Tribological performance of microwave sintered copper–TiC–graphite hybrid composites

Rajkumar, K.; Aravindan, S.

doi:10.1016/j.triboint.2010.11.008

Cited by 200 publications

(99 citation statements)

References 32 publications

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“…Figure ( 12) shows that increasing milling time produces a slight increase in friction coefficient due to the increase in bonding between copper and graphite particles on increasing milling period, which in turn prevents graphite from being squeezed out and reduces the thickness of the graphite lubrication film between the composite specimen and the disc or breaks its continuity. These effects leads to an increase in the coefficient of friction as was found by previous works [8,11]. …”

Section: Effect Of Milling Time On Wear Volume and Coefficient Of Frisupporting

confidence: 76%

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The Influence of Graphite Content and Milling Time on Hardness, Compressive Strength and Wear Volume of Copper - Graphite Composites Prepared Via Powder Metallurgy

Mahdi¹,

Razooqi²,

Irhayyim³

2017

Tikrit j. eng. sci.

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Copper -graphite composites are widely used in sliding bearings and brushes due to their excellent thermal and electrical conductivities and high wear resistance. The aim of this research is to study the Influence of graphite content and milling time on hardness, compressive strength, wear volume and friction coefficient of copper -graphite composites prepared via powder metallurgy. A powder mixture containing 0,5,10,15,20 and 25 vol% graphite was milled for 1,3,5,7 and 9 hours. The milled mixture was cold pressed at 700 MPa for 30 second, followed by sintering at 900 o C for one hour. It was found through this work that increasing milling time results an appreciate increase in hardness and radial compressive strength, slight reduction in wear volume and slight increase in the coefficient of friction for all compositions except that for pure copper in which a considerable increase in wear volume and decrease in the coefficient of friction was observed. On the other hand, increasing the graphite volume fraction increases the composite hardness, till an optimum value, and decreases the radial compressive strength. A great decrease in both wear volume and coefficient of friction was observed on increasing graphite content up to 25 vol%. Finally, a graphite, cast iron chips and fireclay sintering configuration was found to be an effective procedure which minimize oxidation to levels comparative with those observed previously by sintering in argon or hydrogen atmospheres. Keywords:Copper -graphite composites, mechanical properties, milling time. ‫ن‬ ‫لمتراك‬ ‫لى‬ ‫ال‬ ‫حكب‬ ‫نطة‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫حج‬ ‫ا‬ ‫مالنوما‬ ‫الاومة‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫ال‬ ‫الص‬ ‫على‬ ‫الطحن‬ ‫وزمن‬ ‫الكرافيت‬ ‫محتوى‬ ‫تأثير‬ ‫الححنس‬ ‫ت‬

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Section: Effect Of Milling Time On Wear Volume and Coefficient Of Frisupporting

confidence: 76%

“…Moreover, graphite has low density as compared with copper. These two reasons excluded casting and made powder metallurgy the most suitable technique used to produce such composites [5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Graphite Content and Milling Time on Hardness, Compressive Strength and Wear Volume of Copper - Graphite Composites Prepared Via Powder Metallurgy

Mahdi¹,

Razooqi²,

Irhayyim³

2017

Tikrit j. eng. sci.

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show abstract

“…Which in turns prevents squeezing out graphite and reduces the thickness of the graphite lubrication film between the composite specimen and the disc or breaks. These effects lead to an increase in the coefficient of friction as was found by a previous works [8,11]. …”

Section: The Effect Of Milling Time On Wear Volume and Coefficient Ofsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

The Influence of the Graphite Content and Milling Time on the Hardness, Compressive Strength and Wear Volume of Copper - Graphite Composites Prepared Via Powder Metallurgy

Mahdi

Razooqi

Irhayyim

2017

Tikrit j. eng. sci.

View full text Add to dashboard Cite

A B S T R A C TCopper -graphite composites are widely used in sliding bearings and brushes due to their excellent thermal and electrical conductivities and high wear resistance. The aim of this research is to study the Influence of the graphite content and milling time on hardness, compressive strength, wear volume and friction coefficient of copper -graphite composites that prepared via powder metallurgy. A powder mixture containing 0,5,10,15,20 and 25 vol% graphite was milled for 1,3,5,7 and 9 hours. The milled mixture was cold pressed at 700 MPa for 30 second, followed by sintering at 900 ℃ for one hour. It was found through this work that increasing milling time results an appreciate increase in hardness and radial compressive strength. Slight reduction in wear volume and slight increase in the coefficient of friction for all compositions except that for pure copper in which a considerable increase in wear volume and decrease in the coefficient of friction was observed. On the other hand, increasing the graphite volume fraction increases the composite hardness, to reach an optimum value, and decreases the radial compressive strength. A great decrease in both wear volume and coefficient of friction was observed due to increasing the graphite content up to 25 vol%. Finally, a graphite, cast iron chips and fireclay sintering configuration was found to be an effective procedure which minimizes oxidation to levels comparative with those observed previously by sintering in argon or hydrogen atmospheres.

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“…Microwave-heat treating reduces the coefficient of friction and specific wear rate by facilitating the formation of a stable graphite layer at the contact region of the tribo-surface. Moreover, Rajkumar and Aravindan [37] studied the tribological performance of microwave-sintered copper-graphite hybrid composites reinforced with TiC. Figure 11.7 shows the variation of the coefficient of friction and wear rate of the hybrid composites with normal load.…”

Section: Self-lubricating Behavior Of Copper-graphite Compositesmentioning

confidence: 99%

Self-Lubricating Behavior of Graphite-Reinforced Composites

Menezes

Reeves

Rohatgi

et al. 2013

Tribology for Scientists and Engineers

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Lubricants are extensively used between contacting surfaces to reduce friction and wear. Typically, liquid lubricants are used to achieve low friction and wear. However, these lubricants are not effective in elevated temperature applications or vacuum environments. For these reasons, solid lubricants are utilized to meet these operational needs, where liquid lubrication is impractical. Solid lubricants are only effective as long as they are present in the tribo-interface. Therefore, it is desirable to provide a constant supply of solid lubricant material to the contacting surface. This is often achieved by incorporating solid lubricants as a second phase in the base material. These composite materials have the ability to achieve low friction and wear at the contact surfaces without any external supply of lubrication during sliding. Metal matrix composites reinforced with lamellar solid lubricant particles such as graphite are being used as self-lubricating materials for various engineering applications. In this chapter, the tribological behavior of metal and ceramic matrix composites reinforced with graphite particles has been reviewed. More specifically, copper-graphite, nickel-graphite, magnesiumgraphite, silver-graphite, aluminum-graphite, silicon nitride-graphite, and alumina-graphite composites are studied. The influence of various environmental and mechanical parameters on the friction coefficient and wear rate is discussed. It was found that the amount of graphite released on the worn surface forms a thin transfer film on the contact surfaces. This transfer film reduces the overall friction coefficient and wear rate. The presence of the graphite-based transfer film increases the seizure resistance and enables the contacting surfaces to run under boundary lubrication without galling. The formation and retention of this transfer film on the sliding surface as well as its composition, area fraction, thickness, and hardness are important factors in controlling the friction and wear behavior of the material. The effectiveness of the transfer film also depends on the nature of the sliding surface, the test condition, environment, and the graphite content in the composite.

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Tribological performance of microwave sintered copper–TiC–graphite hybrid composites

Cited by 200 publications

References 32 publications

The Influence of Graphite Content and Milling Time on Hardness, Compressive Strength and Wear Volume of Copper - Graphite Composites Prepared Via Powder Metallurgy

The Influence of Graphite Content and Milling Time on Hardness, Compressive Strength and Wear Volume of Copper - Graphite Composites Prepared Via Powder Metallurgy

The Influence of the Graphite Content and Milling Time on the Hardness, Compressive Strength and Wear Volume of Copper - Graphite Composites Prepared Via Powder Metallurgy

Self-Lubricating Behavior of Graphite-Reinforced Composites

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