Mechanisms of the copper third body as an interfacial media on copper matrix friction materials with different compositions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiangyu Du ◽  
Junying Yang ◽  
Fei Gao ◽  
Xiaoming Han ◽  
Linlin Su
Keyword(s):  
Copper Powder ◽  
Copper Matrix ◽  
Third Body ◽  
Friction Materials ◽  
Content Type ◽  
The Third ◽  
Pin On Disc ◽  
Copper Component ◽  
New Perspective ◽  
Pure Cu

Purpose This paper aims to reveal the effects of the copper third body on different copper matrix friction materials with a novel experimental way called “exogenous powder.” Design/methodology/approach An accurate adding device of exogenous copper powder was designed to control the flow rate. The tribological properties with and without exogenous copper powder were investigated by a pin-on-disc tribometer during dry sliding. Findings Experimental results indicate that the Cu addition tends to increase the friction coefficient. For pure Cu material, the exogenous copper third body exhibits poor fluidity on the friction surface, causing serious adhesive wear on the friction interface. For the Cu 90% + 10% Gr material, the plasticity of exogenous copper powder may intensify the deformation of the third body of the surface, presenting layered accumulation distribution. For the pure Cu and Cu 95% + 5% SiO2 material, the Cu addition makes the composition and density of the third body uneven in the direction of depth. Originality/value The role of the copper component on different materials is revealed from a new perspective, and the relationship between the third body structure and the friction properties is explored.

Wear behaviour of copper/carbon nanotubes

2017 ◽  
Vol 69 (3) ◽  
pp. 342-347 ◽  
Author(s):  
Nor Shamimi Shaari ◽  
Jamaliah Md Said ◽  
Aidah Jumahat ◽  
Muhammad Hussain Ismail
Keyword(s):  
Carbon Nanotubes ◽  
Wear Test ◽  
Hardness Test ◽  
Copper Matrix ◽  
Wear Behaviour ◽  
Wear Depth ◽  
Wear Properties ◽  
Test Analysis ◽  
Content Type ◽  
Pure Cu

Purpose The purpose of this paper is to study the wear behaviour of copper matrix composites reinforced with carbon nanotubes (CNTs) prepared by powder metallurgy route. Design/methodology/approach The CNTs were treated by sulphuric acid and nitric acid to deagglomerate the CNTs prior mixing with copper powder. The composites comprised 0 to 4 Vol.% pristine CNTs (PCNTs) and also after acid-treated CNTs (ACNTs). The optimum value (pure Cu, 3 Vol.% PCNTs, 3 Vol.% ACNTs) evaluated by micro-hardness test was selected for wear test analysis. Findings The results showed that the enhancement of hardness, weight loss, coefficient of friction, wear depth and surface roughness (Ra) was due to the effect of homogenous distribution of ACNTs in Cu matrix and significant bonding compared to pure Cu and Cu-reinforced PCNTs. The scanning electron microscopy micrograph of worn surfaces and wear depth of the specimens also showed that the addition of ACNTs in Cu resulted in better wear performances. Originality/value CNTs were treated prior processing to improve hardness and wear properties of Cu/CNTs composites.

Correlations between third body evolution and tribological performance of copper-matrix friction material under abrasive paper interference conditions

2017 ◽  
Vol 232 (6) ◽  
pp. 711-721 ◽  
Author(s):  
Linlin Su ◽  
Fei Gao ◽  
Hualong Tao ◽  
Xiaoming Han ◽  
Rong Fu
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Normal Load ◽  
High Surface ◽  
Copper Matrix ◽  
Friction Material ◽  
Third Body ◽  
Friction Mechanism ◽  
Pin On Disc ◽  
Abrasive Paper

The influence of the degree of morphological variances of third body on the friction coefficient is a foundational question for understanding the friction mechanism. The correlations between the composition and morphology of third body as well as the surface roughness and the friction coefficient of copper-matrix friction material were investigated using a pin-on-disc tribometer by a method of interface interference caused by various grit size abrasive papers by grinding the friction surface during friction. Friction tests were conducted under friction speeds of 200–800 r/min at a normal load of 0.5 MPa. The results indicate that the friction coefficients increase under dry abrasive paper interference condition. It is generally 0.07–0.09 higher than the noninterference case. Large particle sizes of abrasive paper interference causes the change in the morphology of third body. More specifically, high surface roughness caused by plowing of coarse abrasive paper interference is the main cause for high friction coefficient. This phenomenon is weakened with the increase in speed. And small particle size of abrasive paper interference induces the change in the composition and distribution of third body due to fine SiC particles grinding and embedding into the friction interface. These changes increase the hard spots contact area, exacerbate the abrasive wear at all speeds, leading to a higher friction coefficient.

Effect of Graphite Content on the Tribological Performance of Copper-Matrix Composites Under Different Friction Speeds

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Han Xiao-Ming ◽  
Gao Fei ◽  
Su Lin-Lin ◽  
Fu Rong ◽  
Zhang En
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
High Speed ◽  
Copper Matrix ◽  
Tribological Performance ◽  
Matrix Composites ◽  
Third Body ◽  
H13 Steel ◽  
Copper Matrix Composites ◽  
The Third

The effect of graphite (Gr) content on tribological performance of copper-matrix composites against H13 steel was investigated using a pin-on-disk test in the range of 3.14–47.1 m/s. The composites with different weight fractions of Gr (up to 18%) were fabricated by powder metallurgy technique. The results showed that the friction coefficient and wear rate generally decreased with the increase in Gr content. However, the friction coefficient and wear rate differ at various speeds. At 200 and 500 r/min, the friction coefficient and wear rate kept lower with the increase in Gr content, because the third body of Cu–Al–3%Gr specimen had strong fluidity and plasticity. By contrast, the particle third body of Cu–Al–12%Gr specimen, which contained higher content of Gr, could roll easily. Increased Gr feeding to the third body was reasonable for the decreasing of friction coefficient and wear with the increasing of the amount of Gr content at the speed in the range of 1000–2000 r/min. Under the high-speed, the friction coefficient showed slight change because the friction temperature induced all the third bodies to extend and flow effortlessly without componential influence. However, wear decreased significantly because the third body possessed more metal, which favored attachment to the counter disk.

scholarly journals Extended analytical formulae for the perturbed Keplerian motion under low-thrust acceleration and orbital perturbations

2021 ◽  
Vol 133 (3) ◽  
Author(s):  
Marilena Di Carlo ◽  
Simão da Graça Marto ◽  
Massimiliano Vasile
Keyword(s):  
Gravitational Perturbation ◽  
Low Thrust ◽  
Orbital Elements ◽  
Third Body ◽  
The Third ◽  
Orbital Perturbations ◽  
Analytical Formulae ◽  
Numerical Orbit ◽  
Body Potential

AbstractThis paper presents a collection of analytical formulae that can be used in the long-term propagation of the motion of a spacecraft subject to low-thrust acceleration and orbital perturbations. The paper considers accelerations due to: a low-thrust profile following an inverse square law, gravity perturbations due to the central body gravity field and the third-body gravitational perturbation. The analytical formulae are expressed in terms of non-singular equinoctial elements. The formulae for the third-body gravitational perturbation have been obtained starting from equations for the third-body potential already available in the literature. However, the final analytical formulae for the variation of the equinoctial orbital elements are a novel derivation. The results are validated, for different orbital regimes, using high-precision numerical orbit propagators.

Changing concepts in the treatment of colloid cysts

1987 ◽  
Vol 66 (2) ◽  
pp. 186-191 ◽  
Author(s):  
Walter A. Hall ◽  
L. Dade Lunsford
Keyword(s):  
Third Ventricle ◽  
Ct Scanning ◽  
Morbidity Rate ◽  
Ct Guided ◽  
Content Type ◽  
Persistent Symptoms ◽  
The Third ◽  
Stereotaxic Surgery ◽  
Colloid Cysts ◽  
The University

✓ Since computerized tomography (CT) scanning became available at the University Health Center of Pittsburgh in July, 1975, 17 patients have undergone removal of colloid cysts of the third ventricle by transfrontal, transcallosal, or stereotaxic surgery. All patients presented with symptoms and signs of increased intracranial pressure; CT scanning proved to be the best neurodiagnostic test to define the colloid cysts. Since the development of CT-guided stereotaxic surgery, the authors have preferentially performed stereotaxic aspiration in seven patients; three of these subsequently required craniotomies to remove residual cysts producing persistent symptoms. The viscosity of the intracystic colloid material and/or displacement of the cyst away from the aspiration needle were reasons for unsuccessful aspiration; the CT appearance did not correlate with the ability to aspirate the lesion by the stereotaxic technique. Postoperative patency of the ventricular system was documented by intraoperative CT ventriculography performed during stereotaxic surgery. Removal of the cyst wall was not necessary. Because of the low associated morbidity rate, percutaneous stereotaxic aspiration is recommended as the initial treatment of choice for colloid cysts of the third ventricle. If stereotaxic aspiration fails and symptoms persist, craniotomy should be performed.

Policy and institutions facilitating entrepreneurial spin-offs: USA, Asia and Europe

2014 ◽  
Vol 3 (2) ◽  
pp. 186-196 ◽  
Author(s):  
Rosa Caiazza ◽  
David Audretsch ◽  
Tiziana Volpe ◽  
Julie Debra Singer
Keyword(s):  
Institutional Setting ◽  
Policy Debate ◽  
Content Type ◽  
Factors Affecting ◽  
Institutional Settings ◽  
The Usa ◽  
New Perspective ◽  
National Analysis ◽  
The Impact ◽  
Cross National

Purpose – Existing work documents the role that institutional setting plays in the process of spin-off creation. However, despite decades of studies, scholars have not clearly explained why some regions are more involved in spin-off activity than others. Drawing from institutional theory, the purpose of this paper is to compare different institutional settings identifying factors affecting the general environment capability to support spin-off activity of a specific region. Design/methodology/approach – The authors utilize a cross-national analysis of American, Asian, and European areas identifying factors affecting their different rate of spin-off activity. This study contributes to the policy debate concerning entrepreneurship and how best to spur spin-off activities. Findings – In this paper, the authors identify the general and specific factors that explain the cross-national diversity in spin-off creation. The authors then perform an analysis of the impact of these factors in various regions of the USA, Asia, and Europe, providing evidence for the necessity of specific combinations of these factors. Originality/value – The paper offers a new perspective on the causes of spin-offs through a cross-national analysis of many areas around the world.

The Effect of the Third Body on the Fretting Wear Behavior of Coatings

2002 ◽  
Vol 11 (3) ◽  
pp. 288-293 ◽  
Author(s):  
Gui-Zhen Xu ◽  
Jia-Jun Liu ◽  
Zhong-Rong Zhou
Keyword(s):  
Wear Behavior ◽  
Fretting Wear ◽  
Third Body ◽  
The Third

Lessons of the Oil Crisis for the Third World

1975 ◽  
Vol 1 (4) ◽  
pp. 515-522
Author(s):  
György Adam
Keyword(s):  
World Bank ◽  
Third World ◽  
Development Aid ◽  
World Bank Group ◽  
The Third ◽  
The Rich ◽  
Oil Crisis ◽  
New Perspective ◽  
Bank Group ◽  
The Third World

The author argues that the so-called oil crisis may open out a new perspective on development aid to the Third World if the oil-producing countries, instead of allowing the giant Western banks and corporations to make a grab for their petro dollars (as the Western nations had so far made a grab for incredibly cheap oil energy), decide to pool the surplus oil revenues for self-help among the Third World countries. He suggests the setting up of an interregional Third World Bank, which, unlike the existing World Bank group (typecast as the instrument of the rich market economies), would be the instrument of the developing countries, thus breaking the monopoly of the West in international financing.

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