Name: hydrogen charging of aluminum using friction in water
Uploaded: 2020-01-28T14:30:00
Description: Watch this Scientific Journal Video about Hydrogen Charging of Aluminum using Friction in Water at JoVE.com

This work was financially supported in part by The Light Metal Educational Foundation, Inc., Osaka, Japan

1. Material preparation
<ol>
	<li>Use 1 mm thick plates made of an aluminum-magnesium-silicon alloy containing 1 mass% Mg and 0.8 mass% Si (Al-Mg-Si).</li>
	<li>Make test pieces from the Al-Mg-Si alloy plates having a gauge length of 10 mm and width of 5 mm.</li>
	<li>Anneal the test pieces at 520 &#730;C for 1 h using an air furnace. Quench in water as a solution heat treatment.</li>
	<li>Anneal the test pieces at 175 &#730;C for 18 h as a peak aging heat treatment (T6-temper).</li>
	<li>Polish the surface of the test...

<ol>
	<li>Horikawa, K., Matsubara, T., Kobayashi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+charging+of+Al-Mg-Si-based+alloys+by+friction+in+water+and+its+effect+on+tensile+properties.">Hydrogen charging of Al-Mg-Si-based alloys by friction in water and its effect on tensile properties.</a> Materials Science and Engineering A. 764, 138199 (2019).</li><li>Horikawa, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+research+trends+in+aluminum+alloys+for+a+high-pressure+hydrogen+gas+container.">Current research trends in aluminum alloys for a high-pressure hydrogen gas container.</a> Journal of Japan Institute of Light Metals. 60, 542-547 (2010).</li><li>Kuramoto, S., Hsieh, M. C., Kanno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Environmental+embrittlement+of+Al-Mg-Si+base+alloys+deformed+at+low+strain+rates+in+laboratory+air.">Environmental embrittlement of Al-Mg-Si base alloys deformed at low strain rates in laboratory air.</a> Journal of Japan Institute of Light Metals. 52, 250-255 (2002).</li><li>Horikawa, K., Yoshida, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+Hydrogen+in+Tensile-Deformed+Al-5%Mg+Alloy+by+means+of+Hydrogen+Microprint+Technique+with+EBSP+Analysis.">Visualization of Hydrogen in Tensile-Deformed Al-5%Mg Alloy by means of Hydrogen Microprint Technique with EBSP Analysis.</a> Materials Transactions. 45, 315-318 (2004).</li><li>Ueda, K., Horikawa, K., Kanno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suppression+of+high+temperature+embrittlement+of+Al-5%Mg+alloys+containing+a+trace+of+sodium+caused+by+antimony+addition.">Suppression of high temperature embrittlement of Al-5%Mg alloys containing a trace of sodium caused by antimony addition.</a> Scripta Materialia. 37, 1105-1110 (1996).</li><li>Horikawa, K., Ando, N., Kobayashi, H., Urushihara, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+hydrogen+gas+evolution+during+deformation+and+fracture+in+SCM+440+steel+with+different+tempering+conditions.">Visualization of hydrogen gas evolution during deformation and fracture in SCM 440 steel with different tempering conditions.</a> Materials Science and Engineering A. 534, 495-503 (2012).</li><li>Horikawa, K., Yamada, H., Kobayashi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+strain+rate+on+hydrogen+gas+evolution+behavior+during+tensile+deformation+in+6061+and+7075+aluminum+alloys.">Effect of strain rate on hydrogen gas evolution behavior during tensile deformation in 6061 and 7075 aluminum alloys.</a> Journal of Japan Institute of Light Metals. 62, 306-312 (2012).</li><li>Horikawa, K., Okada, H., Kobayashi, H., Urushihara, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+diffusive+hydrogen+in+low+alloy+steel+by+means+of+hydrogen+microprint+technique+at+elevated+temperatures.">Visualization of diffusive hydrogen in low alloy steel by means of hydrogen microprint technique at elevated temperatures.</a> Materials Transactions. 50, 759-764 (2009).</li><li>Horikawa, K., Okada, H., Kobayashi, H., Urushihara, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+hydrogen+during+fatigue+fracture+in+an+Al-Mg-Si+alloy.">Visualization of hydrogen during fatigue fracture in an Al-Mg-Si alloy.</a> Journal of Japan Institute of Light Metals. 56, 210-213 (2006).</li><li>Horikawa, K., Okada, H., Kobayashi, H., Urushihara, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+hydrogen+distribution+in+tensile-deformed+Al-5%Mg+alloy+investigated+by+means+of+hydrogen+microprint+technique+with+EBSP.">Visualization of hydrogen distribution in tensile-deformed Al-5%Mg alloy investigated by means of hydrogen microprint technique with EBSP.</a> Journal of the Japan Institute of Metals. 68, 1043-1046 (2004).</li><li>Yamada, H., Tsurudome, M., Miura, N., Horikawa, K., Ogasawara, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ductility+loss+of+7075+aluminum+alloys+affected+by+interaction+of+hydrogen,+fatigue+deformation,+and+strain+rate.">Ductility loss of 7075 aluminum alloys affected by interaction of hydrogen, fatigue deformation, and strain rate.</a> Materials Science and Engineering A. 642, 194-203 (2015).</li><li>Toda, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+hydrogen+micro+pores+on+mechanical+properties+in+a+2024+aluminum+alloys.">Effects of hydrogen micro pores on mechanical properties in a 2024 aluminum alloys.</a> Materials Transactions. 54, 2195-2201 (2013).</li><li>Yamada, H., Horikawa, K., Matsumoto, T., Kobayashi, H., Ogasawara, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+evolution+behavior+of+tensile+deformation+process+in+6061+and+7075+aluminum+alloys.">Hydrogen evolution behavior of tensile deformation process in 6061 and 7075 aluminum alloys.</a> Journal of Japan Institute of Light Metals. 61, 297-302 (2011).</li><li>Horikawa, K., Kobayashi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+absorption+of+pure+aluminum+by+friction+of+the+surface+in+water+and+its+effect+on+tensile+properties.">Hydrogen absorption of pure aluminum by friction of the surface in water and its effect on tensile properties.</a> Journal of the Japan Institute of Metals. 84, (2020).</li><li>Suzuki, H., Kobayashi, D., Hanada, N., Takai, K., Hagihara, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Existing+state+of+hydrogen+in+electrochemically+charged+commercial-purity+aluminum+and+its+effects+on+tensile+properties.">Existing state of hydrogen in electrochemically charged commercial-purity aluminum and its effects on tensile properties.</a> Materials Transactions. 52, 1741-1747 (2011).</li><li>Horikawa, K., Hokazono, S., Kobayashi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synchronized+monitoring+between+hydrogen+gas+release+and+progress+of+atmospheric+hydrogen+embrittlement+in+7075+aluminum+alloy.">Synchronized monitoring between hydrogen gas release and progress of atmospheric hydrogen embrittlement in 7075 aluminum alloy.</a> Journal of Japan Institute of Light Metals. 66, 77-83 (2016).</li><li>Manaka, T., Aoki, M., Itoh, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+desorption+spectroscopy+study+on+the+hydrogen+behavior+in+a+plasma-charged+aluminum.">Thermal desorption spectroscopy study on the hydrogen behavior in a plasma-charged aluminum.</a> Materials Science Forum. 879, 1220-1225 (2016).</li><li>Ellingham, H. J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reducibility+of+oxides+and+sulphides+in+metallurgical+processes.">Reducibility of oxides and sulphides in metallurgical processes.</a> Journal of the Society of Chemical Industry. 63, 125-133 (1944).</li><li>Pourbaix, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Atlas of electrochemical equilibria in aqueous solutions, Ist ed. , 168-176 (1966).</li><li>Young, G. A., Scully, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+diffusion+and+trapping+of+hydrogen+in+high+purity+aluminum.">The diffusion and trapping of hydrogen in high purity aluminum.</a> Acta Materialia. 46, 6337-6349 (1998).</li><li>Smith, S. W., Scully, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+identification+of+hydrogen+trapping+states+in+an+Al-Li-Cu-Zr+alloy+using+thermal+desorption+spectroscopy.">The identification of hydrogen trapping states in an Al-Li-Cu-Zr alloy using thermal desorption spectroscopy.</a> Metallurgical and Materials Transactions A. 31, 179-193 (2000).</li></ol>

One important aspect of the FW procedure is the attachment of the two specimens to the magnetic stirrer. Because the center of the stirrer bar becomes the non-friction zone, it is best to avoid the attachment of the specimens at the center of the stirrer bar.
Control of the rotation speed of the stirrer bar is also important. When the speed is more than 240 rpm, it becomes difficult to maintain the reaction vessel on the stage of the magnetic stirrer. When the FW procedure is carried out at hi...

In general, aluminum base alloys have higher resistance to environmental hydrogen embrittlement than steel. The high resistance to hydrogen embrittlement of aluminum alloys is due to oxide films on the alloy surface blocking hydrogen entry. To evaluate and compare the high embrittlement sensitivity between aluminum alloys, hydrogen charging is usually performed prior to mechanical testing1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17. However, it is known that hydrogen charging aluminum is not easy, even when utilizing hydrogen charging methods such as cathodic charging15, slow strain rate deformation under humid air16, or hydrogen plasma gas charging17. The difficulty of hydrogen charging aluminum alloys is also due to the oxide films on the aluminum alloy surface. We postulated that higher amounts of hydrogen could be introduced into aluminum alloys if we could remove the oxide film continuously in water. Thermodynamically18, pure aluminum without oxide film reacts easily with water and generates hydrogen. Based on this, we have developed a new method of hydrogen charging of aluminum alloys based on the chemical reaction between water and non-oxide aluminum. This method is able to add high amounts of hydrogen into aluminum alloys in a simple way.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Air furnace</td>
			<td>GC</td>
			<td>QC-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Aluminum alloy plates</td>
			<td>Kobe Steel</td>
			<td></td>
			<td>Al/1.0 mass% Mg/0.8 mass% Si</td>
		</tr>
		<tr>
			<td>Electric balance</td>
			<td>A&#38;D</td>
			<td>HR-200</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass container</td>
			<td></td>
			<td></td>
			<td>Custom made</td>
		</tr>
		<tr>
			<td>Magnetic stirrer</td>
			<td>CORNING</td>
			<td>PC-410D</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical Comparator</td>
			<td>NIKON</td>
			<td>V-12B</td>
			<td></td>
		</tr>
		<tr>
			<td>pH meter</td>
			<td>Sato Tech</td>
			<td>PH-230SDJ</td>
			<td></td>
		</tr>
		<tr>
			<td>Quartz tube</td>
			<td></td>
			<td></td>
			<td>Custom made</td>
		</tr>
		<tr>
			<td>Rotary polishing machine</td>
			<td>IMT</td>
			<td>IM-P2</td>
			<td></td>
		</tr>
		<tr>
			<td>Secondary electrom microscope</td>
			<td>JOEL</td>
			<td>JSM-5310LV</td>
			<td></td>
		</tr>
		<tr>
			<td>Sensor gas chromatograph</td>
			<td>FIS Inc.</td>
			<td>SGHA</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicon carbide emery paper</td>
			<td>IMT</td>
			<td>531SR</td>
			<td></td>
		</tr>
		<tr>
			<td>Tensile testing machine</td>
			<td>Toshin Kogyo</td>
			<td>SERT-5000-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubular furnace</td>
			<td>Honma Riken</td>
			<td></td>
			<td>Custom made</td>
		</tr>
	</tbody>
</table>

hydrogen charging of aluminum using friction in water

A new method of hydrogen charging of aluminum was developed by means of a friction in water (FW) procedure. This procedure can easily introduce high amounts of hydrogen into aluminum based on the chemical reaction between water and non-oxide coated aluminum.

Hydrogen generation/absorption by the FW procedure 
Figure 2 shows the hydrogen generation behavior during the FW procedure of Al-Mg-Si alloys containing different amounts of iron from 0.1 mass % to 0.7 mass %. The specimen continuously emitted a high amount of hydrogen when the stirrer started to rotate. This suggests that hydrogen was generated by a chemical reaction caused by the friction between the alloy surface and water. In addition, the pH value of the water dur...

Watch this Scientific Journal Video about Hydrogen Charging of Aluminum using Friction in Water at JoVE.com

Hydrogen Charging of Aluminum using Friction in Water

In order to introduce high amounts of hydrogen in aluminum and aluminum alloys, a new method of hydrogen charging was developed, called the friction in water procedure.

A new method of hydrogen charging of aluminum was developed by means of a friction in water (FW) procedure. This procedure can easily introduce high ...

When charging aluminum alloys with hydrogen, the presence of oxide film on the surface is a challenge. To solve this problem, we have developed a method that can introduce high amount of hydrogen into aluminum alloys using friction in water. The method is easiest to understand when the rotation of the stir bar and the specimen on the polishing paper can be visualized.Success depends on stabilizing the rotation of the stir bar. Demonstrating the procedure will Ms.Michiko Arayama, an undergraduate student from my laboratory. Fabricate the aluminum alloy test pieces as described in the text.Perform a solution heat treatment by heating the test pieces in an air furnace at 520 degrees Celsius for one hour and then quenching the test pieces in water. For the next step, the peak-aging heat treatment, anneal the test pieces at 175 degrees Celsius for 18 hours. The final step in preparing the test pieces is polishing the surface using silicon carbide emery paper.Before proceeding to the friction in water procedure, weigh and measure the test pieces. Use an electric balance to weigh the test pieces to a precision of 0.0001 grams. Use an optical comparator to measure the thickness and width of the test pieces to a precision of 0.0001 millimeters.The friction in water procedure is carried out in a magnetically stirred custom-made reaction vessel. To begin, use glue to attach two test pieces to a fluorocarbon polymer triangular stir bar. Next, prepare the reaction vessel, a custom-made glass container.Use double-sided tape to attach polishing paper to the inside bottom of the reaction vessel. Place the reaction vessel on the magnetic stirrer. Then place the test pieces and stir bar on top of the polishing paper and the reaction vessel, and add 100 milliliters of distilled water.Place the rubber cover on the reaction vessel. Connect the gas inlet to high-purity argon, and turn on the gas. Connect the gas outlet to a gas chromatograph.Inset the pH probe into the vessel through the rubber cover. Turn on the argon. Once the gas in the reaction vessel as been completely replaced by the argon, the apparatus is ready for charging the aluminum alloy test pieces.Turn on the magnetic stirrer. To stabilize movement of the stir bar in the water, controlling the rotation speed is important. A speed ranging from 60 rpm to 240 rpm is best.Every two minutes, measure the hydrogen concentration using the gas chromatograph, and measure the pH. After one hour, turn off the magnetic stirrer, and remove the test pieces and stir bar from the reaction vessel. To detach the test pieces from the stir bar, immerse them in acetone, and apply ultrasonic vibration for five minutes.Before proceeding to the next step, measure the weight and thickness of the test pieces. Use a tensile test machine to measure the material properties of the test pieces. Set the crosshead speed of the machine to two millimeters per minute.Then measure the stress-strain relationship for the test pieces. To calculate the amount of hydrogen absorbed during the friction in water procedure, first measure the hydrogen released by the test pieces when heated. Cut the test piece to a rectangular shape of one by five by 10 millimeters.Place the test piece inside a quartz tube with a diameter of 10 millimeters, and place the quartz tube in a tubular furnace. Connect the tube to the gas chromatograph and to the argon gas supply. Turn on the flow of argon gas.Heat the quartz tube containing the test piece, increasing the temperature at a constant rate of 200 degrees Celsius per hour until it reaches a temperature of 625 degrees Celsius. While the quartz tube and test piece are being heated, use the gas chromatograph to measure the hydrogen released every two minutes. Aluminum-magnesium-silicon alloys with three different iron concentrations were subjected to the friction in water procedure, 0.1%iron, 0.2%iron, and 0.7%iron.Regardless of the iron concentration, the test pieces emitted large amounts of hydrogen during the procedure. Thermal desorption analysis was performed on both uncharged and hydrogen-charged samples. Regardless of the iron concentration of the alloy, the total hydrogen concentration increased as a result of the friction in water procedure.Compared to the method of pre-stained in humid air, friction in water is an effective method of hydrogen charging an aluminum alloy. Thermal desorption analysis showed a higher hydrogen release rate for alloy charged using the friction in water procedure, and the calculated hydrogen concentration was substantially higher. Compared to uncharged alloy samples, hydrogen-charged alloy samples showed lower ductility.This indicates that the friction in water procedure resulted in hydrogen embrittlement. Secondary electron microscopy was used to examine the fracture morphology of aluminum-magnesium-silicon alloy containing 0.1%iron. After the friction in water procedure, the morphology changed to a grain boundary fracture.This indicates that hydrogen atoms introduced by the friction in water procedure enhanced the decohesion of grain boundaries, leading to hydrogen embrittlement. It is possible to hydrogen-charge aluminum alloys through exposure and humid air with brittle deformation with a slow stirring rate. However, the current method result in a greater amount of hydrogen charging.This method makes it easy for researchers to evaluate the hydrogen embrittlement sensitivity of aluminum alloys that have a variety of different chemical compositions. It may be applied to the development of hydrogen storage materials.

hydrogen-charging-of-aluminum-using-friction-in-water

Research

JoVE Journal

Engineering

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids

Horizontal and vertical liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields (8-20 kV/cm) and polar dielectric liquids. These bridges are unique from capillary bridges in that they exhibit extensibility beyond a few millimeters, have complex bi-directional mass transfer patterns, and emit non-Planck infrared radiation. A number of common solvents can form such bridges as well as low conductivity solutions and colloidal suspensions. The macroscopic behavior is governed by electrohydrodynamics and provides a means of studying fluid flow phenomena without the presence of rigid walls. Prior to the onset of a liquid bridge several important phenomena can be observed including advancing meniscus height (electrowetting), bulk fluid circulation (the Sumoto effect), and the ejection of charged droplets (electrospray). The interaction between surface, polarization, and displacement forces can be directly examined by varying applied voltage and bridge length. The electric field, assisted by gravity, stabilizes the liquid bridge against Rayleigh-Plateau instabilities. Construction of basic apparatus for both vertical and horizontal orientation along with operational examples, including thermographic images, for three liquids (e.g., water, DMSO, and glycerol) is presented.

Horizontal and vertical electrohydrodynamic liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields and polar dielectric liquids. The construction of basic apparatus and operational examples, including thermographic images, for three liquids (e.g., water, DMSO, and glycerol) is presented.

Horizontal and vertical liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields (8-20 kV/cm) and ...

Casting Protocols for the Production of Open Cell Aluminum Foams by the Replication Technique and the Effect on Porosity

Metal foams are interesting materials from both a fundamental understanding and practical applications point of view. Uses have been proposed, and in many cases validated experimentally, for light weight or impact energy absorbing structures, as high surface area heat exchangers or electrodes, as implants to the body, and many more. Although great progress has been made in understanding their structure-properties relationships, the large number of different processing techniques, each producing material with different characteristics and structure, means that understanding of the individual effects of all aspects of structure is not complete. The replication process, where molten metal is infiltrated between grains of a removable preform material, allows a markedly high degree of control and has been used to good effect to elucidate some of these relationships. Nevertheless, the process has many steps that are dependent on individual &#8220;know-how&#8221;, and this paper aims to provide a detailed description of all stages of one embodiment of this processing method, using materials and equipment that would be relatively easy to set up in a research environment. The goal of this protocol and its variants is to produce metal foams in an effective and simple way, giving the possibility to tailor the outcome of the samples by modifying certain steps within the process. By following this, open cell aluminum foams with pore sizes of 1&#8211;2.36 mm diameter and 61% to 77% porosity can be obtained.

Replication is one of the processing techniques used for the production of porous metal sponges. In this paper one implementation of the method for the production of open celled porous aluminum is shown in detail.

Metal foams are interesting materials from both a fundamental understanding and practical applications point of view. Uses have been proposed, and in many ...

Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone.

The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low ...

Reaction Kinetics and Combustion Dynamics of I4O9 and Aluminum Mixtures

Tetraiodine nonoxide (I4O9) has been synthesized using a dry approach that combines elemental oxygen and iodine without the introduction of hydrated species. The synthesis approach inhibits the topochemical effect promoting rapid hydration when exposed to the relative humidity of ambient air. This stable, amorphous, nano-particle material was analyzed using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) and showed an exothermic energy release at low temperature (i.e., 180 &#176;C) for the transformation of I4O9 into I2O5. This additional exothermic energy release contributes to an increase in overall reactivity of I4O9 when dry mixed with nano-aluminum (Al) powder, resulting in a minimum of 150% increase in flame speed compared to Al + I2O5. This study shows that as an oxidizer, I4O9 has more reactive potential than other forms of iodine(V) oxide when combined with Al, especially if I4O9 can be passivated to inhibit absorption of water from its surrounding environment.

Reaction Kinetics and Combustion Dynamics of I4O9 and Aluminum Mixtures

A protocol for measuring flame speeds of a reactive mixture composed of tetraiodine nonoxide (I4O9) and aluminum (Al) is presented. A method for resolving reaction kinetics using differential scanning calorimetry (DSC) is also presented. It was found that I4O9 is 150% more reactive than other iodine(V) oxides.

Tetraiodine nonoxide (I4O9) has been synthesized using a dry approach that combines elemental oxygen and iodine without the introduction of hydrated ...

Experimental Procedure for Warm Spinning of Cast Aluminum Components

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to improve material properties. With a wide array of processing parameters which can affect both the shape attained and resulting material properties, this type of processing is notoriously difficult to commission. A simplified, light-duty version of the process has been designed and implemented for full-size automotive wheels. The apparatus is intended to assist in understanding the deformation mechanisms and the material response to this type of processing. An experimental protocol has been developed to prepare for, and subsequently perform forming trials and is described for as-cast A356 wheel blanks. The thermal profile attained, along with instrumentation details are provided. Similitude with full-scale forming operations which impart significantly more deformation at faster rates is discussed.

An experimental protocol for instrumented warm rotary forming of cast aluminum alloys employing a bespoke industrially scaled apparatus is presented. Experimental considerations including thermal and mechanical effects are discussed, as well as similitude with full-scale processing of automotive wheels.

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to ...

Simultaneous Multi-surface Anodizations and Stair-like Reverse Biases Detachment of Anodic Aluminum Oxides in Sulfuric and Oxalic Acid Electrolyte

After reporting on the two-step anodization, nanoporous anodic aluminum oxides (AAOs) have been widely utilized in the versatile fields of fundamental sciences and industrial applications owing to their periodic arrangement of nanopores with relatively high aspect ratio. However, the techniques reported so far, which could be only valid for mono-surface anodization, show critical disadvantages, i.e., time-consuming as well as complicated procedures, requiring toxic chemicals, and wasting valuable natural resources. In this paper, we demonstrate a facile, efficient, and environmentally clean method to fabricate nanoporous AAOs in sulfuric and oxalic acid electrolytes, which can overcome the limitations that result from conventional AAO fabricating methods. First, plural AAOs are produced at one time through simultaneous multi-surfaces anodization (SMSA), indicating mass-producibility of the AAOs with comparable qualities. Second, those AAOs can be separated from the aluminum (Al) substrate by applying stair-like reverse biases (SRBs) in the same electrolyte used for the SMSAs, implying simplicity and green technological characteristics. Finally, a unit sequence consisting of the SMSAs sequentially combined with SRBs-based detachment can be applied repeatedly to the same Al substrate, which reinforces the advantages of this strategy and also guarantees the efficient usage of natural resources.

A protocol for fabricating nanoporous anodic aluminum oxides via simultaneous multi-surfaces anodization followed by stair-like reverse biases detachments is presented. It can be applied repeatedly to the same aluminum substrate, exhibiting a facile, high-yield, and environmentally clean strategy.

After reporting on the two-step anodization, nanoporous anodic aluminum oxides (AAOs) have been widely utilized in the versatile fields of fundamental ...

In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is known about the effects of high pressure hydrogen on the polymer sealing and barrier materials also found within these components. More study is required in order to determine the compatibility of common polymer materials found in the components of the hydrogen fuel delivery infrastructure with high pressure hydrogen. As a result, it is important to consider the changes in physical properties such as friction and wear in situ while the polymer is exposed to high pressure hydrogen. In this protocol, we present a method for testing the friction and wear properties of ethylene propylene diene monomer (EPDM) elastomer samples in a 28 MPa high pressure hydrogen environment using a custom-built in situ pin-on-flat linear reciprocating tribometer. Representative results from this testing are presented which indicate that the coefficient of friction between the EPDM sample coupon and steel counter surface is increased in high pressure hydrogen as compared to the coefficient of friction similarly measured in ambient air.

In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure

A test methodology for quantifying tribological properties of polymers used in hydrogen infrastructure service is demonstrated and characteristic results for a common elastomer are discussed.

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is ...

Determining Tribocorrosion Rate and Wear-Corrosion Synergy of Bulk and Thin Film Aluminum Alloys

The increasing complexity and severity of service conditions in areas, such as aerospace and marine industries, nuclear systems, microelectronics, batteries, and biomedical devices, etc., impose great challenges on the reliable performance of alloys exposed to extreme conditions where mechanical and electrochemical attack co-exist. Finding ways for alloys to mitigate the combined attack of wear and corrosion (i.e., tribocorrosion) under such extreme conditions is thus highly critical for improving their reliability and service lifetime when used in such conditions. The challenge lies in the fact that wear and corrosion are not independent of each other, but rather work synergistically to accelerate the total material loss. Thus, a reliable method to evaluate the tribocorrosion resistance of metals and alloys is needed. Here, a protocol for measuring the tribocorrosion rate and wear-corrosion synergy of Al-based bulk and thin film samples in a corrosive environment under room temperature is presented.

Here, we present a protocol to measure the tribocorrosion rate and wear-corrosion synergy of thin film and bulk Al alloys in simulated sea water at room temperature.

The increasing complexity and severity of service conditions in areas, such as aerospace and marine industries, nuclear systems, microelectronics, ...

Generating Lap Joints Via Friction Stir Spot Welding on DP780 Steel

Friction stir spot welding (FSSW), a derivative of friction stir welding (FSW), is a solid-state welding technique that was developed in 1991. An industry application was found in the automotive industry in 2003 for the aluminum alloy that was used in the rear doors of automobiles. Friction stir spot welding is mostly used in Al alloys to create lap joints. The benefits of friction stir spot welding include a nearly 80% melting temperature that lowers the thermal deformation welds without splashing compared to resistance spot welding. Friction stir spot welding includes 3 steps: plunging, stirring, and retraction. In the present study, other materials including high strength steel are also used in the friction stir welding method to create joints. DP780, whose traditional welding process involves the use of resistance spot welding, is one of several high strength steel materials used in the automotive industry. In this paper, DP780 was used for friction stir spot welding, and its microstructure and microhardness were measured. The microstructure data showed that there was a fusion zone with fine grain and a heat effect zone with island martensite. The microhardness results indicated that the center zone exhibited a greater degree of hardness compared with the base metal. All data indicated that the friction stir spot welding used in dual phase steel 780 can create a good lap joint. In the future, friction stir spot welding can be used in high-strength steel welding applied in industrial manufacturing processes.

Here, we present a friction stir spot welding (FSSW) protocol on dual phase 780 steel. A tool pin with high-speed rotation generates heat from friction to soften the material, and then, the pin plunges into 2 sheet joints to create the lap joint.

Friction stir spot welding (FSSW), a derivative of friction stir welding (FSW), is a solid-state welding technique that was developed in 1991. An industry ...