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101.
In this work, transient thermal response and ablation behavior of liquid silicone rubber composites containing fluxing/ceramic forming fillers were investigated under different heat flows using an oxyacetylene flame. The results indicated that the introduction of zinc borate (ZB) and aluminum oxide (Al2O3) effectively reduced the temperature at various depths of the samples, and they improved the thermal insulation properties and lowered pyrolysis rates. The above finding was attributed to the heat absorption arising from water release and melt filling as well as the vitrified reaction of solid melt due to the decomposition of ZB. Besides, the melting and exfoliation of Al2O3 and the formation of aluminum silicate (Al2SiO5) caused heat absorption effect. Additionally, the mass ablation rates and line ablation rates increased with rising heat flows coupling with a decrease of compressive strength of the char layers. In a nutshell, the effect of adding ZB/Al2O3 on the thermal insulation behavior of epoxy-modified vinyl silicone rubber (EMVSR) composites under different heat flows was elucidtaed. This work served as a reference for the design and preparation of flexible ablative materials for thermal protection applications. 相似文献
102.
基于飞秒激光精修面齿轮时的能量累积效应,建立了光子-电子-晶格系统间耦合作用的三温传热模型,提出一种确定飞秒激光烧蚀齿面扫描路径间扫描间距的方法。仿真得出,能量密度为6.47 J/cm2时,平衡温度3200 K超过材料的熔化温度,热累积效应明显。根据不同的扫描间距计算激光累积强度,以控制凹坑烧蚀深度和轮廓。实验结果显示,能量密度为6.47 J/cm2时,随着扫描间距的减小,激光累积强度增大,齿面的烧蚀深度线性增大;扫描间距为25 μm时的齿轮表面加工质量良好。 相似文献
103.
S. Tudisco D. MascaliN. Gambino A. AnzaloneS. Gammino F. Musumeci A. Scordino A. Spitaleri 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,653(1):47-51
At DMFCI of Catania University, where a Quanta System Nd:YAG laser 600 mJ of energy, 1064 nm wavelength and 6 ns pulse length operates, experiments about plasma expansion in vacuum (<10−5 mbar), have been performed. Our studies are mostly devoted to nuclear and astrophysical purposes. Some preliminary investigations with aluminum thick targets are reported here. Plasma dynamics have been investigated mainly by means of a movable Langmuir Probe, and time of flight spectra have been acquired at different distances from the laser-target interaction area. The cross-correlation of Langmuir probe signals and hydro-dynamical simulation has permitted to calculate the structure of the inner plasma self-generated electric field that drives the plume expansion. The experimental data reveals also a time variable behavior of the self-generated field. This dependence on time produces also a multi-shell plasma in which the different layers expand with a given velocity, temperature and density. 相似文献
104.
Tao Li Chunlan Zhou Zhengang Liu Wenjing Wang 《International Communications in Heat and Mass Transfer》2011,38(8):1041-1043
In this paper, a numerical model of nanosecond laser ablation of crystalline silicon has been established. Based on the highly nonlinear model of heat transfer and phase change in crystalline silicon after absorbing laser light, heat transfer equation is solved by using finite element method implemented in ANSYS. The simulation of ablation depth of crystalline silicon is obtained under different conditions of laser fluence and pulse overlap. Comparing with the ablation morphology obtained from SEM observations, the computational results and experimental data show good agreement. 相似文献
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106.
《Journal of Adhesion Science and Technology》2013,27(12):1323-1334
Films of amorphic diamond can be deposited with a laser plasma discharge source of multiply-charged carbon ions in an ultrahigh vacuum (UHV) environment without the use of any catalyst in the growth mechanism. The beam from a pulsed Nd-YAG laser is focused at very high power densities onto a graphite feedstock and the resulting plasma ejects carbon ions carrying keV energies through a discharge space to the substrates to be coated. The high energies of condensation produce interfacial layers between the films and substrate materials, resulting in levels of adhesion which can support the protection of fragile and sensitive substrates subjected to harsh environmental conditions. Coatings of 2-5 μm thicknesses have extended the lifetimes of substrate materials such as Si, Ti, Ge, ZnS, and stainless steel against the erosive wear from high-speed particles and droplets by factors of tens to thousands. In this paper, we give details of the adhesion and mechanical properties of amorphic diamond films. Emphasis is placed on the quantitative methods to assess and measure the adhesion of films to a variety of substrates. Parameters such as the bonding of the films are examined by Rutherford backscattering spectrometry and nanoindentation techniques. Resistances to wear and debonding are estimated with a modified sand blaster which simulates erosive environments. 相似文献
107.
108.
激光烧蚀硅所生成的等离子体发射光谱特性 总被引:4,自引:1,他引:3
报道由Q-开关Nd:YAG激光器产生的1.06μm、10ns的脉冲激光辐射大气中的硅靶所产生的等离子体发射光谱的研究结果。当作用在硅靶表面的功率密度为9.3×109W/cm2时,测定了等离子体在200~880nm波长范围内的时间分辨发射光谱。估计了等离子体点燃的时间,测定了等离子体中硅原子的推进速度,讨论了等离子体中N+离子产生的原因。通过测量等离子体辐射谱线的半高宽随延迟时间的变化.得到等离子体中电子密度随时间的延迟近似地以exp(-t1/2)的关系衰减。 相似文献
109.
110.