Semi-solid processing

Remarks on some commercial aluminium alloys. A1 metal and A1 alloys find several applications this is also reflected in the variety of treatments and processing techniques to which they may be subjected. A recent example may be the semi-solid processing (thixoforming) of high-performance alloys. 

Chiarmetta, G. and Rosso, M. (eds.) (2000) Proceedings of the 6th International Conference on Semi-solid Processing of Alloys and Composites Turin, Italy September 2000 (Edimet-Spa, Brescia Italy). 

Y.B. Yu, P.Y. Song, S.S. Kim, and J.H. Lee, Possibility of Improving Tensile Strength of Semi-Solid Processed A356 Alloy by a Post Heat Treatment at an Extremely High Temperature, Scr. Mater., Vol 41, 1999, p 767-771... 

Bal] Balitchev, E., Hallstedt, B., Neuschuetz, D., Thermodynamic Criteria for the Selection of Alloys Suitable for Semi-Solid Processing , Steel Res., 76(2-3), 92-98 (2005) (Phase Relations, Calculation, 22)... 

Solid-phase sorbents are also used in a technique known as matrix solid-phase dispersion (MSPD). MSPD is a patented process first reported in 1989 for conducting the simultaneous disruption and extraction of solid and semi-solid samples. The technique is rapid and requires low volumes (ca. 10 mL) of solvents. One problem that has hindered further progress in pesticide residues analysis is the high ratio of sorbent to sample, typically 0.5-2 g of sorbent per 0.5 g of sample. This limits the sample size and creates problems with representative sub-sampling. It permits complete fractionation of the sample matrix components and also the ability to elute selectively a single compound or class of compounds from the same sample. Excellent reviews of the practical and theoretical aspects of MSPD " and applications in food analysis were presented by Barker.Torres et reported the use of MSPD for the... 

With liquid and semi-solid dosage forms, the rate and the extent of desorption are influenced by the solvent system of the preparation, pH, and temperature conditions during processing and storage. If a severe problem exists, it will usually manifest itself via an outward sign, such as container collapse, product discoloration, or precipitation [14]. 

Details of the specific types of apparatus need not normally be given except for nonstandard processes. A flow chart of the manufacturing operation and the in-process controls (and acceptance limits) is required. Proposals for alternative processes will need to be supported by appropriate data to show that the finished products resulting from these are consistent with the finished product specification. Certain manufacturing operations such as mixing may require additional information on quality parameters monitored during production and prior to batch release. Appropriate quality parameters should be included in the finished product specification regardless of the outcome of validation studies (e.g., content uniformity for solid and semi-solid products). 

Nonaqueous liquids, semi-solids, and dry powders dry heat at 160°C/120 minutes then dry heat under alternative conditions of time and temperature to achieve a sterility assurance level of 10 6 then an alternative to dry heat, e.g., ionizing radiation with a minimum absorbed dose of not less than 25 kGy then a validated alternative irradiation dose (according to ISO 11137) then aseptic filtration and aseptic processing and then the use of presterilized components and aseptic compounding or filling... 

Sometimes chemicals are prepared for distribution without chemical reactions, as when limestone is mined and refined before use. In other cases, the raw materials are converted to other chemicals in a manufacturing process. In both cases, wastes are discharged to air, water, and (if large quantities of- solid or semi-solid wastes are involved) to land. 

Because of the requirements of insolubility in water, in organic solvents and in the medium that it is being used to colour, the application processes for using pigments are quite different from those for dyes. Coloration with pigments is essentially a process of dispersion of solid particles of the pigment in a semi-solid medium. 

In the case of paints and printing inks, the initial preparations will be in the semi-solid state because solvents are needed both in the process of dispersing the pigment in the paint or ink medium and for application purposes. These solvents dry out after the paint or ink is applied. When making coloured plastic articles, both heating and solvents may be used to aid dispersion in the plastic medium as part of the moulding process. However, from the viewpoint of the optical properties in all of these pigment uses, what is most important is that each of these media has a refractive index close to 1.5. 

All polymerisations were carried out in nitrogen purged xylene solutions in a thermostatically controlled one litre glass reactor. Semi-batch processes were carried out in a similar reactor which was provided with calibrated peristaltic pumps (computer controlled when necessary) for delivering the monomer feeds. Typically, experiments were carried out at 80°C with monomer concentrations which gave solids contents in the range 10 - 60% at 100% conversion. 

Extraction using a supercritical fluid (CO2, N20 or CHC1F2 Freon-22) is a well-known process in the food industry (cf. 6.1). Extractors used for analytical purposes operate on the same principle. They incorporate a highly resistant tubular container into which the sample is placed (in solid or semi-solid form) with the supercritical fluid. Two modes of operation are employed ... 

Some basic food analytical methods such as determination of °brix, pH, titratable acidity, total proteins and total lipids are basic to food analysis and grounded in procedures which have had wide-spread acceptance for a long time. Others such as analysis of cell-wall polysaccharides, analysis of aroma volatiles, and compressive measurement of solids and semi-solids, require use of advanced chemical and physical methods and sophisticated instrumentation. In organizing the Handbook of Food Analytical Chemistry we chose to categorize on a disciplinary rather than a commodity basis. Included are chapters on water, proteins, enzymes, lipids, carbohydrates, colors, flavors texture/ rheology and bioactive food components. We have made an effort to select methods that are applicable to all commodities. However, it is impossible to address the unique and special criteria required for analysis of all commodities and all processed forms. There are several professional and trade organizations which focus on their specific commodities, e.g., cereals, wines, lipids, fisheries, and meats. Their methods manuals and professional journals should be consulted, particularly for specialized, commodity-specific analyses. 

Pitch the nonvolatile, brown to black, semi-solid to solid viscous product from the destructive distillation (q.v.) of many bituminous or other organic materials, especially coal has also been incorrectly applied to residua from petroleum processes where thermal decomposition may not have occurred. 

For example, when a warm sol of gelatin is cooled, it sets to a semi-solid mass, which is gel. The process of conversion of a sol to a gel is known as gelation. Gelation may be brought about by either of the methods, (a) cooling the sol, (b) evaporating the sol, (c) addition of electrolytes. 

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