This research was supported by the projects: MAT2014-60615-R and MAT2017-82182-R funded by the&#160;State&#160;Research&#160;Agency (SRA) and&#160;European&#160;Regional&#160;Development Fund (ERDF).

Note: The protocol follows the scheme shown in Figure 2.
1. Sample Preparation
<ol>
	<li>Cutting and cleaning 
	<ol>
		<li>Using a metal shear, cut 250 mm x 250 mm x 0.5 mm sheets of aluminum into 25 mm x 45 mm x 0.5 mm pieces. 
		Note: Special care must be taken when using the metal shear, and special training may be necessary.</li>
		<li>Remove the protective film covering one side of the sample and wash this side using around 50 mL of cleaning solution. Wash the samples gently with gloved hands. Avoid the use of abrasive scourers.</li>
		<li>Rinse the samples abundantly in a flow of distilled water. Subsequently, immerse each sample in 30 mL of 96% ethanol, sonicate it for 300 s, and repeat in 30 mL of ultrapure water for 300 s.</li>
		<li>Remove the samples from the water and dry them for 1 h at room temperature.</li>
	</ol>
	</li>
	<li>Acid etching
	<ol>
		<li>For the etching reaction, prepare a 4 M solution of HCl in ultrapure water13. Immerse each sample in 80 mL of this solution for 480 s. The reaction becomes more vigorous after approximately 360 s, when the native oxide surface layer is removed. 
		CAUTION: For safety, conduct this reaction in a hood. Wear gloves, lab coat and protective glasses.</li>
		<li>Next to the beaker containing the acid solution, prepare another beaker with ultrapure water to abruptly stop the reaction. Using polytetrafluoroethylene tweezers, remove the sample from the acid solution and immerse it in water. Rinse the sample in abundant ultrapure water.</li>
		<li>Dry the samples completely by blowing them with filtered and compressed air. Note that the sample after the etching reaction is superhydrophilic and drying it may be a difficult task. After the macroscopic removal of water by blowing, remove traces of water in an oven at 120 &#176;C for 600 s. 
		Note: This drying process in essential, especially for samples to be later silanized.</li>
	</ol>
	</li>
	<li>Hydrophobization 
	<ol>
		<li>Hydrophobization by FAS-17 silanization
		<ol>
			<li>Prior to the vapor-phase silanization, treat the samples with air-plasma for 600 s using a plasma cleaner operating at 100 W. This process activates the surface functional groups (-OH groups) that act as linker to the silane molecules.</li>
			<li>Subsequently, introduce the samples inside a glass Petri dish slightly tilted with the help of a pipette tip to slightly incline the surface. Deposit two 50 &#181;L drops of 1H,1H,2H,2H-Perfluorodecyl-triethoxysilane (FAS-17 ) on the Petri dish next to the sample13.</li>
			<li>Cover the Petri dish partially and place it in an air-evacuated desiccator overnight. Finally, ventilate the desiccator. Remove the samples, which are ready to use.</li>
		</ol>
		</li>
		<li>Hydrophobization by fluoropolymer (polytetrafluoroethylene) deposition
		<ol>
			<li>Spray the etched samples16 from about 10 cm with a solution of amorphous fluoropolymer in a fluorocarbon solvent in a ratio of 1/20 (v/v)16. A perfume diffuser filled with the solution may be used for this purpose. Leave to dry at room temperature for 600 s. Repeat the same process over a clean non-etched surface to make a smooth-hydrophobic aluminum surface (Ra = 0.25&#177;0.03 &#181;m).</li>
			<li>Apply a second coat and introduce the samples in a 110 &#176;C oven for 600 s to ensure total removal of the solvent and a crosslinking of the fluoropolymer coating. This process increases the durability, as indicated by the manufacturer.</li>
		</ol>
		</li>
		<li>Hydrophobization by ceria-stearic acid deposition
		<ol>
			<li>Clean the etched samples in acetone/ethanol/water, sonicate them for 300 s in water and dry them in a flow of compressed air.</li>
			<li>Immerse the samples31 in 50 mL of aqueous solution containing 2 g of cerium trichloride heptahydrate (CeCl3&#183;7H2O), and 3 mL of 30% hydrogen peroxide (H2O2). Incubate the sample immersed in the solution in a 40 &#176;C oven for 1 h.</li>
			<li>Remove it from the solution, rinse it in distilled water and dry it in a 100 &#176;C oven for 600 s.</li>
			<li>Immerse the sample in a 30 mM ethanol solution of stearic acid for 900 s, rinse it in ethanol and dry it in a 100 &#176;C oven for 600 s. 
			Note: Once dried and cooled down to room temperature, the samples are ready to use. The SH surfaces produced with the ceria-stearic coating acid are hereinafter referred as the Ce-SA coated surface.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
2. Sample Characterization
<ol>
	<li>Wetting analysis 
	<ol>
		<li>Bouncing drop experiments
		<ol>
			<li>Evaluate the water repellency degree of the produced sample by bouncing drops experiments13. Quantify the number of bounces given by a drop that is released from a fixed syringe whose needle is located at (10.1 &#177; 0.2) mm above the surface. The drop volume is typically 4 &#181;L.</li>
			<li>Capture the sequence with a high-speed camera. In the high-speed video acquisition software, fix the acquisition rate to 4200 images per second and the exposure time to 235 &#181;s.</li>
			<li>Once the video is recorded, select the sequence from the moment when the drop is released until the drop is already in full contact with the sample (no more bounces are observed). Save the video file.</li>
			<li>For each image, detect the drop profile using software32. Subsequently, quantify the number of bounces with the naked eye when playing the video sequence. In case that it is not easily identified, count the number of maxima above the center of mass position of the static drop (more than 15-20%).</li>
		</ol>
		</li>
		<li>Tilting plate experiments 
		<ol>
			<li>Use this test only to quantify the damage caused by each specific wear test. Analyze the shear adhesion of water drops with tilting plate experiments (TPE)33 using a lab-designed tilting apparatus34.</li>
			<li>Use side-view image acquisition of a sessile drop deposited on the sample fixed to an inclinable platform. During the image acquisition (at constant acquisition rate of 16 fps), incline the platform with constant angular velocity (5&#176;/s). Therefore, capture a drop image every 0.31&#176;. 
			Note: Above a specific inclination angle, the drop moves (slides/rolls-off) on the surface and this state may serve to determine the advancing and receding contact angles (ACA and RCA, respectively) simultaneously. The minimum tilting angle that produces a global displacement of the contact line (uphill and downhill contact line points move simultaneously) is referred to as the sliding angle (SA). The SA is the value reported here from TPE.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Roughness measurements
	<ol>
		<li>Analyze the micro-roughness of the samples using a white light confocal microscope. Set a scanning area of 0.252 x 0.187 mm per single topography.</li>
		<li>Take at least 4 single topographies per sample. Use the objective of magnification 50X, capturing 200 vertical planes in vertical steps of 0.2 &#181;m. Determine the Ra factor (arithmetic roughness amplitude).</li>
	</ol>
	</li>
</ol>
3. Durability Tests
Note: Evaluate the damage induced by each wear agent separately. Do not conduct more than one wear test per sample.
<ol>
	<li>Lateral abrasion tests 
	Note: The lateral abrasion tests (see Figure 3a) are performed by means of a commercial linear abrasive. This test aims to evaluate the wear induced by tangential displacement of a standard abrasive tip against a surface. This device allows the use of a wide variety of abrasives, setting a wide range of application pressures, lateral speeds and total number of abrasive cycles35.
	<ol>
		<li>Use a standard rubber abrasive CS-10, provided by the manufacturer. Fix the velocity to 20 cycles/min. Control the applied pressure by using weights. Set the minimum pressure allowed by the instrument, which corresponds to a total weight of 350 g. 
		Note: Considering the tip width (6.70&#177;0.05 mm), and the weight used, the corresponding applied pressure for these settings is 97.3&#177;1.4 kPa. The total worn area is limited by the width of the tip and the total length for each abrasion cycle. Set it to 38.1 mm.</li>
		<li>For each sample, evaluate the wear induced after 1, 2, 3 and 5 cycles.
		<ol>
			<li>After each wear treatment, gently brush the surface (using the brush provided by the manufacturer), rinse in water, and blow on using compressed air. Evaluate the wetting properties using TPE, as described in section 2.1.2.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Abrasive particle impact test
	<ol>
		<li>Conduct the particle impact test by using the set-up shown in Figure 3b, which is inspired by the standard abrasion Test D968. Release 30 mL (around 55 g) of abrasive sand from a glass funnel. Locate its extreme bottom at (25&#177;1) cm from the surface.</li>
		<li>Use a funnel tap diameter of (12&#177;1) mm and a length of (97&#177;1) mm. Place the funnel vertically, while inclining the sample 45&#176;. After impacting on the sample, collect the sand in a container placed below.</li>
		<li>Once a wear cycle is conducted, rinse the surface with distilled water, dry it in a flow of compressed air and evaluate the wetting properties by TPE (section 2.1.2). Repeat this entire process up to 3 times for each sample.</li>
	</ol>
	</li>
	<li>UV-ozone surface degradation test
	<ol>
		<li>Conduct the UV-ozone degradation test using an ozone cleaner. Treat each sample at room temperature for 600 s and repeat the cycle once.</li>
		<li>Subsequently, rinse the surfaces in water and dry them with compressed air.</li>
		<li>Evaluate the wetting properties by TPE described in section 2.1.2 to determine whether the superhydrophobic properties remain after UV-exposure.</li>
	</ol>
	</li>
	<li>Water immersion test
	<ol>
		<li>Evaluate the wear induced by water contact after a lengthy immersion in water. Introduce the sample in a 100 mL beaker of ultrapure water for 24 h.</li>
		<li>Remove the samples from the water, dry them with compressed air and place them in a 120 &#176;C oven for 600 s to ensure a total removal of water from the surface. When the surface is fully dried, evaluate the wetting properties after water exposure using the protocol described in section 2.1.2.</li>
	</ol>
	</li>
</ol>
4. Anti-icing Efficiency Evaluation
Note: The anti-icing efficiency evaluation is based on the three aspects shown in Figure 1.
<ol>
	<li>Subcooled water dripping test 
	Note: The subcooled water repellency of the samples is tested by means of the set-up shown in Figure 4a. The sample is introduced inside a freezing chamber at &#8211;20 &#176;C, which is fixed on top of an inclined (30&#176;) platform. A mixture of ice and distilled water in equilibrium (at stabilized temperature of 0 &#176;C) is placed outside the freezing chamber.
	<ol>
		<li>Pump the cold water inside the chamber using a peristaltic pump and have it circulate inside the freezer before being dripped on the sample at a low rate of 1 drop every 3 seconds. Single drops have a volume of roughly 50 &#181;L.</li>
		<li>Once the dripping process is initiated, capture a lateral image of the sample every 10 s to determine whether ice accretion occurs.</li>
	</ol>
	</li>
	<li>Freezing delay test
	<ol>
		<li>Conduct the freezing delay test inside the same freezing chamber mentioned in the previous section.</li>
		<li>Determine the percentage of sessile drops deposited on the sample that freeze, for each temperature, during a cooling process from room temperature down to approximately -25 &#176;C. The set-up for this test is shown in Figure 4b.</li>
		<li>Level the sample (with zero tilt) and deposit sessile drops carefully to avoid roll-off. Due to the high mobility of drops on water-repellent surfaces, place a lower number of them on SH samples. Repeat the experiment for SH surfaces several times.</li>
		<li>Monitor the temperature and relative humidity by using a thermal-probe. Control the relative humidity (RH) with a commercial humidifier. The RH is roughly 95% when the humidifier is switched on, and it decreases down to approximately 40% when the humidifier is switched off.</li>
		<li>Use around 200 drops of 30 &#181;L per sample (drop freezing is a stochastic phenomenon, and the analysis requires the use of a large number of drops). 
		Note: Thus, for this test use larger samples than those used for the rest of the studies. In this case the size is 125 mm x 62.5 mm and adapt the protocol to either etch the sample or hydrophobize their surfaces to the new sample dimensions.</li>
		<li>Place the sample in the middle of the bottom part of the freezer on top of an isolating platform. Gently deposit an array of 70 drops per sample (25 for the superhydrophobic sample). Close the freezer and turn it on. 
		Note: The temperature decreases linearly in time from room temperature down to approximately -25 &#176;C. The rate of cooling depends on the relative humidity. At low relative humidity (humidifier unplugged), the entire process takes roughly 2 hours, while it takes less time (around 1 hour) if the humidifier is connected. Once the temperature is lower than 0 &#176;C, drops start to nucleate.</li>
		<li>Count the number of drops that are frozen for each temperature (in intervals of 0.5 &#176;C), until all the totality of the drops is frozen.</li>
	</ol>
	</li>
	<li>Ice adhesion test
	<ol>
		<li>Quantify the force that must be applied to detach (pull-off) a piece of ice with a controllable contact area that has been formed on each sample. Perform these tests using the set-up illustrated in Figure 4c.</li>
		<li>Cut a polytetrafluoroethylene pipe with internal diameter of 10 mm in cylinders of ~28 mm height using scissors. Press the cylinder against the sample. Fill it with 1.2 mL of distilled water. Introduce the filled cylinder in the freezing chamber and wait for 1 h. 
		Note: Once the water is totally frozen, the sample with the cylinder is firmly fixed to a platform using a striker plate.</li>
		<li>Tie the cylinder to a digital force gauge using a nylon thread. The way this cylinder is tied to the thread and the orientation of the cylinder with respect to the thread depends on which type (shear or the tensile) adhesion is under evaluation. Fix this gauge to a motorized test stand. Close the freezing chamber and wait for 600 s.</li>
		<li>Displace the gauge from the sample at a constant velocity of (10 &#177; 0.5) mm/min.
		<ol>
			<li>Adjust this velocity manually within the control panel of the motorized test stand. Click the icon of the program controlling the dynamometer readings. Press START to record the force.</li>
			<li>Immediately after, move the dynamometer upwards by keeping on pressing the vertical displacement bottom within the motorized stand control panel.</li>
		</ol>
		</li>
		<li>When the displacement of the dynamometer with respect to the sample produces an extension of the thread and a separation of the ice from the sample, click on STOP and save the generated data file. 
		Note: The gauge monitors the force in terms of time. Knowing the velocity in which the dynamometer is displaced (10 mm/min), determine the force in terms of displacement. This serves to determine the rupture force (maximum retaining force) and the adhesion strength per unit area.</li>
		<li>Evaluate the shear adhesion when the pull-off is carried out laterally. The force in this case is parallel applied to the contact area (see Figure 4b). For this purpose, fix the sample vertically and connect the cylinder base to the thread using a metal ring. Pull this ring by the gauge until the sample detaches from the surface by shear displacement. 
		Note: The tensile adhesion test evaluates the peak force and work need to detach a piece of ice from the surface when it is pulled vertically.</li>
		<li>In this case, drill two small holes on the cylinder wall that serve to connect the cylinder to the gauge. Then, pull it vertically until the ice is finally detached from the surface.</li>
	</ol>
	</li>
</ol>

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N., Alexander, D., Mool, C. G., Eric, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Linear+abrasion+of+a+titanium+superhydrophobic+surface+prepared+by+ultrafast+laser+microtexturing.">Linear abrasion of a titanium superhydrophobic surface prepared by ultrafast laser microtexturing.</a> Journal of Micromechanics and Microengineering. 23 (11), 115012 (2013).</li><li>Li, X. -. W., 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=Low-cost+and+large-scale+fabrication+of+a+superhydrophobic+5052+aluminum+alloy+surface+with+enhanced+corrosion+resistance.">Low-cost and large-scale fabrication of a superhydrophobic 5052 aluminum alloy surface with enhanced corrosion resistance.</a> RSC Advances. 5 (38), 29639-29646 (2015).</li><li>Meuler, A. J., 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=Relationships+between+water+wettability+and+ice+adhesion.">Relationships between water wettability and ice adhesion.</a> ACS Applied Materials &amp; Interfaces. 2 (11), 3100-3110 (2010).</li><li>Boinovich, L. B., 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=Combination+of+functional+nanoengineering+and+nanosecond+laser+texturing+for+design+of+superhydrophobic+aluminum+alloy+with+exceptional+mechanical+and+chemical+properties.">Combination of functional nanoengineering and nanosecond laser texturing for design of superhydrophobic aluminum alloy with exceptional mechanical and chemical properties.</a> ACS Nano. 11 (10), 10113-10123 (2017).</li><li>Wan, B., 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=Superhydrophobic+ceria+on+aluminum+and+its+corrosion+resistance.">Superhydrophobic ceria on aluminum and its corrosion resistance.</a> Surface and Interface Analysis. 48 (3), 173-178 (2016).</li><li>G&#243;mez-Lopera, J. F., Mart&#237;nez-Aroza, J., Rodr&#237;guez-Valverde, M. A., Cabrerizo-V&#237;lchez, M. A., Montes-Ru&#237;z-Cabello, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Entropic+image+segmentation+of+sessile+drops+over+patterned+acetate.">Entropic image segmentation of sessile drops over patterned acetate.</a> Mathematics and Computers in Simulation. 118, 239-247 (2015).</li><li>Gao, L., McCarthy, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Teflon+is+hydrophilic.+comments+on+definitions+of+hydrophobic,+shear+versus+tensile+hydrophobicity,+and+wettability+characterization.">Teflon is hydrophilic. comments on definitions of hydrophobic, shear versus tensile hydrophobicity, and wettability characterization.</a> Langmuir. 24 (17), 9183-9188 (2008).</li><li>Ruiz-Cabello, F. J. M., Rodriguez-Valverde, M. A., Cabrerizo-Vilchez, 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+new+method+for+evaluating+the+most+stable+contact+angle+using+tilting+plate+experiments.">A new method for evaluating the most stable contact angle using tilting plate experiments.</a> Soft Matter. 7 (21), 10457-10461 (2011).</li><li>Pierce, E., Carmona, F. J., Amirfazli, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+of+sliding+and+contact+angle+results+in+tilted+plate+experiments.">Understanding of sliding and contact angle results in tilted plate experiments.</a> Colloids Surfaces A. 323 (1-3), 73-82 (2008).</li><li>Ye, H., Zhu, L., Li, W., Liu, H., Chen, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+spray+deposition+of+a+water-based+superhydrophobic+coating+with+high+stability+for+flexible+applications.">Simple spray deposition of a water-based superhydrophobic coating with high stability for flexible applications.</a> Journal of Materials Chemistry. 5 (20), 9882-9890 (2017).</li><li>Rolland, J. P., Van Dam, R. M., Schorzman, D. A., Quake, S. R., DeSimone, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solvent-resistant+photocurable+&amp;#34;liquid+Teflon&amp;#34;+for+microfluidic+device+fabrication.">Solvent-resistant photocurable &amp;#34;liquid Teflon&amp;#34; for microfluidic device fabrication.</a> Journal of the American Chemical Society. 126 (8), 2322-2323 (2004).</li></ol>

We have nothing to disclose.

In this paper, we demonstrate strategies to produce water-repellent surfaces on aluminum substrates. In addition, we show methods to characterize their wetting properties, roughness, durability and anti-icing performance.
To prepare the SH surfaces, we used two strategies. The first strategy incorporated the proper roughness degree to achieve the intrinsic hierarchical structure of SH surfaces by acid etching. This process is particularly critical, which may require further work for other meta...

The ability of superhydrophobic (SH) surfaces to repel water is the reason that they are traditionally proposed as a solution to prevent icing1,2. However, there are concerns about the suitability of SH surfaces for anti-icing agents: 1) the high costs of production, 2) that superhydrophobicity does not always lead to ice-phobicity3, and 3) the questionable durability of the SH surfaces4. Superhydrophobic surfaces hold two properties related to their topography and chemical composition5: they are rough, with particular topographic features; and their surface energy is low (intrinsically hydrophobic).
The roughness on a hydrophobic surface serves to reduce the ratio between the real solid-liquid area and the apparent contact area. The water is not fully in contact with the solid due to the lotus effect6,7, when the drop rests or moves onto the surface asperities. In this scenario, the solid-liquid interface acts heterogeneously with two chemical domains: the solid surface itself and the tiny air-bubbles trapped between the solid and water8. The degree of water repellency is connected to the amount of trapped air because the air patches are smooth and its intrinsic contact angle is 180&#176;. Some studies report the incorporation of a hierarchical surface texture with micro and nano-asperities as the optimal strategy to provide better water-repellent properties (greater presence of air at the solid-liquid interface)9. For some metals, a low-cost strategy to create two-level roughness features is acid-etching10,11. This procedure is frequently used in industry. With certain acid concentrations and etching times, the metal surface reveals the proper hierarchical roughness. In general, the surface roughening is optimized by varying the acid concentration, etching time, or both12. The surface energy of metals is high and for this reason, the fabrication of water-repellent metal surfaces requires later hydrophobization.
Hydrophobization is generally achieved by hydrophobic film deposition using different methods: silanization10,13, dip-coating14, spin-coating15, spraying16 or plasma-deposition17. Silanization has been proposed18 as one of the most promising tool for improving the low durability of SH surfaces. Unlike other deposition techniques, the silanization process is based on a covalent bond between the Si-OH groups with the surface hydroxyl groups of the metal substrate10. A drawback of the silanization process is the need for previous activation of the metal substrate to create enough hydroxyl groups for a high degree of coverage and uniformity. Another strategy recently proposed to produce resistant superhydrophobic surfaces is the use of rare-earth coatings19,20. Ceria coatings have two properties that justify this use: they can be intrinsically hydrophobic21, and they are mechanically and chemically robust. In particular, one of the most important reasons why they are chosen as protective coatings is their corrosion-protection abilities20.
To produce long-lasting SH metal surfaces, two issues are considered: the surface texture must not be damaged, and the hydrophobic film/coating must be firmly anchored to the substrate. Surfaces are typically exposed to wear originated by lateral abrasion or particle impact4. If the asperities are damaged, the water-repellency may be substantially reduced. Under extreme environments, the hydrophobic coating may be partially removed from the surface or may be chemically degraded by UV exposure, humidity or corrosion. The design of durable SH surfaces coatings is an important challenge for coating and surface engineering.
For metals, one of the most demanding requirements is that the anti-icing ability is based on three interconnected aspects22 as illustrated in Figure 1: subcooled water repellency, freezing delay, and low ice-adhesion. Outdoor icing occurs when subcooled water, typically rain drops, comes into contact with a solid surface and is rapidly frozen by heterogeneous nucleation23. The formed ice (rime) is firmly attached to the surface. Thus, the first step to avoid icing is to reduce the solid-water contact time. If the surface is superhydrophobic, rain drops may be expelled from the surface before freezing. In addition, it has been proven that, under humid conditions, surfaces with a high contact angle delay freezing more efficiently than those ones with a low contact angle24. For these two reasons, SH surfaces are the most appropriate surfaces to mitigate icing. However, the lifetime of superhydrophobic surfaces may be a key point since icing conditions are typically aggressive25. Some studies have concluded that SH surfaces are not the best choice for decreasing ice adhesion26. Once the ice forms on the surface, it stays firmly attached due to surface asperities. The roughness increases the ice-surface contact area and the asperities act as interlocking agents26. The use of durable SH surfaces is recommended to avoid icing if there are no traces of ice already present on the surface.
In this work, we present several protocols to produce durable SH surfaces on metal substrates. We use aluminum (Al) as the substrate because it is widely used in industry, and the incorporation of anti-icing properties is particularly relevant for certain applications (ski resorts facilities, aeronautics, etc.). We prepare three types of surfaces: a textured Al surface coated with a fluoropolymer coating, a textured Al surface silanized with a fluorosilane, and a ceria-stearic acid bilayer on an Al substrate. Similar techniques17,27,28,29 provide 100-300 nm film thicknesses or even monolayer films. For each surface, we measured their wetting properties and conducted wear tests. Finally, we analyzed their anti-icing performance by using three tests aimed to probe independently the three properties shown in Figure 1.
Our protocol is based on the scheme shown in Figure 2. Once the SH Al surfaces are prepared, their wetting properties and topography are analyzed to determine their repellency properties and roughness features. The wetting properties are analyzed by bouncing drop experiments, which is a technique connected to the water tensile adhesion. Since the observation of drop bounces is required, this technique is only suitable for superhydrophobic surfaces13. For each surface treatment, we prepared at least four samples to conduct the anti-icing tests and another four samples to perform the durability tests. The damage caused after each durability test was analyzed by measuring the loss of wetting properties and roughness features. Similar durability tests to the proposed ones in this work were recently used for other metal surfaces27,30.
Concerning the anti-icing tests, the aim of this study is to determine whether the use of the produced SH Al surfaces are convenient as anti-icing agents. Hence, we analyzed, for comparison, the performance of two control samples: a) an untreated Al sample (smooth hydrophilic sample) and b) a hydrophobized but not textured sample (smooth hydrophobic sample). For the same purpose, the use of a textured but not hydrophobized surface might be of interest. Unfortunately, this surface is extremely wettable and anti-icing tests cannot be carried out for them.

<table>
	<tbody>
		<tr>
			<td>Hydrochloric acid, 37%</td>
			<td>SICAL, S.A.</td>
			<td>AC07411000</td>
			<td>used for acid etching</td>
		</tr>
		<tr>
			<td>1H,1H,2H,2H-Perfluorodecyltriethoxysilane, 97%</td>
			<td>Sigma-Aldrich</td>
			<td>658758</td>
			<td>used for silanization with FAS-17</td>
		</tr>
		<tr>
			<td>Dupont AF1600</td>
			<td>Dupont</td>
			<td>D10389631</td>
			<td>used for fluropolymer deposition</td>
		</tr>
		<tr>
			<td>FC-72</td>
			<td>3M, Fluorinet</td>
			<td>1100-2-93</td>
			<td>used for fluropolymer deposition (flurocarbon solvent)</td>
		</tr>
		<tr>
			<td>Cerium(III) chloride heptahydrate, 99.9%</td>
			<td>Sigma-Aldrich</td>
			<td>228931</td>
			<td>used for Ceria coating deposition</td>
		</tr>
		<tr>
			<td>Hydrogen peroxide solution, 30%</td>
			<td>Sigma-Aldrich</td>
			<td>H1009</td>
			<td>used for Ceria coating deposition</td>
		</tr>
		<tr>
			<td>Stearic acid, &#8805;98.5%</td>
			<td>Sigma-Aldrich</td>
			<td>S4751</td>
			<td>used for Ceria coating deposition</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>SICAL, S.A.</td>
			<td>16271</td>
			<td>used throughout</td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>SICAL, S.A.</td>
			<td>1090</td>
			<td>used throughout</td>
		</tr>
		<tr>
			<td>Aluminum sheets 0.5mm</td>
			<td>MODULOR (Germany)</td>
			<td>125993</td>
			<td>substrates used throught</td>
		</tr>
		<tr>
			<td>Micro-90 concentrated cleaning solution</td>
			<td>Sigma-Aldrich</td>
			<td>Z281506</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra pure Milli-Q water</td>
			<td>Millipore</td>
			<td>discontinued</td>
			<td>used throughout</td>
		</tr>
		<tr>
			<td>Plasma Etcher/Asher/Cleaner EMITECH K1050X</td>
			<td>Aname</td>
			<td>K1500XDEV-001</td>
			<td>used throughout</td>
		</tr>
		<tr>
			<td>PCC software</td>
			<td>AMETEK</td>
			<td>discontinued</td>
			<td>sofware controlling the high speed camera Phantom MIRO 4</td>
		</tr>
		<tr>
			<td>High Speed Camera Phantom Miro 4</td>
			<td>AMETEK</td>
			<td>discontinued</td>
			<td>used for bouncing drop experiments</td>
		</tr>
		<tr>
			<td>Open Loop PL&#181; 2.32</td>
			<td>UPC-CD6 &#38; Sensofar Tech S.L.</td>
			<td>version 2.32</td>
			<td>Sofware controlling PL&#181; Confocal Imaging Profiler</td>
		</tr>
		<tr>
			<td>Pl&#181;-Confocal Imaging Profiler 2300</td>
			<td>Sensofar Tech S.L.</td>
			<td>discontinued</td>
			<td>used for roughness measurements</td>
		</tr>
		<tr>
			<td>TABER 5750 LINEAL ABRASER</td>
			<td>TABER</td>
			<td>5750</td>
			<td>used for lateral abrasion tests</td>
		</tr>
		<tr>
			<td>Abbrasive sand: ASTM 20-30 SAND C778</td>
			<td>U.S. SILICA COMPANY (USA)</td>
			<td>1-800-635-7263</td>
			<td>used for abrasive partcile impact tests</td>
		</tr>
		<tr>
			<td>Ozone cleaner: PSDP-UV4T, Digital UV Ozone System</td>
			<td>Novascam</td>
			<td>discontinued</td>
			<td>UV-ozone degradation test</td>
		</tr>
		<tr>
			<td>Peristalitic Pump GILSON 312, France</td>
			<td>GILSON (France)</td>
			<td>discontinued</td>
			<td>used for water dripping test</td>
		</tr>
		<tr>
			<td>Nylon thread</td>
			<td>Dracon fishing line, Izorline internacional, inc. (USA)</td>
			<td>discontinued</td>
			<td>used for ice adhesion tests</td>
		</tr>
		<tr>
			<td>Digital force gauge (ZTA-200N, ZTA Series</td>
			<td>IMADA (USA)</td>
			<td>370199</td>
			<td>used for ice adhesion tests</td>
		</tr>
		<tr>
			<td>Motorized test stand I, MH2-500N-FA</td>
			<td>IMADA (USA)</td>
			<td>366942</td>
			<td>used for ice adhesion tests</td>
		</tr>
		<tr>
			<td>Force Recorder Professional</td>
			<td>IMADA (USA)</td>
			<td>version 1.0.2</td>
			<td>software provided by IMADA to register the force</td>
		</tr>
		<tr>
			<td>HYGROCLIP XD - STANDARD PROBE</td>
			<td>Rotronic</td>
			<td>discontinued</td>
			<td>Temperature and humidity probe</td>
		</tr>
		<tr>
			<td>HW3 Lite software</td>
			<td>Rotronic</td>
			<td>version 2.1.2</td>
			<td>Sofware controlling the HYGROCLIP Probe</td>
		</tr>
	</tbody>
</table>

fabrication of superhydrophobic metal surfaces for anti-icing applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

The wetting and roughness properties of the SH surfaces that were used in this study are shown in Figure 5. The average number of bounces measured for each sample is displayed in Figure 5a and the average roughness is shown in Figure 5b. There is no correlation between the roughness and wetting properties. The number of bounces measured for the polytetrafluoroethylene coated sample agrees with the Ce...

Watch this Scientific Journal Video about Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications at JoVE.com

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

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8.4K Views.  University of Granada. We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

Video: Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Hyperpolarized Xenon for NMR and MRI Applications

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2.
Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method.
The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode.

The production of hyperpolarized xenon by means of spin exchange optical pumping (SEOP) is described. This method yields a ~10000-fold enhancement of the nuclear spin polarization of Xe-129 and has applications in nuclear magnetic resonance spectroscopy and imaging. Examples of gas phase and solution state experiments are given.

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 ...

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

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 ...

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

This manuscript shows the fabrication process for the manufacture of dielectric elastomer soft actuators based on silicone membranes. The three key stages of production are presented in detail: blade casting of thin silicone membranes; pad printing of compliant electrodes; and the assembly of all the components.

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Scalable Solution-processed Fabrication Strategy for High-performance, Flexible, Transparent Electrodes with Embedded Metal Mesh

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a polymer film. This paper also presents a low-cost, vacuum-free fabrication method for this novel TE; the approach combines lithography, electroplating, and imprint transfer (LEIT) processing. The embedded nature of the EMTEs offers many advantages, such as high surface smoothness, which is essential for organic electronic device production; superior mechanical stability during bending; favorable resistance to chemicals and moisture; and strong adhesion with plastic film. LEIT fabrication features an electroplating process for vacuum-free metal deposition and is favorable for industrial mass production. Furthermore, LEIT allows for the fabrication of metal mesh with a high aspect ratio (i.e., thickness to linewidth), significantly enhancing its electrical conductance without adversely losing optical transmittance. We demonstrate several prototypes of flexible EMTEs, with sheet resistances lower than 1 &#937;/sq and transmittances greater than 90%, resulting in very high figures of merit (FoM) &#8211; up to 1.5 x 104 &#8211; which are amongst the best values in the published literature.

This protocol describes a solution-based fabrication strategy for high-performance, flexible, transparent electrodes with fully-embedded, thick metal mesh. Flexible transparent electrodes fabricated by this process demonstrate among the highest reported performances, including ultra-low sheet resistance, high optical transmittance, mechanical stability under bending, strong substrate adhesion, surface smoothness, and environmental stability.

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a ...

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition metal dichalcogenides (TMDs) MoS2 and WS2 can be prepared on sapphire substrates. By controlling the metal film thicknesses, good layer number controllability, down to a single layer of TMDs, can be obtained using this growth technique. Based on the results obtained from the Mo film sulfurized under the sulfur deficient condition, there are two mechanisms of (a) planar MoS2 growth and (b) Mo oxide segregation observed during the sulfurization procedure. When the background sulfur is sufficient, planar TMD growth is the dominant growth mechanism, which will result in a uniform MoS2 film after the sulfurization procedure. If the background sulfur is deficient, Mo oxide segregation will be the dominant growth mechanism at the initial stage of the sulfurization procedure. In this case, the sample with Mo oxide clusters covered with few-layer MoS2 will be obtained. After sequential Mo deposition/sulfurization and W deposition/sulfurization procedures, vertical WS2/MoS2 hetero-structures are established using this growth technique. Raman peaks corresponding to WS2 and MoS2, respectively, and the identical layer number of the hetero-structure with the summation of individual 2D materials have confirmed the successful establishment of the vertical 2D crystal hetero-structure. After transferring the WS2/MoS2 film onto a SiO2/Si substrate with pre-patterned source/drain electrodes, a bottom-gate transistor is fabricated. Compared with the transistor with only MoS2 channels, the higher drain currents of the device with the WS2/MoS2 hetero-structure have exhibited that with the introduction of 2D crystal hetero-structures, superior device performance can be obtained. The results have revealed the potential of this growth technique for the practical application of 2D crystals.

Through the sulfurization of pre-deposited transition metals, large-area and vertical 2D crystal hetero-structures can be fabricated. The film transferring and device fabrication procedures are also demonstrated in this report.

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...

Fused Filament Fabrication (FFF) of Metal-Ceramic Components

Technical ceramics are widely used for industrial and research applications, as well as for consumer goods. Today, the demand for complex geometries with diverse customization options and favorable production methods is increasing continuously. With fused filament fabrication (FFF), it is possible to produce large and complex components quickly with high material efficiency. In FFF, a continuous thermoplastic filament is melted in a heated nozzle and deposited below. The computer-controlled print head is moved in order to build up the desired shape layer by layer. Investigations regarding printing of metals or ceramics are increasing more and more in research and industry. This study focuses on additive manufacturing (AM) with a multi-material approach to combine a metal (stainless steel) with a technical ceramic (zirconia: ZrO2). Combining these materials offers a broad variety of applications due to their different electrical and mechanical properties. The paper shows the main issues in preparation of the material and feedstock, device development, and printing of these composites.

Fused Filament Fabrication FFF of Metal-Ceramic Components

This study shows multi-material additive manufacturing (AM) using fused filament fabrication (FFF) of stainless steel and zirconia.

Technical ceramics are widely used for industrial and research applications, as well as for consumer goods. Today, the demand for complex geometries with ...