Pulsed Electric Current Sintering of the Al2O3 - 15wt% ZrO2 Nanocomposites with 3wt% of Different Solid Lubricants

2011 ◽  
Vol 695 ◽  
pp. 473-476 ◽  
Author(s):  
M. Erkin Cura ◽  
Seung Ho Kim ◽  
Sung Hun Cho ◽  
Tomi Suhonen ◽  
Tatu Muukkonen ◽  
...  
Keyword(s):  
Electric Current ◽  
Solid Lubricant ◽  
Solid Lubricants ◽  
Instrumented Indentation ◽  
Scratch Testing ◽  
Low Friction ◽  
Laser Method ◽  
Optimal Processing ◽  
Pulsed Electric Current ◽  
Reduce Energy Consumption

High temperature low friction materials are sought for use in engines in order to reduce energy consumption of the machines. Due to the high service temperatures solid lubricating materials are necessary. This study is designed to find the optimal processing conditions for preparing these materials by pulsed electric current sintering. In this study, the Al2O3- 15wt% ZrO2(AZ) nanocomposite was modified with 3 wt% of self-lubricating component (CaF2, BaF2, MoS2, WS2, h-BN, or graphite). After the preparation of the alumina-zirconia powder mixture solid lubricant powder was added. Powders were then mixed in ethanol for 24 h, dried in a rotary evaporator, and in oven at 80°C for 24 h. The particle size distribution of the powders was established with the laser method. Powders were compacted by using pulsed electric current sintering technique at 1300 °C with 50 MPa for 5 min in vacuum. The structure of the materials was studied with XRD and SEM. Density of the compacts was measured with the Archimedes method and their hardness was evaluated by applying HV1 hardness with the instrumented indentation techniques. Their mechanical behavior was further studied with the instrumented scratch testing.

scholarly journals Understanding the Unique Role of Phospholipids in the Lubrication of Natural Joints: An Interfacial Tension Study

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 264 ◽  
Author(s):  
Aneta D. Petelska ◽  
Katarzyna Kazimierska-Drobny ◽  
Katarzyna Janicka ◽  
Tomasz Majewski ◽  
Wiesław Urbaniak
Keyword(s):  
Interfacial Tension ◽  
Lipid Bilayers ◽  
Solid Lubricant ◽  
Solid Lubricants ◽  
Phospholipid Bilayer ◽  
Low Friction ◽  
Unique Role ◽  
Lamellar Phases ◽  
Chemical Inertness

Some solid lubricants are characterized by a layered structure with weak (van der Waals) inter-interlayer forces which allow for easy, low-strength shearing. Solid lubricants in natural lubrication are characterized by phospholipid bilayers in the articular joints and phospholipid lamellar phases in synovial fluid. The influence of the acid–base properties of the phospholipid bilayer on the wettability and properties of the surface have been explained by studying the interfacial tension of spherical lipid bilayers based on a model membrane. In this paper, we show that the phospholipid multi-bilayer can act as an effective solid lubricant in every aspect, ranging from a ‘corrosion inhibitor’ in the stomach to a load-bearing lubricant in bovine joints. We present evidence of the outstanding performance of phospholipids and argue that this is due to their chemical inertness and hydrophilic–hydrophobic structure, which makes them amphoteric and provides them with the ability to form lamellar structures that can facilitate functional sliding. Moreover, the friction coefficient can significantly change for a given phospholipid bilayer so it leads to a lamellar-repulsive mechanism under highly charged conditions. After this, it is quickly transformed to result in stable low-friction conditions.

Sliding Friction Behavior of Sintered Ni-Cr Composites with Solid Lubricants

2021 ◽  
Vol 875 ◽  
pp. 272-279
Author(s):  
Wan Farhana Mohamad ◽  
Amir Azam Khan ◽  
Pierre Barroy ◽  
Olivier Durand-Drouhin ◽  
Clement Puille ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Solid Lubricant ◽  
Sliding Friction ◽  
Solid Lubricants ◽  
Sem Analysis ◽  
Low Friction ◽  
Friction Behavior ◽  
Hardness Tester ◽  
Disc Configuration ◽  
Ball On Disc

High temperature applications of self-lubricated sliding surfaces have gained industrial importance during the recent years. One popular system is based on sintered Ni-Cr composites with addition of solid lubricants. In the present work these composites were prepared under controlled sintering conditions with different combinations of solid lubricants (MoS2, Ag and CaF2) at 1200 °C under flowing argon. The physical properties such as sintered density, relative density and porosity were studied. The microstructures and phase studies of the Ni-Cr based composites were conducted using SEM analysis while the hardness of the composites was measured by Vickers Micro Hardness Tester. The friction tests were conducted with ball on disc configuration following ASTM G-99-95a standard. The MoS2 solid lubricant provides best lubrication at room temperature which is demonstrated by a low friction coefficient compared to pure Ni-Cr composites. The SEM pictures of worn out tracks show solid debris distribution, and filling of pores with solid lubricant phases. The time taken for stabilization of friction coefficient also varies with the type of solid lubricant. Dual and multiple additions of solid lubricants are also able to reduce the friction of coefficient compared to pure Ni-Cr composite.

Microstructure and tribological properties of pulsed electric current sintered alumina–zirconia nanocomposites with different solid lubricants

2013 ◽  
Vol 39 (2) ◽  
pp. 2093-2105 ◽  
Author(s):  
M. Erkin Cura ◽  
Seung-Ho Kim ◽  
Tatu Muukkonen ◽  
Simo Varjus ◽  
Antti Vaajoki ◽  
...  
Keyword(s):  
Electric Current ◽  
Tribological Properties ◽  
Solid Lubricants ◽  
Pulsed Electric Current

Adaptive Solid Lubricant Transfer Films for Conductivity and Oxidation Control

2012 ◽  
Author(s):  
Patrick S. M. Dougherty ◽  
Cecily M. Sunday ◽  
C. Fred Higgs
Keyword(s):  
Solid Lubricant ◽  
Composite Coatings ◽  
Solid Lubricants ◽  
Operating Conditions ◽  
Low Friction ◽  
Composite Powders ◽  
Electrically Conductive ◽  
Transfer Films ◽  
Oxidation Resistant ◽  
Complex Deposition

The success of solid lubricants to exhibit ultra-low friction and wear behaviors in oil-prohibiting environments, has led to a major effort to optimize their performance and enhance their applicability. Depending on the operating conditions, solid lubricants may take on a plethora of forms including fabricated composite coatings, thick-film powder lubricants, nano-particle additives for hard surfaces or liquid lubricants, and self-replenishing transfer films. One of the benefits of transfer films are their freedom from the complex deposition techniques required for most other solid lubricant systems. In this work, the potential for adaptive self-replenishing transfer films was explored by creating composite powders of well-known powder lubricants and electrically conductive or anti-oxidation materials. MoS2, WS2, and Graphite Powders were mixed in varying composition with Cu, Sb2O3, and BO3 additives and compacted to form “tuned” or adaptive powder pellets. Relationships between friction, wear, electrical resistance, tribo-induced oxidation and powder composition, will be presented in order to investigate the potential of composite property optimization for lubricious, highly conductive, and oxidation resistant transfer films.

Formation Mechanisms of Tribo-Coating for Low Friction in UHV

2005 ◽  
Author(s):  
Koshi Adachi ◽  
Hisakazu Sato ◽  
Koji Kato
Keyword(s):  
Friction Coefficient ◽  
Composite Structure ◽  
Solid Lubricant ◽  
Silicon Oxide ◽  
Solid Lubricants ◽  
Solid Lubrication ◽  
Formation Mechanisms ◽  
Coating Film ◽  
Low Friction ◽  
Indium Film

Solid lubrication film formed by tribo-coating, which deposits a solid lubricant by evaporation to the contact interface during friction in vacuum, gives low friction coefficient below 0.03 that can not be observed by any other solid lubricants of soft metals. The tribo-coating film formed on the pin has nano-order composite structure which the crystalline indium of nano size are distributed in an amorphous matrix of silicon oxide and chromium oxide. Because of the nano composite structure, a very thin indium film is formed without break down like conventional pre-coated thin film. The thinner indium film can give smaller value of friction coefficient than that of conventional solid lubricant.

Sapphire/Nd:YAG composite by pulsed electric current bonding for high-average-power lasers

2018 ◽  
Vol 43 (13) ◽  
pp. 3065 ◽  
Author(s):  
Hiroaki Furuse ◽  
Yuki Koike ◽  
Ryo Yasuhara
Keyword(s):  
Electric Current ◽  
Average Power ◽  
High Average Power ◽  
Pulsed Electric Current

Pulsed Electric Current Sintered Cr2O3-rGO Composites

2016 ◽  
Vol 721 ◽  
pp. 419-424
Author(s):  
M. Erkin Cura ◽  
Vivek Kumar Singh ◽  
Panu Viitaharju ◽  
Joonas Lehtonen ◽  
Simo Pekka Hannula
Keyword(s):  
Fracture Toughness ◽  
Graphene Oxide ◽  
Electric Current ◽  
Chromium Oxide ◽  
High Hardness ◽  
High Wear Resistance ◽  
Carbide Formation ◽  
Indentation Fracture ◽  
Pulsed Electric Current ◽  
Indentation Fracture Toughness

Chromium oxide is a promising material for applications where excellent corrosion resistance, high hardness, and high wear resistance are needed. However, its use is limited because of low fracture toughness. Improvement of fracture toughness of chromium oxide while maintaining its afore mentioned key properties is therefore of high interest. In this communication we study the possibility of increasing the toughness of pulsed electric current sintered (PECS) chromium oxide by the addition of graphene oxide (GO). The indentation fracture toughness was improved markedly with the addition of graphene oxide. Materials prepared by direct chemical homogenization had better fracture toughness. In composites with 10 vol.% GO piling of thin graphene oxide layers resulted in the formation of graphite layers between Cr2O3 and in carbide formation, which were observed to be the main reasons for the degradation of the mechanical properties. The distribution of graphene oxide was more homogeneous, when the GO amount was 0.1 vol.% and the formation of graphitic layers were avoided due to lesser amount of GO as well as ultrasonic treatment following the ball milling.

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