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Heat treatment vacuum

GC is arguably the most common carbon electrode material in current use, and its applications are too extensive to list here in any comprehensive fashion. Examples are listed here to illustrate GC electrode performance, particularly for voltammetry. Figure 10.12 shows the effect of vacuum heat treatment on ascorbic acid oxidation on initially polished GC [41]. Note that the less positive peak... [Pg.321]

Makhlis et al. [66] proved that more than one degradative processes are operative in thermal-oxidative dagradation of EPR. The low activation energy also indicates the existence of weak bonds. The rate of thermal degradation of y-irradiation cured vulcanizates can be effectively reduced by vacuum heat treatment at 200-250 °C. During thermal degradation [67] at 65° and > 350 °C in vacuum. EPR exhibited an... [Pg.183]

Figure 6.9 Depth distribution profiles of tin-graficd zeolite grains. A, After deposition. B. After vacuum heat treatment. C. After air treatment. Figure 6.9 Depth distribution profiles of tin-graficd zeolite grains. A, After deposition. B. After vacuum heat treatment. C. After air treatment.
Yang, Y.C. (2007) Influence of residual stress on bonding strength of the plasma-sprayed hydroxyapatite coating after the vacuum heat treatment. Surf. Coat. Int., 201, 7187-7193. [Pg.442]

In some cases the mixture was exposed to water vapour (p(H20) 440 torr) in a static air atmosphere at 358 K for 0.5, 11.0 and 20.5 hours. The spectra of the mixtures were measured without any heat treatment and after vacuum heat treatment at 420, 620 and 770 K for 1 hour. [Pg.269]

Usually, the stationary phase including CDs in GC was prepared by depositing the modified CDs dissolved in a dimethylformamide solution onto the support (e.g. Chromosorb W) and then evaporated the solvent by vacuum heat-treatment. Some reports described glass or fused silica capillary GC column coated with peralkylated a-, P- and y-CDs dissolved in polysiloxanes. However, the coverage of CD in the surface is limited and results in limited preparative capacity [26]. In addition, the kinetics of inclusion are relatively slow and result in poor peak shape which also hinders the use of CDs as preparative phases. [Pg.239]

Another approach, as described by Carlson and Schmidt (1%7), involved the preparation of yttrium metal by the Ca reduction of YCI3 in the presence of Mg. The Mg and Ca were removed from the Y by a vacuum heat treatment followed by arc melting the resultant Y sponge. In a similar process Schmidt and Carlson (1974) prepared scandium metal by reducing ScCh with Ca and/or Mg. The reduced metal was purified by arc melting or vacuum distillation. [Pg.185]

VC powder is prepared by the reaction of vanadium oxide or ammonium vanadate with carbon at 1500-1700 C in hydrogen followed by a vacuum heat treatment. The reaction of vanadium metal with carbon under vacuum is also used. VC coatings are deposited by CVD, evaporation or sputtering (see Clusters 14 and IS). [Pg.92]

Reaction of vanadium oxide or ammonium vanadate with carbon at 1500-1700°C in hydrogen followed by a vacuum heat-treatment Reaction of vanadium metal Avith carbon under vacuum... [Pg.251]

M50 Steel Produced by Chemical Reduction. Nanopowders of M50 steel produced by the chemical reduction technique were characterized by SEM/EDAX. The SEM of the powders showed a similar porous coral-like morphology as shown in Figure 1 for powders synthesized by the sonochemical method. In Figures 9(a) and (b) is shown the EDAX spectrum of the powders before and after the vacuum heat treatment at 650 °C. It indicates that the lithium chloride by-product has been successfully removed by vacuum sublimation. The average particle size, calculated from X-ray line broadening analysis was 34 nm. Current efforts are under way to compact these powders and to study their structural and physical properties. [Pg.225]

ITO can also be cleaned and activated by vacuum heat treatment. The treatment should be performed in a vacuum that is relatively free of residual oxygen. Relatively low temperatures should be used to avoid desorbing the ITO film from the substrate or decomposing... [Pg.148]

Pre-treatment of carbon materials can significantly improve their catalytic activity towards ORR and change their electrochemical behavior. A variety of treatment methods have been used, including polishing the electrode, radio frequency plasma treatment, heating at low pressures, in situ laser irradiation, vacuum heat treatment, chemical oxidation, and electrochemical oxidation [25-28]. [Pg.106]

In contrast to the spherical carbon onions observed in the first experiments by Ugarte, OLC particles were subsequently produced with polyhedral facets, more closely matching the polyhedral structures predicted from the consideration of nested fullerene structures described above. These polyhedral onion-like particles were synthesized by vacuum heat treatment of carbon sooF and diamond nanoparticles." Figure 10.5 presents HRTEM images of the polyhedral OLC particles produced in the experiments of Kuznetsov et al. The range of synthesis methods available has led to the production of different types of OLC. In addition to their shape, such carbon onions can be characterized by other parameters, such as the number of concentric shells, the spacing between adjacent shells, the size of the innermost shell, and the presence of different types of defects. [Pg.283]

Heat Treatment. Titaniiun-nickel can be heat treated in air up to 500 °C (930 °F). No a case is formed, but a surface oxide of rutile develops quickly. Above 500 °C (930 °F), the oxide layer begins to flake (depending on time). Nitrogen and hydrogen atmospheres are not recommended. Argon, helium, and vacuum heat treatments are commonly used to preserve bright finishes. [Pg.674]

The adsorption sites are not mineral specific. The areas were only slightly influenced by vacuum-heat-treatment, while the pore volume was significantly increased for one of the samples. [Pg.737]

The optimal outgassing condition for the samples is limited by a possible thermal decomposition of the mineral surface layers. In order to evaluate this we have carried out a systematic study of nitrogen adsorption as function of increasing vacuum-heat-treatment temperatures. [Pg.738]

Fig. 3. Nitrogen adsorption at 77.60 K onto sample 25 AB upon an overnight vacuum heat-treatment at 170 C. iia, /rnioles of N2 adsorbed per g sample, p equilibrium pressure of N2, Po saturation vapour pressure of N2, y = p/na(po-p). Only the absorption branch is shown here. Fig. 3. Nitrogen adsorption at 77.60 K onto sample 25 AB upon an overnight vacuum heat-treatment at 170 C. iia, /rnioles of N2 adsorbed per g sample, p equilibrium pressure of N2, Po saturation vapour pressure of N2, y = p/na(po-p). Only the absorption branch is shown here.
In conclusion, the nitrogen adsorption isotherms indicate the presence of two types of surface sites in each of the two samples. Vacuum heat-treatment has no marked influence on the values of the specific surface areas. Sample 25 AB shows no major change in the pore volume upon VHT, while for sample 62 AB a major increase is observed. [Pg.745]


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See also in sourсe #XX -- [ Pg.101 ]

See also in sourсe #XX -- [ Pg.152 ]




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Heat treatment

Vacuum treatment

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