CHEMICAL WORLD THIS WEEK
RESEARCH PROGRESS Metal alloys containing phosphorus are shown to be highly resistant to cor rosion and chemical attack . . . Hard surfaces are attainable in a commercially feasible procedure for electrodepositing cobalt or nickel with phosphorus Λ COMMERCIALLY feasible method for -**' producing electrodeposits of cobalt or nickel alloyed with as much as 15% of phosphorus has been developed by Abner Brenner, Dwight E. Couch, and Eugenia K. Williams of the National Bureau of Standards. The new phosphorus alloys are more easily deposited, than chromium and are hard, corrosion-resistant, and bright. They are expected to be of value for many of the applications in which chromium plate is now used to obtain a hard, wear-resistant surface or a decora tive finish. Plating baths for depositing the phos phorus alloys consist of common nickel or cobalt salts such as the sulfate or chloride, to which is added phospliorous acid as a source of phosphorus in the deposit. The baths are operated at a pH between 0.5 and 1.5. To maintain t h e desired acidity in the cathode film, the solution is buffered with phosphoric acid. Plating baths are kept at 75° C. or above because at room temperature the cathode current efficiency
is low and the deposits are weak. C urrent densities should b e between 5 and 40 am peres per square decimeter. At the usual current density—about 10 amperes per square decimeter—the rate of deposition is fairly high, amounting to a few thou sandths of an inch an hour. The appearance of the deposits depends upon their phosphorus content. Alloys with less than 29o of phosphorus are us ually smooth with a mat finish; but as the percentage of phosphorus increases, they become brighter, reaching a peak of bright ness at a phosphorus content of about 10%. When such deposits are plated on a dull surface, they increase in brightness as they become thicker. As a result of the slightly dark cast of the high-phosphorus alloys, their reflectivity is 45 to 509&, as compared with about 60% for buffed nickel coatings. When some of the phosphorus alloys are immersed momentarily in a solution of an oxidizing agent, such as ferric chloride, or made anodic in the plating bath, a jet black film is formed on the surface of the
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metal. This film is hard, adherent, and appears to have decorative possibilities. Photomicrographs of the low-phosphorus alloys show a columnar structure while the high-phosphorus alloys are found to have a laminated or banded structure. X-ray diffraction patterns of the high-phosphorus alloys show no crystalline structure. When heat-treated, the deposits develop a fine-grained structure instead of the large crystals characteristic of pure nickel or cobalt. The hardness of the deposits as plated varies from 350 to 720 on the Vickers scale, increasing with phosphorus content. When the alloys are heat-treated at 400° C , they become much harder. For example, a heat-treated cobalt-phosphorus deposit containing about 10% of phosphorus reaches a hardness of over 1100 Vickers, which is greater than that of electrodeposited chromium. Deposits which have been heated as high as 800° C. and cooled are not appreciably softer than the initial deposit. Flowever, the alloys have poor "hot hardness" and above a temperature of 600° C. are softer than unalloyed nickel or cobalt. Ethîonîne in Liver Studies A new approach in the study of fatty livers has been devised by three biochemists at the University of California in research sponsored by the American Cancer Society. Emmanuel Farber, Melvin Simpson, and Harold Tarver of the division of biochemistry have shown that it is possible to induce livers to contain large amounts of fat in rats in one day, by feeding fasted animals ethionine, a methionine analog. Under the ethionine treatment, a more rapid method of producing fatty livers than the normal fatty-diet approach, the protein metabolism of the animals is also altered. Because of the structural similarity between ethionine and methionine, the two amino acids appear to compete with each other for positions in protein molecules. It is thought that ethionine occupies space on the surface of the enzymes which are protein-builders. Consequently when the animal is given no food and ethionine, some of the protein tissue in the liver is broken down and is replaced by fat. Ethionine is expected to be a useful tool in the study of several phases of animal metabolism. T h e work on rapid fatty-liver production is continuing. G r a n t f o r Hormone Research C. H. Li, professor of biochemistry on the Berkeley campus of the University of California, has received a grant of $50,000 for research on hormones of the anterior pituitary gland. At present Dr. Li's work is concerned with an effort to synthesize a fraction of the ACTH (adrenocorticotropic hormone) molecule, which retains the beneficial biological activity of the whole ACTH but has a simpler structure and gives promise of synthesis. AND
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