scholarly journals The passive state and adhesion

1930 ◽  
Vol 126 (803) ◽  
pp. 630-631 ◽  
Keyword(s):  
Aqueous Solution ◽  
Copper Surface ◽  
Copper Plate ◽  
Passive State ◽  
Metallic Surfaces ◽  
Absolute Alcohol ◽  
Surface Layers ◽  
Copper Surfaces ◽  
Chemical Substances ◽  
Magnesia Powder

In the course of an investigation into the tensile strength of joints formed by thin films of pure chemical substances between surfaces of steel or copper (‘Roy. Soc. Proc.,’ A, vol. 118, p. 209 (1928)), a curious effect due to the production of passivity at a copper surface was noticed. In making such measurements it is, of course, essential that the metallic surfaces should be absolutely clean and dry. Owing to the ease with which copper surfaces acquire a tarnish film, their cleaning presented some difficulty. On one occasion the copper plate was boiled in absolute alcohol and plunged, whilst still hot, into water containing a few drops of concentrated nitric acid, in order that it might cool in a non-tarnishing medium. When taken out, the surface was found to have assumed a uniform dull reddish tint quite unlike the patchy appearance produced by the usual visible tarnish film. This appearance persisted when the plate was boiled in alcohol or water and cooled in air and also when it was left exposed to impure damp air for several hours, i. e. , it survived conditions under which a normal copper surface would have tarnished rapidly. Gentle polishing with very finely divided magnesia powder on silk did not remove the reddish-tint, although abrasion with fine emerypaper, by removing the upper surface layers did. Normality was most conveniently restored by boiling the plate in a 2-5 per cent. aqueous solution of ammonia when the surface tarnished and blackened in patches; this tarnish was removed by polishing with magnesia powder on a wet leather and the process repeated until the surface tarnished uniformly. The surface of the plate, after removal of this tarnish, was found to be normal.

Evaporation of Silver-Graphene Hybrid Nanofluid Droplet on its Nanostructured Residue and Plain Copper Surfaces at Elevated Temperatures

2020 ◽  
Author(s):  
Farooq Riaz Siddiqui ◽  
Chi Yan Tso ◽  
Sau Chung Fu ◽  
Huihe Qiu ◽  
Christopher Yu Hang Chao
Keyword(s):  
Substrate Temperature ◽  
Evaporation Rate ◽  
Elevated Temperatures ◽  
Droplet Evaporation ◽  
Copper Surface ◽  
Copper Plate ◽  
Hybrid Nanofluid ◽  
Copper Surfaces ◽  
Latent Energy ◽  
Droplet Sizes

Abstract Droplet evaporation is an efficient process as it removes a large amount of heat by using the latent energy, making it suitable for heat transfer applications. In this research, evaporation of the silver-graphene hybrid nanofluid (SGHF) droplet, because of its synergistic thermal conductivity, is investigated for substrate temperature in a range of 25–100 °C. The experiments for droplet evaporation were performed in an environmental facility for two droplet sizes, 3 μL and 30 μL volume, on a copper plate. A 100 W silicone heater mat was used to heat the copper plate from the underside, while two T-type thermocouples were used to monitor its surface temperature. As droplet evaporation ended, a porous residue was formed on the copper surface. Subsequently, a 3 μL volume of the SGHF droplet was dispensed on the porous residue surface. The results showed a tremendous rise in the evaporation rate (up to 160%) for the subsequent SGHF droplet sitting on the porous residue as compared to the non-wetted copper surface. Moreover, the evaporation rate of the SGHF droplet on the copper surface increased up to 56% as compared to the water droplet for a substrate temperature range of 25–100 °C.

Rapid Spray Method for Improving Cu-Epoxy Interface Strength

2010 ◽  
Author(s):  
Robert C. Wetherhold ◽  
Elena Pisanova ◽  
Hani Alarifi
Keyword(s):  
Aqueous Solution ◽  
Copper Foil ◽  
Surface Coverage ◽  
Peel Strength ◽  
Copper Surface ◽  
Interface Strength ◽  
Range Effect ◽  
Trade Off ◽  
Copper Surfaces ◽  
Spray Method

A simple spray method using a plain orifice atomizer has been developed for depositing γ-aminopropyltriethoxysilane (APS) from solutions in water and in methanol onto copper surfaces. The peel strengths between copper foil and epoxy resin were measured with and without APS deposition. In all cases, a higher concentration of APS gives higher peel strength. APS applied from 1 wt% solution in methanol resulted in higher peel strength than when applied from a 1 wt% aqueous solution; the opposite was true with 0.2 wt% APS solutions, indicating a trade-off between deposited APS film thickness and surface coverage. APS was very effective when chemisorption occurred at the surface but much less effective when there was only physisorption. A study of the fracture surfaces showed that the failure is cohesive, inside the epoxy layer, and that the deposited APS on the copper surfaces had a long-range effect which was seen deep in the epoxy layer, well away from the copper surface.

The Use of Ratio-Recording Interferometry for the Measurement of Infrared Emission Spectra: Applications to Oxide Films on Copper Surfaces

1975 ◽  
Vol 29 (6) ◽  
pp. 496-500 ◽  
Author(s):  
D. Kember ◽  
N. Sheppard
Keyword(s):  
Emission Spectra ◽  
Black Body ◽  
Infrared Emission ◽  
Thin Layers ◽  
Oxide Surface ◽  
Surface Layers ◽  
Selective Reflection ◽  
Copper Surfaces ◽  
Emission And Absorption Spectra ◽  
Direct Correspondence

Infrared emission spectra from metal samples with oxide surface layers are shown to be very advantageously studied using the spectrum-ratioing facility of a recording infrared interferometer. The emission from a given sample is ratioed against that from a black-body emitter at the same temperature so as to give emittance as a function of wavenumber directly. This method has very useful application to irregularly shaped metal emitters. In the absence of selective reflection there is a direct correspondence between emission and absorption spectra for thin layers of an emitting substance. However, the presence of selective reflection leads to reduced emission and to considerable differences in the appearance of “absorption” and emission spectra in regions of strong absorption. Emission spectra obtained from copper plates heated, above 150°C, for different periods in air are shown clearly to indicate the presence of cuprous, Cu(I), and cupric, Cu(II), oxides in the surface layer.

Pool Boiling Heat Transfer of Water on Hydrophilic Surfaces With Different Wettability

2016 ◽  
Author(s):  
Adam R. Girard ◽  
Jinsub Kim ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Copper Surface ◽  
Contact Angles ◽  
Copper Surfaces ◽  
Nanoscale Structures ◽  
Flat Surfaces ◽  
Hydrophilic Surfaces ◽  
Alkali Solutions

The effect of wettability on boiling heat transfer (BHT) coefficient and critical heat flux (CHF) in pool boiling of water on hydrophilic surfaces having different contact angles was investigated. Hot alkali solutions were utilized to promote cupric and cuprous oxide growth which exhibited micro and nanoscale structures on copper surfaces, with thicknesses on the order of a couple of micrometers. These structure and surface energy variations result in different levels of wettability and roughness while maintaining the effusivity of the bare copper surface. The study showed that the BHT coefficient has an inverse relationship to wettability; the BHT coefficient decreases as wettability increases. Furthermore, it was shown that this dependency between BHT coefficient and wettability is more significant than the relationship between BHT coefficient and surface roughness. The CHF was also found to increase with increases in wettability and roughness. For the most hydrophilic surface tested in this study, CHF values were recorded near the 2,000 kW/m2 mark. This value is compared with maximum values reported in literature for water on non-structured flat surfaces without area enhancements. Based on these results it is postulated that there exists a true hydrodynamic CHF limit for pool boiling with water on flat surfaces, very near 2,000 kW/m2, independent of heater material, representing an 80% increase in the limit suggested by Zuber [1].

Studies of Copper Surfaces modified by Thermal and Plasma Treatments

2000 ◽  
Vol 612 ◽  
Author(s):  
G.P. Beyer ◽  
M. Baklanov ◽  
T. Conard ◽  
K. Maex
Keyword(s):  
Chemical Composition ◽  
Thermal Treatment ◽  
Photoelectron Spectroscopy ◽  
Hydrogen Plasma ◽  
Copper Film ◽  
Copper Surface ◽  
Ex Situ ◽  
Clean Room ◽  
Copper Surfaces ◽  
The Difference

AbstractIt was found that copper surfaces, which had been exposed to a clean room atmosphere, were covered by a layer, whose chemical composition can be described by Cu(OH)2·CuCO3. This layer can effectively be removed by either a short thermal treatment in vacuum at 350°C, a hydrogen plasma treatment, or a combination of both. Ex-situ photoelectron spectroscopy measurements show little difference of the chemical composition of the surface after the respective treatments. The thermal treatment, however, gives rise to re-crystallisation of the copper film due to the difference in temperature of deposition and the anneal. Ex-situ ellipsometry measurements indicate that the hydrogen plasma not only removes Cu(OH)2·CuCO3 but also passivates the copper surface.

Toward Easily Enlarged Superhydrophobic Copper Surfaces with Enhanced Corrosion Resistance, Excellent Self-Cleaning and Anti-Icing Performance by a Facile Method

2020 ◽  
Vol 20 (10) ◽  
pp. 6317-6325 ◽  
Author(s):  
Xueting Shi ◽  
Libin Zhao ◽  
Jing Wang ◽  
Libang Feng
Keyword(s):  
Corrosion Resistance ◽  
Superhydrophobic Surface ◽  
Cost Effective ◽  
Copper Plate ◽  
Plate Surface ◽  
Water Contact ◽  
Copper Surfaces ◽  
Self Cleaning ◽  
Water Repellence

This work reports a facile method for fabricating superhydrophobic surface on copper plate by AgNO3 treatment and dodecyl mercaptan modification. The as-prepared superhydrophobic copper plate presents hierarchical and rough morphology composed of nanosheets and nanoparticleformed matrix. Meanwhile, long alkyl chains are assembled onto the rough surface successfully. Consequently, the copper plate is endowed with excellent superhydrophobic performance with a water contact angle of 156.8° and a rolling angle of ca. 3°. Moreover, the superhydrophobicity has long-term durability and excellent stability. Grounded on the strong water repellence, the resultant superhydrophobic copper plate surface exhibits multi-functions. The excellent performance can be well explained by “Cushion effect” and Capillary phenomena. As a result, water and corrosive species can be prevented from contacting with the copper plate surface, and contaminants can be taken away easily by the rolling water droplets. Meanwhile, the icing process of water is delayed on the superhydrophobic surface. Therefore, the superhydrophobic copper is endued with enhanced corrosion resistance, excellent self-cleaning and anti-icing performance. We believe that this facile method provides a simple and cost-effective process to improve the properties of copper plate, and which may see practical application of the superhydrophobic materials.

Enabling Low Temperature Copper Bonding with an Organic Monolayer

2009 ◽  
Vol 74 ◽  
pp. 133-136 ◽  
Author(s):  
Ang Xiao Fang ◽  
Jun Wei ◽  
Chen Zhong ◽  
Wong Chee Cheong
Keyword(s):  
Bonding Temperature ◽  
Copper Surface ◽  
Mems Devices ◽  
Ambient Conditions ◽  
Copper Surfaces ◽  
Organic Monolayer ◽  
Metallurgical Bonding ◽  
Alternative Approach ◽  
Copper Material ◽  
Joint Integrity

Typically, copper material is used as a bonding material in MEMs devices for its excellent mechanical, electrical and hermetic properties. Direct copper bonding, however, requires high temperature (>300°C) to forge a bond due to the oxidative nature of copper. In this study, using an alternative approach based on an organic monolayer coating, we demonstrate metallurgical bonding between two copper surfaces under ambient condition at low bonding temperature below 140°C, while maintaining reliable mechanical joint integrity of 50MPa. This monolayer is believed to behave as a passivation layer, protecting the copper surface against oxidation under ambient conditions. In contrast to a bulk oxide layer, this layer can be easily displaced during mechanical deformation at the bonding interface.

Microstructure and Properties of Surface Nanostructured Copper

2011 ◽  
Vol 328-330 ◽  
pp. 1606-1609
Author(s):  
Wan Ming Lin ◽  
Yin Hui Wei ◽  
Li Feng Hou
Keyword(s):  
Copper Plate ◽  
Surface Mechanical Attrition Treatment ◽  
Hardness Testing ◽  
Surface Layers ◽  
Materials Properties ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
The Matrix ◽  
Novel Method ◽  
Potentiodynamic Anodic Polarization

Surface nanocrystallization (SNC) is a novel method for improving materials properties. Nanostructured surface layers of about 20 μm thickness were produced in copper plate samples by means of surface mechanical attrition treatment (SMAT). The behaviors of the SMAT samples were investigated by using transmission electron microscopy (TEM), Vickers hardness testing and potentiodynamic anodic polarization tests. The experimental results showed that the longer the peening time was performed on the copper pate samples, the thicker the deformation layers formed. The microhardness results for the top surface layer of the copper plate sample are 1.723 GPa and 1.752 GPa for 45 and 60 min, respectively, which are about two times higher than that of the matrix. The primary passivate potential of nanocrystalline copper was more negative than that of coarse-grain copper.

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