The Effect of Annealing under Non-vacuum on the Optical Properties of TiAlN Non-vacuum Solar Selective Absorbing Coating Prepared by Cathodic Arc Evaporation

TiAIN solar selective absorbing coatings which were deposited on 304L stainless steel using cathodic arc evaporation method were annealed under non-vacuum at different temperatures with different times. The optical properties （absorptance and emittance） of the coatings were measured by a spectrophotometer. It was found that, after being annealed for 2 hours at different temperatures, the absorptance of the coatings reached the highest value of 0.92 at 700 ℃ while the emittance got the lowest value of 0.38 at 800 ℃. When the coatings were annealed at 600 ℃ for 24 hours, the optical properties changed to 0.92/0.44 （absorptance/ emittance）. By measuring the structure, morphology, elements and surface roughness of the coatings, it was found that both the elemental composition and the surface roughness of the coatings changed as a result of annealing, and these changes caused the change of the optical properties of the coatings.

The bactericidal effect of continuous wave laser with strongly absorbing coating at the fiber tip

The bactericidal effect of laser radiation with a quartz fiber-based transmission system with a strong absorption coating converter against bacteria associated with urological stones has been studied.Gr am-negative rod Escherichia coli and the Gram-positive coccus Staphylococcus epi-dermidis,Staphylococcus aureus,Enterococcus faecalis and Enterococcus faecium were used in this study.Each bacterial species was treated by continuous-wave near infrared laser coupled with bare fiber tip or strongly absorption coating fiber tip.After treatment,the temperature of bacterial suspension was measured.In addition,the temperature dist ribution was analyzed.It has been shown that using laser with a strongly absorption coating fiber tip results in significant bactericidal effect.The decrease of the amount of E.coli and S.epidermidis was 100%after treatment with an output power of6 W of radiation at a wavelength of 0.97 pum for 40s.Number of S.aureus and Ent.facium colony-forming unit was reduced to 70%after same exposure.The peak temperature of bacterial suspension was 86℃ after treatment by laser with a strongly absorption coating fiber tip.Laser with a strongly absorpt ion coating fiber tip provides large scale hydrodynamic flows directed away from the fiber tip.The laser with a strongly absorption coating fiber tip has bactericidal effect.The main role is associated with the effect of high temperature,which,in the form of flow in a liquid medium,afects bacteria.

Wave-absorbing Properties of a Cement-based Coating with MnO2/Activated Carbon Composite

MnO_2/activated carbon composite（Mn-ACC） wave absorber was prepared by the reaction between Mn（CH_3COO）_2 and KMnO_4 on activated carbon. Then, a novel cement based composite absorbing coating（CB-CAC） was prepared by adding the Mn-ACC, manganese zinc ferrite and rubber particles into cement. XRD method was used to analyze the reaction products of the Mn-ACC. The tensile bond strength and the wave absorbing properties of the CB-CACs were also tested. The results showed that the crystallinity of MnO_2 formed in the Mn-ACC was poor. Adding Mn-ACC into the CB-CAC led to first increase and then decrease of the tensile bond strength. The tensile bond strength reached 1.89 MPa with 8.51% of the Mn-ACC. The CB-CACs obtained the optimal absorbing properties with the cement, manganese zinc ferrite, Mn-ACC, rubber particles and H_2O mass ratio of 7.5？7.5？1？1？5.5, respectively. The band width of the reflection below-10 dB was up to 8.8 GHz, which accounted for 57.14% of the test band.

Q-Switched Erbium-Doped Fiber Laser Using Cadmium Selenide Coated onto Side-Polished D-Shape Fiber as Saturable Absorber

A stable Q-switched erbium doped fiber laser emitting at 1558 nm is demonstrated using a cadmium selenide（CdSe） material coated onto a side-polished D-shape fiber as the saturable absorber（SA）. By elevating the input pump power from the threshold of 91 mW to the maximum available power of 136 mW, a pulse train with a maximum repetition rate of 57.44 kHz, minimum pulse width of 3.76 us, maximum average output power of7.99 mW, maximum pulse energy of 0.1391 uJ, and maximum peak power of 36.99 mW are obtained. The signalto-noise ratio of the spectrum is measured to be around 75 dB. This CdSe based SA is simple, robust, and reliable,and thus suitable for making a portable pulse laser source.

Enhanced Microwave Absorption for High Filler Content Composite Molded from Polymer Coated Flaky Carbonyl Irons Modified by Silane Coupling Agents

A microwave absorbing sheet with a high complex permeability and a relatively low complex permittivity is obtained by molding of the densely coated flaky carbonyl iron particles(FCIPs)by styrenebutadiene-styrene block copolymer(SBS)in the assistance of coupling agent modification.Direct molding of the core-shell FCIPs without adding extra binder results in a large permeability due to the high filling ratio(55vol%)of absorbents.Importantly,the permittivity is well suppressed by the dense insulate polymer shell on the FCIPs,avoiding the severe impedance mismatch problem of the high filler content microwave absorbing materials.Investigations show that modifying the surface of FCIPs by proper amount of silane coupling agent is critical for the coating quality of the SBS shell,which is verified by resistivity and corrosion current density measurements,and can be interpreted by improved interfacial compatibility between the modified FCIPs and SBS.The obtained microwave absorbing sheet shows a minimum reflection loss of-38.74 dB at 1.57 GHz and has an effective absorption bandwidth from 1.1 to 2.3 GHz at a relatively small thickness of 2 mm.

Preparation and Mechanical Properties of Glass Coats with High Temperature Radar Absorber

BaO-La2O3-B2O3 （BLB） glass, suitable to be used as a sealing between metals, was chosen to be the binder in preparing glass coats on the Ti-alloy substrate. The SiCN nano-powder was introduced as the filler for the absorbing coat because it is considered to be a good high temperature absorber. The effect of the coating temperature and coating time on the tensile strength of the glass coat was investigated and the proper coating parameters to get good mechanical properties were determined. In addition, the effects of the SiCN content on the tensile strength of the absorbing coat were also discussed. Results show that it is possible to prepare the glass coat using the BLB glass as a binder. That the coat formed at 730℃ for 30 min has the best tensile strength witnesses 730 ℃, 30 min to be the proper parameter to prepare the glass coat. The BLB glass coat without SiCN powder possesses good tensile strength and the introduction of the SiCN absorber into the glass coat will lower the tensile strength. As the SiCN content increases, the tensile strength of the absorbing coat decreases, which could be attributed to the aggregation of SiCN in the coats.

Study on the electromagnetic properties of a coated radar absorbent

The sol-gel method is used to fabricate Fe crystalline powders coated with SiO2. By controlling the molar ratio R of diluted water to tetraethoxysilane （TEOS）, Fe powders coated with SiO2 with different morphological characteristics are fabricated. The influence of the core diameter on electroragnetic parameters is investigated. The effect of the amount of the coating material SiO2 on electromagnetic parameters is given. Radar wave absorbing properties of Fe coated with SiO2 and TiO2 respectively are compared.

The influence on biotissue laser resection of a strongly absorbing layer at the optical fiber tip

In this paper,we consider a method of laser resection using the silica glass core from which the cladding layer has been removed as the cutting part of a laser scalpel.An absorbing layer coating the silica fiber tip markedly alters its biotissue cutting character istics.The results of histological studies of skin after exposure to a laser scalpel with and without a strongly absorbing coating(SAC)at a wavelength of 097μm show that resection using a coated scalpel is more sparing.When an uncoated scalpel was used,skin injury was more apparent in both its surface spread and the depth of structural damage,resulting in poorer tissue regeneration.

Electromagnetic Waves Absorbing Characteristics of Composite Material Containing Carbonyl Iron Particles

Results of measurements of permeability, permittivity and radar absorption properties of composites on basis of carbonyl iron particles R-10 brand are presented in this paper. The calculations and experimental studies have shown that in the super high frequency (SHF) and extremely high frequency (EHF) ranges on the basis of two-layer structures with different content of carbonyl iron particles can create a radar absorbing coatings with a reflectivity of less than -10 dB over a wide bandwidth from 3.1 to 17.1 GHz and from 27 to 37 GHz. Absorbing properties of composites are saved in terahertz frequency range from 250 to 525 GHz.

Comparative Analysis of Biotissue Laser Resection Using Strongly Absorbing Optical Fiber Tips

We present a laser resection technique to be used when biotissue is heated by laser radiation to the temperature of material softening and then moved apart by the lateral edge of the optical fiber with a strongly absorbing tip. The absorbing tip allows the decrease in the power of effective cutting of the laser scalpel at the wavelength of 0.97 μm. And it changes the resection speed as well as the characteristics of the damage of the tissues adjacent to the incision in experiments on model media and experimental animals.

全玻璃真空太阳集热管关键技术参数研究进展

全玻璃真空太阳集热管是太阳能热利用系统的重要组成部分,其性能参数的优劣直接影响到太阳能热利用系统的热性能、耐久可靠性和节能效果。文章从真空管基本结构和工作原理的介绍出发,对影响真空管性能的光学性能、热性能等关键技术参数及玻璃管材料、真空性能等其他技术要求的研究进展做了详细分析,并在长期从事科研和检测工作的基础上,给出了提升真空管的产品性能可从玻璃管生产优化、新涂层开发、真空性能加强、技术创新、先进设备开发、标准修订等方面的建议。

具有抗紫外线功能的光固化涂料组合物的制备与性能研究

以羟基二苯甲酮、2-巯基苯并噁唑、芳基酰氯为原料,采用简单、温和的方法合成了新型二苯甲酮衍生物和含苯并噁唑的硫酯类衍生物,采用核磁氢谱1H NMR、核磁碳谱13C NMR和高分辨质谱HRMS等测试手段对目标化合物进行表征,并对其进行了光学性能测试,并用其制备了具有抗紫外线功能的光固化涂料。结果表明:两类衍生物能有效吸收220~350 nm的紫外光,与低聚物、单体相容性好,无气味。新合成的二苯甲酮衍生物作为光引发剂可使涂层固化时间大幅缩短到9 s,固化膜的外观、附着力和凝胶率相较于市售光引发剂BP有明显提高;硫酯类衍生物作为紫外吸收剂不仅能够增加光固化涂层的抗紫外线功能,且易于光固化涂料的制造、贮存。该组合物在罩面剂、油墨、胶黏剂等领域也有良好的应用前景。

塔式太阳能吸热器曲面涂层吸收率测试方法研究

吸热器涂层吸收率的准确测量对吸热器性能评估、优化具有重要意义。目前吸热器涂层吸收率的实验研究大多局限于平面金属基材。以塔式太阳能熔盐吸热器圆柱形吸热管为研究对象,提出蓝丁胶法和漫反射盒法2种广泛适用的测量曲面涂层吸收率测试方法。蓝丁胶法器材准备简单,操作复杂;漫反射盒法器材准备复杂,操作简单。2种方法在测量过程中隔绝环境光线干扰,得到各种涂层附着于平板和圆管表面的测量吸收率,通过不同涂层在平板和圆管上的吸收率对应关系建立拟合曲线,从而修正测量数据得到吸热管涂层吸收率,拟合曲线精确性R^(2)≥0.995;不遮光条件下直接测量2.5cm直径吸热管吸收率,最大相对误差为13.39%,使用蓝丁胶法和漫反射盒法后相对误差分别降为0.27%和0.45%,2种方法各点结果相对误差之差小于0.30%,测量过程中涂层吸收率越大,各因素对测量结果影响越小;在蓝丁胶测试方法中,吸热管直径越大,测得的吸收率越小。

表面纹理对水泥吸波路面微波除冰性能的影响

为了增强水泥混凝土路面除冰效率,制备了吸波及疏水涂层,并在此基础上,构建了8种不同表面纹理,用于探究表面纹理、吸波材料对微波升温性能的影响。首先,以石墨为微波吸收剂,掺加纳米SiO_(2)制备了兼具疏水和吸波性能的水泥基涂层;通过机器学习改进铺砂法获得不同纹理的平均构造深度(mean texture depth,MTD);为了评估MTD对微波升温效率、均匀性的影响,采用课题组自行研发的微波除冰车进行微波升温试验;同时,测试了普通及涂层混凝土表面的接触角,进行了冰-混凝土冰黏附性剪切试验,用于评价本文所制备涂层的除冰效果。最后,为了保证本文设计涂层的抗滑性能,还进行了表面抗滑摆值测试。结果表明:不同程度纹理和吸波涂层两者耦合作用增强水泥路面的吸波升温效率,但纹理对升温均匀性有负面影响;当MTD从0.41 mm(未处理表面)提高至2.11mm时,吸波涂层试件的吸波升温效率提高1.42倍。同时,涂层也显著增强了试件表面的接触角,接触角从25.5°提升至104°,进而冰黏附强度降低。当设计厚度为1.5 mm时,在满足抗滑性的同时涂层仍具有较好的吸波性能。

高温雷达吸波涂层研究进展

在现代信息化战争中,探测和制导技术迅猛发展。在众多探测信号中,雷达探测占比高达60%,因此武器装备雷达隐身能力尤其重要。随着新一代装备性能的提升,热端部件的服役温度不断升高,对高温雷达吸波涂层提出了更加严苛的要求。在高温服役环境下,部分雷达吸波材料存在氧化、居里温度低而失去吸波性能的问题。高温雷达吸波材料主要依靠介电损耗和电导损耗机制实现对电磁波的损耗吸收。基于此,综述了以碳化物、硼化物、氧化物、金属材料、MAX相材料为吸波剂的高温雷达吸波涂层研究情况,分析了各材料的优势及存在的问题,其中氧化物吸波剂高温稳定性好,易于制备,成本低,其吸波性能可通过掺杂改性调控,是面向未来更加严苛服役环境下更具应用潜力的吸波材料。此外,还从梯度结构和超材料设计2个角度分析了涂层结构设计在拓宽涂层吸波频带,降低涂层厚度方面的作用。结合当前研究进展提出了新材料研发、新结构设计和与材料结构相适应的制备工艺研究是未来高温雷达吸波涂层的发展方向。

水性苯丙吸波涂层的制备与性能研究

吸波涂料是一种能够吸收和衰减入射电磁波的功能涂料,而水性吸波涂料更具有环保健康的特点。选择炭黑和羰基铁粉作为复合吸波剂,加入水性苯丙乳液中制备成本较低的复合吸波涂层。首先测试了炭黑和羰基铁粉的电磁参数,并计算得出成分为12%炭黑和70%羰基铁粉,厚度为2mm时吸波性能最佳,反射损耗优于-5dB的有效吸收频宽达到9.9GHz,反射损耗峰值达到-28.6dB。然后制备了含12%炭黑和70%羰基铁粉,厚度为2mm的苯丙吸波涂层,测试分析了苯丙吸波涂层的吸波性能以及涂料相关性能。

吸波涂层应用方案自动寻优方法

在有限质量约束下实现宽频隐身性能最优,是隐身飞机吸波涂层应用方案设计所追求的目标。本文针对多种吸波涂层的最优化分区应用问题开展研究,建立了一套吸波涂层应用方案的自动优化方法。首先,基于时域有限差分法计算模型在不同频率、方位、极化下的电磁场,对各状态电磁场做归一化和加权计算后得到总电磁场。然后,将总电磁场按照特定方向、数量进行分区,并将每个分区分别赋予相应的吸波涂层,采用传输矩阵法计算吸波涂层的反射系数以将吸波涂层的影响叠加到电磁场中。对加载吸波涂层后的总电磁场进行近-远场变换,实现模型雷达散射截面(radar cross section,RCS)的快速计算。基于改进的单纯形法和Karush-Kuhn-Tucker条件建立自动优化方法,以降低RCS或减轻吸波涂层质量为目标函数,优化吸波涂层分区方案。最后,以行波板为例,开展包含3种厚度吸波涂层的应用方案减质优化。结果表明,优化方案相比1.5 mm厚吸波涂层方案可实现吸波涂层减重50%,且行波板RCS均值提高不超过1 dB,优化效果显著。

磁性金属吸波剂的高温氧化问题及其对策研究进展

目的针对磁性金属吸波剂由组成元素化学性质活泼导致的高温氧化和电磁性能恶化问题展开现状调研和讨论,解析磁性金属吸波剂高温氧化的机理,并提出相应的解决策略。方法从氧气在金属吸波剂中的吸附、反应和传质过程出发,讨论高温氧化对吸波剂电磁性能的影响规律,系统总结并评述表面包覆隔绝氧气、生成致密金属氧化膜和抑制氧原子扩散3种策略对吸波剂抗高温氧化的作用机制。结论表面包覆策略通过引入有机高分子、无机化合物或磁性金属等包覆物质,以隔绝氧气,从而抑制磁性金属吸波剂的高温氧化。其中,无机化合物包覆体系最具潜力,但尚未达到理想的超薄致密状态。生成致密氧化膜策略通过溶质元素的选择性氧化,形成保护膜,能够有效抑制氧化进程,但引入较高含量的非铁磁性溶质元素容易降低磁导率、恶化吸波性能。抑制氧原子扩散策略通过形成晶界氧化物来有效减缓氧化,目前其实现手段有限且不够成熟。在耐温磁性吸波剂的研制中应综合考虑使用温度、基体材料、目标吸波频段和期望吸波性能等,采用合适的抗氧化策略。

钐铁氮(SmFeN)含量对等离子喷涂SmFeN/LaMA复合材料涂层组织及电磁损耗性能的影响

观察并分析了在35 kW条件下等离子喷涂的不同质量比(2∶1,1∶1,1∶2)Sm_(2)Fe_(17)N_(X)(SmFeN)/LaMgAl_(11)O_(19)(LaMA)复合吸波涂层样品的相结构以及样品在0~18 GHz电磁波频率波段内的电磁参数(ε′、ε″、μ′、μ″)和电磁波反射率RL值,并对其电磁损耗机理进行了研究。结果表明,SmFeN含量会对喷涂样品的相组成和吸波性能产生较大影响。喷涂样品包含Fe_(8)N、Fe_(16)N_(2)、Al_(2)O_(3)、AlN、Fe_(12)Sm、La_(3)MgAlO_(7)、LaMgAl+(11)O_(19)多种相,SmFeN质量比增大使Fe_(8)N、Fe_(16)N_(2)相相对含量升高,使Fe_(12)Sm、La_(3)MgAlO_(7)、LaMgAl_(11)O_(19)相相对含量降低,AlN相相对含量较为稳定;高温下出现非晶相,温度上升使非晶相的相对强度增大,导致样品在高温下吸波性能变差。LaMgAl_(11)O_(19)相对含量升高使样品的ε′,ε″降低,优化了喷涂样品的阻抗匹配;AlN相对含量升高使样品ε′的波谷、ε″的波峰向高频方向移动。性能最佳的喷涂样品质量比为m(SmFeN)∶m(LaMA)=1∶2:在4.24 GHz,4.83 mm下反射率达到-40.31 dB,达到有效吸收(RL<-10 dB)的带宽和厚度范围分别为3.61~6.94 GHz,2.93~5 mm和8.4~12.2 GHz,1.98~3.45 mm。40,400,700℃下1∶1比例喷涂样品在8~18 GHz波段内最低反射率分别为-5.46,-3.62,-0.37 dB,经弓形梁室温测试值与计算值对比证实,计算值与测试值较为符合。

耐高温吸波陶瓷及其涂层的研究进展

随着近现代科技的发展,高速飞行器对生存能力需求不断提高,其鼻锥、机翼、尾喷管等高温部件极易暴露。传统吸波材料普遍不能应用于高温环境,为了能够隐藏高速飞行器的高温部件,吸波材料的高温应用引起了研究人员的重视,耐高温吸波陶瓷材料可以实现上述背景下的应用。为提供分析和改善陶瓷吸波材料高温程度有限和吸收带宽较窄问题的依据,对引入温度影响后,耐高温吸波陶瓷材料的吸波机理进行了阐述。耐高温吸波陶瓷材料与涂层可以分为碳化物陶瓷、氮化物陶瓷、氧化物陶瓷和聚合物转化陶瓷。本文在此分类的基础上,对陶瓷吸波材料和涂层损耗电磁波机理及其高温条件下的吸波性能进行了归纳总结,并指出未来耐高温吸波陶瓷材料应改善现有材料耐高温程度不足以及有效吸收带宽较窄的问题,进而加强其在高温条件下的服役能力。