Viscometer, Brookfield process

The stable dispersion of slurry is required to casting process. Thus, we investigate the interaction between starting materials and other organics by measuring electrokinetic sonic amphtude(ESA, MBS-8000, Matec Apphed Sc., U.S.A) and the rheology of slurry with viscometer(Brookfield DV-II). Therefore, the optimal condition for dispersion was determined. The compacted green sheets with various composition are sintered and then characterized. 

Slurry Viscosity. Viscosities of magnesium hydroxide slurries are determined by the Brookfield Viscometer in which viscosity is measured using various combinations of spindles and spindle speeds, or other common methods of viscometry. Viscosity decreases with increasing rate of shear. Fluids, such as magnesium hydroxide slurry, that exhibit this type of rheological behavior are termed pseudoplastic. The viscosities obtained can be correlated with product or process parameters. Details of viscosity deterrnination for slurries are well covered in the Hterature (85,86). 

Bronze plating, 9 767, 810-811 Bronze route process, 16 170-171 Brookfield viscometer, 21 737 Brook trout, common and scientific names, 3 187t... 

Most mills control the cooking cycle by automatic time-temperature controllers and recorders. The rate of temperature rise to the conversion plateau must be slow to prevent hot pockets or cold areas. The rate of temperature increase to the inactivation plateau must be rapid to prevent excessive depolymerization in the intermediate temperature range. The viscometers operate according to different mechanisms time to expel paste from a sample device (Norcross) vibration of a probe in the paste (Dynatrol) torque readings (Brookfield) or pressure drop on passage through an orifice (Escher Wyss). Potential errors in viscosity can result from variations in starch solids due to differences in moisture content of the starch, errors in slurry preparation and the quantity of condensate added by the steam. The process yields a maximum paste concentration of about 32%. 

Procedmes for extracting valid shear stress versus shear rate data from measurements involving wide gap coaxial cylinder systems (the Brookfield viscometer being an extreme example of wide gap devices) are therefore of considerable interest in making quantitative measurements of the flow properties of non-Newtonian process products. Most of these data-treatment procedures necessarily involve some assumption regarding the functional form of the flow curve of the material. One example is that made in the derivation of data from the Brookfield-type instrument, which assumes that the speed of rotation of the cylinder or spindle is proportional to the shear rate experienced by the fluid. This assumption implies that the flow curve is adequately described by a simple power-law (which for many shear-thinning non-Newtonian fluids may be acceptable), but this assiunption is widely taken to exclude all fluids which display an apparent yield stress and/or non-power law type behaviour. 

Before making the castings, pot life determinations were performed to determine the processing window of the prepolymer and chain extender materials. As a standard practice, both the prepolymer and chain extender were preheated to the desired temperatures, degassed thoroughly, mixed at the desired stoichiometry (90 or 95%) and poured into a thermostatted vial. The viscosity was measnred, nsing a Brookfield viscometer, as a function of time. The measurements were terminated when either the time of measurement reached 20 minutes or the viscosity of the mix reached 0.1 Pa-s. 

As a relatively fast product quality and process control, the Scott Cup viscometer is often used. The starch paste is prepared according to a defined protocol and maintained at 100°C, then a fixed volume is timed as it passes through an orifice of defined dimensions. Sample weight is adjusted so that a constant flow time is obtained. Viscosity is then defined as weight Scott in grams. Of the universally used instruments, the Brookfield viscometer is extensively employed. Again, this technique is only of value if sample preparation is standardized. 

A new, 24-page "Process Control Viscometer Catalog" Is now available. The first section of the catalog presents answers to basic questions. Including "Why measure viscosity In-line " and "Why choose Brookfield " It also Includes a list of typical questions to be considered when choosing a process viscometer. 

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