Vacuum evaporation


V acuum drying Vacuum dynamics Vacuum evaporation Vacuum furnaces Vacuum gas oil Vacuum gas oils (VGO)  [c.1044]

Thin-Film Media Preparation Technologies. A thin film can be defined as an area (volume) on top of a carrier (substrate) with properties differing from it. The interface between substrate and thin film has a great influence on the properties of the layer. The interface is determined by the properties of the substrate, the material(s) used for the thin film, and the method of deposition. During thin-layer processes the environment can be a hquid, gas, or vacuum. Such layers can be deposited by electro- or by electroless plating, chemical vapor deposition, and physical vapor deposition methods. A close relationship exists between deposition conditions, nucleation, and growth of the layer and their physical properties. Thin layers have properties that differ greatly from those of the bulk materials. These unique properties can be due to (/) their small thickness of a few atomic layers up to micrometer values, which, as a consequence, makes the surface/volume ratio of the layer completely different to that of the bulk (2) because of their typical growth processes they are found in certain microstmctures which are, in many cases, directly related to the physical properties and (3) layer and substrate form a composite system resulting in a combination of properties based partly on the substrate properties and partly on the layer itself. By changing the deposition method and/or varying the different deposition parameters various layer stmctures and morphologies can be created over a wide range. The interaction between layer and substrate, ie, the interface, plays an important role by defining the stmcture and properties. In contrast to other fabrication methods it is possible to deposit soHd materials which can have equiUbrium as well as nonequilihrium properties. In the case of thin-film media for magnetic recording four deposition methods have been used, namely, electroless deposition, electro deposition, vacuum evaporation, and sputtering. More information about deposition technologies and other properties of thin films in general can be found in the Hterature (38,39).  [c.178]

Vacuum Evaporation Oblique-Incidence Deposition. Evaporation processes are usually carried out under vacuum within a pressure range of about 10 to 10 Pa (10 -10 torr). The various steps in the production of thin films with vacuum evaporation can generally be subdivided into the creation of the vapor-phase species, transport from source to substrate, and nucleation and growth on the substrate. The material fiux is produced by the evaporation source which heats the material to the sublimation temperature this can be done by resistance, radiation, eddy currents, electron and laser beams, etc. After evaporation the fiux condenses on a cooler substrate. The low pressure is essential for having as few coUisions as possible with the background gas species (a straight-line path) and a clean process. The emission characteristics of the source are discussed in detail in the Hterature. The growth speed on the substrate is not equal to the evaporation rate of the source and depends on the deposition geometry, the emission characteristics of the source, and the condensation coefficient in turn depending on the surface conditions and substrate temperature. Oxides, nitrides, etc, can be prepared by adding reactive gas during evaporation.  [c.178]

Sputtering. From the physical point of view sputtering is a different process from vacuum evaporation. Generally the sputter deposition process implies the ejection of atoms from a target by energetic particles. The ejected atoms then condense on the substrate to form a thin film. The accepted theory of sputtering is based on a momentum transfer process. Therefore the sputtered atoms leave the target (source) with an appreciable kinetic energy (3—10 eV). A part of this energy is dissipated by coUision processes with atoms of the sputtering gas. Upon arrival at the substrate the energy is stiU 1—3 eV whereas for vacuum evaporation it is smaller than 0.1 eV. Typical deposition rates are 0.5-50 nm/s.  [c.179]

Metal Evaporated Tape. Very pure films and to a certain extent preselected stmetures and morphologies can be obtained by vacuum evaporation. Atoms and molecules are emitted from the sources by heating and exist in a gaseous state. The pressure in the vacuum chamber, a certain equHibrium pressure (saturated-vapor pressure), is estabHshed at a given temperature. The deposition rate (R) depends on the vapor pressure. The best results can be obtained if the evaporated elements and their aHoys have a similar vapor pressure, but this is a limitation of the method. In the case of deposition of Co—Ni as a recording media this problem is not present. There are two methods to overcome the low by evaporation, namely a Cr underlayer and deposition by varying the angle of incidence of the arriving metal atoms (102).  [c.184]

Sputtering offers advantages over vacuum evaporation. Using sputtering techniques, angle of incidence effects are absent, film composition is generally the same as target composition, and melt composition need not be periodically altered. Additionally deposition rate and film thickness are easily controlled. The effect of argon pressure and sputtering-power density on coercivity and magnetoresistance of 500-nm 80.6 wt % Ni—19.4 wt % Fe films has been studied (7), and the results are shown in Figure 1. Magnetoresistance behavior of Permalloy films is important because these are used for detection in bubble memory devices. As shown in Figure la, resistivity and coercivity decrease with increasing sputtering-power density, whereas the magnetoresistance coefficient increases. The magnetoresistance coefficient is defined as Ai (100) /  [c.388]

Fig. 2. Simple schematic lepiesentation of (a) vacuum evaporation and (b) cathodic sputtering. Fig. 2. Simple schematic lepiesentation of (a) vacuum evaporation and (b) cathodic sputtering.
Some impurities, eg, Cu, Ag, Ni, Co, and Fe in Ge, and In, Ga, and As in Si, have diffusion coefficients that are large enough to permit doping by sohd-state diffusion at well below the melting point of the host crystal. A thin layer of the diffusant, which is deposited on the surface of the crystal by electroplating, vacuum evaporation, or electrochemical replacement, serves as the source for diffusion. After homogeneity is achieved, the sample is quenched. The alloyed surface layer must be removed by lapping and etching before the electrical contacts are appHed. The impurity concentration should be as large as possible, within limits, in order to maximize the absorption coefficient. In some cases, the concentration is limited by the impurity solubiUty, which maybe small depending on the element. For impurities of high solubiUties, the upper limit is set by the onset of impurity banding. When the average separation of impurity atoms in the lattice is small enough, conduction by direct transfer of carriers from atom to atom can occur. Impurity handing limits the extent by which cooling can reduce the dark current and, therefore, the noise, in Ge and Si. This is significant above impurity concentrations of ca  [c.435]

The Stamicarbon (22) and Kaltenbach high concentration processes are designed to use the evaporated water vapor produced by pressure neutralization to heat the evaporator used for concentration. The Kaltenbach neutralizer operates at 350 kPa (3.5 bar) and 175°C, and produces steam used to concentrate the solution to 95% in a vacuum evaporator. A recent variation uses a final atmospheric evaporator to produce a 99.7% melt (22).  [c.366]

Since about 1965, efficient vacuum evaporators have been used in most plants. Second stage evaporators, where the ammonium nitrate is concentrated to more than 99%, are designed to retain only a small volume of melt, have short residence times, and are protected from overheating and contamination by sensitizers. Falling film units are especially suited for this appHcation.  [c.366]

Fig. 1. Vacuum evaporation process with use of electron beam heating where A represents the material to be deposited. The flux profile ( ) is at a Fig. 1. Vacuum evaporation process with use of electron beam heating where A represents the material to be deposited. The flux profile ( ) is at a
Processes involving oxygen and nitrogen oxides as catalysts have been operated commercially using either vapor- or Hquid-phase reactors. The vapor-phase reactors require particularly close control because of the wide explosive limit of dimethyl sulfide in oxygen (1—83.5 vol %) plants in operation use Hquid-phase reactions. Figure 2 is a schematic diagram for the Hquid-phase process. The product stream from the reactor is neutralized with aqueous caustic and is vacuum-evaporated, and the DMSO is dried in a distillation column to obtain the product.  [c.111]

Concentrators frequendy not only concentrate the acid, but may purify it as well, removing both organic and inorganic materials. Examples of some options available are discussed ia Reference 140. Vacuum evaporation is widely used. Its main advantage is the abiUty to produce relatively high product acid concentrations at low operating temperatures, thus reduciag corrosion. Flash evaporation is sometimes employed as an initial purification step (140,142). In addition, small amounts of organic contaminants are frequently partially oxidized and sometimes can be largely removed by treating with small amounts of hydrogen peroxide or nitric acid to accelerate oxidation (143) (see Evaporation).  [c.190]

Vacuum Deposition. Vacuum deposition, sometimes called vacuum evaporation, is a PVD process in which the material is thermally vaporized from a source and reaches the substrate without coUision with gas molecules in the space between the source and substrate (1 3). The trajectory of the vaporized material is therefore line-of-sight. Typically, vacuum deposition takes place in the pressure range of 10 10 Pa (10 10 torr), depending on the level of contamination that can be tolerated in the resulting deposited film. Figure 3 depicts a simple vacuum deposition chamber using a resistively heated filament vaporization source.  [c.514]

The advantages of ion plating are as follows. Controlled bombardment can be used to modify film properties such as adhesion, film density, residual film stress, and optical properties. Surface coverage can be improved over vacuum evaporation and sputter deposition owing to gas scattering and sputtering/redeposition effects. Film properties are less dependent on the angle of incidence of the flux of depositing material than with sputter deposition and vacuum deposition owing to gas scattering, sputtering/redeposition, and atomic peening effects. In reactive ion plating, the plasma can be used to activate reactive species, and create new chemical species that are more readily adsorbed so as to aid in the reactive deposition process. Moreover, in reactive ion plating, bombardment can be used to improve the chemical composition of the film material by bombardment-enhanced chemical reactions, which lead to increased reaction probabiUty, and preferential sputtering of unreacted species from the growing surface.  [c.522]

Thiosulfates are generally prepared by treating aqueous solutions of either calcium or barium thiosulfate with the corresponding carbonate or sulfate of the desired metal. The insoluble calcium or barium sulfates or carbonates are filtered and the thiosulfate recovered from the filtrate by vacuum evaporation.  [c.31]

Both anatase and mtile are broad band gap semiconductors iu which a fiUed valence band, derived from the O 2p orbitals, is separated from an empty conduction band, derived from the Ti >d orbitals, by a band gap of ca 3 eV. Consequendy the electrical conductivity depends critically on the presence of impurities and defects such as oxygen vacancies (7). For very pure thin films, prepared by vacuum evaporation of titanium metal and then oxidation, conductivities of 10 S/cm have been reported. For both siugle-crystal and ceramic samples, the electrical conductivity depends on both the state of reduction of the and on dopant levels. At 300 K, a maximum conductivity of 1 S/cm has been reported at an oxygen deficiency of  [c.121]

Thin-Film Techniques. Many integrated optical and electronic components require thin films (qv), usually 5—50 lm deep, of materials. Amorphous thin films can be prepared by chemical vapor deposition, evaporation, and sputtering, in addition to the sol—gel process. In both evaporation and sputtering, the target is vaporized and redeposited onto a cold substrate. Vapor deposition can be carried out by using electron beams. It frequendy results in porous films, and it can cause compositional changes in multicomponent glasses, because of differing vapor pressures at the deposition temperature. Vacuum evaporation can cause non stoichiometry, but this problem can be alleviated for oxides by adding oxygen to the evaporation chamber. Sputtering is typically carried out by radio-frequency heating of argon gas to produce beams of argon ions that are directed at the sample. Some glasses prepared by thin-film techniques differ from bulk glasses in that they crystallize before reaching T (14).  [c.335]

Photochromic silver—copper haUde films were produced by vacuum evaporation and deposition of a mixture of the components onto a sUicate glass substrate (13). The molar ratio of the components was approximately 9 1 (Ag Cu) and film thicknesses were in the range of 0.45—2.05 p.m. Coloration rate upon uv exposure was high but thermal fade rates were very slow when compared with standard silver haUde glass photochromic systems.  [c.162]

Simultaneous deposition of cadmium chloride and copper chloride by vacuum evaporation onto fused siUca or optical glass resulted in photochromic thin films (14). The thickness ranged from 0.25 to 1.3 pm.  [c.162]

Extract is stored in insulated tanks prior to drying. Because high soluble soHds concentration is deskable to reduce aroma loss and evaporative load in the driers, most processors concentrate the 15—30% extract to 35—55% prior to drying (33). This may be accompHshed by vacuum evaporation or freeze concentration. Clarification of the extract, normally by centrifiigation, may be used to assure the absence of insoluble fine particles.  [c.388]

Fig. 1. Lacquer-coated optical readout laser disk master. Plating by (a) electroless silver spray coating and by (b) vacuum evaporation. Scale bar, cm. Fig. 1. Lacquer-coated optical readout laser disk master. Plating by (a) electroless silver spray coating and by (b) vacuum evaporation. Scale bar, cm.
The reconcentration of dilute (50—60%) sulfuric acid is one of the more costly operations in the manufacture of ethanol by this process. An acid reboiler, followed by a two-stage vacuum evaporation system, raises acid concentration to about 90%. The 90% acid is then brought to 96—98% strength by fortification with 103% oleum (fuming sulfuric acid).  [c.404]

There are numerous applications in solvent recovery processes where evaporation equipment are employed. Figure 14 provides an example of a process scheme for toluene-di-isocyanate recovery. This is an example of continuous vacuum evaporation of distillation residues.  [c.108]

The reaction mixture is diluted with 250 ml of water, the mixture is transferred to a 2 liter flask using methanol as a wash liquid, and the organic solvents are distilled at 20-25 mm using a rotary vacuum evaporator. The product separates as a solid and distillation is continued until most of the residual toluene has been removed. The solid is collected on a 90 cm, medium porosity, fritted glass Buchner funnel and washed well with cold water. After the material has been sucked dry, it is covered with a little cold methanol, the mixture is stirred to break up lumps, and the slurry is kept for 5 min. The vacuum is reapplied, the solid is rinsed with a little methanol followed by ether, and the material is air-dried to give 9.1 g (85%), mp 207-213° after sintering at ca. 198°. Reported mp 212-213°. The crude material contains 1.0-1.5% of unreduced starting material as shown by the UV spectrum. Further purification may be effected by crystallization from methanol.  [c.55]

In a 250 ml Erlenmeyer flask covered with aluminum foil, 14.3 g (0.0381 mole) of 17a-acetoxy-3j5-hydroxypregn-5-en-20-one is mixed with 50 ml of tetra-hydrofuran, 7 ml ca. 0.076 mole) of dihydropyran, and 0.15 g of p-toluene-sulfonic acid monohydrate. The mixture is warmed to 40 + 5° where upon the steroid dissolves rapidly. The mixture is kept for 45 min and 1 ml of tetra-methylguanidine is added to neutralize the catalyst. Water (100 ml) is added and the organic solvent is removed using a rotary vacuum evaporator. The solid is taken up in ether, the solution is washed with water and saturated salt solution, dried over sodium sulfate, and then treated with Darco and filtered. Removal of the solvent followed by drying at 0.2 mm for 1 hr affords 18.4 g (theory is 17.5 g) of solid having an odor of dihydropyran. The infrared spectrum contains no hydroxyl bands and the crude material is not further purified. This compound has not been described in the literature.  [c.56]

Filter Cool and vacuum evaporate 1 Heat in oxygen above 1000  [c.960]

In the commonly used Welland process, calcium cyanamide, made from calcium carbonate, is converted to cyanamide by reaction with carbon dioxide and water. Dicyandiamide is fused with ammonium nitrate to form guanidine nitrate. Dehydration with 96% sulfuric acid gives nitroguanidine which is precipitated by dilution. In the aqueous fusion process, calcium cyanamide is fused with ammonium nitrate ia the presence of some water. The calcium nitrate produced is removed by precipitation with ammonium carbonate or carbon dioxide. The filtrate contains the guanidine nitrate that is recovered by vacuum evaporation and converted to nitroguanidine. Both operations can be mn on a continuous basis (see Cyanamides). In the Marquerol and Loriette process, nitroguanidine is obtained directly ia about 90% yield from dicyandiamide by reaction with sulfuric acid to form guanidine sulfate followed by direct nitration with nitric acid (169—172).  [c.16]

Many different filter types are used, including horizontal rotary table, belt, in-line pan, and horizontal rotary tilting pan. The dihydrate acid containing 28—32% P2O5 is concentrated further for most uses, usually in single-effect vacuum evaporators. A variety of types are used, including forced circulation, natural circulation, and falling film. Direct-heated spray towers and submerged combustion have also been used but these are no longer preferred. Because corrosion is a serious problem in wet-process acid plants, carbon brick linings and mbber linings are used extensively. Filters, pumps, and agitators are of stainless steel, and piping is made of mbber-lined steel and a variety of plastics.  [c.226]

Paraformaldehyde. Paraformaldehyde [9002-81-7] or paraform, is a soHd mixture of linear poly(oxymethylene glycols) of fairly short chain length, H0(CH20) H (143) (the range of n is 8—100). The average degree of polymerization is only roughly given by the formaldehyde content. The specifications of commercial paraformaldehyde are given in Table 8 (117). Gaseous formaldehyde can be generated from Oparaformaldehyde by heating (144). A current process for paraformaldehyde is based on continuous, staged vacuum evaporations, starting with 50% aqueous formaldehyde (145,146).  [c.498]

Most type A gelatin is made from pork skins, yielding grease as a marketable by-product. The process includes macerating of skins, washing to remove extraneous matter, and swelling for 10—30 h in 1—5% hydrochloric [7647-01-0], phosphoric [7664-38-2], or sulfuric acid [7664-93-9]. Then four to five extractions are made at temperatures increasing from 55—65°C for the first extract to 95—100°C for the last extract. Each extraction lasts about 4—8 h. Grease is then removed, the gelatin solution filtered, and, for most apphcations, deioni2ed. Concentration to 20—40% soflds is carried out in several stages by continuous vacuum evaporation. The viscous solution is chilled, extmded into thin noodles, and dried at 30—60°C on a continuous wire-mesh belt. Drying is completed by passing the noodles through 2ones of successive temperature changes wherein conditioned air blows across the surface and through the noodle mass. The dry gelatin is then ground and blended to specification.  [c.207]

Vacuum evaporation or sputteriag techniques can produce thin films of amorphous metal elements as well as a wide variety of amorphous alloys (46). Liquid quenching at rates greater than 10 K/s is limited to alloys containing metalloids (47). Although glass-forming abiUty cannot be predicted with certainty, a low temperature eutectic ia a system of high melting metals often forms a metallic glass (48,49) (see also Glassy metals).  [c.289]

Role of the Cr Underlayer. One of the methods to overcome the problem of low coercivity in vacuum evaporated films is an underlayer between the substrate and the ferromagnetic layer, which was already proposed in 1967 (88). By slow deposition (0.1 nm/s) of a Co layer (thickness less than 100 nm) on a Cr underlayer with bcc stmcture the coercivity increases at a level suitable for magnetic recording. The is strongly dependent on the rate of deposition, the thickness of the Co as weU as the Cr layers, and the substrate temperature. The Cr underlayer induces the growth of the Co layer with an exclusive hexagonal crystalline stmcture and a narrow crystaUite-size distribution. If the Cr layer increases, its crystal size also increases and the Co grows more quasiepitaxial. The i -axis orientation of the Co becomes more in-plane if the substrate temperature increases. An important fact is that this effect is strongest if the deposition of the Co occurs immediately after the deposition of the Cr underlayer (no oxidation). The role of the Cr underlayer is thus the creation of the right conditions for epitaxial growth of the polycrystaUine layer having the hep texture i -axis in the plane of the medium.  [c.184]

Thin Film. In the thin-film approach, raw material usage is generally more than two orders of magnitude less and patterning is more direct. In some thin-film approaches, certain individual layers may be only 50 atoms thick, which means that large-area uniformity of coating is the key to success. These coatings must be both optically and electrically uniform over areas the si2e of about a square meter. The technical decisions ate complex and may be ordered as follows (/) What substrate is to be coated The principal choices are glass, steel, ceramic, or plastic. (2) What materials are to be deposited The principal semiconductor options are amorphous and polysilicon, cadmium teUuride, copper indium diselenide, and alloys of these basic options. The most significant conductor options are silver, nickel, aluminum, tin oxide, 2inc oxide, indium oxide, and some alloys of these choices. (3) What deposition process is to be utilhed The options are vacuum evaporation, sputtering, glow discharge, chemical vapor deposition (CVD), electroplating, spraying, and screen printing. (4) How are the layers to be patterned These options include screen printing, laser scribing, mechanical scribing, and photoUthographicaHy defined wet etching.  [c.471]

Table salt is typical of the fine, evaporated—granulated salt produced in vacuum pan evaporators. Virtually all food-grade salt sold or used in the United States is produced by vacuum evaporation (qv) of brine. Prior to mechanical evaporation, the brine may be treated to remove minerals that can cause scaling in the evaporators and adversely affect salt purity. Chemical treatment of the brine, followed by settling, reduces levels of dissolved calcium, magnesium, and sulfate. Chemicals typically used are calcium hydroxide, Ca(OH)2 sodium carbonate, Na2C02 sodium hydroxide, NaOH calcium chloride, CaCl2 flocculating agents and stack gas, CO2. Sulfuric acid treatment or chlorination may be used to remove hydrogen sulfide, and hydrochloric acid neutralizes brine used in diaphragm cell production of chlorine and caustic soda. Brine purification has become increasingly important for production of high purity salt for use in chlor—alkaU production, particularly in Europe where dry salt is used extensively for this purpose.  [c.180]

Vacuum evaporation consists of heating a reservoir of the source material to its boiling or sublimation poiat ia a high vacuum. Material vapor travels a distance and condenses on a relatively cold substrate, forming a very thin uniform film. In sputteting, energetic ions are accelerated iato a target material at relatively high pressures, and particles are kinetically driven from the surface. Several newer techniques are plasma polymerization and chemical vapor deposition (see Plasma technology Vacuum technology) (7,8).  [c.126]

Ultrafiltration (qv) (uf) is increasingly used to remove water, salts, and other low molecular-weight impurities (21) water may be added to wash out impurities, ie, diafiltration. Ultrafiltration is rarely used to fractionate the proteins because the capacity and yield are too low when significant protein separation is achieved. Various vacuum evaporators are used to remove water to 20—40% dry matter. Spray drying is used if a powdery intermediate product is desired. Tyophilization (freeze-drying) is only used for heat-sensitive and highly priced enzymes.  [c.290]

Thin films of metal can be prepared by vacuum evaporation and condensation on a suitable support. For exatrrple, tlrin films of silver can be formed on a  [c.6]

The information depth achieved by use of the GD technique is determined, in principle, by the depth of penetration of the incident ions, which is in the range of a few nanometers at the relatively low energies employed in the discharge. The practical depth resolution is, however, almost larger and determined by several effects which are introduced by the sputter process (preferential sputtering, atomic miring), the sample properties (surface roughness, polycrystaUine structure), and most seriously by the non-uni-form erosion of the sample material. Most of these effects are inherent also in other techniques which use sputtering for surface and depth-profile analysis. In practice, the depth resolution obtained on technical surfaces is roughly proportional to the sputtered depth, and usually deteriorates from the nanometer-range for near-surface layers to the micron-range at depths of several micrometers [4.192,4.193]. Excellent depth resolution is realized on multilayer coatings, cf Fig. 4.37, as produced by vacuum evaporation or by plasma vapor deposition (PVD) [4.194], especially if the curved sputtering crater bottom is taken into consideration in quantification by an iterative deconvolution technique [4.195]. The lateral resolution of the GD-OES technique, on the other hand, is restricted by the size of the sputtered area of the sample surface (usually 4-8 mm diameter) and is much larger than with other surface techniques. The lateral and depth resolution of GD-OES are, however, usually both adequate for rapid quantitative determination of the elemental composition of technical surfaces.  [c.227]

This evaporation during which a solid separates is very conveniently carried out in a rotary vacuum evaporator (manufactured by Rinco Instrument Co., Greenville, Illinois). An equally convenient alternative arrangement for solvent stripping that is in use in some laboratories is shown in Fig. 1. The splash-head A permits rai>id removal of solvent under reduced pressure. Any solid carried l)cyoii(l the flask H by sjrattcring is arrested in A and lan be washed down into B by introdueing a low-boiling  [c.83]

The crude ketal from the Birch reduction is dissolved in a mixture of 700 ml ethyl acetate, 1260 ml absolute ethanol and 31.5 ml water. To this solution is added 198 ml of 0.01 Mp-toluenesulfonic acid in absolute ethanol. (Methanol cannot be substituted for the ethanol nor can denatured ethanol containing methanol be used. In the presence of methanol, the diethyl ketal forms the mixed methyl ethyl ketal at C-17 and this mixed ketal hydrolyzes at a much slower rate than does the diethyl ketal.) The mixture is stirred at room temperature under nitrogen for 10 min and 56 ml of 10% potassium bicarbonate solution is added to neutralize the toluenesulfonic acid. The organic solvents are removed in a rotary vacuum evaporator and water is added as the organic solvents distill. When all of the organic solvents have been distilled, the granular precipitate of 1,4-dihydroestrone 3- methyl ether is collected on a filter and washed well with cold water. The solid is sucked dry and is dissolved in 800 ml of methyl ethyl ketone. To this solution is added 1600 ml of 1 1 methanol-water mixture and the resulting mixture is cooled in an ice bath for 1 hr. The solid is collected, rinsed with cold methanol-water (1 1), air-dried, and finally dried in a vacuum oven at 60° yield, 71.5 g (81 % based on estrone methyl ether actually carried into the Birch reduction as the ketal) mp 139-141°, reported mp 141-141.5°. The material has an enol ether assay of 99%, a residual aromatics content of 0.6% and a 19-norandrost-5(10)-ene-3,17-dione content of 0.5% (from hydrolysis of the 3-enol ether). It contains less than 0.1 % of 17-ol and only a trace of ketal formed by addition of ethanol to the 3-enol ether.  [c.52]

Fig. 2. TEM image of a CNT obtained by CVD of 2-methyl-1,2 -naphlhylketone on a vacuum-evaporated nickel film (5 nm in thickness) at 700°C. Fig. 2. TEM image of a CNT obtained by CVD of 2-methyl-1,2 -naphlhylketone on a vacuum-evaporated nickel film (5 nm in thickness) at 700°C.

See pages that mention the term Vacuum evaporation : [c.461]    [c.57]    [c.40]    [c.296]    [c.337]    [c.450]    [c.16]    [c.285]   
Corrosion, Volume 2 (2000) -- [ c.12 , c.107 ]