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BOOKS

Zone-Meliing Techniques M'ith development of the transistor,

solid state electronics came of age. Trie evolution of this exciting new in­dustry was stimulated by a major tech­nological advance in chemical purifica­tion known as zone refining, a "zone-in eltiiig" technique. The zone-melting process, simple in conception, yet spec­tacular in results, has permitted the elec­tronic conduction properties of solids t o be exploited on a truly prodigious seule. It has not only allowed the prep­aration of exceptionally pu re solids, but it has allowed the preparation of solids with controlled solute concentrations and controlled solute distributions.

The application of zone refining to purifying metals, semiconductors, or­ganic and inorganic chemicals, halide salts, and sea water has yielded favor­able results. This technique has al­lowed semiconductor materials to be prepared in which the harmful impuri­ties have been reduced to less than one part in ΙΟ10. Besides its broad indus­trial application, zone melting is a pow­erful research tool in the study of struc­ture-sensitive and impurity-sensitive properties of solids.

Purification or separation by re­pea t ed fractional crystallization is based on the well-known fact that a freezing crystal differs in composition from its l iquid. The basic zone-refining tech­nique resulted from the additional idea of melting par t , rather than all, of a charge at a given time. Repeated pas­sage of a molten zone in one direction along the charge causes segregation of the solutes t o one end or the other de­pending on the partition coefficient of the solutes between the two phases; thus, a portion of the charge becomes very pure after a number of zone passes. Other zone-melting techniques enable the introduction of a particular solute concentration and the control of solute distributions in the solid.

This book, the first on the subject, was written by \V. G. Pfann, the inven­tor of zone melting. It has an easy-flowing style that is a pleasure to read. Pfann has prepared the book for stu­dents, scientists, engineers, and manu­facturers, in a manner that will arouse their interest and with contents that will satisfy this diverse audience.

T h e author covers fully the theory and practice of zone melting. He first deals with the basic zone-melting proc­

ess, leading then to the quantitative analysis of batch and continuous zone refining. This is followed by a descrip­tion of an array of ingenious practical methods by which purification can be achieved. The remainder of the book deals with other zone-melting tech­niques—techniques by which solute seg­regation can be either prevented or manipulated in a controlled way during crystal growth.

This book contains information not published elsewhere. It is a basic pre­requisite for any person interested in crystal growth or contemplating solid state materials research or preparation.

Zone Melt ing. W. G. PFANN. xvi + 236 pages. John Wiley & Sons, Inc.. 440 Fourth Ave., New York 16, N. Y. $7.50. Reviewed by \V. A. Tiller, Westinchouse Electric Go.

Automatic Control Anyone who designs systems which

are to b e automatically controlled or operates automatically controlled equip­ment or services it should have as much understanding of automatic control theory as possible. Unfortunately, the exact presentation of automatic control theory can only be accomplished through the liberal use of differential equations, and many who are closely associated with automatic control have too little mathematical training to fol­low a mathematical presentation of the subject. "Automatic Control, Princi­ples and Practice" is designed to fill the needs of such people. Minimum pre­requisites for reading it profitably are a good understanding of algebra and of elementarv phvsics. At the same time, readers with considerably more background will find it interesting and worth-while reading.

The book begins with a description of the control system and its charac­teristics, introducing the reader to the factors that determine the type of con­trol equipment and adjustments re­quired for a particular system. This leads naturally into a description of the types of control action, starting with simple two-position action and progressing up the series of more com­plex types to proportional plus reset plus rate action. Simple formulas are

8 6 C & E N F E B . 9. 1 9 5 9

given which permit calculating the proper settings for the various control responses in i€?rnis oi ui·'1 .iiCiisviraOiC characteristics of the system.

T h e next section of the book is de­voted to a discussion of frequency re­sponse methods. It covers procedures used in obtaining the data, methods for presenting the data, criteria for stability of the control system, and sim­ple calculations involving frequency response data. Simple formulas for cal­culating the proper settings for con­troller responses from frequency re­sponse data a re included.

Since a controller must consist of real mechanical components, the next section describes the physics of springs, levers, diaphragms, bellows, nozzle-flapper systems, and other mechanical components found in pneumatic con­trollers. Λ similar discussion of the physics of components found in hydrau­lic control equipment follows. The next section attempts to give the reader an understanding of the electrical com­ponents used in control gear.

After describing a number of force balance systems and computing circuits, the author discusses primary measuring elements. He is careful to point out the time constants of these and the factors that influence the time constants. The operating principles of a few well-chosen types of commercially available controllers are also described. The dis­cussion of final control elements is limited to valves of various types.

A number of types of control systems, including averaging control, cascade control, ratio control, totalizing control, and time schedule control, are dis­cussed. Finally, some typical industrial applications to operations such as steam generation, water treatment, and gaso­line refinery control are analyzed.

i n its J^OV pages, tuis υοοκ covers control theory as it relates to automatic control of chemical processes. It is probably the best nonmathematical treatment of this subject available. While it is carefully written, well illu­strated, logically arranged, and non-mathematical, it is not eas_y reading be­cause of the large amount of material covered in the volume.

Automatic Control, Principles a n d Practice. Werner G. I\>lzbock. iv -f- 28 pages. Reinhold Publishing Co. , 430 Park Ave., New York 22, N . Y. Reviewed by Ralph H. Munch, Monsanto Chemical Co.

(Continued on page 111)

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PRODUCTION (Continued from page 81)

of uranium, surrounded by magnes ium fluoride slag, is found in the cup a t t h e bottom. The slag is knocked off, and the last traces are removed b y washing in acids and other solutions.

• Vacuum Cast . The pure uranium billet is still a long way from being a finished fuel e lement for use in a nu­clear reactor. It must b e vacuum cast into rods, which are then carefully tempered, machined, and sealed into finned "cans" of aluminum or mag­nesium alloy. Because one faulty fuel rod can cause an expensive shutdown in an atomic power plant, t h e specifi­cations are high. Testing is exhaust ive. Complete records on each rod are kept so that the history of a specific rod can b e traced back through t h e plant if necessary.

The new canning factory a t Spring-fields puts this exacting process on a l ­most an assembly line basis. This work plus the cost of t h e o re and t h e chemical processing adds u p to a n average $60,000 p e r ton of fabricated fuel element.

Springfields has supplied most of t h e fuel elements used in British reactors, except for those m a d e of enriched ma­terials, which will continue t o be made a t Dounreay, Scotland. Wi th the new plant , Springfields will b e able to meet present demand for fuel elements, and the time needed to construct new power plants will ensure that t he UKAEA will h a v e time to expand to meet its needs . If demand is too great, a new plant •ÎT-» ο τ ι nfVi<=»7- l r*r»af ir\r\ m io rV i f r-»r-»cciV»1v V»<*

rvijf u*"*. in anv case trie Li IC A y*. A feels confident that it can supply fuel ele­ments fcr Britain's nuclear p o w e r pro­gram, as well a s for any reactors Britain sells ab road .

• Yttrium m e t a l , once considered too brit t le for structural uses, has been m a d e into a pliant, easily formed mate­rial by Bureau of Mines metallurgists. Though not revealing product ion tech­niques, BuMines says the process is similar to the Kroll process for tita­n ium and zirconium. Nietal made b y the bureau contains about 0.02*7^ oxy­gen, which is t h e principal offender limiting ductility.

BOOKS (Continued from page 87)

Cilove Boxes and Shielded Cells for Han­dling Radio-Active Materials. G. N. WALTON, xii 4 -515 pages. Academic Press, Inc., I l l Fifth Ave., New York 3, Ν. Υ. 1958. $16.80.

Papers from the 1957 Harwell Symposium and the United Kingdom Atomic Energy Authority on operating experiences in han­dling radioactive materials. Designed as a textbook on radiation shielding.

Electronic Apparatus for Biological Re­search. P. Ε. Κ. DONALDSON et al. xi 4- 718 pages. Academic Press, Inc., I l l Fifth Ave., New York 3, Ν. Υ. 1958. $20.

A handbook for biological research workers concerned with design, construction, and maintenance of electronic equipment.

Paperbound Elasticity, Plasticity and Structure of

Matter. 2nd. ed. R. HOUWINK. vxii 4-368 pages. Dover Publications, Inc. 920 Broadway, New York 10, Ν. Υ. 1958. $2.45.

The Theory of the Properties of Metals and Alloys. N. F. Μοττ and H. JONES. χ + 326 pages. Dover Publications, Inc., 920 Broadway, New York 10, Ν. Υ. 1958. $1.85.

Current Research and Development in Scientific Documentation. No. 3. Na­tional Science Foundation, Washington 25, D. C. 1958. Free.

Power Reactors. U. S. Atomic Energy Commission Technical Information Serv­ice, iii 4- 02 pages. U. S. Govern­ment Printing Office, Washington 25, D. C. 1958. 65 cents.

Productive Uses of Nuclear Energy. Re­port on Prospects for Nuclear Energy in Puerto Rico. viii 4- 87 pages. Na­tional Planning Association. 1606 New Hampshire Ave., N.W., Washington, D. C. 1958. $1.25.

The Water Pollution Control Program of the_U. S^Public Health Service.^ 1957-Iyo8. Public Health Service Publica­tion No. 631. 26 pages. U. S. Govern­ment Printing Office, Washington 25, D. C. 1958. 25 cents.

The Unfixed Pressure Vessel Code Simpli­fied. ROBERT CHOSE. 48 pages. The Unfired Pressure Vessel Code Simplified, P. O. Box 91, Leonia, N. J. 1958. $6.50.

ASTM Standards on Gaseous Fuels. ASTM Committee D-3 on Gaseous Fuels, vi 4- 198 pages. American So-cietv for Testing Materials. 1916 Race St.,'Philadelphia 3, Pa. 1958. $3.00.

Specifications and Tests for Electrode-posited Metallic Coatings. American Society for Testing Materials and Elec-troplaters' Society. vii 4- 116 pages. ASTM, 1916 Race St., Philadelphia 3, Pa. 1958. $2.25.

Fundamentals of Pipe Drafting. CHARLES H. THOMPSON. 66 pages. John Wrilev & Sons, Inc., 440 Fourth Ave., New York 16, Ν. Υ. 1958. $3.50.

F EB. 9, 1 9 5 9 C & E N 111