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Seizure resistance of the cast graphite particle‐aluminium composite alloys, containing graphite particles of varying sizes has been studied using a Hohman wear tester. The size of the spheroidal graphite particles was varied from 30 µm to 400 µm, and in one case 80 µm size flake graphite was used to observe the effect of shape of graphite. When the graphite content of graphitic aluminium alloys is more than 2 per cent, these alloys can be self‐mated under condition of boundary lubrication without seizing. The size and shape of the graphite particles had no significant effect on the seizure resistance of these alloys, in the range of conditions investigated in this study. This is attributed to the extensive deformation and fragmentation of graphite due to the low yield strength of the aluminium matrix and the low flow stress of the graphite particles. During wear, the deforming aluminium matrix accentuates the deformation and fragmentation of subsurface graphite particles and causes them to come to the mating surface, thus providing continuous lubrication and preventing seizure. Even after a short run‐in period, a continuous layer of graphite is observed on the mating surfaces of graphite particle‐aluminium composite alloys. This layer persists even after extensive wear deformation.

The first part of this article (February issue) dealt with a failure in a boiler raising steam by using heat from a 7% SO2‐in‐air mixture; the protective corrugated cast iron shell round the boiler tubes opened, exposing them to oxidation. The present case concerns cracking of a 22‐in. connecting main between two SO3 absorbers; this was found to be caused by SO3 passing into the cast iron through the graphite flakes and attacking the adjoining ferrite.

The purpose of this paper is to understand the sliding wear response of a cast iron as influenced by applied load and changing concentration of solid lubricant (graphite) particles in oil lubricant, and operating material removal mechanisms in different sets of experimental conditions.

The sliding wear response of a grey cast iron has been examined as a function of test environment and load. Properties evaluated were wear rate, friction coefficient and frictional heating. The wear behaviour of the samples has been substantiated through the characteristics of their wear surfaces, subsurface regions and debris particles.

The wear rate and frictional heating increased with load while friction coefficient was affected in an opposite manner. The presence of oil lubricant led to a substantial improvement in wear response (in terms of decreasing wear rate, friction coefficient and frictional heating) while the presence of graphite particles in the oil lubricant proved to be still better. A critical content of graphite in the oil lubricant becomes most effective towards improving the wear response of the samples. Formation of dark patches on the wear surface, substantial subsurface deformation and fine debris led to improved wear response.

The study enables one to understand the wear behaviour of a cast iron as influenced by the changing concentration of solid lubricant (graphite) particles in the oil lubricant. It also enables one to understand the operating material removal mechanisms responsible for the observed wear characteristics of the samples under varying test conditions. The investigation helps one to see that only a critical concentration of the solid lubricant particles in oil can lead to the best wear performance of materials.

From a practical standpoint, the observations made here gain importance from the fact that solid lubricants are added frequently in oil in engineering applications but it becomes imperative to understand that only a critical concentration can lead to the best wear behaviour of materials.

The purpose of the paper is to assess the influence of the volume fraction solid lubricants like talc lead and graphite in oil separately and in combination towards controlling the sliding wear behaviour of a grey cast iron and understand the factors controlling the response of the material in a given set of experimental conditions.

The composition of the lubricating medium (oil) has been changed by dispersing 5 per cent graphite, talc and lead particles separately and in combination. Sliding wear tests were conducted on grey cast iron samples over a range of applied pressures. Parameters determined were wear rate and frictional heating. The wear behaviour of the samples was further substantiated through the features of wear surfaces, subsurface regions and debris particles. Material removal mechanisms and factors responsible for a specific response of the samples have also been analysed.

The wear rate increased with increasing applied pressure. Addition of graphite and lead to the oil separately or in combination brought about a reduction in the wear rate of the samples; talc and talc + lead produced a reverse trend. Temperature near the specimen surface increased with test duration and applied pressure. The test environment influenced the frictional heating in a manner similar to that of the wear rate. Adhesion and abrasion were observed to be the operating material removal mechanisms. Smearing of the solid lubricating phase and delamination resulting from cracking tendency also controlled the wear response.

Oil is a very popular lubricant used in engineering applications involving friction and wear. Solid lubricants are used along with the oil. The nature, characteristics and content of the solid lubricants very much control the performance. Limited information is available pertaining to assessing the influence of the type and fraction of solid lubricants in the oil towards controlling the wear behaviour of cast irons (popularly known tribomaterials). The present study enables to understand the effectiveness of talc, lead and graphite in oil towards governing the wear characteristics of cast iron and analyse wear mechanisms and controlling parameters.

Graphite and talc are available in nature in abundance. Graphite is a popularly known solid lubricant, while talc is less explored. Lead is also well-known as a solid lubricant but poses health hazard in practice due to its toxic nature. The present study explores the lubricating capability of talc when mixed with oil separately or in combination with lead and graphite towards controlling the wear response of a grey cast iron. It enables to understand the factors responsible for the specific response of talc.

Assessment of the lubricating potential of talc as a possible substitute to lead is important in view of the toxic nature of the latter. If successful, the exercise could enable to replace lead with talc.

The present manuscript is an original piece of the author's research work.

Owing to their relatively high alloy content, Ni‐Resist austenitic irons exhibit a higher degree of corrosion/erosion resistance than ordinary cast irons or cast carbon steels in all environments. The influence of the nickel alloying addition increases the “nobility” of Ni‐Resist, placing it in the galvanic table between the nickel‐free ferrous metals and copper‐base alloys such as gunmetal and aluminium bronze. Ni‐Resist irons vary in alloy content, to meet specific requirements, and are produced with both flake‐graphite and spheroid‐graphite structures. Practical experience indicates that in most applications the corrosion resistance of an SG Ni‐Resist iron is similar or superior to the corresponding flake‐graphite grade.

R. A. Heindl and N. H. Mohler of the U.S. National Bureau of Standards' refractories laboratory have recently completed an investigation of the relative oxidation rates of 20 domestic and foreign graphites, including both the flake and amorphous varieties. The study shows that the coarser sizes of graphites having a graphitic content of about 85% are difficult to oxidise either in air or in a stream of oxygen at 400°C. However, when fine and coarse sizes are combined, as in finished but unglazed crucible bodies, a slow oxidation begins at 400°C., and the rate increases at higher temperatures with a definite deterioration of the body. One result of the study has been the establishment of numerical constants for graphite oxidation rates in oxidising atmospheres.

The purpose of this study is to investigate the tribological properties of society of automotive engineers (SAE) 430B bronze-graphite composite, supplied in the form of machined and graphite embedded, used in sheet forming industry.

Pin-on-disc wear tests were performed under a constant normal load of 15 N and a sliding velocity of 60 mm/s. Due to the extended usage of Fe-based alloys in forming dies, pin materials were selected as cold work tool steel, gray and ductile irons. The weight losses of the disc (SAE 430B bronze-graphite composite) and the pins (Fe-based alloys) were measured separately under various sliding distances (5,000, 10,000 and 15,000 m). The average friction coefficients and wear tracks were obtained.

It is concluded that dry sliding behavior of SAE 430B bronze-graphite composite is the worst when operated with GGG-70 ductile iron due to its highest abrasive effect. The high hardness and nodular shape of graphite increased the abrasiveness of ductile iron. The improvement in wear resistance reached up to maximum 90 per cent and the degradation in friction coefficient was about 50 per cent by embedding graphite solids in bronze disc at dry sliding conditions.

Although the machined and graphite embedded bronze composites are indispensable parts of forming dies, there is no scientific knowledge on their dry sliding behavior.

A method extensively used in the production of optically flat and finely finished surfaces is that of lapping the surface upon a plate using a loose abrasive mixed into a slurry form with a carrying fluid. If the surfaces finished in this way are in continuous or intermittent sliding contact, it is the author's opinion that any abrasives retained in their surfaces will affect surface wear. This paper reported on some exploratory work to indicate the degree of embedment of abrasive in certain materials lapped by hand.

WEAR is one of the major ways by which a material part ceases to be useful, others are corrosion, obsolescence and breakage. It is the consequence of relative motion and in industrial plant and equipment it has always been accepted as inevitable that it should lead to heavy expenditure for maintenance and replacement. Historically, wear is a well established fact, yet our knowledge of the technology is extremely limited. It has become a way of life that we compensate for wear when it no longer can be tolerated, yet need this be so? This article examines the problem, and primarily from the unlubricated point of view, describes the various types of wear and the way material selection or modification can be used to limit wear.