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151.
152.
We have grown thin carbon films by pulsed laser deposition and have investigated the extent to which the properties of such
films, as well as the processes responsible for these properties, are laser wavelength dependent. Films were grown by ablating
material from a graphite target onto room temperature Si(100) substrates with 1064 and 248 nm laser radiation. The films were
analyzed byin situ electron energy loss spectroscopy and byex situ Raman spectroscopy. The results indicated that films grown with 1064 nm ablation were graphitic, while those grown with 248
nm radiation were diamond-like. We have also examined the mass and kinetic energy distributions of the particles ejected from
graphite by the two laser wavelengths. The results indicated that irradiation of graphite with 1064 nm laser radiation results
in the ejection of a series of carbon cluster ions C
n
+
(1 ≤ n ≤ 30) with mean kinetic energies less than 5 eV. Ablation of graphite with 248 nm radiation results in the ejection
of primarily C
2
+
and C
3
+
with mean kinetic energies of 60 and 18 eV, respectively. These results suggest that large, low energy clusters produce graphitic
films, while small, high energy clusters produce films of diamond-like carbon. 相似文献
153.
D. E. Wetzler P. F. Aramendía M. L. Japas R. Fernández-Prini 《International Journal of Thermophysics》1998,19(1):27-42
Thermal diffusivities of supercritical CO2 and C2H6 were determined over a wide density range with a photothermal technique. The thermal lens, formed by the degradation of the absorbed light energy as heat by the sample, allows the employment of a nonequilibrium method in the critical region. Controlling the refractive-index gradient, i.e., a density gradient, perturbations can be maintained at levels where convection is negligible. An easy-to-operate setup allowed us to measure thermal diffusivities in the density ranges 5 to 20 mol·dm–3 for CO2 at 308 and 313 K and 2 to 12 mol·dm–3 for C2H6 at 308 K with a standard precision of 15%. 相似文献
154.
简要论述了一般空调环境下的主要微生物种类及其主要传播方式,分析了影响其传播的因素,同时介绍了现在常用的防治方法,提出了一些改进的意见。 相似文献
155.
Aggregates of carbon black (CB) in a polymer matrix have a tendency to form a CB network. The dynamic mechanical properties of binary systems of chlorinated polyethylene (CPE) and CB or 3,9‐bis{1,1‐dimethyl‐2[β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl)propionyloxy]ethyl}‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) and their ternary systems were investigated. It was found that the dynamic mechanical properties of those systems depend on the colloidal properties, surface oxides, and surface modification of CB. For binary systems of CPE and CB, oxidized CB gives a high modulus at low strain amplitude and a large Payne effect compared with untreated CB. In contrast, the reverse effect was observed for their ternary systems. Consequently, a good micro‐dispersion is obtainable by surface modification due to physical adsorption of AO‐80 on oxidized CB particles via hydrogen bonds. © 2003 Society of Chemical Industry 相似文献
156.
简要介绍了国内少有的干气催化部分氧化转化制氢工艺,重点讨论了转化水碳比的控制条件,对降低水碳比操作进行了有益地探讨。 相似文献
157.
低碳钢热变形过程中铁素体的织构形成规律 总被引:2,自引:0,他引:2
利用背散射电子衍射取向成像技术定量分析了热模拟单向压缩条件下Q235碳素钢热变形时铁素体的织构形成规律。结果表明,在710℃纯铁素体热压缩过程中,形成〈100〉和〈111〉方向的线织构。〈111〉方向织构增强的速度较快,到应变为1.0时达最大值,然后随应变的加大而减弱;〈100〉方向织构在形变量较小时增强的速度较慢,在大应变时增强的速度很快。大应变时虽导致一定程度的动态再结晶,使铁素体晶粒细化,但组织不均匀,织构过强,造成强烈的各向异性。在奥氏体与铁素体两相区变形时,先共析铁素体因形变同样产生强烈的织构。随着形变温度的提高和先共析铁素体的减少,织构减弱。 相似文献
158.
159.
以材料的力学性能分析为基础,利用双界限系数将碳纤维增强混凝土受弯构件划分成三种正截面的破坏形态,对每一种破坏形态,建立了单、双筋矩形截面极限承载力的计算式,使碳纤维增强混凝土构件正截面计算与现行的规范相一致。 相似文献
160.
Works of adhesion at the carbon fiber-liquid interface determined using a modified wetting technique
Works of adhesion WSL between aqueous solutions with pH values in the range from 1 to 14 and carbon fibers from different sources, which were additionally treated in an inert atmosphere or in oxygen, were measured by use of a microbalance. These works of adhesion WSL were found to show distinct stepwise dependencies on the pH value. The works of adhesion WSL are attributed to dispersion interactions WSL1 and various acid-base interactions wslab—in the latter case between the acidic and basic surface groups of carbon and the various basic and acidic aqueous solutions. 相似文献