The corresponding author would like to acknowledge the Mexican Government&#8217;s National Council of Science and Technology CONACYT for provision of a scholarship.

NOTE: The instructions below are for Protocol A (Figure 1). Modifications for Protocol B, C, and D are listed as well.
1. Aluminum Bar Preparation
<ol>
	<li>Place a large piece (500 g &#8211; 1 kg) of commercial purity aluminum ingot into a crucible.</li>
	<li>Place the crucible in a furnace at 800 &#176;C for about 1 hr, until molten.</li>
	<li>Take the crucible out of the furnace and pour the molten aluminum into a cylindrical mold that is 50 mm in diameter, slightly smaller than the final diameter of the chamber to be used for infiltration (51 mm) giving a gap of about &#189; mm.</li>
	<li>Wait 1 hr for the bar to cool down.</li>
	<li>Remove the bar from the mold.</li>
	<li>Using a band saw, cut it into 4 same-size pieces.</li>
	<li>Sand the edges of each piece to ensure a good fit in the infiltration mold.</li>
</ol>
2. Furnace Preparation
<ol>
	<li>Program the furnace to reach a 740 &#176;C plateau for at least 2 hr.</li>
	<li>Set the heating rate of the furnace to 20 &#176;C/min.</li>
</ol>
3. Preform Preparation
NOTE: Depending on the height of the foam aimed for, vary the amount of NaCl to use for infiltration between 100 g and 300 g.
<ol>
	<li>Choose the infiltration NaCl to use, with a diameter corresponding to the pore size range required (for example a range between 1.4 mm and 1.7 mm). The material can be obtained from chemical suppliers in high purity, or supermarket bought table salt can be used (such material will have additives such as iodine and anti-caking agents, but these do not in practice influence the process to a significant extent).</li>
	<li>Select sieves of an appropriate size range and stack on a base container with the smaller opening size at the bottom.</li>
	<li>From the suppliers&#8217; bag of NaCl, take approximately 500 g and pour it in the stacked sieves.</li>
	<li>Agitate the sieves, either manually or using a sieve shaker, for 1 min.</li>
	<li>Discard the NaCl left in the larger aperture size sieve and the bottom container, the NaCl left in the smaller aperture sieve is used for infiltration.</li>
	<li>Weigh the amount of infiltration NaCl obtained.</li>
	<li>If the amount is insufficient, repeat steps 3.4 to 3.7. 
	NOTE: For Protocols B, C or D, obtain 100 g of fine NaCl (&#60; 500 &#181;m). This creates an extra space in the mold for air trapped in the preform during infiltration in case the air in the preform does not escape the chamber adequately.</li>
</ol>
4. Mold Preparation
<ol>
	<li>Using sandpaper and laboratory paper roll, clean the mold cylinder (Figure 2), taking special consideration for both the top and bottom edges, and keeping the mold free of any noticeable impurities from previous use.</li>
	<li>Spray the inside of the mold cylinder with boron nitride aerosol spray, creating a thin coat covering the inside of the mold. 
	NOTE: This is achieved when the original color of the mold is replaced by a white layer of the spray; it is not necessary to measure its specific concentration.</li>
	<li>Let the mold cylinder dry for at least 5 min at RT (heating to around 100 &#176;C for up to 1 hr may be applied for further drying if desired).</li>
	<li>Using fine sandpaper, remove any residue of boron nitride from the edges of the mold cylinder, to improve the seal between the mold cylinder and the mold base. 
	NOTE: The next 3 steps are for Protocols A and B; for Protocols C and D cut only one gasket ring for the lid.</li>
	<li>Cut 2 gasket rings from 1 mm thick graphite sheet (OD = 60 mm, ID = 51 mm), one for the union between the top edge of the mold cylinder and the mold lid leading up to the valve system, the other for the union between the bottom edge of the mold cylinder and the mold base.</li>
	<li>Place one of the gaskets in the mold base groove.</li>
	<li>Place the bottom of the mold cylinder into the groove with the gasket.</li>
	<li>Tap lightly with a mallet on the top of the mold cylinder to secure the bottom to the base groove. 
	NOTE: For Protocol B, C, or D, add the following step.
	<ol>
		<li>Pour the 100 g of fine NaCl (&#60; 500 &#181;m) into the mold cylinder and flatten the top with an uncut aluminum bar tapping the top of it lightly with the mallet to ensure the fine NaCl is packed to a high density. 
		NOTE: For Protocol D add the following step.</li>
		<li>Cut 2 circles of soft 2 mm thick ceramic Kaowool blanket the size of the mold diameter (51 mm) and place them on top of the fine NaCl, use the uncut aluminum bar and the mallet to press them against the fine NaCl.</li>
	</ol>
	</li>
	<li>Pour the NaCl to be infiltrated into the mold cylinder. 
	NOTE: For Protocol D add the following step.
	<ol>
		<li>Attach the mold and base to a vibrating table, making sure the mold cylinder does not move from the base groove. Vibrate for 1 min at 50 Hz with a 0.01 m amplitude.</li>
	</ol>
	</li>
	<li>Holding the top of the cylinder in place, pick up the base and shake lightly until the NaCl inside the mold forms a flat surface at the top.</li>
	<li>Place the prepared aluminum bar on top of the NaCl preform.</li>
	<li>Place a graphite gasket in the groove of the mold lid.</li>
	<li>By hand screw the 4 stainless steel studs to the base and secure them with 4 sets of stainless steel nuts and washers on the top of the base using a wrench and place the mold lid on top of the mold cylinder through the studs.</li>
	<li>With a torque wrench set at 16 N&#183;m, screw the 4 sets of steel nuts and washers on the 4 threaded rods screwed into the base and extending up through the lid, where the nuts are tightened to lock the mold lid in place.</li>
	<li>Attach the top of the lid to the valve system with the gasket, clamp, bolt and butterfly nut.</li>
	<li>Close all the valves of the system.</li>
	<li>Open the valve leading to the vacuum pump and the mold (valve 3).</li>
	<li>Turn on the vacuum pump until the dial gauge of the valve system indicates the lowest pressure possible.</li>
	<li>Turn off the vacuum pump.</li>
	<li>If the loss of vacuum in the system is lower than a rate of 50 Torr/sec for the first 10 sec after shutting down the vacuum pump the seal is sufficiently good for infiltration.</li>
	<li>Leave the lid valve open (valve 3) to keep the system at ambient pressure and close the vacuum pump valve (valve 1).</li>
	<li>Without detaching the valve system, place the mold in the preheated furnace and wait for 1 hr.</li>
</ol>
5. Infiltration
<ol>
	<li>Close all the valves of the system (Figure 3).</li>
	<li>Open the valve leading to the argon gas cylinder (valve 2).</li>
	<li>Open the main valve on the argon gas tank and set the infiltration pressure with the regulator valve (for a range of 1.4 mm to 1.7 mm of NaCl particle size, use a pressure of 3.5 bars). 
	NOTE: For Protocol B, an infiltration pressure of 3 bar is used. Use a pressure of 1 bar for Protocols C and D.</li>
	<li>In a swift manner, open the lid valve (valve 3).</li>
	<li>After 1 min, remove the mold from the furnace and place it on top of a cooling surface (in this case a copper block). 
	NOTE: While cooling, the pressure in the system will change. For the first 5 min of this process, pay close attention to the pressure indicated by the regulator and adjust back to the infiltration pressure if necessary.</li>
</ol>
6. Sample Extraction
<ol>
	<li>After 30 min, when the mold is cool enough to handle with light heat resistant gloves, detach the valve system and place the mold base on a workbench vise. Unscrew the lid from the top of the cylinder.</li>
	<li>With the lid off, lightly tap the top of the mold cylinder with a mallet in a perpendicular direction to the vise&#8217;s grip to loosen the mold cylinder from the base groove.</li>
	<li>Remove the mold base from the vise and place the mold cylinder in the vise grip.</li>
	<li>With the mallet tap the remaining aluminum on top of the sample to push it out of the mold cylinder.</li>
	<li>Using a band saw, cut the bottom part of the foam sample, removing the surplus aluminum.</li>
	<li>Depending on the height of foam required, cut where desired, close to the top of the sample.</li>
	<li>Place the infiltrated foam in a beaker with water and a magnetic stirring bar on a stirring hot plate to dissolve the NaCl preform.</li>
	<li>Set the temperature of the hot plate to 60 &#176;C. Change the water every 10 min until there is no NaCl left in the foam. 
	NOTE: To ensure there is no NaCl left in the foam, change the water approximately 10 times. It is also possible to make periodic checks of the sample weight after a brief drying stage. When this ceases to change significantly with further immersion, the NaCl must be completely removed.</li>
	<li>Finally using an electric air drier remove all the water left in the foam. The foam sample is ready.</li>
</ol>

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The authors declare that they have no competing financial interests.

The basic method described here has been used in different forms by other researchers. Some of the key variants that allow foams of different types to be created are discussed. In characterizing these foams we have measured the porosity, as this is a quick and easy assessment to make, but characterization of other structural characteristics, such as pore size, specific surface area or strut thickness might be required to obtain a full understanding of foam characteristics for different applications. In practice, for prod...

A journal reference was corrected in the publication of <a href="http://www.jove.com/video/52268">Casting Protocols for the Production of Open Cell Aluminum Foams by the Replication Technique and the Effect on Porosity</a>. Reference 21 and 22 were originally merged together as one reference. They have been separated into references 21 and 22 in the article. The reference numbers have been updated in the article to reflect this additional reference citation. It has been updated from:
<ol start="21"><li>LeMay, J.D., Hopper, R.W., Hrubesh, L.W., &#38; Pekala, R.W. Low-Density Microcellular Materials. Materials Research Society Bulletin. 15 (12), 19&#8211;20 (1990).Seliger, H., &#38; Deuther U. Die Herstellung von Schaum- und Zellaluminium. Feiburger Forschungshefte. 103&#8211;129 (1965).</li></ol>
to:
<ol start="21"><li>LeMay, J.D., Hopper, R.W., Hrubesh, L.W., &#38; Pekala, R.W. Low-Density Microcellular Materials. Materials Research Society Bulletin. 15 (12), 19&#8211;20 (1990).</li>
<li>Seliger, H., &#38; Deuther U. Die Herstellung von Schaum- und Zellaluminium. Feiburger Forschungshefte. 103&#8211;129 (1965).</li></ol>

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

Metal foams have attracted a large amount of interest and research effort in recent years as shown by the large body of work cited in wide ranging review articles such as Banhart1, Conde et al.2 or more recently Goodall and Mortensen3. Among the methods used for production of the material, the replication process is distinguished by its experimental simplicity and the degree of control over the final foam structure that can be offered. It should be noted that although in the literature such materials are often described as foams (and are here) as they are not produced by bubbles of gas within a liquid they are more appropriately called porous metals or microcellular metals.
The first report of the replication process was in the early 1960s4, and it has been developed further at different stages since then, with notable advances by the research group of Mortensen at the Ecole Polytechnique Federale de Lausanne in Switzerland.
The process relies on the casting of the metal around a preform of particles that defines the shape of the porosity in the final material2, 5. After cooling the preform can be removed by solvent leaching or pyrolysis that causes oxidation. A popular use of this technique utilizes NaCl as a space holder to produce aluminum5-10 or aluminum alloy foams11-14. NaCl has several advantages such as being readily accessible, non-toxic and can be removed from the foam by dissolution in water. By having a melting point of 801 &#176;C, it can be used with metals that have a melting point lower than this value, most commonly aluminum, but examples also exist of the use with materials such as bulk metallic glasses, by humidifying a mix of liquid palladium-based bulk metallic glass alloy and NaCl granules15. Substitution of the NaCl with higher melting point materials also permits the production of foams from higher melting point metals16. This may include other water-soluble materials, or insoluble ones including different types of sand. In this form the process becomes more like conventional sand casting as to remove the sand, high pressure water jets17, 18 or different forms of washing19 or agitating20 are required.
The essential process21 proceeds by taking grains of NaCl and placing them in a mold4, 22, 23. The basic method has been used to make aluminum and aluminum alloy foams24-26 for a wide range of foam behavior investigations. Additional steps have been introduced to further control the density and to increase the interconnectivity of the pores; these include the densification of the preform. To densify the preform, sintering has been employed27, 28 and has been used in different experiments since13, with the sintering behavior of NaCl based on temperature, granule size and density described by Goodall et al.29. Another method used for this purpose is cold isostatic pressing (CIP)5, 30; this is a faster technique that can achieve a larger spectrum of comparable densities. The procedure can also be performed in the solid state with metal powder and NaCl grains, and is then sometimes called the Sintering and Dissolution Process31.
A full survey of the use of the replication technique to date and comparison with other techniques is given in Goodall and Mortensen3.
In this work we report in detail equipment and experimental protocols that have been used for the processing of metal foams by the replication method, and which are relatively easy to implement in a research laboratory setting. It is important to acknowledge that other versions of the equipment, with different capabilities exist in other research groups, and that while the equipment presented here is suitable to process the material, it is not the only version or protocol that can be made to work. In any case, a thorough understanding of any particular method is essential for experimental success.
The precise protocols used are detailed below. The protocol variations (A, B, C and D) have small changes between them, principally intended to alter the density of the foams produced. The porosity has been calculated from measurements of the bulk weight of the samples, their volume and the density of aluminum (2.7 g/cm3). In developing the methods described for aluminum foam production by replication, attempts have been made to reduce the amount of advanced equipment to the smallest possible extent, such that the method is as easy to implement as possible. Other variations that may be used at different stages are discussed later.

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	<tbody>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Name of Reagent/ Equipment</td>
			<td style="width:187px;">Company</td>
			<td style="width:429px;">Catalog Number</td>
			<td style="width:833px;">Comments/Description</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Salt</td>
			<td style="width:187px;">Hydrosoft</td>
			<td style="width:429px;">Granular Salt 25 kg 855754</td>
			<td>http://www.travisperkins.co.uk/p/hydrosoft-granular-salt-25kg/855754/3893446</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Aluminum</td>
			<td style="width:187px;">William Rowland</td>
			<td style="width:429px;">Aluminum Ingots 99.87% pure 25 kg drum</td>
			<td>http://www.william-rowland.com/products/high-purity-metals#product-id-1</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Crucible</td>
			<td style="width:187px;">Morgan Advance Materials</td>
			<td style="width:429px;">Syncarb Crucible</td>
			<td>http://www.morganmms.com/crucibles-foundry-products/crucibles/syncarb/</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Furnace</td>
			<td style="width:187px;">Elite Thermal Systems</td>
			<td style="width:429px;">TLCF10/27-3216CP &#38; 2116 O/T</td>
			<td>http://www.elitefurnaces.com/eng/products/furnaces/1200%20Top%20Loading%20Furnaces.php</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Bar Mold</td>
			<td style="width:187px;">The University of Sheffield</td>
			<td style="width:429px;">Custom Made</td>
			<td>Stainless Steel 304, 15 cm height, 5 cm inner diameter, 6 cm outer diameter</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Band Saw</td>
			<td style="width:187px;">Clarke</td>
			<td style="width:429px;">CBS45MD (6&#34; x 4 1/2&#34;) 370W 060710025</td>
			<td>http://www.machinemart.co.uk/shop/product/details/cbs45md-41-2in-x-6in-metal-cutting-ban</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Sandpaper</td>
			<td style="width:187px;">Wickes</td>
			<td style="width:429px;">Specialist wet &#38; dry sandpaper 501885</td>
			<td>http://www.wickes.co.uk/Specialist-Wet+Dry-Sandpaper-PK4/p/501885</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Sieves</td>
			<td style="width:187px;">Fisher Scientific</td>
			<td style="width:429px;">Fisherbrand test sieves 200 mm diamater</td>
			<td>http://www.fisher.co.uk/product/brand_listing.php/F/Fisherbrand/Sieve</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Balance</td>
			<td style="width:187px;">Precisa</td>
			<td style="width:429px;">XB 6200C</td>
			<td>http://www.precisa.co.uk/precision_balances.php</td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">Boron Nitride</td>
			<td style="width:187px;">Kennametal</td>
			<td style="width:429px;">500 ml spray can</td>
			<td style="width:833px;">http://www.kennametal.com/content/dam/kennametal/kennametal/common/Resources/Catalogs-Literature/Advanced%20Materials%20and%20Wear%20Components/B-13-03401_ceramic_powders 
			_brochure_EN.pdf</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Infiltration Mold, Base and Lid</td>
			<td style="width:187px;">The University of Sheffield</td>
			<td style="width:429px;">Custom Made</td>
			<td>Stainless Steel 304, 15 cm height, 5.1 cm inner diameter, 6 cm outer diameter</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Cylindrical Mold</td>
			<td style="width:187px;">The University of Sheffield</td>
			<td style="width:429px;">Custom Made</td>
			<td>Low carbon steel 1020, 15 cm height, 5 cm inner diameter, 6 cm outer diameter</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Graphite Gasket</td>
			<td style="width:187px;">Gee Graphite</td>
			<td style="width:429px;">Geegraf Stainless Steel Reinforced Graphite 1 mm thick</td>
			<td>http://www.geegraphite.com/steel_reinforced.html</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Mallet</td>
			<td style="width:187px;">Thor Hammer Co. Ltd.</td>
			<td style="width:429px;">Round Solid Super Plastic Mallet</td>
			<td>http://www.thorhammer.com/Mallets/Round/</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Wrench</td>
			<td style="width:187px;">Kennedy Professional</td>
			<td style="width:429px;">13 mm Ratchet Combination Wrench KEN5822166K</td>
			<td>https://www.cromwell.co.uk/KEN5822166K</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Nuts</td>
			<td style="width:187px;">Matlock</td>
			<td style="width:429px;">M8 Steel hex full nut galvanized</td>
			<td>https://www.cromwell.co.uk/CTL6400068J</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Washers</td>
			<td style="width:187px;">Matlock</td>
			<td style="width:429px;">M8 Form-A steel washer bzp</td>
			<td>https://www.cromwell.co.uk/CTL6451208H</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">SS Nuts</td>
			<td style="width:187px;">Matlock</td>
			<td style="width:429px;">M8 A2 st/st hex full nut</td>
			<td>https://www.cromwell.co.uk/CTL6423008F</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">SS Washers</td>
			<td style="width:187px;">Matlock</td>
			<td style="width:429px;">M8 A2 st/st Form-A washer</td>
			<td>https://www.cromwell.co.uk/CTL6464008H</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Stainless Steel Studding</td>
			<td style="width:187px;">Cromwell</td>
			<td style="width:429px;">M8 x 1 Mtr A2 Stainless Steel Studding QFT6397080K</td>
			<td>https://www.cromwell.co.uk/QFT6397080K</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Valves</td>
			<td style="width:187px;">Edwards</td>
			<td style="width:429px;">C33205000 SP16K, Nitrile Diaphragm</td>
			<td>https://www.edwardsvacuum.com/Products/View.aspx?sku=C33205000</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Fitting Cross</td>
			<td style="width:187px;">Edwards</td>
			<td style="width:429px;">C10512412 NW16 Cross Piece Aluminum</td>
			<td>https://www.edwardsvacuum.com/Products/C10512412/View.aspx</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Fitting T</td>
			<td style="width:187px;">Edwards</td>
			<td style="width:429px;">C10512411 NW16 T-Piece Aluminum</td>
			<td>https://www.edwardsvacuum.com/Products/C10512411/View.aspx</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Vacuum Pump</td>
			<td style="width:187px;">Edwards</td>
			<td style="width:429px;">A36310940 E2M18 200-230/380-415V,3-ph, 50Hz</td>
			<td>http://www.edwardsvacuum.com/Products/View.aspx?sku=A36310940</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Dial Gauge</td>
			<td style="width:187px;">Edwards</td>
			<td style="width:429px;">D35610000 CG16K, 0-1040mbar</td>
			<td>http://www.edwardsvacuum.com/Products/View.aspx?sku=D35610000</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Argon Gas</td>
			<td style="width:187px;">BOC</td>
			<td style="width:429px;">Pureshield Argon Gas</td>
			<td>http://www.boconline.co.uk/en/products-and-supply/industrial-gases/inert-gases/pureshield-argon/pureshield-argon.html</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Stainless Steel Hose</td>
			<td style="width:187px;">BOC</td>
			<td style="width:429px;">Stainless Steel Hose</td>
			<td>http://www.boconline.co.uk/en/products-and-supply/speciality-equipment/hoses-and-pigtails/index.html</td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">Regulator</td>
			<td style="width:187px;">BOC</td>
			<td style="width:429px;">HP 1500 Series Regulator</td>
			<td style="width:833px;">http://www.boconline.co.uk/en/products-and-supply/speciality-equipment/regulators/single-stage-regulators/hp1500-series/hp1500-series.html</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Copper Block</td>
			<td style="width:187px;">William Rowland</td>
			<td style="width:429px;">Copper Ingot 25 kg</td>
			<td>http://www.william-rowland.com/products/high-purity-metals#product-id-18</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Vise</td>
			<td style="width:187px;">Record</td>
			<td style="width:429px;">T84-34 H/Duty Eng Vice 4 1/2&#34; Jaws REC5658326K</td>
			<td>https://www.cromwell.co.uk/REC5658326K</td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">Beaker</td>
			<td style="width:187px;">Fisher Scientific</td>
			<td style="width:429px;">11567402 - Beaker, squat form, with graduations and spout 800mL</td>
			<td style="width:833px;">https://webshop.fishersci.com/insight2_uk/getProduct.do;jsessionid=16D5812 
			D71B8CB37B475E94281E2BEA 
			5.ukhigjavappp11?productCode=11567402&#38;resultSet 
			Position=0</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Stirring Hot Plate</td>
			<td style="width:187px;">Corning</td>
			<td style="width:429px;">Corning stirring hot plate Model 6798-420d</td>
			<td>http://www.corning.com/lifesciences/us_canada/en/technical_resources/product_guid/shp/shp.aspx</td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">Stir Bar</td>
			<td style="width:187px;">Fisher Scientific</td>
			<td style="width:429px;">11848862 - PTFE Stir bar + Ring 25x6 mm</td>
			<td style="width:833px;">https://webshop.fishersci.com/insight2_uk/getProduct.do;jsessionid=16D5812 
			D71B8CB37B475E94281E2BEA 
			5.ukhigjavappp11?productCode=11848862&#38;resultSet 
			Position=0</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Air dryer</td>
			<td style="width:187px;">V05</td>
			<td style="width:429px;">V05 Max Air Turbo Dryer DR-120-GB</td>
			<td>http://reviews.boots.com/2111-en_gb/1120627/v05-v05-max-air-turbo-hair-dryer-dr-120-gb-reviews/reviews.htm</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Ceramic Sheet</td>
			<td style="width:187px;">Morgan Advance Materials</td>
			<td style="width:429px;">Kaowool Blanket 2 mm thick</td>
			<td>http://www.morganthermalceramics.com/downloads/datasheets?f[0]=field_type%3A84</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:216px;">Vibrating Table</td>
			<td style="width:187px;">Pevco</td>
			<td style="width:429px;">Pevco Vibrating Table 1.25m x 0.625m x 0.6m</td>
			<td>http://www.peverilmachinery.co.uk/equipment/vibrating-tables</td>
		</tr>
	</tbody>
</table>

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.

In Figure 4 the morphology of the NaCl grains can be seen (angular and spherical), for illustrative purposes. The foams obtained with Protocol A were made using angular shaped grains and the rest were made with the spherical grains. It was found that the use of different shape NaCl grains had no observed effect on the porosity obtained in the samples.
From the results we can determine that samples a, b, and c (made with Protocol A), are on average 63% porous (Figure 5<...

Watch this Scientific Journal Video about Casting Protocols for the Production of Open Cell Aluminum Foams by the Replication Technique and the Effect on Porosity at JoVE.com

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

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 ...

casting-protocols-for-production-open-cell-aluminum-foams-replication

Research

JoVE Journal

Engineering

14.5K Views.  The University of Sheffield. 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.

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

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

Fast Imaging Technique to Study Drop Impact Dynamics of Non-Newtonian Fluids

In the field of fluid mechanics, many dynamical processes not only occur over a very short time interval but also require high spatial resolution for detailed observation, scenarios that make it challenging to observe with conventional imaging systems. One of these is the drop impact of liquids, which usually happens within one tenth of millisecond. To tackle this challenge, a fast imaging technique is introduced that combines a high-speed camera (capable of up to one million frames per second) with a macro lens with long working distance to bring the spatial resolution of the image down to 10 &#181;m/pixel. The imaging technique enables precise measurement of relevant fluid dynamic quantities, such as the flow field, the spreading distance and the splashing speed, from analysis of the recorded video. To demonstrate the capabilities of this visualization system, the impact dynamics when droplets of non-Newtonian fluids impinge on a flat hard surface are characterized. Two situations are considered: for oxidized liquid metal droplets we focus on the spreading behavior, and for densely packed suspensions we determine the onset of splashing. More generally, the combination of high temporal and spatial imaging resolution introduced here offers advantages for studying fast dynamics across a wide range of microscale phenomena.

Drop impact of non-Newtonian fluids is a complex process since different physical parameters influence the dynamics over a very short time (less than one tenth of a millisecond). A fast imaging technique is introduced in order to characterize the impact behaviors of different non-Newtonian fluids.

In the field of fluid mechanics, many dynamical processes not only occur over a very short time interval but also require high spatial resolution for ...

Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents and hence higher efficiencies. Photon up-conversion by way of triplet-triplet annihilation (TTA-UC) is an attractive technique for using these otherwise wasted low energy photons to produce photocurrent, while not interfering with the photoanodic performance in a deleterious manner. Further to this, TTA-UC has a number of features, distinct from other reported photon up-conversion technologies, which renders it particularly suitable for coupling with DSC technology. In this work, a proven high performance TTA-UC system, comprising a palladium porphyrin sensitizer and rubrene emitter, is combined with a high performance DSC (utilizing the organic dye D149) in an integrated device. The device shows an enhanced response to sub-bandgap light over the absorption range of the TTA-UC sub-unit resulting in the highest figure of merit for up-conversion assisted DSC performance to date.

An integrated device, incorporating a dye-sensitized solar cell and triplet-triplet annihilation up-conversion unit was produced, affording enhanced light harvesting, from a wider section of the solar spectrum. Under modest irradiation levels a significantly enhanced response to low energy photons was demonstrated, yielding a record figure of merit for dye-sensitized solar cells.

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents ...

Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure.

A method of fabricating, in ambient conditions, organic photovoltaic tandem devices in a parallel configuration is presented. These devices feature an air-processed, semi-transparent, carbon nanotube common cathode.

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two ...

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

Experiments on Ultrasonic Lubrication Using a Piezoelectrically-assisted Tribometer and Optical Profilometer

Friction and wear are detrimental to engineered systems. Ultrasonic lubrication is achieved when the interface between two sliding surfaces is vibrated at a frequency above the acoustic range (20 kHz). As a solid-state technology, ultrasonic lubrication can be used where conventional lubricants are unfeasible or undesirable. Further, ultrasonic lubrication allows for electrical modulation of the effective friction coefficient between two sliding surfaces. This property enables adaptive systems that modify their frictional state and associated dynamic response as the operating conditions change. Surface wear can also be reduced through ultrasonic lubrication. We developed a protocol to investigate the dependence of friction force reduction and wear reduction on the linear sliding velocity between ultrasonically lubricated surfaces. A pin-on-disc tribometer was built which differs from commercial units in that a piezoelectric stack is used to vibrate the pin at 22 kHz normal to the rotating disc surface. Friction and wear metrics including effective friction force, volume loss, and surface roughness are measured without and with ultrasonic vibrations at a constant pressure of 1 to 4 MPa and three different sliding velocities: 20.3, 40.6, and 87 mm/sec. An optical profilometer is utilized to characterize the wear surfaces. The effective friction force is reduced by 62% at 20.3 mm/sec. Consistently with existing theories for ultrasonic lubrication, the percent reduction in friction force diminishes with increasing speed, down to 29% friction force reduction at 87 mm/sec. Wear reduction remains essentially constant (49%) at the three speeds considered.

We present a protocol for using a piezoelectrically-assisted tribometer and optical profilometer to investigate the dependence of ultrasonic wear and friction reduction on linear velocity, contact pressure, and surface properties.

Friction and wear are detrimental to engineered systems. Ultrasonic lubrication is achieved when the interface between two sliding surfaces is vibrated at ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling immensely. However, in soft electronics, in which organic semiconductors play a critical role, the devices will be bent or folded repeatedly. The effect of bending on the crystal packing and thus the charge transport is crucial to the performance of the device. In this manuscript, we describe the protocol to bend a single crystal of 5,7,12,16-tetrachloro-6,13-diazapentacene (TCDAP) in the field-effect transistor configuration and to obtain reproducible I-V characteristics upon bending the crystal. The results show that bending a field-effect transistor prepared on a flexible substrate results in nearly reversible yet opposite trends in charge mobility, depending on the bending direction. The mobility increases when the device is bent toward the top gate/dielectric layer (upward, compressive state) and decreases when bent toward the crystal/substrate side (downward, tensile state). The effect of bending curvature was also observed, with greater mobility change resulting from higher bending curvature. It is suggested that the intermolecular &#960;-&#960; distance changes upon bending, thereby influencing the electronic coupling and the subsequent carrier transport ability.

This manuscript describes the bending process of an organic single crystal-based field-effect transistor to maintain a functioning device for electronic property measurement. The results suggest that bending causes changes in the molecular spacing in the crystal and thus in the charge hopping rate, which is important in flexible electronics.

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling ...

High-speed Continuous-wave Stimulated Brillouin Scattering Spectrometer for Material Analysis

Recent years have witnessed a significant increase in the use of spontaneous Brillouin spectrometers for non-contact analysis of soft matter, such as aqueous solutions and biomaterials, with fast acquisition times. Here, we discuss the assembly and operation of a Brillouin spectrometer that uses stimulated Brillouin scattering (SBS) to measure stimulated Brillouin gain (SBG) spectra of water and lipid emulsion-based tissue-like samples in transmission mode with &lt;10 MHz spectral-resolution and &lt;35 MHz Brillouin-shift measurement precision at &lt;100 ms. The spectrometer consists of two nearly counter-propagating continuous-wave (CW) narrow-linewidth lasers at 780 nm whose frequency detuning is scanned through the material Brillouin shift. By using an ultra-narrowband hot rubidium-85 vapor notch filter and a phase-sensitive detector, the signal-to-noise-ratio of the SBG signal is significantly enhanced compared to that obtained with existing CW-SBS spectrometers. This improvement enables measurement of SBG spectra with up to 100-fold faster acquisition times, thereby facilitating high spectral-resolution and high-precision Brillouin analysis of soft materials at high speed.

We describe the construction of a rapid continuous-wave-stimulated-Brillouin-scattering (CW-SBS) spectrometer. The spectrometer employs single-frequency diode-lasers and an atomic vapor notch-filter to acquire transmission spectra of turbid/non-turbid samples with high spectral-resolution at speeds up to 100-fold faster than those of existing CW-SBS spectrometers. This improvement enables high-speed Brillouin material analysis.

Recent years have witnessed a significant increase in the use of spontaneous Brillouin spectrometers for non-contact analysis of soft matter, such as ...