Shear Strength and Tribological Properties of Stearic Acid Films—Part I: On Glass and Aluminum-Coated Glass

1992 ◽  
Vol 114 (1) ◽  
pp. 150-158 ◽  
Author(s):  
R. S. Timsit ◽  
C. V. Pelow
Keyword(s):  
Shear Strength ◽  
Film Thickness ◽  
Stearic Acid ◽  
Tribological Properties ◽  
Contact Stress ◽  
Frictional Force ◽  
Aluminum Film ◽  
Langmuir Blodgett ◽  
Coated Glass ◽  
Sliding Interfaces

The mechanical shear strength of dry and lubricated interfaces is evaluated by measuring the frictional force during sliding of a hemispherical pin in contact with a flat slide. The solids investigated include bare glass and aluminum-coated glass and interfaces are generated from pairings of these materials. Lubrication is obtained by depositing a stearic acid Langmuir-Blodgett layer on the slide. Shear strength is measured at contact stresses ranging from ~ 0.05 to 0.8 GPa and at a sliding speed of 60 μm s−1. The shear strength of dry interfaces is found to increase with contact stress, and increases slightly with aluminum film thickness. Because stearic acid adheres to glass and aluminum, the shear strength of lubricated interfaces originates from the interaction of two stearic acid layers generated from molecular redistribution over the surfaces during sliding. For lubricated interfaces, the shear strength increases nearly linearly with contact stress, in agreement with the results of earlier work. The shear strength of stearic acid is found to depend slightly on the combination of sliding materials. Lubricant durability is found to be largest in glass/glass sliding interfaces.

Shear Strength and Tribological Properties of Stearic Acid Films—Part II: On Gold-Coated Glass

1992 ◽  
Vol 114 (1) ◽  
pp. 159-166 ◽  
Author(s):  
R. S. Timsit ◽  
C. V. Pelow
Keyword(s):  
Shear Strength ◽  
Stearic Acid ◽  
Gold Film ◽  
Metal Films ◽  
Vacuum Deposition ◽  
Mechanical Wear ◽  
Compressive Stresses ◽  
Flat Side ◽  
Boundary Lubricant ◽  
Sliding Interfaces

This paper reports measurements of the shear strength of dry and lubricated Au/Au, Al/Au and glass/Au couples from measurements of the frictional force during sliding of a hemispherical pin in contact with a flat side. The Au and Al surfaces are generated by vacuum deposition of thin metal films on glass. Shear strength is measured at a sliding speed of 60 μm s−1 and at contact stresses ranging from ~ 0.05 to 0.8 GPa. Lubrication is achieved by depositing a stearic acid on the slide. The shear strength of dry glass/Au sliding interfaces is found to increase linearly with contact stress but decreases slightly with increasing thickness of the gold film. The shear strength of dry Au/Au interfaces is larger than that of dry glass/Au. Stearic acid does not protect gold from mechanical wear during sliding because the acid is expelled from the gold/gold interface, even at the lowest compressive stresses used. These observations are interpreted in terms of the weak adhesion of stearic acid to gold. In contrast, stearic acid sustains mechanical shear in interfaces consisting of gold sliding on either bare glass or aluminum, to which the acid adheres. These observations suggest that a boundary lubricant film protects against mechanical wear if it adheres only to one of the contacting surfaces.

Formation and tribological properties of octacosanoic acid monomolecular Langmuir–Blodgett films

2021 ◽  
pp. 1-7
Author(s):  
Viktoryia Akulova ◽  
Aliaksandr Salamianski ◽  
Ignat Chishankov ◽  
Vladimir Agabekov
Keyword(s):  
Tribological Properties ◽  
Langmuir Blodgett ◽  
Langmuir Blodgett Films

scholarly journals A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47753-47760 ◽  
Author(s):  
M. C. Righi ◽  
S. Loehlé ◽  
M. I. De Barros Bouchet ◽  
S. Mambingo-Doumbe ◽  
J. M. Martin
Keyword(s):  
Shear Strength ◽  
Comparative Study ◽  
Surface Chemistry ◽  
Tribological Properties ◽  
Experimental Analysis ◽  
First Principles ◽  
Lubricant Additives ◽  
First Principles Calculations

Sulfur reduces the adhesion and shear strength of iron more effectively than phosphorus. The surface chemistry, well described by first principles calculations, impacts macroscale tribological properties.

PREPARATION AND CHARACTERIZATION OF ORGANIC THIN FILM OF STEARIC ACID/PYRAZOLINE NANOPARTICLES

2006 ◽  
Vol 05 (02n03) ◽  
pp. 199-205
Author(s):  
YOUNG SOO KANG ◽  
SUN WHA OH ◽  
JONG HWA SUH
Keyword(s):  
Stearic Acid ◽  
Organic Thin Films ◽  
Solid Substrate ◽  
Organic Thin Film ◽  
Blodgett Film ◽  
Optical Absorbance ◽  
Langmuir Blodgett ◽  
Pressure Area

The organic thin films of stearic acid/pyrazoline nanoparticles were prepared by transferring Langmuir monolayer of stearic acid/pyrazoline nanoparticle onto the solid substrate. The complex of stearic acid/pyrazoline nanoparticle was studied with pressure–area isotherm at the air/water interface and identified with linearly increasing optical absorbance around 370 nm by increasing the number of deposited layers. The in situ domain structure and molecular orientation of the complex were measured with BAM. The surface morphology of the Langmuir–Blodgett film was observed with AFM. The dispersion of pyrazoline nanoparticle in the film was studied with TEM.

New Strategies for Preparing Electrically Conductive Langmuir-Blodgett Films

1992 ◽  
Vol 247 ◽  
Author(s):  
J. H. Cheung ◽  
R. B. Rosner ◽  
M. F. Rubner
Keyword(s):  
Electrical Properties ◽  
Stearic Acid ◽  
Structural Changes ◽  
Solid State Reactions ◽  
Emeraldine Base ◽  
Structure Property ◽  
Electrically Conductive ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Langmuir Blodgett Films

ABSTRACTThe fabrication, structure and electrical properties of new electrically conductive Langmuir-Blodgett (LB) films of polyaniline and polypyrrole have been investigated. Polyaniline in its emeraldine-base form was mixed with stearic acid (PAN-B/SA) to produce stable films at the air-water interface (5/1 or 10/1 mole ratio of PAN-B/SA). These films were then transferred into multilayer films which were found to exhibit conductivities of about 1 S/cm upon doping with hydrochloric acid. The alkyl chains of the stearic acid molecules were found to be distributed randomly throughout the LB film thereby exerting a minimal influence on the electrical properties of the polyaniline phase. In addition to this mixed monolayer approach, a novel method of fabricating highly conductive polypyrrole LB films has been developed. This method is based on the sequential exposure of ferric stéarate LB films to hydrogen chloride (HC1) gas and pyrrole vapor. Each of these two solid state reactions was found to impart dramatic chemical and structural changes to the film. Polypyrrole LB films with conductivities as high as 5 S/cm were produced via this process. The electrical and optical properties of films made by both techniques were examined in order to elucidate their structure/property relationships.

Parametric study of electronics components joining using reactive films for high temperature applications

2019 ◽  
Vol 2019 (HiTen) ◽  
pp. 000016-000021
Author(s):  
Rabih Khazaka ◽  
Donatien Martineau ◽  
Toni Youssef ◽  
Thanh Long Le ◽  
Stéphane Azzopardi
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Film Thickness ◽  
Void Ratio ◽  
Phase Distribution ◽  
Applied Pressure ◽  
Acoustic Microscopy ◽  
External Power Source ◽  
Solder Reflow ◽  
Joint Quality

Abstract In this paper, in order to assemble electronic components onto substrates, a local rapid soldering process using an exothermic reactive foil sandwiched between solder preforms was evaluated. Among others, the main interest of this technique is that it can allow the use of high temperature melting solders, without the need to heat the whole assembly above this melting temperature. The reactive foil is commercially available and is formed from alternatively stacked nanolayers of Ni and Al until it reaches the total film thickness. Once the film is activated by using an external power source, a reaction takes place and releases such an amount of energy that is transferred to the solder preforms. If this amount of energy is high enough, solder preforms melt and insure the adhesion between the materials of the assembly. The process was evaluated using a standard SAC305 and a high temperature Au80Sn20 preforms. The influences of the applied pressure, the reactive film thickness as well as the solder and the attached materials nature and thicknesses were investigated. The initial joint quality was evaluated using scanning acoustic microscopy, scanning electron microscopy, and shear strength measurements. It was shown that the applied pressure during the process has a strong effect on the joint initial quality. The voids ratio between metallized diode dice and an Active Metal Braze (AMB) substrate decreases from 64% to 26% for pressure values between 0.5kPa and 100kPa respectively. Otherwise, under a constant low pressure of 13kPa, reducing the substrate metal thickness on a low thermal conductivity insulator allows the improvement of the initial joint quality and a voids ratio of about 15% was reached when using 35μm of copper on FR4 substrate. The use of aluminum instead of copper as a metal for the ceramic metallized substrate (with the same gold finishing layer) led to a reduction in the void ratio in the joint. The microstructure of the AuSn joint achieved using the reactive films shows very fine phase distribution compared to the one obtained using conventional solder reflow process in the oven. The mechanical properties of the joint were evaluated using shear tests performed on 350μm thick silicon diodes assembled on AMB substrates under a pressure of 100kPa. The reactive films were 60μm thick and were sandwiched between two 25μm thick SAC preforms. The void ratio was about 37% for the tested samples and shear strength values above 9.5MPa were achieved which remains largely higher than MIL-STD-883H requirements. Finally, the process impact on the electrical properties of the assembled diodes was compared with a commonly used solder reflow assembly and results show a negligible variation.

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