Showing papers by "Cabot Corporation published in 1986"

Bound Rubber and Carbon Black Reinforcement

Abstract: The first description of the bound rubber phenomenon was by Twiss in 1925, who made the observation that the resistance of carbon black-natural rubber mixes to solvents was related to improved mechanical properties. Boiry studied many of the factors influencing the insolubilization of NR by fillers including type and amount of fillers, and mixing and testing variables. In 1937 J. H. Fielding of Goodyear developed a so-called “bound rubber” test because of his interest in the possibility of chemical bond formation between fillers and rubber. During the start of the U.S. synthetic rubber program, Baker and Walker reported in 1945 an insolubilization of SBR when mixed with carbon black significantly greater than the amount of normal gel in the unfilled elastomer. They were also the first to report that the amount of gel increased with increasing molecular weight and that a selective adsorption of high molecular weight material occurred. Since that time, many investigations have confirmed these findi...

High temperature corrosion of superalloys in an environment containing both oxygen and chlorine

Abstract: The corrosion behavior of a series of commercial superalloys in flowing argon-20 pct oxygen-2 pct chlorine at 900 °C has been investigated using thermogravimetric analysis and examination of the condensed corrosion products using X-ray diffraction analysis and optical and scanning electron microscopy. Most of the alloys exhibited decreases in mass due to formation of volatile chloride or oxychloride corrosion products. An exception is the alloy 214 which showed little change in mass due to the formation of a protective alumina scale. Alloys which are high in refractory metals, notably alloys S and C-276, snowed the highest rates of attack. In addition to the metal wastage, several of the alloys were subject to internal attack in the region near the corroded surface.

On the fcc→hcp transformation in a cobalt-base superalloy (Haynes alloy no. 25)

Abstract: Etude de la transformation en fonction du travail a froid et des conditions de vieillissement

Health effects of work at waste water treatment plants: a review of the literature with guidelines for medical surveillance.

Abstract: Potential health hazards associated with work at waste water treatment plants include bacteria, viruses and protozoa in domestic waste and heavy metals and other hazardous substances in industrial wastes. The primary exposure route for hazardous material is through inhalation of aerosols generated in the secondary phase of water treatment that contain pathogenic organisms. Although few epidemiological studies have investigated the health of waste water treatment facility workers, hazards noted have been limited to acute, self-limited gastrointestinal illnesses. Due to the potential for long term or subtle adverse health effects, a medical surveillance program is proposed that includes attention to infectious diseases, such as hepatitis and to illness/absenteeism records.

Exploratory corrosion tests on alloys in molten salts at 900 °C

Abstract: Exploratory corrosion tests were conducted on 16 commencai alloys in carbonate, chloride, and hydroxide molten salts at 900 °C for up to three weeks. Corrosion information, including weight change, observations of the coupons, metallographic examination, and evaluation of the corrosion product by SEM, was obtained on the coupons exposed to these salts. These tests indicated that a number of the alloys showed significant resistance to metal loss in the carbonate molten salt with corrosion rates on the order of several millimeters per year. The corrosion product is an interpenetrating structure of metal from the more noble alloy ingredients and of an oxide made up of the reaction between melt components and oxidizable metals from the alloys.

Reduction of Phosphate Ores by Carbon: Part I. Process Variables for Design of Rotary Kiln System

Abstract: Feasibility is established for the reduction of phosphate ores in a rotary kiln, avoiding electric submerged arc furnace technology. This represents a totally new approach to phosphoric acid. Reduction rates of phosphate ore-silica mixtures by carbon in the temperature range of 1100 to 1500 °C under several CO partial pressures in nitrogen were measured in thermogravimetric analyzers. Parameters such as carbon and silica contents, particle and pellet sizes, and gas flow rate were also evaluated with various domestic and foreign phosphate ores. Furthermore, a variety of carbon sources such as subbituminous coals, bituminous coals, anthracite, petroleum coke, and metallurgical coke were tested as reducing agents. Thermodynamic considerations elucidate the temperature dependence of overall conversion as well as the role of excess silica in establishing equilibrium pressure. These findings provide the background for analysis of the kinetics of conversion in Part II of this work. These studies, in conjunction with a previously published work, indicate the importance of intergranular melt phases in the kinetics of otherwise solid state reactions.

Properties and characterization of coatings made using jet kote™ thermal spray technique

Abstract: The JET KOTE” system is a new thermal spray technique which relies on the continuous internal combustion of a fuel gas with oxygen to produce a high velocity exhaust jet. Powder is injected into this pressurized gas stream, where it is heated and accelerated toward the part to be surfaced. Using this technique, coatings of several wear resistant materials have been made for applications in petrochemical and chemical, materials processing, aerospace, and other engineering fields. In this paper, data relating to JET KOTE coatings of tungsten carbide-cobalt (of various cobalt contents), chromium carbide-nickel chromium, and a new iron-base wear resistant alloy called TRISTELLE” alloy TS-2 are presented. It has been shown that the JET KOTE process can be used to produce dense coatings of WC-Co with properties equivalent to those produced using the detonation gun and are much superior to plasma sprayed coatings. JET KOTE coatings of WC-Co also appear to have the added advantage of containing a higher amount of WC phase and considerably less eta phase thereby increasing their resistance to cracking.

Polarization Effects in Galvanic Corrosion

Abstract: Galvanic corrosion in couples of AISI 304 stainless steel (SS), Ferralium Alloy 255, Hastelloy Alloys B-2 and G-3, grade 2 titanium, and graphite was examined in boiling 10% sulfuric and ambient-temperature hydrochloric acids The galvanic corrosion rates were determined by measurement of the galvanic current using (1) a zero resistance ammeter technique and (2) weight loss measurements Prediction of galvanic corrosion was attempted by determining the potentiodynamic polarization curves of the individual alloys and combining these with an iterative numerical solution for the zero potential difference between the alloys In some cases, a reasonably good correlation was obtained between the predicted and measured galvanic corrosion rates No correlation was found between the measured open circuit potentials (OCPs) (galvanic series) and galvanic corrosion rates The effect of changing the area ratios was also examined

Corrosion- and wear-resistant duplex steel

Abstract: Disclosed is a "duplex" stainless steel especially suited for use in conditions requiring a high degree of wear and corrosion resistance; for example structural fasteners, such as nuts and bolts as used in chemical processing. The alloy typically contains, in weight percent, 12 cobalt, 20 chromium, 11 nickel, 5 silicon, 1.5 molybdenum, 2 copper, up to 0.2 nitrogen and up to 0.01 carbon. The "duplex" structure preferably consists of about 30% ferrite and the balance essentially austenite.

Long term high temperature corrosion studies of high temperature alloys in chlorine contaminated environments

Abstract: High temperature chlorine contaminated environments may be encountered in a number of modern industrial and energy conversion systems. Such environments have been shown to be extremely severe from a corrosion control standpoint. Rather little information is available on the corrosion properties of alloys in these environments, and the bulk of this information has been obtained in shortterm tests (24 hours or less). This paper will report the results of a series of high temperature corrosion tests performed on superalloys for periods up to 400 hours in an oxidizing environment consisting of argon containing 20 pet oxygen and 0.25 pct chlorine at 900 ° C.

Carbon black treadwear ratings from laboratory tests

Abstract: It has been seen from the above survey that a few of the treadwear predictor correlations have the required accuracy to provide a satisfactory alternative to road testing of tires for the wear performance of carbon blacks, depending on requirements and circumstances. Correlations based on laboratory rubber testing of rubber mixes and tread compounds are to be preferred over those based solely on carbon black colloidal and morphological measurements. In the author's opinion, Cotten and Dannenberg's correlation of treadwear index with Angle Abrasion measurements of 30 phr compounds and heated bound rubber, and Westlinning and Wolff's correlation with rebound resilience, and the Monsanto Rheometer determination of αF are satisfactory in most instances for the prediction of the treadwear index behavior of carbon blacks.

Reduction of phosphate ore by carbon: Part II. Rate limiting steps

Abstract: Considerations of intraparticle mass transport processes are presented for the reduction of phosphate ore by carbon in the presence of silica. Under conditions of temperature and composition which produce reaction rates of commercial interest, the conversion is limited by product mass transport away from the reaction sites. This results in a pseudo-first order dependence of conversion on reaction time which is explained by our model. Thermochemical data derived from conversion is consistent with published data on heat of formation. At lower temperatures, where the reaction is limited by reactant diffusion in a silicate melt, contained within the overall matrix, diffusivities and activation energy were measured. Detailed diffusion studies were conducted in a graphite crucible where the interfacial reaction between the apatite-silica mixture and the graphite boundary could be detected. A mathematical model based on diffusion theory was developed, and it was found to be consistent with the diffusion data and the overall conversion at lower temperature.

High temperature process for producing fine magnetic particles of M-phase structure

Abstract: A method for producing fine magnetic particles having the barium or strotium ferrite M-phase crystal structure. An iron and alkaline earth metal halide feed solution is vaporized to form a precursor and oxidizing vapor phase. The precursor and hydrolyzing or oxidizing vapor phases are held in a reactor at a temperature sufficient to effect vaporization of the feed solution yet which is below the melting point of the desired M-phase crystal structure. Small iron oxide particles precipitate from the vapor phase and alkaline earth oxides thereafter. The alkaline earth oxide particles diffuse into the iron oxide particles to form the desired M-phase structure. When the desired width and thickness of the M-phase crystal platelets is achieved, the M-phase particles are cooled by quenching. Composition of the feed solution may be modified by substituting divalent metal halides for the alkaline earth metal halide or by substituting trivalent halides or a combination of a divalent metal halide and either a penta or quatravalent metal halide for the ferric halide.

Flow Localization during Plane Strain Punch Stretching of a Ferrite-Austenite Steel

Abstract: This is an exploratory study of plastic flow and sheet forming characteristics of a 60 pct ferrite-40 pct austenite duplex stainless steel. Variations in austenite arrangement are shown to have little effect on tensile or punch stretching behavior. Flow and forming properties of the duplex alloy are dominated by its continuous ferrite phase. Flow localization during plane strain stretching over a hemispherical punch takes place at two levels of scale, by mechanisms that are physically different. Macroscopic shear bands develop as the final process of flow localization throughout the sheet as a whole. Macroscopic shear bands initiate at the surface of sheet at the edges of a localized neck and grow inward, as finite element models predict. Fracture takes place by void sheet coalescence within intersecting shear bands. These bands grow in from opposite sides of the sheet. Macroscopic shearing limits ductility during plane strain thinning. Row localization takes place also at the microscopic level within individual grains of the two-phase alloy. Coarse slip bands develop within individual grains of ferrite, and deformation twins develop in austenite as plastic flow takes place. Bands of in-homogeneous flow that develop on the microscopic scale form as an inherent part of the crystalline deformation mechanism of individual grains.

Flame spray method

Abstract: Disclosed is a method of, and apparatus for, flame spraying particulate material utilizing the thermal energy of a very hot gaseous primary stream (27) produced in an oxy­ fuel combustion chamber (11) combined with kinetic energy from a surrounding annular sheath of warm high velocity secondary air (28), the velocity of the said sheath of sec­ ondary air (28) being sufficiently close to the velocity of the primary stream (27) to avoid significant mixing between the two streams.

Regulation of the flow-rate of carbon black into a pelletizer

Abstract: The disclosure relates to a process and apparatus for dispensing a uniform flow of carbon black from a tank. The process is carried out by stirring the carbon black in a surge tank, providing equal movement of the carbon black away from the center of the surge tank towards the outlet(s) of the surge tank and removing caked carbon black from the wall of the tank and/or minimizing caking of carbon black on the wall of the surge tank. The apparatus includes horizontal blades for stirring the carbon black, lifters for lifting carbon black from the bottom of the tank, impeller vanes shaped in the form of curves such that each segment of rotation of the vanes causes an equal movement of the carbon black away from the center of the surge tank towards the tank outlet(s), and side scrapers for removing caked carbon black from the wall of the tank and/or minimizing caking of carbon black on the wall of the surge tank.

Environmental embrittlement of nickel and nickel-base alloys—an analogy to steels and austenitic stainless steels

Abstract: Hydrogen embrittlement characteristics, especially pertinent to sulfide stress cracking, of steels has been investigated to a great extent. Investigations of hydrogen embrittlement and sulfide stress cracking of nickel and nickel-base alloys have not been quite as extensive as in the case of steels. However, there are many areas of similarities between the behaviors of the two alloy systems which are discussed in this paper. These include the effect of applied stress, strength, temperature, strain rate, and impurity segregation. Areas of dissimilarities are also pointed out. In the area of stress corrosion cracking, especially involving chloride solutions, there are many parallels between the behaviors of austenitic stainless steels and nickel-base alloys. These include the effects of oxygen and chloride, temperature, H2S, and composition. An appreciation of these similarities can lead to a better understanding of the environmental cracking behavior of nickel and nickel-base alloys and point out the aspects needing further investigation.

Sulfidation-resistant Co-Cr-Ni alloy with critical contents of silicon and cobalt

Abstract: Disclosed is a sulfidation-resistant alloy. The alloy preferably may contain about 27% each cobalt and chromium, 8% iron, 2.7% silicon and the balance nickel plus normal impurities found in alloys of this class. The alloy is eminently suitable for applications in high temperature, hostile environments generated by many industrial processes, such as refinery, chemical processing and power generations.