Flame, high temperature


Figure 6.27 shows a grand composite curve with a flue gas matched against it to provide a hot utility. The flue gas starts at its theoretical flame temperature (shifted for AT ,m on the grand composite curve) and presents a sloping profile because it is giving up sensible heat. Theoretical flame temperature is the temperature attained when a fuel is burnt in air or oxygen without loss or gain of heat. Methods are presented elsewhere for its calculation. It should be emphasized that the theoretical and real flame temperatures will be quite different. The real flame temperature will be lower than the theoretical flame temperature because, in practice, heat is lost from the flame and because part of the heat released provides heat for a variety of endothermic dissociation reactions that occur at high temperatures, such as  [c.188]

A bitumen sample is oxidized at high temperature under well defined conditions and its physical characteristics are measured before and after this artificiai ageing process. The method is defined in France as AFNOR T 66-032 and in the USA by ASTM D 2872 (Rolling Thin-Film Oven Test).  [c.290]

The corrosion rate of steel in carbonic acid is faster than in hydrochloric acid Correlations are available to predict the rate of steel corrosion for different partial pressures of CO2 and different temperatures. At high temperatures the iron carbonate forms a film of protective scale on the steel s surface, but this is easily washed away at lower temperatures (again a corrosion nomogram is available to predict the impact of the scale on the corrosion rate at various CO2 partial pressures and temperatures).  [c.94]

Thus the oxidation of light metals such as sodium, calcium, or magnesium follows Eq. VII-31, the low-temperature oxidation of iron follows Eq. VII-29, and the high-temperature oxidation follows Eq. VII-30. The controlling factor seems to be the degree of protection offered by the coating of oxide [160]. If, as in the case of the light metals, the volume of the oxide produced is less than that of the metal consumed, then the oxide tends to be porous and nonprotective, and the rate, consequently, is constant. Evans [160] suggests that the logarithmic equation results when there is discrete mechanical breakdown of the film of product. In the case of the heavier metals, the volume of the oxide produced is greater than that of the metal consumed, and although this tends to give a dense protective coating, if the volume difference is too great, flaking or other forms of mechanical breakdown may occur as a result of the compressional stress produced. There may be more complex behavior. In the case of brass alloyed with tin, corrosion appears first to remove surface Zn, but the accumulated Sn then forms a protective layer [161].  [c.283]

The rate of diffusion through an oxide film depends on a number of factors, such as the temperature, oxygen partial pressure and stmcture of the oxide. At high temperatures (>0.7 of the melting point of the metal) lattice diffusion dominates through the crystalline oxide fonned on a metal. However, at moderate temperatures diffusion via oxide grain boundaries is predominant. In this case, the rate of oxidation of a metal or alloy depends on the oxide grain size, which is often dictated by substrate grain orientation, surface pretreatment etc [130]. Deviation from parabolic oxidation behaviour is often observed and can be the result of the oxide grain size changing with time at a particular temperature. In this case, the number of oxide grain boundary easy diffusion paths decreases with time, causing an apparent decrease in oxidation rate. If tme parabolic behaviour is observed, then the change in oxidation  [c.2729]

If a compact film growing at a parabolic rate breaks down in some way, which results in a non-protective oxide layer, then the rate of reaction dramatically increases to one which is linear. This combination of parabolic and linear oxidation can be tenned paralinear oxidation. If a non-protective, e.g. porous oxide, is fonned from the start of oxidation, then the rate of oxidation will again be linear, as rapid transport of oxygen tlirough the porous oxide layer to the metal surface occurs. Figure C2.8.7 shows the various growth laws. Parabolic behaviour is desirable whereas linear or breakaway oxidation is often catastrophic for high-temperature materials.  [c.2729]

It is often advisable to lubricate ground-glass joint surfaces with an extremely thin film of vaseline. This applies particularly to joints employed in assemblies for distillation under reduced pressure. For distillations under greatly reduced pressures or at very high temperatures it is essential to employ a special lubricant, e.g., silicone grease.  [c.42]

It is often advisable to lubricate ground-glass joint surfaces with an extremely thin film of vaseline. This applies particularly to joints employed in assemblies for distillation under reduced pressure. For distillations under greatly reduced pressures or at very high temperatures it is essential to employ a special lubricant, e.g., silicone grease.  [c.42]

A calculation of ion yields is shown in Figure 14.5. The equation in Figure 14,5 illustrates how the number of singly charged positive ions [M+] can be calculated in relation to the number of neutral particles [M], For example, with potassium at 8000 K, the ratio of ions to neutral atoms in a plasma is about 2000 1. Thus, at high temperatures, [M ] [M], and the yield of ions reaches close to 100% for all elements. Therefore high sensitivities for detection of ions depends partly on having a high plasma flame temperature. However, at the higher temperatures, new molecular ions such as ArO+ begin to form, and to suppress them it may be necessary to operate the flame at a lower temperature.  [c.92]

Any sample to be introduced into the center of the plasma flame is often first nebulized (broken down into small droplets) by using argon gas as a spraying medium. The argon gas and the spray of droplets flow down a central tube of the plasma torch (Figures 14.1 and 14.4) and into the center of the plasma flame. Given the high temperatures in the plasma, the droplets rapidly lose low-boiling solvent molecules, and both solvent and solute molecules diffuse into the plasma, where a number of processes occur leading to molecular fragmentation.  [c.93]

Other vapor introduction systems are discussed in Parts B and C (Chapters 16 and 17) because, although liquids and solids are ultimately introduced to the plasma flame as vapors, these samples are usually prepared differently from naturally gaseous ones. For example, electrothermal (oven) or laser heating of solids and liquids to form vapors is used extensively to get the samples into the plasma flame. At one extreme with very volatile liquids, no heating is necessary, but, at the other extreme, very high temperatures are needed to vaporize a sample. For convenience, the electrothermal and laser devices are discussed in Part C (Chapter 17) rather than here.  [c.102]

DSI is discussed in Part C (Chapter 17), since the approach usually requires an initial evaporation of solvent from a solution by moderate heating in a gas stream so as to leave the solute (the analytical sample). The resulting residual sample is then heated strongly to vaporize it. Typically, a solution is placed onto a heat-resistant wire or onto a graphite probe, and then the solvent is allowed to evaporate or is encouraged to do so by application of heat, directly or indirectly. The residual solid on its metal or graphite support is placed just below the plasma flame, which is allowed to stabilize for a short time. The probe and sample are then driven into the high-temperature flame, which causes vaporization, fragmentation, and ionization (Figure 16.2). Because the heat capacity of the flame is relatively small, the sample holder and sample should have as low a thermal mass as possible so as not to interfere with the operation of the flame. With the direct-insertion method, samples appear transiently in the flame therefore, if a wide range of elements is to be examined, the mass spectrometer should be one that can span a wide m/z range in the short space of time the sample takes to pass through the flame (quadrupole, time-of-flight). Further details of the DSI technique are discussed in Part C (Chapter 17).  [c.105]

A plasma flame commonly has a diameter of about 1 cm and a length of about 2-3 cm. If this flame is regarded as being approximately cylindrical, the volume of the flame at about 5300 K is 1.6 ml and at 300 K is 0.1 ml. With a specific heat for argon of 0.124 cal/g/K and a density of 1.78 x 10 g/ml (at 3(X) K), the heat content of the flame is 0,1 cal. However, since gas flow through the hot flame occur.s in a period of about 2 msec, the power output of the flame is about 50 W. This output should be compared with a power input from the high-frequency electromagnetic field of about 1 kW, The seeming inconsistency between the high temperature and the low heat content arises because of the low number density of hot particles, (The concentration of electrons and other particles in the hot flame is approximately ICH M.)  [c.110]

Suffice it to say at this stage that the surfaces of most solids subjected to such laser heating will be heated rapidly to very high temperatures and will vaporize as a mix of gas, molten droplets, and small particulate matter. For ICP/MS, it is then only necessary to sweep the ablated aerosol into the plasma flame using a flow of argon gas this is the basis of an ablation cell. It is usual to include a TV monitor and small camera to view the sample and to help direct the laser beam to where it is needed on the surface of the sample.  [c.112]

In practice, direct insertion of samples requires a somewhat more elaborate arrangement than might be supposed. The sample must be placed on an electrode before insertion into the plasma flame. However, this sample support material is not an electrode in the usual meaning of the term since no electrical current flows through it. Heating of the electrode is done by the plasma flame. The electrode or probe should have small thermal mass so it heats rapidly, and it must be stable at the high temperatures reached in the plasma flame. For these reasons, the sort of materials used  [c.114]

If a sample is introduced as a solution into the middle of the start of the flame, the combination of high temperatures, energetic electrons, and ions breaks down the sample molecules into constituent atoms and their ions. These elemental ions and atoms emerge from the end of the flame.  [c.395]

The main problem in this technique is getting the atoms into the vapour phase, bearing in mind the typically low volatility of many materials to be analysed. The method used is to spray, in a very fine mist, a liquid molecular sample containing the atom concerned into a high-temperature flame. Air mixed with coal gas, propane or acetylene, or nitrous oxide mixed with acetylene, produce flames in the temperature range 2100 K to 3200 K, the higher temperature being necessary for such refractory elements as Al, Si, V, Ti and Be.  [c.65]

A similar method of nanoscale patterning involves the use of an elastomeric resist film onto which the desired pattern is generated by compression molding at high temperature (ie, higher than the glass-transition temperature) (186,187). As a result of the compression, the film is thinned in the regions where the master pattern is present. Subsequent to controUed reactive ion etching, the thinned regions of the resist film are removed, leaving behind the thicker regions (which are partially thinned due to etching) and these form the desired pattern on the surface. This pattern can now be used as a resist layer. Poly(methyl methacrylate) (PMMA) is one candidate for this purpose, because it does not shrink or sweU over large temperature and pressure ranges and is nonadhesive to siHca. Metal (5 nm Ti and 15 nm Au) patterns with feature size of 25 nm have been fabricated by use of these resist templates in conjunction with metal deposition and lift-off (186,187).  [c.207]

The synthesis recycle loop has the stripped gas going to two high pressure carbamate condensers in series and to a high pressure separator and then back to the reactor. The flow is maintained by using an NH -driven Hquid—Hquid ejector. The reactor is operated at 15 MPa (150 bat) with a NH —CO2 molar feed ratio of 3.5. The stripper is a falling-film type and since high temperatures (200—210°C) ate requited for efficient thermal stripping, stainless steel tubing is not suitable. Titanium was initially used, but it also was not satisfactory because of erosion neat the bottom. At this time a bimetallic tube of zirconium and 25-22-2 stainless steel is used. The zirconium is corrosion-free and the only problem is the difficulty in getting proper welds and separation of the two layers at the bottom ends. Fabrication mistakes have been the only source of problems with this vessel to date.  [c.301]

The subsequent development of ABS (acrylonitrile—butadiene—styrene) resins [9003-56-9], which contain an elastomeric component within a SAN matrix, further boosted commercial appHcation of the basic SAN copolymer as a portion of these mbber-toughened thermoplastics (see Acrylonitrile POLYMERS, ABS resins). When SAN is grafted onto a butadiene-based mbber, and optionally blended with additional SAN, the two-phase thermoplastic ABS is produced. ABS has the usehil SAN properties of rigidity and resistance to chemicals and solvents, while the elastomeric component contributes real impact resistance. Because ABS is a two-phase system and each phase has a different refractive index, the final ABS is normally opaque. A clear ABS can be made by adjusting the refractive indexes through the inclusion of another monomer such as methyl methacrylate. ABS is a versatile material and modifications have brought out many specialty grades such as clear ABS and high temperature and flame retardant grades. Saturated hydrocarbon elastomers or acryHc elastomers (3,4) can be used instead of those based on butadiene, [106-99-0].  [c.191]

Fig. 9. Monolithic multilayer ceramics (MMCs) derived from multilayer capacitor, high temperature cofire, and thick film technologies. Fig. 9. Monolithic multilayer ceramics (MMCs) derived from multilayer capacitor, high temperature cofire, and thick film technologies.
Major sources of nitrogen oxide emission are nitrogen fixation during high temperature combustion, nitric acid manufacture and concentration (see Nitric acid), organic nitrations (see Nitration), and vehicular emissions. During combustion in the presence of air, N2 and O2 react in the high temperature of the flame to produce NO. This reversible reaction favors NO formation as the temperature increases (see Table 4). Because the kinetic rate of the decomposition reaction drops essentially to zero at temperatures below 870°C, reversion of the NO to N2 and O2 upon cooling does not occur.  [c.390]

Polyimide. Polyimide is a biaxiaHy oriented high performance film that is tough, flexible, and temperature- and combustion-resistant. Its room temperature properties compare to poly(ethylene terephthalate), but it retains these good characteristics at temperatures above 400°C. Its electrical resistance is good and it is dimensionally stable. The principal detriment is fairly high moisture absorbance. The main uses are for electrical insulation, particularly where high temperatures are prevalent or ionizing radiation is a problem. The films may be coated to reduce water absorption and enhance  [c.377]

In order to make a multipurpose plant even more versatile than module IV, equipment for unit operations such as soHd materials handling, high temperature/high pressure reaction, fractional distillation (qv), Hquid—Hquid extraction (see Extraction, liquid-liquid), soHd—Hquid separation, thin-film evaporation (qv), dryiag (qv), size reduction (qv) of soHds, and adsorption (qv) and absorption (qv), maybe iastalled.  [c.438]

Compounds of chlorine and bromine are the halogen compounds having commercial significance as flame-retardant chemicals. Fluorine compounds are expensive and, except ia special cases, iaeffective. Iodine compounds, although effective, are expensive and too unstable to be used. Halogenated flame retardants can be broken down iato three classes brominated aHphatic, chlofinated aHphatic, and brominated aromatic. As a general rule, the thermal stabiHty iacreases as brominated aHphatic < chlorinated aHphatic < brominated aromatic. The thermal stabiHty of the aHphatic compounds is such that with few exceptions, thermal stabilizers such as a tin compound must be used (see Tin compounds). Brominated aromatic compounds are much more stable and may be used in thermoplastics at faidy high temperatures without the use of stabilizers and at very high temperatures with stabilizers. It is commonly thought that it is desirable for the flame retardant to decompose with the Hberation of halogen at a somewhat lower temperature than the decomposition temperature of the polymer. This view is overly simplistic. In fact, in some systems, it is degradation of the polymer that promotes degradation of the flame retardant and not vice versa (24).  [c.466]

Commercial Cells. AH commercial duorine installations employ medium temperature cells having operating currents of >5000 A. The medium temperature cell offers the following advantages over low and high temperature cells (/) the vapor pressure of HF over the electrolyte is less (2) the composition of the electrolyte can vary over a relatively wide range for only a small variation in the operation of the cell (J) less corrosion or deterioration of the anode occurs (4) tempered water can be used as cell coolant and (5) the formation of a highly resistant film on the anode surface is considerably reduced compared to the high temperature cell.  [c.125]

SQUID sensor The SQUID converter and the coupling coil are thin film devices prepared of the high temperature superconductor Y]Ba2Cu307 on SrTiOs substrates. Typical substrate dimensions are 10 mm by 10 mm In one version, fig.4, the SQUID converter and the coupling coil are integrated on one substrate to improve the coupling in another version two substrates have been apphed and the magnetic coupling has been made by a flip chip technique. This results in a looser coupling on the one hand but a much simpler preparation process on the other hand. The SQUID converter is a one layer device applying an artificial crystalline grain boundary on a bicrystalline substrate for the preparation of the Josephson junctions. A flux to voltage conversion of about lOOpV/Oo could be obtained. A first stage of the flux  [c.300]

Piezoelectric polymer films such as PVDF (polyvinylidene fluoride) are now relatively cheap and offer the possibility of developing transducers which would be inexpensive enough to be permanently attached to a structure. PVDF has been used in compression wave ultrasonic transducers for some years and has also been used in arrays (see, for example, the review article by Chen and Payne [9]). It has the advantage over piezoelectric ceramics of being flexible so bonding it to curved structures would not present problems. Its internal damping is also higher than that of ceramics so the excitation of guided waves in the film is less likely to be a problem. However, it is less sensitive than ceramics and it cannot be used at high temperatures which may preclude its use in some structures. There are a few reports of PVDF being used for interdigital transducers. Matiocco et al [10] have generated and received Rayleigh waves on a duralumin substrate at a frequency of 7 MHz and Toda and Sawaguchi [11] have produced a leaky Lamb wave transducer. Nasr et al [12] have used polymer transducers to generate and detect Scholte waves at a water-silica interface. This paper describes the transducer design and construction methods and presents samples of results obtained with transducers designed to inspect the whole of a plate-like structure from a single transducer position.  [c.714]

Armed with the empirical knowledge that each element in the periodic table has a characteristic spectmm, and that heating materials to a sufficiently high temperature dismpts all interatomic interactions, Bunsen and Kirchoflf invented the spectroscope, an instmment that atomizes substances in a flame and then records their emission spectmm. Using this instmment, the elemental composition of several compounds and minerals were deduced by measuring the wavelength of radiation that they emit. In addition, this new science led to the discovery of elements, notably caesium and mbidium.  [c.1]

EPR has been snccessfnlly applied to radicals m the solid, liquid and gaseons phase. Goniometer techniqnes have been adopted to measure anisotropic magnetic interactions in oriented (e.g. single-crystal) and partially oriented (e.g. film) samples as a fnnction of the sample orientation with respect to the external field. Variable temperature studies can provide a great deal of mfonnation about a spur system and its interactions with its enviromnent. Therefore, low-temperature as well as high-temperature EPR experiments can be condncted by either heating or cooling the entire cavity in a temperature-controlled cryostat or by heating or cooling the sample in a jacket inserted into the cavity. Specialized cavity designs have also been worked ont to perfomi EPR studies under specific conditions (e.g. high pressures). Sample irradiation is facilitated throngh shielded openings in the cavity.  [c.1563]

Precision combustion measurements are primarily made to detennine enthalpies of fonnation. Since the combustion occurs at constant volume, the value detennined is the energy change AJJ. The enthalpy of combustion A //can be calculated from A U, provided that the change in the pressure within the calorimeter is known. This change can be calculated from the change in the number of moles in the gas phase and assuming ideal gas behaviour. Enthalpies of fonnation of compounds that do not readily bum hr oxygen can often be detennined by combusting in fluorine and the enthalpy of fonnation of volatile substances can be detennined using flame calorimetry. For compounds that only combust at an appreciable rate at high temperature, such as zhconium in chlorine, the teclmique of hot-zone calorimetry is used. In this method one heats the sample only very rapidly with a known amount of energy until it reaches a temperature where combustion will occur. Alternatively, a well characterized material such as benzoic acid can be used as an auxiliary material which, when it bums, raises the temperahire sufficiently for the material to combust. These methods have been discussed in detail [2, 3 and 4].  [c.1910]

There are two basic methods of preparing PDLCs [121]. In the first, the liquid crystal is dispersed as an emulsion in an aqueous solution of a film-fonning polymer (often polyvinyl alcohol) [121]. This emulsion is then coated onto a conductive substrate and the emulsion is dried to fonn the dispersed liquid crystal-in-polymer film. In the second method, the phase separation of a polymer is exploited to disperse the liquid crystal [123]. In the method of polymerization-induced phase separation [121], polymerization is induced tlirough the application of heat, light or radiation e.g. tlirough cross-linking of a network. A commonly used example exploits the cross-linking of epoxy adhesives to fonn a solid stmcture containing phase-separated liquid crystal droplets. In thennally induced phase separation, the liquid crystal is mixed with a thennoplastic polymer at high temperatures. Wlien the system is cooled, the liquid crystal phase separates from the solidifying polymer. In solvent-induced phase separation, a polymer and a liquid crystal are mixed to fonn a single-phase mixture in an organic solvent. Evaporation of the solvent then drives the phase separation of polymer and liquid crystal [121].  [c.2564]

The role of solid and liquid lubricants at solid-solid interfaces is to reduce friction forces during sliding. Liquid lubrication is commonly described as occurring in tliree regimes that depend upon the nonnal forces and sliding speeds of two surfaces in contact. At low nonnal force and high sliding speeds liquid films can completely separate two surfaces, preventing solid-solid contact. Under these conditions, usually referred to as hydrodynamic lubrication, the frictional forces between two surfaces are detennined by the rheological properties of the thin fluid film that separates them. As the nonnal force is increased and the sliding speed decreased the interface enters the boundary regime of lubrication. The surfaces have defonned under the high nonnal forces and are thought to be separated by monomolecular films of adsorbed molecules. These are typically surfactant-like species that are added to lubricant fluids for just this purjDose. Under even higher nonnal forces the interface enters the extreme pressure regime during which direct solid-solid contact occurs. The surfaces are defonned even further and high rates of wear are observed exposing clean solid surfaces. Lubricant fluids usually contain extreme pressure additives which can react with clean exposed surfaces under high pressure and high temperature conditions to fonn thin solid films with low shear yield strengths. It is these thin solid films that provide lubrication. As implied by the discussion above, lubricant fluids are often very complicated mixtures containing as many as ten or 20 additives, each of which serves a specific purjDose in reducing friction and wear of solid surfaces in sliding contact [2].  [c.2743]

At high temperatures oxygen reacts with the nitrogen in the air forming small amounts of nitrogen oxide (p. 210). Sulphur burns with a blue flame when heated in air to form sulphur dioxide SO2, and a little sulphur trioxide SO3. Selenium and tellurium also burn with a blue flame when heated in air, but form only their dioxides, Se02 and Te02.  [c.266]

Because rubidium can be easily ionized, it has been considered for use in "ion engines" for space vehicles however, cesium is somewhat more efficient for this purpose. It is also proposed for use as a working fluid for vapor turbines and for use in a thermoelectric generator using the magnetohydrodynamic principle where rubidium ions are formed by heat at high temperature and passed through a magnetic field. These conduct electricity and act like an amature of a generator thereby generating an electric current. Rubidium is used as a getter in vacuum tubes and as a photocell component. It has been used in making special glasses. RbAgrls is important, as it has the highest room conductivity of any known ionic crystal. At 20oC its conductivity is about the same as dilute sulfuric acid. This suggests use in thin film batteries and other applications.  [c.92]

Bismanol" is a permanent magnet of high coercive force, made of MnBi, by the U.S. Naval Surface Weapons Center. Bismuth expands 3.32% on solidification. This property makes bismuth alloys particularly suited to the making of sharp castings of objects subject to damage by high temperatures. With other metals such as tin, cadmium, etc., bismuth forms low-melting alloys which are extensively used for safety devices in fire detection and extinguishing systems. Bismuth is used in producing malleable irons and is finding use as a catalyst for making acrylic fibers. When bismuth is heated in air it burns with a blue flame, forming yellow fumes of the oxide. The metal is also used as a thermocouple material, and has found application as a carrier  [c.146]

The principal use of thorium has been in the preparation of the Welsbach mantle, used for portable gas lights. These mantles, consisting of thorium oxide with about 1% cerium oxide and other ingredients, glow with a dazzling light when heated in a gas flame. Thorium is an important alloying element in magnesium, imparting high strength and creep resistance at elevated temperatures. Because thorium has a low work-function and high electron emission, it is used to coat tungsten wire used in electronic equipment. The oxide is also used to control the grain size of tungsten used for electric lamps it is also used for high-temperature laboratory crucibles. Glasses containing thorium oxide have a high refractive index and low dispersion. Gonsequently, they find application in high quality lenses for cameras and scientific instruments. Thorium oxide has also found use as a catalyst in the conversion of ammonia to nitric acid, in petroleum cracking, and in producing sulfuric acid.  [c.175]

In a plasma, collisions between atoms, positive ions, and electrons thermolize their kinetic energies the distribution of kinetic energies corresponds to what would be present in a hot gas thermally heated to an equivalent temperature. Direct heating of a gas is not used to form the plasma. Instead, a high-frequency electromagnetic field is applied through the load coil. This rapidly oscillating electromagnetic field interacts inductively with the charged species electrons and ions try to follow the field and are speeded up, gaining kinetic energy. In the rapidly oscillating field, random collisions of electrons and ions with neutral species redistributes this extra kinetic energy, and the whole ensemble becomes hotter. If the rapidly oscillating electromagnetic field is maintained, the ions and electrons continue to follow a chaotic motion as they gain more speed and undergo more collisions, which continue to redistribute the kinetic energies. Eventually, the kinetic energies become so high that the plasma reaches temperatures of 8,000-10,000°C. At these high temperatures, the plasma behaves like a flame issuing from the ends of the concentric quartz tubes, hence the derivation of the name plasma torch. As in a normal flame, atoms and ions are excited electronically in the collision processes and emit light. In the plasma torches used for mass spectrometry, the argon that is used emits pale-blue-to-lilac light as excited atoms relax and as a proportion of the electrons and ions recombine.  [c.87]

A plasma flame commonly has a diameter of about 1 cm and a length of about 2-3 cm. If this flame is regarded as approximately cylindrical, the volume of the flame at about 5300 K is 1.6 ml and at 300 K is 0.1 ml. With a specific heal for argon of 0.124 cal/g/K and a density of 1.78 x ICf g/ml (at 300 K), the heat content of the flame is 0.1 cal. However, since gas flow through the hot flame occurs in a period of about 2 msec, the power output of the flame is about 50 W. This output should be compared with a power input from the high-frequency electromagnetic field of about 1 kW. The seeming incon.sistency between the high temperature and the low heat content arises because of the low number density of hot particles. (The concentration of electrons and other particles in the hot flame is approximately ICf M.)  [c.98]

As stated above, the development of multifimctional MLCs based on existing technologies offers excellent growth potential since MMCs combine the possibilities of both the high cofire (packaged) substrates and burial of surface devices (54—57). Burial of surface devices promises gains in both chcuit density and device hermiticity, leading to increased reUability. Processing trade-offs are expected since current electronic materials for multilayer appHcations (capacitors, transducers, sensors) are densifted at very different firing temperatures. Consequendy, integrated components will likely be of lower tolerance and limited range, at least in the eady developmental stages. Current efforts have been dhected toward incorporation of multilayer capacitor-type power planes and burial of thick film components, including resistors and capacitors. The latter processing technology offers more immediate possibilities as it is developed to cofire at conventional thick film processing temperatures for which a wide range of materials exist.  [c.315]

Plasticizers. Over 70% of plasticizer range alcohols are ultimately consumed as plasticizers for PVC and other resins. Of this amount, 80% is used as the diester of phthaUc acid, for instance di-2-ethylhexyl phthalate (DOP) or diisodecyl phthalate (DIDP) [26761-40-0]. Other plasticizers made from these alcohols are the diesters of adipic acid, azeleic acid, and sebacic acid, plus the triesters of phosphoric acid and trimeUitic acid. A small amount of alcohol is used as the terminating agent in specialty polyester plasticizers. The adipates, azelates, and sebacates are employed as specialty materials in some food contact appHcations and in areas where low temperature flexibiUty is important, such as automobile interiors eg, the diadipate ester of hexanol is the plasticizer in poly(vinyl butyral) used for automobile safety glass. The phosphates find appHcation as good low temperature plasticizers and as flame retardant additives, whereas the trimeUitates are used for high temperature appHcations such as the insulation of electrical wiring. The phthalates, however, are the general purpose plasticizers. Phthalate esters of alcohols from 4—13 carbons are available although most are in the Cg through C q range. AH plasticizers are chosen on the basis of performance, cost, and ease of processing DOP and DIDP are the workhorses of the industry. When compared to DOP, phthalates of mixed linear alcohols (for instance, mixed heptyl, nonyl, and undecyl alcohols) give improved low temperature properties and resistance to volatile loss whereas those made of higher molecular weight alcohols (for instance, isodecyl or tridecyl alcohols) give improved resistance to extraction and volatile loss but exhibit some loss of plasticizing abHity. In general, esters of mixtures of alcohols are favored as plasticizers because they give a broader range of properties than esters of a single alcohol.  [c.450]

Smoke, Flash, and Fire Points. These thermal properties may be determined under standard test conditions (57). The smoke poiat is defined as the temperature at which smoke begias to evolve continuously from the sample. Flash poiat is the temperature at which a flash is observed whea a test flame is appHed. The fire poiat is defiaed as the temperature at which the fire coatiaues to bum. These values are profouadly affected by minor coastitueats ia the oil, such as fatty acids, moao- and diglycerides, and residual solvents. These factors are of commercial importance where fats or oils are used at high temperatures such as ia lubricants or edible frying fats.  [c.132]


See pages that mention the term Flame, high temperature : [c.189]    [c.81]    [c.1098]    [c.2723]    [c.268]    [c.4]    [c.155]    [c.4]   
Modern spectroscopy (2004) -- [ c.66 ]