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1.
Fourier transform infrared spectroscopy (FT-IR) and ζ-potential were introduced to study the effect of different modification parameters on the surface properties of nanodiamond (NO). Results showed that under stirring grinding conditions, ND hard aggregates were smashed and some active spots on them reacted with surfactant molecules, which led to the increase in its ζ-potential and stability. Different models of surface modification were also given in this study.  相似文献   

2.
Fumed silica is an important industrial material, which is widely used in medical, cosmetic, and electronic products. One important industrial application of the fumed silica powder is using it as fillers, which are key materials for reinforcing the high-performance/high-functional industrial products. However, the use of fumed silica as filler is limited to micrometer or millimeter sized particles, because nanometer sized silica particles tend to aggregate. In this study, the surface of fine silica powder is modified with n- and t-butyl alcohols, which exhibit different steric hindrance effects. The surface wettability of each modified silica powders is determined in two ways: macroscopic and microscopic wettability. Macroscopic wettability refers to preference dispersion test and microscopic wettability refers to evaluation of the molecular level by Fourier transform infrared spectroscopy (FT-IR). The modification ratio of each sample is confirmed by thermogravimetry-differential thermal analysis (TG-DTA), and the hydrophobicity of these modified silica powders is evaluated by the preference dispersion test. Molecular level evaluation of surface wettability by FT-IR confirms an obvious structural difference due to the steric hindrance of the n- and t-butoxy groups on the surface of silica. In addition, a correlation between macroscopic and microscopic evaluation results for the surface wettability of modified silica powders is confirmed.  相似文献   

3.
Nanodiamond is a relatively new nanomaterial with broad prospects for application. In this paper, a variety of methods were used to analyze comprehensively the structures and the surface states of the nanodiamond synthesized by detonation, for example, X-ray diffraction (XRD) spectroscopy, energy diffraction spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (Raman) and differential scanning calorimeter (DSC). The results show that, the nanodiamond particles are spherical or elliptical in shape. The average grain size is approximately 5 nm. The surfaces of the nanodiamond contain hydroxy, carbonyl, carboxyl, ether-based resin, and other functional groups. The initial oxidation temperature of the nanodiamond in the air is about 550 °C, which is lower than that of the bulk diamond.  相似文献   

4.
The present paper provides first a state of art on hydrogenation treatments performed either by plasma or by annealing. To compare with other surface terminations, specific assets of hydrogenated diamond surface for grafting are detailed and the different grafting routes achievable on hydrogenated nanodiamonds are summarized. In the last part, their reactivity with water molecules as well as their colloidal properties are presented and it will be shown that it is possible to render hydrogenated nanodiamonds active for radiosensitization applications.  相似文献   

5.
本文讨论了在粉体材料的处理过程中添加少量表面活性剂所引起的改性作用,以及它在机械合金化、粉体材料粉碎工程和其它材料工程中的应用。  相似文献   

6.
16Mn钢常压等离子束表面渗硼改性的初步研究   总被引:2,自引:0,他引:2  
借助电子探针、透射电镜对16Mn钢常压等离子快速渗硼改性机理进行了探讨。结果表明,由于高能离子束的轰击,金属表层组织明显细化,同时产生更多的活性原子,大大加快其合金过程,并形成FeB、Fe3B,Fe3(Si,B)等相,产生第二相强化,使金属硬度显著提高 。  相似文献   

7.
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9.
Ultradisperse detonation diamond (UDD), a nanodiamond having particle size around 4 nm has been treated with ozone in an aqueous slurry. The reaction kinetics appeared to be relatively slow and long ozonation times were needed in order to functionalize the surface of a special nanodiamond sample with a very low degree of oxidation and foreign groups. The resulting ozonated nanodiamond has been studied by FT-IR and electronic spectroscopy. It has been shown that the ozonation of cyclohexane and adamantane can be taken as a model reaction for the ozonation of diamond. Together with ketonic groups of various nature formed on the surface of nanodiamond, the ozonation leads also to the formation of simple molecules like for instance HCOOH and HCHO which remain in the water solution and which have been detected by HPLC analysis using a diode-array detector. The thermal stability of the nanodiamond sample has been studied by thermogravimetric analysis (TGA-DTG) combined with differential thermal analysis (DTA) both under inert atmosphere and in air flow. The studies on thermal stability have been conducted in comparison to a sample of bulk diamond. It appears that the behavior of nanodiamond is completely different than the bulk diamond sample. For instance, under inert atmosphere and at 900°C the weight loss undergone by the nanodiamond is 11.5% while it is negligible in the case of bulk diamond under the same conditions. Similarly, in air flow the nanodiamond burns abruptly above 450°C while bulk diamond starts to burn only above 850°C. These differences have been explained in terms of different particle size and surface functionalization.  相似文献   

10.
Abstract

Ultradisperse detonation diamond (UDD), a nanodiamond having particle size around 4 nm has been treated with ozone in an aqueous slurry. The reaction kinetics appeared to be relatively slow and long ozonation times were needed in order to functionalize the surface of a special nanodiamond sample with a very low degree of oxidation and foreign groups. The resulting ozonated nanodiamond has been studied by FT‐IR and electronic spectroscopy. It has been shown that the ozonation of cyclohexane and adamantane can be taken as a model reaction for the ozonation of diamond. Together with ketonic groups of various nature formed on the surface of nanodiamond, the ozonation leads also to the formation of simple molecules like for instance HCOOH and HCHO which remain in the water solution and which have been detected by HPLC analysis using a diode‐array detector. The thermal stability of the nanodiamond sample has been studied by thermogravimetric analysis (TGA‐DTG) combined with differential thermal analysis (DTA) both under inert atmosphere and in air flow. The studies on thermal stability have been conducted in comparison to a sample of bulk diamond. It appears that the behavior of nanodiamond is completely different than the bulk diamond sample. For instance, under inert atmosphere and at 900°C the weight loss undergone by the nanodiamond is 11.5% while it is negligible in the case of bulk diamond under the same conditions. Similarly, in air flow the nanodiamond burns abruptly above 450°C while bulk diamond starts to burn only above 850°C. These differences have been explained in terms of different particle size and surface functionalization.  相似文献   

11.
    
Electric discharge machining (EDM) is an electrothermal process where recast layer on the machined surface and heat-affected (HAZ) zone just below the machined surface are common phenomena. Thus, the assessment of surface integrity in EDM is a very important task. In this study, an attempt was made to modify the surface integrity of C-40 steel in EDM. WC-Cu powder metallurgy (P/M) green compact tools were used so that the tool material could be transferred to the work surface and thereby the surface characteristics could be altered. WC was used as tool material because of its ability to produce a hard layer over the work surface. A detailed experimental study was performed. The effect of various process parameters on the surface characteristics were presented with the support of analyses such as material transfer rate (MTR), tool wear rate (TWR), surface roughness, optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), microhardness testing, etc. It was established that the surface integrity of the workpiece changes with the desired deposition of a hard composite layer of WC and copper over the work surface.  相似文献   

12.
H. Zhang  H.M. Meyer III 《Vacuum》2008,82(11):1285-1290
The surface morphology, and chemical/structural modifications induced during chemical sputtering of ATJ graphite by low-energy (<200 eV/D) deuterium atomic and molecular ions are explored by Scanning Electron Microscopy (SEM), Raman and Auger Electron Spectroscopy (AES) diagnostics. At the lowest impact energies, the ion range may become less than the probe depth of Raman and AES spectroscopy diagnostics. We show that such diagnostics are still useful probes at these energies. As demonstration, we used these surface diagnostics to confirm the characteristic changes of surface texture, increased amorphization, enhanced surface reactivity to impurity species, and increased sp3 content that low-energy deuterium ion bombardment to steady-state chemical sputtering conditions produces. To put these studies into proper context, we also present new chemical sputtering yields for methane production of ATJ graphite at room temperature by impact of D2+ in the energy range 10-250 eV/D, and by impact of D+ and D3+ at 30 eV/D and 125 eV/D, obtained using a Quadrupole Mass Spectroscopy (QMS) approach. Below 100 eV/D, the methane production in ATJ graphite is larger than that in HOPG by a factor of ∼2. In the energy range 10-60 eV/D, the methane production yield is almost independent of energy and then decreases with increasing ion energies. The results are in good agreement with recent molecular dynamics simulations.  相似文献   

13.
We present experimental methane production yields for H+, ions incident on ATJ graphite in the energy range 10–250 eV/H. Below about 60 eV/H, the molecular H species give higher methane yields/H when compared with isovelocity H+, similar to our earlier measurements for incident deuterium atomic and molecular ions. For both D and H atomic and molecular projectiles, the yields/atom coalesce onto a single curve below projectile energies of 60 eV/atom, when plotted as a function of maximum energy transfer, under the assumption that, below this energy, the incident molecular species are largely undissociated when undergoing C–C bond breaking collisions during their collision cascade and thus produce more damage. Raman spectroscopy of a graphite sample exposed to high fluences of D+ and beams at high and low energies qualitatively confirmed the assumption that more surface damage is produced by the low-energy incident molecular species than by isovelocity atomic ions. While the two high-energy beam-exposed spots showed similar damage, the low-energy molecular-beam-exposed spot showed slightly more damage than the corresponding D+-beam-exposed spot.  相似文献   

14.
扫描隧道显微镜(STM)是对材料表面进行表面修饰(surface modification)和表面原子操纵(atomcraft)的重要工具。为了了解其机理,选择了场蒸发阈值从大到小有代表性的钨、铂、金、铜做针尖,扫描过程中在针尖与石墨表面之间施加针尖为正的脉冲电压,获得了一些新现象,并对实验结果作了比较,从而在一定程度上确定了脉冲制STM表面修饰实验中针尖与样品之间电场的重要作用。  相似文献   

15.
采用正硅酸乙酯水解法在SiC表面包覆SiO2,并通过实验探讨了TEOS用量、总体系CTEOS等因素对包覆效果影响。实验确定了制备包覆粒子的优化工艺条件:SiC/TEOS的最佳物质量比值为5:1,最佳总体系CTEOS为0.2mol/L。采用ZETA、IR、XRD等测试手段对SiO2改性的碳化硅粉体进行了表征。沉降实验表明:碳化硅表面改性后,在硅溶胶中浆料的稳定悬浮性提高。  相似文献   

16.
纳米二氧化硅表面改性研究   总被引:1,自引:0,他引:1  
采用甲苯二异氰酸酯(TDI)接枝聚乙二醇(PEG)对纳米SiO2进行表面改性,并利用红外光谱(FTIR)和热重(TG)、扫描电镜(SEM)、粒径分析、重力沉降法等方法对改性前后的纳米SiO2的表面形貌和在介质中的分散稳定性进行了表征和分析.结果表明,改性后的纳米SiO2表面接枝上了TDI、PEG的有机官能团,降低了颗粒...  相似文献   

17.
本文阐述了等离子体的发生及其引起材料表面改性的主要特点。就近年来,国内外运用等离子体技术制备固定化酶载体的方法及应用情况作了综述。  相似文献   

18.
纯钛Mo-N渗镀改性层在人工体液中的腐蚀行为   总被引:2,自引:0,他引:2  
利用等离子技术在纯钛表面制备Mo-N改性层,对改性层组织进行了观察,测试了改性层的元素分布,着重考核纯钛基材和改性层在模拟人工体液环境下的电化学特性。结果表明,改性层为渗镀复合层,表层为Mo-N沉积层,中间为合金扩散层,改性后的钛材不但表面硬度明显提高,而且在人工体液环境下耐蚀性也相应得到改善。  相似文献   

19.
Surface functionalized apatite nanoparticles were prepared by covalent grafting of nitrilotrismethylenetriphosphonates (NTP) into a mesoporous apatite layer, which has been converted from phosphate rock by dissolution-precipitation methods. BET measurements show that the specific surface area of the particles is between 88 and 193 m2/g, depending on the grafted phosphonate.  相似文献   

20.
    
Fluoropolymer surfaces with new and specific functionalities, such as metal‐free conductivity, biocompatability, and bondability to metals, can be obtained through the intelligent choice of functional monomers for graft copolymerization on pre‐activated fluoropolymer surfaces, as highlighted in this review. The Figure shows a gold/fluoropolymer laminate held together by crosslinked glycidyl methacrylate polymer grafted on both surfaces.  相似文献   

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