Substitute magnetic materials

Magnetic materials are classified into two main groups : soft magnetic materials and permanent magnets. Soft magnetic materials are used on tonnage scale as cores of transformers and armatures of dynamos and motors and principally work in a.c. circuits. Permanent magnets can deliver a constant amount of energy in it given air gap with or without any external aid and are used in a wide variety of electrical and electronic instruments such as electricity meters, ammeters, voltmeters, loud speakers, telephones. teleprinters,motors, generators, televisions, lifting devices,etc. The manufacture of soft & permanent magnet materials presents a number of problems. They either contain metals like nickel and cobalt which do not occur in India or require high grade starting materials which are not manufactured at present or offer processing difficulties. To find suitable solutions of these problems and to develop suitable substitute materials a programme of research on the development of magnetic materials was initiated at the National Metall-urgical Laboratory sometime back and results are reported in this paper together with a review of the existing magnetic materials to bring out their technical and eco-nomic merits and demerits

Physical metallurgy of Aluminium Alloys

Aluminium is essentially a soft and weak metal which has to be strengthened by alloying with suitable elements. The elements which are added to aluminium in appreciable quantities to increase its strength and improve other properties are surprisingly limited to only four, namley, magnesium, silicon, copper and zinc.These are added singly or in combination. It may be oberved that these elements are situated close to aluminium in the periodic table. Magnesium and silicon are its close neighbours of alum- inium in the next period

Physical Metallurgy of Aluminium Alloys

Aluminium is a soft and weak and is strengthened by alloying with suitable elements. The elements which are added to aluminium in appreciable quantities to increase its strength are limited to only four elements namely magnesium, silicon, copper and zinc. These may be, added singly or in combination. It will be Seen that the alloying elements magnesium and silicon belong to aluminium period itself while the copper and zinc metals belong to the copper period in the periodic table. Out of these foux elements magnesium has biggAr atomic diameter (3. 1906 A) than aluminium (d = 2.857 A), while silicon, gopper and zinc have smaller diameters, 2.345 A, 2.551 A and 2.659° respectively. These values are within 15% of the aluminium diameter values. Therefore these alloying elements are favourably placed fer- forming. Substitutional solid solutions with aluminium

TERPENOIDS AS SOURCE OF ANTI-INFLAMMATORY COMPOUNDS

ABSTRACTTerpenoids accounts for the major class of secondary metabolites produced by plants. It shows defense activity against environmental stress and helpto heal injuries. Medicinal plants are rich in monoterpenoids, diterpenoids, sesquiterpenes, triterpenes, tetraterpenes, and ceramide. A number oftherapeutic applications such as antibacterial, antimicrobial, antitumor, anti-inflammatory activity have been identified. Terpenoids are compoundssimilar to terpenes derived from 5-carbon monomer isoprene units. The review puts and detail insight on different class of compounds isolated fromnatural source from 2000 to 2016 showing anti-inflammatory potential of pharmacologically interesting agent and their mechanism of action.Keywords: Anti-inflammatory, Mechanism of action, Natural source, Plant, Terpenoid, Bioactive compound

Determination of progressive corrosion of clay flux blocks

The Problem. Corrosion of refractories by molten corrosive liquids like molten slags and glasses is of general occurrence in those parts of the furnaces where they come in contact with the liquids. The life of a furnace generally depends upon the progressive rate of corrosion of the refractories by the slags and glasses. There have been various methods used by the investigators to ascertain the useful life of a refractory product before its use in the furnaces, but the problem is so complex that even after decades of research work by the research engineers and technologists a satisfactory and easy test which may not be only of very long duration but also which should not be very costly and complex in set-up has not so far been accepted as standard. Simulative tests have been proposed, modified and finally given up for the lack of quite reliable information obtained from them. What factors make this problem so complex and difficult of solution are discussed in detail in the next section. The purpose of this study has been to investigate and suggest some method, or a combination of tests, which may be tried by the research engineers to satisfactorily predict, and determine the rate of progressive corrosion of refractories by slags and glasses to be met with by a refractory under actual working conditions. With that end in view a very important segment of the fireclay refractories used in the Ceramic industry was selected. Flux-blocks used in the side-walls and bottom of the glass tank furnaces have been experimented upon in this investigation, and tests have been made to determine and correlate, wherever possible, their relative resistance to corrosion by a very corrosive type of glass with the information made available by the manufacturer. Although the erosion of the refractory by the movement of a glass has not been taken into consideration, and the glass used in the tests has been quite small in amount, yet it Is reasonable to assume that the rate of corrosion in the first few hours of a test may be representative of the rate of corrosion under conditions where a large quantity of glass is continually moving past a refractory. As mentioned before, the problem offers an unlimited scope of work which ought to be done to develop new techniques for the testing of refractory materials against slags and glasses in the liquid state, and, therefore, herein only an attempt has been made to try and suggest quite a new approach for the determination of slag, or glass attack, on refractories in general and clay flux-blocks in particular. Also, some modified tests are presented, which should be quite helpful in the estimation of the corrosion-resistant properties of a refractory, an attempt has also been made to explore the possibilities of adaptation of an electrochemical method to the problem, which, however, has not been promising due to apparently inexplicable observations reported in this investigation --Chapter I, pages 1-2