Friction and Wear of Self-Lubricating Metallic Materials

1975 ◽  
Vol 97 (2) ◽  
pp. 217-220 ◽  
Author(s):  
E. Rabinowicz
Keyword(s):  
Friction And Wear ◽  
Analytical Study ◽  
Fine Particles ◽  
Simple Calculation ◽  
Hard Metal ◽  
Filler Concentration ◽  
Matrix Surface ◽  
Large Particles ◽  
The Matrix ◽  
Better Than

An experimental and analytical study has been carried out to discover the factors which determine the friction and wear coefficients of composites consisting of a hard metal matrix and a softer filler. To be effective the filler should have a lower metallurgical compatibility than the matrix against the other sliding surface. The concentration of the filler should be at least a few percent so that it can be smeared out over the matrix surface, and there is an upper limit to filler concentration associated with loss of bulk strength of the composite. A simple calculation suggests that large particles of filler material are better than fine particles with 20 micrometer particles being the smallest that are fully effective.

A Review on In Situ Synthesis of Al/TiC and Al/SiC-Composites

2016 ◽  
Vol 684 ◽  
pp. 287-292 ◽  
Author(s):  
Hrusikesh Nath
Keyword(s):  
Fine Particles ◽  
Matrix Composites ◽  
Homogeneous Microstructure ◽  
Large Particles ◽  
The Matrix ◽  
Matrix Reinforcement ◽  
Sic Composites ◽  
Al Matrix Composites ◽  
Al Matrix

The in-situ synthesis of ceramic particles in Al-matrix composites gives an uniform and homogeneous microstructure. The matrix reinforcement interface is compatible with the matrix, interface is clean and provides good interface bonding. The evenly distributed sub micron sized reinforcement particles in Al-matrix enhances the strength and toughness of the composite. The formation of particle clusters and agglomerations are minimized or eliminated by suitably choosing the in-situ process parameters. Large particles and agglomerate are easily fractured where as evenly distributed fine particles are resistant to crack propagation and improves the strength of the composites. The problem encountered with the formation of secondary intermetallic Al3Ti and Al4C3 phases are addressed.

The Analysis on the Tribological Properties of TPU/PVC Blends under Oil Lubrication

2013 ◽  
Vol 774-776 ◽  
pp. 94-98
Author(s):  
Dao Yuan Pan ◽  
Peng Peng Wu ◽  
Zhong Xue Gao ◽  
Yu Zeng Zhang
Keyword(s):  
Working Conditions ◽  
Friction And Wear ◽  
Oil Lubrication ◽  
Wear Properties ◽  
Operation Conditions ◽  
Hydraulic Steering ◽  
Pros And Cons ◽  
Friction And Wear Properties ◽  
Lubrication Conditions ◽  
Better Than

Based on actual working conditions and parameters of the hydraulic steering gear, the purpose is optimizing the rubber seal of steering gear by different rubbers mixing technology. Compare the five kinds of rubber with metal of the friction characteristics in dynamic fit, it can obtain a performance excellent rubber real in the specific operation conditions. And then improve the overall service life of the steering gear. It is first prepared the same hardness TPU and PVC and blends that the ratio is 3:7, 5:5and7:3 in this article. The pros and cons of the five rubbers are analyzed in friction and wear properties of the above experimental. The test curve of coefficient friction and wear with time has been done under different load at constant low speed. It determines TPU/PVC = 3:7 blends through friction and wear and wear mechanism of five rubbers with steel comparatively analyses, and the heat resistance and wear resistance of them are better than the other TPU/PVC blends and PVC under oil lubrication conditions.

scholarly journals Characterization of percolation behavior in conductor–dielectric 0-3 composites

2014 ◽  
Vol 04 (04) ◽  
pp. 1450035 ◽  
Author(s):  
Lin Zhang ◽  
Patrick Bass ◽  
Zhi-Min Dang ◽  
Z.-Y. Cheng
Keyword(s):  
Dielectric Constant ◽  
Percolation Threshold ◽  
Frequency Dependence ◽  
Experimental Results ◽  
Effective Dielectric Constant ◽  
Filler Concentration ◽  
Percolation Behavior ◽  
The Matrix ◽  
The Relationship

The equation ε eff ∝ (ϕc - ϕ)-s which shows the relationship between effective dielectric constant (εeff) and the filler concentration (φ), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold φc and the power constant s in conductor–dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to φc is almost independent of the matrix.

Percolation Theory Applied to Study the Effect of Shape and Size of the Filler Particles in Thermal Interface Materials

2000 ◽  
Author(s):  
Amit Devpura ◽  
Patrick E. Phelan ◽  
Ravi S. Prasher
Keyword(s):  
Percolation Theory ◽  
Flip Chip ◽  
Filler Concentration ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Chip Technology ◽  
The Matrix ◽  
Different Shapes ◽  
Filler Particles ◽  
Interface Materials

Abstract An important aspect in electronic packaging is the heat dissipation. Flip-chip technology is widely being used to increase the rate of heat transfer from the chip. A method to further enhance the thermal conductivity is by the use of a thermal interface material between the device and the heat sink attached to it in the flip-chip technology. Percolation theory holds a key to understanding the behavior of thermal interface materials. Percolation, used widely in electrical engineering, is a physical phenomenon in which the highly conducting particles distributed randomly in the matrix form at least one continuous chain connecting the opposite faces of the matrix. This phenomenon was simulated using the matrix method, to study the effect of different shapes and size of the filler particles. The different shapes considered were spherical, vertical or horizontal rods, and flakes in horizontal or vertical orientation. The effect of the size of these particles was also examined. The results indicate that the composites with particles having the largest side in the direction of heat flow will always have a better conductivity than the particles oriented normal to it. Also, from the results, we can choose the best filler size in the composite if we know the filler concentration we are aiming at.

Microstructures and Creep of AM50-Sb-Gd Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 749-752 ◽  
Author(s):  
Su Gui Tian ◽  
Keun Yong Sohn ◽  
Hyun Gap Cho ◽  
Kyung Hyun Kim
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Stress Exponent ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Deformation Mechanism ◽  
Creep Resistance ◽  
Fine Particles ◽  
Dislocation Climb ◽  
The Matrix

Creep behavior of AM50-0.4% Sb-0.9%Gd alloy has been studied at temperatures ranging from 150 to 200°C and at stresses ranging from 40 to 90 MPa. Results show that the creep rate of AM50-0.4%Sb-0.9%Gd alloy was mainly controlled by dislocation climb at low stresses under 50 MPa. The activation energy for the creep was 131.2 ± 10 kJ/mol and the stress exponent was in the range from 4 to 9 depending on the applied stress. More than one deformation-mechanism were involved during the creep of this alloy. Microstructures of the alloy consist of a–Mg matrix and fine particles, distinguished as Mg17Al12, Sb2Mg3, and Mg2Gd or Al7GdMn5 that were homogeneously distributed in the matrix of the alloy, which effectively reduced the movement of dislocations, enhancing the creep resistance. Many dislocations were identified to be present on non-basal planes after creep deformation.

Martin Shapiro: An Appreciation

The Forum ◽  
2016 ◽  
Vol 14 (2) ◽  
Author(s):  
R. Shep Melnick
Keyword(s):  
Institutional Environment ◽  
Empirical Studies ◽  
The Political ◽  
Public Officials ◽  
Thick Description ◽  
Past Half Century ◽  
The Us ◽  
The Matrix ◽  
The One ◽  
Better Than

AbstractOver the past half century no judicial politics scholar has been more respected or influential than Martin Shapiro. Yet it is hard to identify a school of thought one could call “Shapiroism.” Rather than offer convenient methodologies or grand theories, Shapiro provides rich empirical studies that show us how to think about the relationship between law and courts on the one hand and politics and governing on the other. Three key themes run through Shapiro’s impressive oevre. First, rather than study courts in isolation, political scientists should view them as “one government agency among many,” and seek to “integrate the judicial system in the matrix of government and politics in which it actually operates.” Law professors may understand legal doctrines better than political scientists, but we know (or should know) the rest of the political system better than they do. Second, although judges inevitably make political decisions, their institutional environment leads them to act differently from other public officials. Most importantly, their legitimacy rests on their perceived impartiality within the plaintiff-defendant-judge triad. The conflict between judges’ role as impartial arbiter and enforcer of the laws of the regime can never be completely resolved and places powerful constraints on their actions. Third, the best way to understand the complex relationship between courts and other elements of the regime is comparative analysis. Shapiro played a major role in resuscitating comparative law, especially in his work comparing the US and the EU. All this he did with a rare combination of thick description and crisp, jargon-free analysis, certainly a rarity the political science of our time.

Friction and wear characteristics of fibre-reinforced plastic composites

2018 ◽  
Vol 33 (6) ◽  
pp. 828-850 ◽  
Author(s):  
R Vinayagamoorthy
Keyword(s):  
Friction And Wear ◽  
Wear Behaviour ◽  
Tribological Behaviour ◽  
Reinforced Plastics ◽  
Reinforced Plastic ◽  
The Matrix ◽  
Comprehensive Survey ◽  
Working Parameters ◽  
Sliding Distance ◽  
Friction And Wear Characteristics

The dominance of fibre-reinforced plastics in industries has enhanced the need for research to develop new composites and assess their properties. Among the various property analyses, tribological characteristics of the composites help to understand the friction and wear behaviour. This article presents a comprehensive survey on the tribological behaviour of polymeric composites, which includes the influence of various working parameters such as the velocity of sliding, sliding distance, pressure applied and temperature on the friction and wear. The article also addresses about the importance of the composite constituents such as fibre composition, fibre geometry and fibre orientation on the tribological behaviour. The major reasons causing the tribological failure like the debonding between the fibre and the matrix, failure of the matrix and the fibre are also extensively addressed. This review would be an insight to the industries and tribology researchers towards achieving optimum design for the components made of polymers.

Recent Advances in Biohybrid Materials for Tissue Engineering and Regenerative Medicine

2016 ◽  
Vol 04 (01) ◽  
pp. 1640001 ◽  
Author(s):  
Ying Wan ◽  
Xing Li ◽  
Shenqi Wang
Keyword(s):  
Tissue Engineering ◽  
Regenerative Medicine ◽  
Cell Function ◽  
Rapid Prototype ◽  
Artificial Organs ◽  
Specific Cell ◽  
Cell Matrix ◽  
Matrix Surface ◽  
The Matrix ◽  
Cell Matrix Interactions

Biohybrid materials play an important role in tissue engineering, artificial organs and regenerative medicine due to their regulation of cell function through specific cell–matrix interactions involving integrins, mostly those of fibroblasts and myofibroblasts, and ligands on the matrix surface, which have become current research focus. In this paper, recent progress of biohybrid materials, mainly including main types of biohybrid materials, rapid prototype (RP) technique for construction of 3D biohybrid materials, was reviewed in detail; moreover, their applications in tissue engineering, artificial organs and regenerative medicine were also reviewed in detail. At last, we address the challenges biohybrid materials may face.

scholarly journals Evaluation of the Efficacy of Plant Materials for the Control of Flea Beetles Podagrica spp on Okra Abelmoschus esculentus L

2021 ◽  
Vol 25 (4) ◽  
pp. 529-535
Author(s):  
S. Danjuma ◽  
I. Muhammed ◽  
G. Yahaya
Keyword(s):  
Fine Particles ◽  
Short Interval ◽  
Flea Beetle ◽  
Plant Materials ◽  
Plant Parts ◽  
Whatman Filter Paper ◽  
Synthetic Chemicals ◽  
Zanthoxylum Zanthoxyloides ◽  
African Locust Bean ◽  
Better Than

The efficacy of the Senegal prickly-ash Zanthoxylum zanthoxyloides (Lam.) roots and the African locust bean tree Parkia biglobosa (Jacq.) pod back was study for their efficacy in the control of okra pest, Podagrica spp. The study was carried out in the laboratory and on the field in the farming season of 2018. Z. zanthoxyloides roots were obtained from Jima-Doko forest and P. biglibosa fruit back from Takunpara. Both plant materials were air-dried under shade for 120 hours. Both plant parts were pounded separately in wooden mortar with the aid of wooden pestle until the materials turns to fine particles. Determined weight of 100, 150, 200, 250, and 300 grams were taken for each plant materials and soaked in water for 24 hours and stirred at intervals of an hour. The mixture were then sieved with a muslin cloth and filtered with Whatman filter paper to eliminate all finest particles of varying sizes. These concentrations were applied individually on 10 adults of Podagrica spp. in the laboratory. It was observed that the concentration of 200 – 300g performed better for both plant materials in the control of okra flea beetle. These resulted to the death of above 50% of the insect within 2 hours. These significant laboratory trials were then formulated and taken to the field. Both plant materials acted as anti-feedants and repellants against Podagrica spp. It was also revealed that Z. zanthoxyloides performed significantly (p<0.05) better than the P. biglibosa. Furthermore, short interval applications (<or=3days) of these plant materials could be a good  replacement for synthetic chemicals, hence bio-pesticides that could be adopted for organic agriculture.

Machinability and Microstructure of SiC/h-BN Nano-Composites

2008 ◽  
Vol 569 ◽  
pp. 45-48
Author(s):  
Hai Yun Jin ◽  
Guan Jun Qiao ◽  
Zong Ren Peng ◽  
Ji Qiang Gao
Keyword(s):  
Fracture Strength ◽  
Nano Composites ◽  
Weak Interface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Particles ◽  
N2 Atmosphere ◽  
The Matrix ◽  
Better Than

SiC particles coated with nano-BN were synthesized and the machinable SiC/BN ceramic nano-composites were fabricated by Plasma Active Sintering (PAS) in N2 atmosphere. The existing and distribution of h-BN phase were revealed by X-ray diffraction (XRD), and SEM. For the existing of weak interface between h-BN and SiC grains, the machinability of both SiC/BN micro-composites and nano-composites were improved obviously. Because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites was better than the SiC/h-BN micro-composite.

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