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1 – 10 of over 2000P.K. ROHATGI and C.C. PAI
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…
Abstract
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.
Price rises were underpinned by higher-than-expected steel production, requiring additional graphite for the industrial process. Prices were also supported by fresh environmental…
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DOI: 10.1108/OXAN-DB266286
ISSN: 2633-304X
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C. Gomez‐Garcia, M.E. Rodríguez, V.M. Castaño and A. Herrera
The purpose of this paper is to know the effect of graphite particles distribution on wear behavior of ingots of an aluminium‐graphite, Al‐Gr(p), composite.
Abstract
Purpose
The purpose of this paper is to know the effect of graphite particles distribution on wear behavior of ingots of an aluminium‐graphite, Al‐Gr(p), composite.
Design/methodology/approach
By SEM and optical microscope, it was observed that the graphite particles were entrapped and placed at different regions of the aluminium ingots as they were cooled under three different cooling rate during solidification, mantaining 4.5 wt% of graphite content. Size of particles entrapped, were measured at three different region of the ingots.
Findings
Smaller size of graphite particles distribution were found in regions where the cooling rate was higher, while bigger size were located in regions where the cooling rate was lower, this phenomenon could improve the wear resistant performance found in ingots containing smaller graphite particles.
Research limitations/implications
A suitable dispersion of small graphite particles entrapped into a fine structure of the aluminium‐graphite composite as a result of high cooling rate while casting, could be extended to another processes for future researches.
Practical implications
This material could be used in sliding mechanical pieces improved by a uniform dispersion of small particles inside.
Originality/value
The improvement of wear behavior could be succeeded by dispersion of smaller graphite particles into the ingots, influenced by a higher cooling rate, and maintaining the weight fraction content of reinforcement.
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Kunal Arora, Mohit Kumar and Varun Sharma
The paper aims to fabricate shape memory composites using polylactic acid (PLA) matrix and graphite. Shape memory polymers are a promising family of materials for biomedical…
Abstract
Purpose
The paper aims to fabricate shape memory composites using polylactic acid (PLA) matrix and graphite. Shape memory polymers are a promising family of materials for biomedical applications because of their favourable mechanical properties, fast reactions and good biocompatibility. For most SMPs, however, achieving controllable sequential shape change is challenging.
Design/methodology/approach
In the present work, 4D printing technology is used to fabricate shape memory composites using polylactic acid (PLA) matrix and graphite. A comparative study of pure PLA and graphite’s different weight % composition has been done.
Findings
By carefully managing the deformation state, PLA with graphite shape memory composites produced controllable sequential deformation with an amazing shape memory effect. Surface morphology, thermal properties, melt flow index and shape recovery tests have all been carried out to assess the qualities of manufactured samples.
Originality/value
This is a one-of-a-kind to fabricate shape memory composites using graphite and a PLA matrix. Thus, this research attempts to deliver the possible use of PLA/graphite composites fabricated using 4D printing in robotics and biomedical devices.
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Shares in China's new energy vehicle and battery makers rose on the news, as did the market valuations of several Western graphite explorers and developers. Prices for natural…
Details
DOI: 10.1108/OXAN-DB283201
ISSN: 2633-304X
Keywords
Geographic
Topical
Karunamunige Sandun Madhuranga Karunamuni, Ekanayake Mudiyanselage Kapila Bandara Ekanayake, Subodha Dharmapriya and Asela Kumudu Kulatunga
The purpose of this study is to develop a novel general mathematical model to find the optimal product mix of commercial graphite products, which has a complex production process…
Abstract
Purpose
The purpose of this study is to develop a novel general mathematical model to find the optimal product mix of commercial graphite products, which has a complex production process with alternative sub-processes in the graphite mining production process.
Design/methodology/approach
The network optimization was adopted to model the complex graphite mining production process through the optimal allocation of raw graphite, byproducts, and saleable products with comparable sub-processes, which has different processing capacities and costs. The model was tested on a selected graphite manufacturing company, and the optimal graphite product mix was determined through the selection of the optimal production process. In addition, sensitivity and scenario analyses were carried out to accommodate uncertainties and to facilitate further managerial decisions.
Findings
The selected graphite mining company mines approximately 400 metric tons of raw graphite per month to produce ten types of graphite products. According to the optimum solution obtained, the company should produce only six graphite products to maximize its total profit. In addition, the study demonstrated how to reveal optimum managerial decisions based on optimum solutions.
Originality/value
This study has made a significant contribution to the graphite manufacturing industry by modeling the complex graphite mining production process with a network optimization technique that has yet to be addressed at this level of detail. The sensitivity and scenario analyses support for further managerial decisions.
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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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Research limitations/implications
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.
Practical implications
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.
Social implications
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.
Originality/value
The present manuscript is an original piece of the author's research work.
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R. Fuentes, E. Rubio, C. Gómez, A. Herrera and V.M. Castaño
The wear behavior of a novel composite aluminum‐graphite composite prepared by simple powder metallurgy techniques is reported. Graphite powders were surface‐treated with copper…
Abstract
The wear behavior of a novel composite aluminum‐graphite composite prepared by simple powder metallurgy techniques is reported. Graphite powders were surface‐treated with copper to activate the powder surface and to improve the wettability of the graphite surface. The mixed Al‐C (7 percent, 5 percent, 3 percent, 1 percent y 0.5 percent C weight content) powders <100 μm were pressed at room conditions and then heat‐treated at 600°C. The tests showed improvements in wear resistance as the graphite content decreases, achieving the optimal behavior at 1 percent content.
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The mechanical properties of carbon and graphite as structural materials have been improved considerably since the 1940s, and graphite equipment is widely used in chemical and…
Abstract
The mechanical properties of carbon and graphite as structural materials have been improved considerably since the 1940s, and graphite equipment is widely used in chemical and other plant. Here is part of a talk given at the recent British industrial exhibition in Moscow by Dennis Hills, sales director of Powell Duffryn Chemical Engineering Ltd., who have specialised in carbon/graphite equipment under the trade name Delanium.
Tomasz Matusiak, Arkadiusz Dabrowski and Leszek Golonka
The purpose of this paper is to present the properties of thick-film resistors made of novel pastes prepared from glass and graphite.
Abstract
Purpose
The purpose of this paper is to present the properties of thick-film resistors made of novel pastes prepared from glass and graphite.
Design/methodology/approach
Graphite-based resistors were made of thick-film pastes with different graphite-to-glass mass fraction were prepared and examined. Sheet resistance, temperature coefficient of resistance, impact of humidity and short-term overload were investigated. The properties of the layers fired in atmospheres of air at 550°C and nitrogen at 875°C were compared.
Findings
Graphite-based resistors with various graphite-to-glass ratios made possible to obtain a wide range of sheet resistance from single O/square to few kO/square. These values were dependent on firing atmosphere, paste composition and the number of screen-printed layers. The samples made of paste with 1:1 graphite-to-glass ratio exhibited the temperature coefficient of resistance of about −1,000 ppm/°C, almost independently on the firing atmosphere and presence of a top coating. The resistors fired in the air after coating with overglaze, exhibited significantly lower sheet resistance, reduced impact of humidity and improved power capabilities.
Originality/value
In this paper, graphite-based resistors for applications in typical high-temperature cermet thick-film circuits were presented, whereas typical graphite-based resistors were fabricated in polymer thick-film technology. Owing to very low cost of the graphite, the material is suitable for low-power passive circuits, where components are not subjected into high temperature, above the typical temperature of operation of standard electronic components.
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