Baking Cycle Research Articles

Air Pollution Control in the Carbon Baking Process

Carbon baking process involves evolution of fumes containing hydrocarbons and soot particles which cannot be discharged directly into the atmosphere. An incinerator can be used to clean these fumes. However, length of the baking cycle, nature of the fumes and variations in fume volume and temperature may result in excessive auxiliary fuel usage and inefficient incineration, if the incinerator is not designed properly. This paper describes the application of fundamental knowledge of aerodynamics, reaction kinetics and combustion, together with clear understanding of the process, in design of a highly efficient, fully automated incinerator. The design incorporates a unique but simple control system which results in reduction of auxiliary fuel usage without endangering the safety and efficiency of the incineration process. Operations and economics of the incinerator are described by illustrating a typical baking cycle and comparing actual fuel usage with the thermal ratings of the incinerator. Operating expe...

Mass spectrometric investigations of background gases during the sputtering of tantalum

The time dependence of the partial pressures of H + 2, O + 2, CH + 4, H 2 O +, N + 2 and a combination of CO + and C 2H + 4 have been monitored continuously during and after the sputtering of Ta. With the exception of O + 2, these components undergo a transient increase on initiation of sputtering. The increase in the background CH + 4 is attributed to desorption and dissociation of heavier hydrocarbons by the discharge. This CH 4 may itself be dissociated, thus contributing to the increase in the background H 2 partial pressure. H 2 is also produced by the desorption and dissociation of H 2O. The background oxygen partial pressure is reduced by a factor of five during sputtering. An oxygen exposure of 1 × 10 2 Langmuir produces about one monolayer of oxide on sputtered Ta. For films reactively sputtered in oxygen the resistivity decreases as the lenght of the baking cycle prior to sputtering is increased. This shift with baking time may be attributed to a decrease in the quantity of water vapour desorbed by the discharge, and thus a decrease in the total oxygen concentration in the films.

Pyrolysis of coal tar pitch binders

Thermogravimetric analysis techniques have been adapted to study the thermal decomposition of six coal tar pitches. Two material constants are introduced to describe the thermal stability and/or reactivity of coal tar pitches. These constants can be correlated with the softening point of the pitches. It is also shown that both the temperature where the rate of volatilization is at maximum, ( T m ), and the temperature range where most volatiles are evolved, ΔT, can also be used to describe the thermal stability of coal tar pitches. The practical importance of T m and ΔT in determining the proper choice of the baking cycle of green carbon bodies is discussed.

Contamination in Ultra-High Vacuum Plant

Using an electron bombarded target the presence of silicone vapor was detected in the vessel of a bakeable ultra-high vacuum system made of stainless steel exhausted by a silicone oil diffusion pump. Silicone molecules temporarily adsorbed on the target were desaturated by the impinging electrons and polymerized to form a deposit. The deposit thickness was measured by multiple-beam interferometry. The diffusion pump was charged with silicone 704 and fitted with a chevron (trap II) and a container trap (trap I) next to the vessel. Liquid nitrogen cooling both the chevron and container-type trap next to the vessel after baking (pultimate≃10−9 Torr) gave a deposit growth rate of <5 Å/h. When the chevron trap was not operated during ultra-high vacuum pumping the container-type trap condensed sufficient oil vapor for the vessel to be contaminated when the vessel and trap were subsequently baked. The contamination rate measured during baking was dependent on the time the system had been previously under ultra-high vacuum without the chevron trap being cooled. Ultra-high vacuum pumping for 38 h at 10−9 Torr gave rise to a deposit growth rate of 160 Å/h on the next baking cycle. The contamination rate was reduced to its lowest amount during baking (35 Å/h) when the chevron baffle was cooled throughout the pumping cycle. Using a new silicone fluid (705) gave a deposit growth rate of about one-half to one-quarter of fluid 704.

Survey of Application Data on Baked Phenolic Coatings Used in Process Industries

Abstract A summary of experience data concerning baked phenolics used as coatings in vessels storing chemicals, with emphasis on organies. Principal characteristics of phenolic coatings are reviewed. Sandblasted, meticulously clean surfaces are stipulated. Necessity for proper drying between coats is underlined and the virtual impossibility of achieving pinhole-free coatings emphasized. Thickness recommendations are made and proper backing procedure discussed, with a review of changes that take place during the baking cycle. Two methods of achieving pinhole-free coatings systems using metallic undercoating and organic overcoatings are described. Characteristic properties of baked coatings are summarized. Chemical resistance of baked phenolic coatings to 18 classes of organic acids, anhydrides, aldehydes, alcohols, hydroxy compounds, organic esters, amines and others is tabulated. Cautions to be observed in cleaning are given. Coatings are not recommended for inorganic acids. Oxidizers or alkalis rapidly d...