氧化物发生脱水反应形成致密的掺铝氧化锌(AZO)纳米粒子,同时PVA纳米纤维在高温煅烧中被炭化,形成一种新型AZO@C纳米复合材料。采用红外光谱(FT-IR)、热重分析仪(TGA)、扫描电镜(SEM)等对纳米纤维结构与性能进行测试及表征,AZO@C纳米纤维的平均直径为(320±45)nm。并通过太阳光下降解甲基橙实验证明了AZO@C柔性纳米纤维的光催化降解性能。     

The anti-oxidation behavior and infrared emissivity property of SiC/ZrSiO4–SiO2 coating

In order to improve the oxidation resistance and decrease the infrared emissivity of carbon/carbon(C/C) composites, the SiC and SiC/ZrSiO₄–SiO₂ (SZS) coating were prepared by pack cementation and slurry painting method. The phase compositions and microstructures of the as-prepared coatings were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. The anti-oxidation property, failure and infrared emissivity of single SiC coating and SZS coating were investigated. The results show that the weight loss of single SiC coated sample reached 2.1 ± 0.025 % after 58 h isothermal oxidation at 1,500 °C. While the SZS coating exhibits superior oxidation resistance and can protect C/C matrix from oxidation for more than 198 h with a weight-gain of 3.67 ± 0.025 %. The failure mechanisms of single SiC coating are mainly resulting from unself-healing defects caused by the CO₂ gas which generated during the oxidation process of SiC. The investigation of infrared emissivity property reveals that, the infrared emissivity of SZS coating increases gradually from 0.45 to 0.72 between 3 and 14 μm. The infrared emissivity at 500 °C increases gradually from 0.2 to 0.65 between 3 and 14 μm. The coupled effect between dipole moments and lattice vibration in higher temperature becomes weaker, which in turn lead to the reducing of infrared emissivity in turn. From the anti-oxidation and infrared emissivity property point of view, the SZS coating may be one of the most promising candidates for the anti-oxidation at high temperature and low infrared emissivity of C/C composite.     

低红外发射率耐高温涂层的制备及机理

以漂浮态铝粉为填料,有机硅树脂作为粘合剂,制备了耐高温低红外发射率涂层。对填料的添加量、涂层的固化温度进行了优化研究,对填料及涂层进行了结构、形貌的表征,并测试了涂层的红外发射率与耐热性能。研究结果表明,填料添加量为30%、400℃固化2h,涂层红外发射率(3～5μm,8～14μm)最低可达0.10～0.12,且涂层可在600℃条件下长时间使用。此外,分析认为涂层发射率的降低是消除粘合剂吸收及致密的片层连续结构两者协同作用的结果,并提出新的涂层结构模型对低发射率机理进行了阐述。     

Synthesis and characterization of uniformly coated particles (cobalt compounds on copper compounds)

Spherical particles (～3 μm) of copper(II) oxalate were produced in the form of precipitated solids by gently mixing aqueous solutions of oxalic acid and copper nitrate with predetermined concentrations at room temperature. These particles were isolated from the mother liquor and then coated with cobalt basic carbonate. The coating trials involved heating of the aqueous dispersions, containing known amounts of the dispersed copper oxalate particles (cores), urea, and cobalt nitrate, at 70–85 °C for various periods of time with constant stirring. The heating process decomposed urea, increased pH, liberated carbonate ions, which resulted in the precipitation of the dissolved cobalt ions in the form of shells of cobalt basic carbonate around each core particle. The coating process was sensitive to the applied experimental parameters, since uniformly coated particles were obtained under a narrow range of coating mixture composition. In the absence of the cores, the same reactants solutions produced coating precursor particles (cobalt basic carbonate), when subjected to similar heating conditions. Physical and chemical analyses indicated that the coating material of the coated particles and the coating precursor particles had the same chemical compositions. The as-prepared core, coating precursor, and coated particles were converted into oxide forms by heating their dry powders at elevated temperatures under controlled heating conditions. The heat treatment produced obvious changes in the surface morphology of these particles due to loss of material. Moreover, the heat-treated particles preserved shape integrity to a maximum extent, showing their thermal stability. Selected batches of the as-prepared and heat-treated products were characterized by various physical methods.     

Infrared emitting properties and environmental stability performance of aluminum/polymer composite coating

In this paper, the aluminum/polymer composite coating was prepared and the infrared emitting properties and environmental stability performance of the as-prepared coating were studied. The factors, such as polymer binders, pigment/binder ratios, preparation technology and coating thickness were investigated in detail. Firstly, the study of the polymer binders indicated that modified fluorocarbon resin was the best candidate due to its low infrared emissivity and well-performed physical and chemical properties. Secondly, the optimal pigment/binder ratio was 1.25:1. Thirdly, the optimum coating thickness was 75 μm and the scrape coating method was suitable to prepare the coating. Finally, the optimized aluminum/polymer composite coating showed low infrared emissivity of 0.31. The adhesive force of the coating was first grade and the impact resistance was more than 50 kg cm. In addition, it exhibited excellent salt, acid and alkali resistance. The as-prepared aluminum/polymer composite coating can be used as infrared stealth coating in the wavelength of 8–14 μm.     

氧化锌包覆纳米碳化硅的制备

为了解决纳米碳化硅的应用问题,采用溶胶-凝胶法制备出氧化锌包覆纳米碳化硅颗粒,并对其前驱物的煅烧工艺进行了研究．借助差热-热重分析仪（TG-DSC）、X射线衍射分析仪（XRD）、红外光谱（FT-IR）、高分辨透射电镜（HRTEM）和能谱仪（EDS）等测试手段,发现经500℃煅烧2h后,产物的包覆层从水合草酸锌被煅烧成为氧化锌;氧化锌峰形尖锐,结晶良好,被覆物SiC的峰相对变弱;包覆产物的红外谱图上出现了Zn-O特征吸收峰,煅烧生成的10—20nm氧化锌颗粒较好地包覆在大粒径的碳化硅颗粒周围．     

多波段伪装隐身涂层织物的制备研究与应用

采用着色颜料、红外低发射率填料、水性聚氨酯树脂等制备水性多波段伪装涂料,采用刮涂工艺,制备可见光/近红外/热红外多波段伪装涂层织物。通过双波段发射率测量仪、光谱反射率测试仪、光泽度仪等测试手段对涂层的红外发射率、光谱反射率、镜面光泽度等性能进行了表征,此外还对涂层的理化及环境性能进行了测试。结果表明:涂层的颜色满足《GJB 1082—1991伪装网用颜色》的要求,近红外光谱反射特性在380~1100nm范围内与应用背景基本实现了"同色同谱",不同颜色斑块的发射率梯度在0.13以上,在红外成像下能够形成有效的梯度分割,与应用背景具有较好的融合效果,具有可见光/近红外/热红外隐身性能,各项指标均达到了实用要求。     

Infrared spectrally selective low emissivity from Ge/ZnS one-dimensional heterostructure photonic crystal

Ge/ZnS one-dimensional heterostructure photonic crystal (1DHPC) was successfully prepared by alternating thin films of Ge and ZnS on the quartz substrate by using the optical coating technology. The microstructure and spectral emissivity of as-prepared 1DHPC were characterized by using scanning electron microscopy (SEM) and fourier transform infrared spectrometer (FTIR), respectively. The test result of spectral emissivity shows that the average emissivities of as-prepared Ge/ZnS 1DHPC in the atmospheric windows of 3–5 μm and 8–14 μm can be as low as 0.046 and 0.190, respectively, but the average emissivity in the non-atmospheric window of 5–8 μm can be as high as 0.579. The results indicate that the as-prepared Ge/ZnS 1DHPC has obviously infrared spectrally selective low emissivity characteristic, basically meets the requirements of our design. The as-prepared 1DHPC with infrared spectrally selective low emissivity is promising for use as a material to unify the infrared stealth and effective cooling of the aircraft.     

CR/PU共混粘合剂红外透明性对涂层发射率的影响

用氯丁橡胶(CR)共混聚氨酯(PU)制备了不同红外透明性的粘合剂,并分别添加不同含量的铜粉等填料,制得不同发射率的红外隐身涂层。对粘合剂的红外光谱、发射率及涂层的发射率、微观形貌等进行了分析。结果表明,随粘合剂中聚氨酯含量的增大,粘合剂的透明性变差、发射率增大,涂层的发射率也增大;当铜粉添加量较大时,涂层发射率较小,粘合剂的红外透明性对涂层发射率的影响也相对小一些;并着重对其原因进行了分析。