Search results

This study aims to evaluate the dry-sliding tribological properties of fine-grained tin–bronze alloy under reciprocating sliding conditions.

A fine-grained tin–bronze alloy was processed by multiaxial forging (MAF) and annealing treatment. Friction and wear experiments were conducted on a reciprocating sliding tribometer. Microstructure, tensile mechanical properties, hardness, wear rate, friction coefficient and wear morphologies of coarse-grained sample, MAF sample and MAF and annealing sample were compared.

After MAF, the strength and hardness increased distinctly, but the elongation decreased. The wear rate is increased, though friction coefficient is lower. Weaker work hardening leads up to higher sliding wear rate. After MAF and annealing, the alloy has higher strength, hardness and elongation. Lower wear rate of the alloy is correlated with the higher hardness, elongation and work hardening. The adhesion wear and abrasive wear are the primary wear mechanism.

It was found that the fine-grained alloy shows lower sliding wear rate only by combining severe plastic deformation with heat treatment. The process of MAF and annealing is useful in improving the wear resistance of tin–bronze alloy.

THE demands of modern engineering employing machinery that has to operate at high power, and to include rapidly‐moving units, has forced the metallurgist to depart from the old‐established alloys and to introduce new mixtures to which it is possible to impart specific or enhanced properties by thermal treatments. This aspect of metallurgy has also been given impetus by the demand for reliability, whether in factory plant or the fabricated product. This becomes obvious when it is realised, on the one hand, that the basis of all systemised workshops is the maintenance of continuity in output and an ever‐increasing production; and, on the other, that the failure of even a minor accessory may cause disaster with loss of material, labour or human life. Thus, it no longer occurs that one regards the ferrous metals only as being manipulable by selected heat treatments, and, in the non‐ferrous scries, annealing to be the only means of modification by heat. To‐day, various copper‐rich alloys are available that are susceptible to hardening and tempering processes closely similar to those long since employed for steels. Those containing beryllium and aluminium have been the most exploited. However, the reluctance with which the engineer accepts the advantages offered by these developments is understandable, because the information appertaining to the subject is not always available in a form which enables him to appreciate the economies to be accrued. Further, he often prefers production to be straightforward, using raw materials in the “as‐received” condition, rather than to introduce processes, the value of which has not been elucidated. Yet this is a situation that cannot be tolerated indefinitely, if economies in material weights and dimensions and increased service life are mutually to be secured. It is, therefore, from this angle that the study and comprehension of the properties and possibilities of aluminium bronze cannot be ignored.

The addition of aluminium to copper results in an improvement in the corrosion‐resisting properties of the metal; this article discusses why aluminium bronzes are noted for their performance in a number of industrial applications in which a wide range of corrosive materials—gaseous, liquid and solid—are encountered.

Whilst it may be possible to produce alloys possessing a very high degree of resistance to corrosion, frequently they are deficient in mechanical or physical properties. Alternatively, the difficulties encountered in manufacture, or the prohibitive cost of materials, preclude their wide industrial application. By suitably varying the alloying additions to a very small number of basic metals a wide range of alloys can be produced, which not only possess good corrosion resistance but are also endowed with strength, ductility, hardness and wear‐resistance, etc.

INTEREST in tin powder for powder metallurgy is growing; not only does it find a place in non‐ferrous powder metallurgy, as in sintered porous bronzes used for bearings, but it is valuable as a sintering acid in ferrous powder metallurgy. Work at the Tin Research Institute demonstrates the advantages of small additions of tin powder in iron‐copper‐tin compacts for reducing the sintering temperature and increasing the dimensional stability and wear resistance. Tin powders are beingused worldwide for this purpose and not least in Japan.

In this article the author discusses various aspects of sacrificial corrosion. He refers to the relationship which exists between corrosion and electrolysis and draws attention to the considerable development of knowledge in this field since the war. He concludes by referring to the relationship which exists between atomic number, atomic weight and corrodibility.

Chester Street, Aston, Birmingham, 6. The ‘Donald’ Patent Barrel Lifter Truck and Stand, the three‐in‐one appliance. Barrels up to 7 cwts. lifted and transported by one man. ‘Donald’ Patent Barrel Lifter Stands for Oil Stores.

THE mechanical testing of engineering materials, such as tensile testing, hardness measurements, etc., has already attained a reasonable degree of standardization. The results of such tests can be expressed numerically and they furnish to a great extent adequate data to the designer who wishes to use them. Lubrication and bearing practice, however, has hardly emerged from the cradle of empiricism. Theory has had, as yet, but slight influence in developing reasonable design data and there still remains a wide field of research before the results can be expressed in such a simple tangible way as to transform efficient bearing design into mere slide rule manipulation. Precedent, past experience and a few odd rules are normally the designer's only guide and expensive practical experience his only check.

On November 26 and 27 last year, the Institute of Petroleum and the Society of Chemical Industry held a joint symposium in London at the Federation of British Industries. The subject of the symposium was ‘Corrosion Problems of the Petroleum Industry.’ However, the papers discussed had a much wider field of interest as is evident from the following summaries and abstracts.