Corrosion and Protective Films'

Service. The interest of the Rubber Service Laboratories Company in its products does not cease as soon as its products are sold to a customer. A numb...
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Vol. 22, No. 5

INDUSTRIAL AND ENGINEERING CHEMISTRY

Kesearch on Products

Before any new product developed in the research laboratories of the company is introduced to the rubber trade, a complete study is made of the product in all types of rubber stocks to determine the best ratios and effects of all compounding ingredients, the manner in which the various stocks age, how they resist abrasion and flexing, whether or not they discolor or are affected by ultra-violet and sunlight, and frequently by other special tests. I n many instances tires are built and subjected to regular road tests.

investigated in the service laboratory of the company maintained a t Akron, Ohio. This laboratory, like that a t Nitro, is equipped for carrying out all the recognized and approved tests on rubber goods. The equipment includes two experimental laboratory mills, a small laboratory 3-roll calender, two hydraulic presses, an open steam and a dry heat vulcanizer, an oven and a bomb ager, a flexing machine, a plastometer, an abrasion machine and a Scott testing machine. It is no idle boast of the company that “service” is its middle name. Other Products

Service

The interest of the Rubber Service Laboratories Company in its products does not cease as soon as its products are sold to a customer. A number of experienced rubber compounders are busily engaged in calling upon rubber manufacturers to give as much service as may be desired of them. Studies are made of the compounding problems of the trade and changes in practice recommended that frequently are of great value to the customer. The technical service given by the salesmen has always been a feature of this company’s activities and has been greatly appreciated by the rubber trade. Cooperation of the salesmen with the technical staff of a rubber company results in the development of a large number of rubber compounds. Before these rubber compounds are adopted and put into production by the customers, the stocks are thoroughly

In addition to manufacturing twenty-four products particularly designed for the rubber trade, the company manufactures a number of xanthates for mineral flotation, operates a large phenol plant, and manufactures a number of phenol derivatives, triphenyl phosphate, sulfuryl and thionyl chlorides, various grades of sodium sulfite and bisulfite, and other products. The Rubber Service Laboratories Company last July was merged with the Monsanto Chemical Works and is now operated as a division of that company. L i t e r a t u r e Cited (1) Bierer and Davis, IND. END.CHEM.,16, 711 (1924). (2) Hand, U.S.Patent 1,696,479(December 25, 1928). (3) North, U. S. Patents 1,467,984 (September 11, 1923) and 1,659,152 (February 14, 1928). (4) North, U. S. Patent 1,659,151(February 14, 1928).

Corrosion and Protective Films’ A. C. H a n s o n ROCKISLAND ARSENALLABORATORY, ROCKISLAND, ILL.

ARIOUS theories of corrosion have been advanced from time to time, two of which are more or less accepted today. Fujihara (1) says that the initial phase of corrosion is electrolytic, which soon forms a film on the metal, while the secondary phase is acidic, dissolving the protective film. According to Speller (6),films start to form shortly after the metal comes into contact with a corroding agent. After a film forms over an anodic area the potential may be reversed, and this change of potential may occur repeatedly, resulting in fairly uniform corrosion. We have here a little difference of opinion as to the secondary phase of corrosion, although all agree that the first phase is electrolytic. I n attempting to obtain more data on the development of rust, the author watched its development with a binocular microscope magnifying 46 diameters. A drop of water saturated with oxygen was placed upon a steel specimen which had been given a high polish. Brown spots began to appear on the metal in 40 to 45 seconds and rust was fairly well developed in 5 minutes. The second experiment consisted of using water saturated with carbon dioxide. The rust developed around the edge of the drop in 60 to 80 seconds, while the remainder of the surface did not appear to be attacked until from 6 to 8 minutes. No rust appeared on the metal as in the first experiment. As shown by Fujihara (I), rust forms quicker in the presence of carbon dioxide on polished steel when a film is first formed, than when oxygen only is present. After watching the development of rust in this manner, the author came to the conclusion that electrolytic action

V

I Received

January 2, 1930.

begins in the presence of water according to the following equation: Fe

+ 2H+ (ionic) + 2(OH)-

= F e + + (ionic)

+ 2(OH)- + Ha

The product of this reaction, ferrous hydroxide, forms a film on the metal and protects it from further corrosion. Carbon dioxide then reacts with this film dissolving ferrous carbonate which is later precipitated in the form of ferric hydroxide, when oxygen from the air dissolves in the water. Fe(0H)z Protective film

+

2HZCO3 = Fe(HCO& Dissolved COZ Soluble

+

2Hz0

Electrolytic action then sets in again and thus continues. L i t e r a t u r e Cited (1) Fujihara, Chem. Met. Eng., 32, 810 (1925). (2) Speller, Ibid., 36, 85 (1929).

Lac Research in India A bill called the “Indian Lac Cess Bill” was introduced in the Legislative Assembly of India on February 12, 1930. Under the Act of 1921 the net proceeds of the lac cess are paid to the Lac Association. Control of these funds is vested in a committee of the association composed of three representatives of Calcutta shippers, two Indian manufacturers, two Indian brokers, one European manufacturer, and one European broker. The Lac Association has represented to the government that it is not in a position effectively to control research. It has accordingly recommended that the existing Lac Cess Act be replaced by the proposed new act providing for a continuance of the lac cess and constituting a statutory committee. The governments of Bihar and Orissa concur in this recommendation.