Early Stage Of Heating Research Articles

Surface precipitation and its application to coatings

The precipitation phenomena on the surfaces of two types of stainless steels were observed when they were heated at high temperatures in vacuum. One was the precipitation of titanium carbide on the surface of commercial 321 stainless steel, and the other was the precipitation of boron nitride on the surface of laboratory-melted 304 stainless steel doped with nitrogen and boron (304-NB) and that doped with nitrogen, boron, and cerium (304-NBCe). In the case of 304-NBCe stainless steel, a boron nitride layer almost uniformly covered the surface at the early stage of heating. Such surface precipitation phenomena will be applied to control the structure and properties of metal surfaces and will be a promising process for materials design. The titanium carbide film deposited by ion plating on the surface of 321 stainless steel was stable against the thermal cycle. This means that the precipitated titanium carbide could be a bonding agent between ceramics and metals. The surface covered with boron nitride was inert to the adsorption of gas. Therefore, stainless steel doped with nitrogen, boron, and cerium will be a candidate material for vacuum vessels.

Surface precipitation of boron nitride on the surface of type 304 stainless steels doped with nitrogen, boron, and cerium

The surface compositions of two types of stainless steels in vacuum were observed with AES and XPS at 1000–1100 K; a 304 stainless steel doped with nitrogen and boron (304-NB) and a 304 stainless steel doped with nitrogen, boron, and cerium (304-NBCe). The changes of surface compositions of these steels were compared with that of commercial 304 stainless steel. A thin layer of boron nitride came out from grain boundaries and spread over the surface of the 304-NB, but did not uniformly cover the surface. The spreading mechanism of the boron nitride layer at the initial stage of heating can be explained by Avrami’s model. In the case of 304-NBCe, a boron nitride layer almost uniformly covered the surface at the early stage of heating, and rendered the surface inert to the adsorption of carbon and oxygen. Therefore, the 304-NBCe stainless steel is a candidate material for vacuum vessels.

Relativistic adiabatic invariants of electron motion under ECRH

Three adiabatic invariants of the electron motion under electron cyclotron resonance heating have been derived. The relativistic effect has been included in the analysis. It is shown that the relativistic effect always tends to reduce the parallel energy of the electrons during the early stage of heating.

Thermal decomposition studies on double-base propellant compositions

Thermal reactivity studies were carried out in the temperature range 100–160‡ on two double-base propellant compositions which differ significantly in chemical composition, calorimetric value and ballistic characteristics. The course of decomposition was followed by two methods: (i) determining the rate of NO evolved with the Bergman and Junk method; (ii) estimating the volume of gases evolved in a vacuum stability test method. The activation energy values computed using the Arrhenius equation and the Jacobs-Kureishy method were comparable and in the range 134–170 kJ mol−1. In the temperature range 100–140‡, nitroglycerine volatilization was significant during the early stages of heating. Above 180‡, the rate of decomposition was very fast, leading to ignition of the propellant, followed by slow oxidation of the carbonaceous residues. The thermoanalytical data indicated a twostep decomposition process for propellant I, and a single-step process for propellant II.

ChemInform Abstract: DEHYDRATION BEHAVIOR OF ALUMINUM SULFATE HYDRATES

AbstractBei der thermischen Dehydratisierung gut kristalliner Proben von A12(SO4)3°C 16 H2O, AI2(SO4 )3 ‐ 14 H2O und A12 (SO4)3 ‐ 9 H2O tritt ein exothenner Übergang in der DTA‐Kurve auf, wenn die Aufheizung anfangs im Vakuum erfolgt.

Dehydration Behavior of Aluminum Sulfate Hydrates

An exothermic transition is observed near 400°CC on thermal dehydration of highly crystalline AI2(SO4)3.16H2O, Al2(S04)3 14H2O, and Al2(S04)3 9H2O when the early stages of heating are carried out in vacuum. Amorphous or partially crystalline hydrates do not show the exotherm. No systematic relation is apparent between the decomposition behavior and the pore volume distribution of the various anhydrous A12(SO4)3 products.

Stabilization of poly(vinyl chloride). V. Synergism between metal soaps and polyols upon stabilization of poly(vinyl chloride)

The marked discolorations observed on aged poly(vinyl chloride) (PVC) containing synergetic metal soaps, in the early heating stage, were due to the excessive coloration of π complex of metal chloride and double bonds in the polyene chain. These excessive colorations were inhibited by masking the excessive metal chloride with some masking agents, thereby slowing down the abrupt discoloration of PVC. In this paper, the masking effect of various alcohols such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, hexylene glycol, glycerol, 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, meso-erythritol, pentaerythritol, sorbitol, and dipentaerythritol is investigated. The polyhydric alcohols, except dihydric alcohols, showed superior masking effect and markedly improved the thermal stabilization effects of synergetic metal soaps. The mechanism for the synergetic effects between polyols and metal soaps should be based on the masking effect of polyols, owing to the formation of the colorless complex of polyols with excess metal chlorides obtained from the metal soap.

Stabilization of poly(vinyl chloride). V. Synergism between metal soaps and polyols upon stabilization of poly(vinyl chloride)

AbstractThe marked discolorations observed on aged poly(vinyl chloride) (PVC) containing synergetic metal soaps, in the early heating stage, were due to the excessive coloration of π complex of metal chloride and double bonds in the polyene chain. These excessive colorations were inhibited by masking the excessive metal chloride with some masking agents, thereby slowing down the abrupt discoloration of PVC. In this paper, the masking effect of various alcohols such as 1,2‐butanediol, 1,3‐butanediol, 1,4‐butanediol, 2,3‐butanediol, hexylene glycol, glycerol, 1,2,4‐butanetriol, trimethylolethane, trimethylolpropane, meso‐erythritol, pentaerythritol, sorbitol, and dipentaerythritol is investigated. The polyhydric alcohols, except dihydric alcohols, showed superior masking effect and markedly improved the thermal stabilization effects of synergetic metal soaps. The mechanism for the synergetic effects between polyols and metal soaps should be based on the masking effect of polyols, owing to the formation of the colorless complex of polyols with excess metal chlorides obtained from the metal soap.

Studies of pyrolysis and air heating of rayon by inverse gas chromatography

Inverse gas chromatography using water probing at 110°C was carried out to characterize rayon yarns after prior heating at 200 and 250°C in both inert (nitrogen) and oxidative (dry air) atmospheres for successively longer time intervals. During the early stages of heating in either atmosphere, the affinity of the rayon for water drops rapidly. However, whereas continued heating in N 2 results in a further loss of activity, data have been obtained showing that after an initial period yarns heated in air at 250°C exhibit an increasing attraction for water even while losing more weight.

Nucleation of recrystallized grains in heavily cold-worked α-brass

Abstract The effect of heating on the substructure of heavily rolled 70:30 brass is described. Colonies of very fine ‘recovery’ twins (0.002–0.01 μm thick) develop in the shear bands at an early stage of heating and subsequently grow lengthwise in the matrix. Dislocation loss from the matrix regions associated with the recovery twins is gradual and the nuclei for recrystallization are not developed until well after the twins have formed. Nucleation appears to occur by lateral growth of either the twins or matrix regions but in the early stages of this growth there is no clear boundary distinguishing the potential nucleus from the cold-worked matrix. Examination of specimens deformed in torsion shows that similar changes occur in slowly heated specimens. The results are discussed with reference to the currently accepted view that the return of short-range order is the major contributory factor to the release of stored energy from coldworked 70:30 brass prior to recrystallization.

High temperature heating of the Allende meteorite

Allende bulk samples were heated up to 2000°C by DC arc and resistance heating. The chemical composition of evaporation residues was measured by instrumental neutron activation analysis (INAA) and electron probe microanalyser (EPMA). The evaporation sequence of elements observed was: (Na)-(Fe, Ni, Co, Au, Ir)—(Fe, Mn, Cr) (Mg, Si)-(Al, Ca, Ti, Sc, REE). Chemical compositions of 65% and 4% residual fractions were in agreement with those of a chondrule and a Ca, Al-rich inclusion of the Allende meteorite, respectively. Iridium was lost from residual solid in the early stage of heating. The early loss of the refractory siderophile elements may provide a clue to distinguish between two possibilities for the origin of Allende Ca, Al-rich inclusions: early condensates vs. evaporation residue. Ca, Al-rich inclusions (CAI) in the Allende meteorite may provide information on the physical and chemical conditions prevailing in the early solar system. So far we have two possibilities for the origin of CAI: 1. (1) High temperature condensates from a “hot” solar nebula (GROSSMAN, 1972, 1973; WANKE et al., 1974); 2. (2) Evaporation residues of the pre-existing primordial dust in the early solar system (KURAT, 1970; TANAKA and MASUDA, 1973; CHOU et al., 1976; CLAYTON, 1977). A condensation origin has been supported by theoretical considerations of equilibrium condensation from a cooling nebula, while an evaporation origin has received no endorsement from either theoretical or experimental approaches. We have heated bulk Allende samples to determine whether or not the chemical composition of CAI can be derived in the course of fractional vaporization of pre-solar matter which, in this experiment, is approximated by the bulk Allende composition.

低炭素25Cr-20Ni系鋼におけるσ相生成におよぼす引張変形の影響

In order to investigate the σ phase formation in a series of 25 Cr-20 Ni steels, the effect of prestrain up to 20% by tension on the σ phase formation at 800°C was studied for low carbon 25 Cr-20 Ni steel with and without an approximately 3% addition of Mo or Si.The results obtained are as follows:(1) The effect of prestrain on the σ phase formation was observed in all of the three specimens and the σ phase was formed in the early stages of heating in the prestrained specimens.(2) The morphology of the σ phase thus formed was not the widmanstätten type, but the σ phase existed along the annealing twin boundaries and its amount, slightly increased with increasing prestrain.(3) In the strongly prestrained specimens, the σ phase formation also occurred on the slip bands in the vicinity of grain boundaries.(4) In the undeformed specimens with Si and Mo, there were denuded zones where the σ phase formation was hardly observable.(5) It seems probable that the σ phase formation in the prestrained specimen is enhanced by the deformation-induced crystal defects, while that in the undeformed specimens depends on the point defect concentration.

Microflora of heat-damaged rapeseed

Microfloral components present on two sound lots (1 and 2) and three sample grade, heat-damaged lots (3 to 5) of stored Canadian rapeseed (Brassica campestris L. and B. napus L.) were determined with and without surface disinfection. Lots 1 and 2 were from a granary and a warehouse, respectively, and lots 3 to 5 were from primary elevators. Seed in lots 4, 5, and 3 showed progressively increased effects of heat damage as shown by the crush test. Sound lots 1 and 2 had mainly Alternaria and Cladosporium spp. with traces of Eurotium amstelodami, E. repens, and Penicillium spp. Lot 4 seed had low–medium levels of Alternaria alternata, Absidia ramosa, E. amstelodami, and Mucor pusillus. Lot 5 had high levels of E. amstelodami and low levels of Talaromyces thermophilus but A. alternata and M. pusillus were largely absent. Lot 3 had deeper-seated E. amstelodami, T. thermophilus, and Penicillium spp. than lots 4 and 5. Eurotium amstelodami was the predominant storage fungus in the heat-damaged lots. During the early stages of heating, E. amstelodami was often accompanied by the primary sugar fungi M. pusillus and A. ramosa, and after severe heating, by T. thermophilus. The thermal death point was between 50 and 60 °C for moist seed and between 80 and 90 °C for dry seed after 30-min exposure. With the exception of E. amstelodami, heat resistance of the fungal flora did not exceed that of the seed.

Inactivation of Clostridium perfringens type A spores at ultrahigh temperatures.

The inactivation of Clostridium perfringens type A spores (three strains of different heat resistances) at ultrahigh temperatures was studied. Aqueous spore suspensions were heated at 85 to 135 C by the capillary tube method. When survivors were enumerated on the standard plating medium, the spores appeared to have been rapidly inactivated at temperatures above 100 C. The addition of lysozyme to the plating medium did not affect the recovery of spores surviving the early stages of heating, but lysozyme was required for maximal recovery of spores surviving extended heat treatments. The percentage of survivors requiring lysozyme for colony formation increased greatly with longer exposure times or increasing treatment temperature. Time-survivor curves indicated that each spore suspension was heterogeneous with respect to the heat resistance of spore outgrowth system or in the sensitivity of the spores to lysozyme. Recovery of survivors on the lysozyme containing medium revealed greater heat resistance for one strain than has been reported for spores of many mesophilic aerobes and anaerobes. The spores of all three strains were more resistant to heat inactivation when suspended in phosphate buffer, but a greater percentage of the survivors required lysozyme for colony formation.

Inactivation of Clostridium perfringens Type A Spores at Ultrahigh Temperatures1

The inactivation of Clostridium perfringens type A spores (three strains of different heat resistances) at ultrahigh temperatures was studied. Aqueous spore suspensions were heated at 85 to 135 C by the capillary tube method. When survivors were enumerated on the standard plating medium, the spores appeared to have been rapidly inactivated at temperatures above 100 C. The addition of lysozyme to the plating medium did not affect the recovery of spores surviving the early stages of heating, but lysozyme was required for maximal recovery of spores surviving extended heat treatments. The percentage of survivors requiring lysozyme for colony formation increased greatly with longer exposure times or increasing treatment temperature. Time-survivor curves indicated that each spore suspension was heterogeneous with respect to the heat resistance of spore outgrowth system or in the sensitivity of the spores to lysozyme. Recovery of survivors on the lysozyme containing medium revealed greater heat resistance for one strain than has been reported for spores of many mesophilic aerobes and anaerobes. The spores of all three strains were more resistant to heat inactivation when suspended in phosphate buffer, but a greater percentage of the survivors required lysozyme for colony formation.

EFFECT OF HEAT TREATMENT UPON THE GERMINATION OF WHEAT

Grain of known moisture content was exposed m sealed pouches to constant temperatures between 60 and 99 C (140–210 F). The heating periods varied from 15 min to 10 hours. The loss of viability of wheat, resulting from these heat treatments, was found to occur at two rates. During the early stages of heating particularly at temperatures below 65 C (150 F), the rate of loss of viability was quite small. After a period of heating, the rate of loss of viability increased markedly. The length of the heating period required to initiate this rapid loss of viability varied with the moisture content of the grain and with the temperature to which the grain was exposed. Moist grain was much more susceptible to thermal damage than was dry grain.There did not appear to be a specific "killing temperature", or "threshold temperature" above which the seed was damaged. Damage to viability resulted from the cumulative effect of time and temperature, and there was a semi-logarithmic relationship between time and temperature for a given amount of loss of viability. It appears that there may be two kinetic mechanisms involved.

Composition of Distillable Products

In the previous paper the author observed that distillable products are formed when oils are heated at 300°C. The author considered it may be helpfull to elucidate the characteristic changes of heated oil when chemical compositions of this distillable products would be identified.The distillable products consist of acidic, carbonyl and neutral fractions. The acidic fraction mainly consists of free fatty acids. The pattern of fatty acids is resemble to that of original fatty acids composition at the early stage of heating and as the heating time increases the content of lower fatty acids increases.In the neutral fraction more than 15 peaks were observed by gas chromatography. The main components were hydrocarbons, the carbon number of which was 8, 9, 10, 11 and 12.The author concluded that cleavage of ester linkage is dominant at the early stage of heating at 300°C and that the cleavage of oxidative products follow, causing the formation of lower fatty acids.

A Study on the Color-Developing Process of Copper Ruby Glass

For the purpose of elucidating the phenomena of nucleation and thermal reduction process of developing color by the dispersion of fine metallic crystals a glass of the composition of Na2O 15.0, CaO 10.0, SiO2 75.0, Cu2O 0.225, SnO 1.125 (wt. ratio) was subjected to the heat treatment under various conditions, and the development of the absorption around 570mμ was observed.The absorption of the specimens heated between 480° and 710°C was found to follow the Lambert-Beer's law.It was confirmed that the amount of copper, B, dispersed in glass in an early stage of heating was represented byB=const.×aIGt5/2which means that the reaction proceeded with the homogeneous nucleation of velocity I, and later with the thermal reduction controlled by the rate of the reactionCu++Sn2+=Cu°+Sn4+, and was represented by a saturation curve of the formB=const.×C0g(t)Moreover, the value of (log I+log G) which includes the growth coefficient G reached to the maximum between 580°-647°C.