ÿþ<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><!-- InstanceBegin template="/Templates/empfasis-article_newtmp.dwt" codeOutsideHTMLIsLocked="false" --> <head> <!-- InstanceBeginEditable name="Head" --><title>Empfasis - Electroless Plating of Palladium and Palladium Alloy Membranes</title> <!-- InstanceEndEditable --> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css"> <!-- @import url(http://www.empf.org/empfasis/emphasis.css); .style1 { font-size: 16px; font-weight: bold; color: #1A2A57; } .style5 {font-size: 14px; font-weight: bold; } .style6 { color: #1A2A57; font-weight: bold; } .style7 {font-family: Arial, Helvetica, sans-serif} .style9 { font-size: 12px; font-weight: bold; color: #1A2A57; } .style14 {font-size: 10} .style17 {font-size: 12px} .style24 {color: #1A2A57; font-weight: bold; font-size: 14px; } --> </style> <script language="JavaScript" type="text/JavaScript"> <!-- function MM_preloadImages() { //v3.0 var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array(); var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++) if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}} } function MM_findObj(n, d) { //v4.01 var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) { d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);} if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n]; for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document); if(!x && d.getElementById) x=d.getElementById(n); return x; } function MM_nbGroup(event, grpName) { //v6.0 var i,img,nbArr,args=MM_nbGroup.arguments; if (event == "init" && args.length > 2) { if ((img = MM_findObj(args[2])) != null && !img.MM_init) { img.MM_init = true; img.MM_up = args[3]; img.MM_dn = img.src; if ((nbArr = document[grpName]) == null) nbArr = document[grpName] = new Array(); nbArr[nbArr.length] = img; for (i=4; i < args.length-1; i+=2) if ((img = MM_findObj(args[i])) != null) { if (!img.MM_up) img.MM_up = img.src; img.src = img.MM_dn = args[i+1]; nbArr[nbArr.length] = img; } } } else if (event == "over") { document.MM_nbOver = nbArr = new Array(); for (i=1; i < args.length-1; i+=3) if ((img = MM_findObj(args[i])) != null) { if (!img.MM_up) img.MM_up = img.src; img.src = (img.MM_dn && args[i+2]) ? args[i+2] : ((args[i+1])? args[i+1] : img.MM_up); nbArr[nbArr.length] = img; } } else if (event == "out" ) { for (i=0; i < document.MM_nbOver.length; i++) { img = document.MM_nbOver[i]; img.src = (img.MM_dn) ? img.MM_dn : img.MM_up; } } else if (event == "down") { nbArr = document[grpName]; if (nbArr) for (i=0; i < nbArr.length; i++) { img=nbArr[i]; img.src = img.MM_up; img.MM_dn = 0; } document[grpName] = nbArr = new Array(); for (i=2; i < args.length-1; i+=2) if ((img = MM_findObj(args[i])) != null) { if (!img.MM_up) img.MM_up = img.src; img.src = img.MM_dn = (args[i+1])? args[i+1] : img.MM_up; nbArr[nbArr.length] = img; } } } //--> </script> </head> <body onLoad="MM_preloadImages('http://www.empf.org/empfasis/nav/images/empfasis_nav_01-over.gif','http://www.empf.org/empfasis/nav/images/empfasis_nav_02-over.gif','http://www.empf.org/empfasis/nav/images/empfasis_nav_03-over.gif','http://www.empf.org/empfasis/nav/images/empfasis_nav_04-over.gif','http://www.empf.org/empfasis/nav/images/empfasis_nav_05-over.gif','http://www.empf.org/empfasis/nav/images/empfasis_nav_06-over.gif','../../nav/images/empfasis_nav_01-over.gif','../../nav/images/empfasis_nav_02-over.gif','../../nav/images/empfasis_nav_03-over.gif','../../nav/images/empfasis_nav_04-over.gif','../../nav/images/empfasis_nav_05-over.gif','../../nav/images/empfasis_nav_06-over.gif')"> <table width="100%" border="0"> <tr> <td width="19%"><img src="http://www.empf.org/empfasis/archive/images/empfasis.jpg" width="360" height="71" border="0"></td> <td width="81%"><div align="right"><a href="http://www.empf.org" target="_parent"><img src="http://www.empf.org/empfasis/archive/images/empf.jpg" width="144" height="90" border="0"></a></div></td> </tr> </table> <div align="center"><!-- #BeginLibraryItem "/Library/empfasis_nav.lbi" --> <table border="0" cellpadding="0" cellspacing="0"> <tr> <td><a href="http://www.empf.org/empfasis/index.html" target="_top" onClick="MM_nbGroup('down','group1','empfasis','',1)" onMouseOver="MM_nbGroup('over','empfasis','../../nav/images/empfasis_nav_01-over.gif','',1)" onMouseOut="MM_nbGroup('out')"><img src="../../nav/images/empfasis_nav_01.gif" alt="" name="empfasis" width="64" height="34" border="0" onload=""></a></td> <td><a href="http://www.empf.org" target="_top" onClick="MM_nbGroup('down','group1','aci','',1)" onMouseOver="MM_nbGroup('over','aci','../../nav/images/empfasis_nav_02-over.gif','',1)" onMouseOut="MM_nbGroup('out')"><img src="../../nav/images/empfasis_nav_02.gif" alt="" name="aci" width="58" height="34" border="0" onload=""></a></td> <td><a href="http://www.aciusa.org" target="_top" onClick="MM_nbGroup('down','group1','empf','',1)" onMouseOver="MM_nbGroup('over','empf','../../nav/images/empfasis_nav_03-over.gif','',1)" onMouseOut="MM_nbGroup('out')"><img src="../../nav/images/empfasis_nav_03.gif" alt="" name="empf" width="48" height="34" border="0" onload=""></a></td> <td><a href="http://www.empf.org/empfasis/index.html#archive" target="_top" onClick="MM_nbGroup('down','group1','archive','',1)" onMouseOver="MM_nbGroup('over','archive','../../nav/images/empfasis_nav_04-over.gif','',1)" onMouseOut="MM_nbGroup('out')"><img src="../../nav/images/empfasis_nav_04.gif" alt="" name="archive" width="70" height="34" border="0" onload=""></a></td> <td><a href="http://store.aciusa.org" onClick="MM_nbGroup('down','group1','techpubs','',1)" onMouseOver="MM_nbGroup('over','techpubs','../../nav/images/empfasis_nav_05-over.gif','',1)" onMouseOut="MM_nbGroup('out')"><img src="../../nav/images/empfasis_nav_05.gif" alt="" name="techpubs" width="154" height="34" border="0" onload=""></a></td> <td><a href="mailto:empf@aciusa.org" target="_top" onClick="MM_nbGroup('down','group1','contact','',1)" onMouseOver="MM_nbGroup('over','contact','../../nav/images/empfasis_nav_06-over.gif','',1)" onMouseOut="MM_nbGroup('out')"><img src="../../nav/images/empfasis_nav_06.gif" alt="" name="contact" width="74" height="34" border="0" onload=""></a></td> </tr> </table> <!-- #EndLibraryItem --></div> <table width="100%" border="0"> <tr> <td width="85%" class="style17">A publication of the National Electronics Manufacturing Center of Excellence</td> <!-- InstanceBeginEditable name="Date" --><td width="15%"><div align="right">October 2010 </div></td> <!-- InstanceEndEditable --> </tr> </table> <table width="100%" border="0"> <tr> <td width="237" valign="top"> <div align="center"> <table width="237" height="1280" border="0" cellpadding="30" cellspacing="0"> <tr> <td width="237" valign="top" background="../../archive/images/left_banner4.jpg"><div id="lft_banner"> <table width="185" border="0" cellspacing="0" cellpadding="0"> <tr> <td><a href="http://www.aciusa.org" target="_blank"><img src="http://www.empf.org/empfasis/archive/images/aci_sm.gif" alt="Go to the ACI website" width="69" height="44" border="0" align="left" longdesc="http://www.aciusa.org"></a></td> <td><a href="http://www.empf.org" target="_blank"><img src="http://www.empf.org/empfasis/archive/images/empf_sm.gif" alt="Go to the EMPF website" width="65" height="44" border="0" align="right" longdesc="http://www.empf.org"></a></td> </tr> <tr> <td colspan="2"><div align="center"> <!--link here--> <table width="175" border="0" align="center" cellpadding="0" cellspacing="0"> <tr> <td valign="top"><span class="style24"><br>In This EMPFasis Issue<br><br></span></td> </tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="plating.html">Electroless Plating of Palladium and Palladium Alloy Membranes</a></p> </td> </tr> <tr><td valign="top">&nbsp;</td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="help-1010.html">Ask the EMPF Helpline!</a></p> </td> </tr> <tr><td valign="top"><p align="left">&nbsp;</p></td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="fuelcell.html">Fuel Cell Thin Film Morphology Research</a></p> </td> </tr> <tr><td valign="top"><p align="left">&nbsp;</p></td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="tech-tips-1010.html">Tech Tips: Power Interfaces</a></p> </td> </tr> <tr><td valign="top"><p align="left">&nbsp;</p></td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="manf-corner-1010.html">Manufacturer&rsquo;s Corner: Manncorp</a></p></td> </tr> <tr><td valign="top"><p align="left">&nbsp;</p></td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="electronics.html">Characteristic Properties of Materials used in Electronics Assemblies</a></p></td> </tr> <tr><td valign="top"><p align="left">&nbsp;</p></td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="http://store.aciusa.org">EMTC Online Registration</a></p></td> </tr> <tr><td valign="top"><p align="left">&nbsp;</p></td></tr> <tr><td valign="top" style="padding-left:10px"> <p align="left"><a href="../html/empfasis/emlcupcoming.pdf" target=_blank>Training Center Course Schedule</a></p></td> </tr> </table> <!--link here--> <br> <br> <hr align="center" size="1"> <br> <a href="http://store.aciusa.org"><img src="http://www.aciusa.org/images/lower-pricing-ad.gif" alt="Discount pricing on IPC training course J-STD-001, 610, 600, 7711, 7712" width="150" height="288" border="1"></a> <a href="http://www.empf.org/empfasis/subscribe.htm"> </a> <p class="style9"><script language="JavaScript"> <!-- function random_imglink(){ var myimages=new Array() myimages[1]="http://www.aciusa.org/wwwaci/html/random/boot.gif" myimages[2]="http://www.aciusa.org/wwwaci/html/random/lead.gif" myimages[3]="http://www.aciusa.org/wwwaci/html/random/help.gif" myimages[4]="http://www.aciusa.org/wwwaci/html/random/service.gif" myimages[5]="http://www.empf.org/empfasis/archive/images/subscribe2.gif" var imagelinks=new Array() imagelinks[1]="http://www.aciusa.org/courses/train_boot.htm" imagelinks[2]="http://www.empf.org/empfasis/leadfree.htm" imagelinks[3]="http://www.empf.org/helpline/helpline.htm" imagelinks[4]="http://www.aciusa.org/ana/ana_home.htm" imagelinks[5]="http://www.empf.org/empfasis/subscribe.htm" var ry=Math.floor(Math.random()*myimages.length) if (ry==0) ry=1 document.write('<a href='+'"'+imagelinks[ry]+'"'+'><img src="'+myimages[ry]+'" border=0></a>') } random_imglink() //--> </script></p> </div></td> </tr> <tr> <td colspan="2"><div align="center"><span class="style5">ACI Technologies Inc.</span><br> One International Plaza<br> Suite 600 <br> Philadelphia, PA 19113 <br> (610) 362-1200 <br> <span class="style6">FAX: </span>(610) 362-1290<br> <span class="style6">HELPLINE: </span>(610) 362-1320<br> <span class="style6">WEBSITE: </span><a href="http://www.empf.org">www.empf.org</a><br> <a href="http://www.aciusa.org">www.aciusa.org</a></div></td> </tr> </table> <p>&nbsp;</p> <p><br> <br> </p> <div align="center"> <p align="center" class="style7">Michael D. Frederickson<br> <strong><em>EMPF Director </em></strong><br> <br> Barry Thaler, PhD.<br> bthaler@aciusa.org <br> <strong><em>Empfasis Technical Editor<br> </em></strong><br> Paul Bratt<br> pbratt@aciusa.org <br> <strong><em>Empfasis Editor</em></strong><br> </p> <p align="center" class="style7"><img src="http://www.empf.org/empfasis/archive/images/iab_sm.gif" alt="IAB" width="100" height="52"><br> <span class="style9">Industrial Advisory Board</span><br> <span class="style14"><em>Gerald R. Aschoff</em>, The Boeing Company<br> <em>Dennis M. Kox</em>, Raytheon<br> <em>Gregory X. Krieger</em>, BAE Systems<br> <em>Edward A. Morris</em>, Lockheed Martin<br> <em>Jane Krueger </em>, Rockwell Collins<br> <em>Gary Kirchner</em>, Honeywell<br> <em>Andrew Paradise</em>, Northrop Grumman<br> <em>Richard Kidwell </em>, ITT Industries</span></p> </div> <p align="center" class="style7"><br> </p> </div> </td> </tr> </table> </div></td> <!-- InstanceBeginEditable name="Body1" --><td width="70%" rowspan="2" valign="top"><div class="body_style" id="body_content"> <p align="center"><img src="images/plating.gif" alt="title"></p> <p class="body_text"><span class="style20">T</span>he EMPF has investigated a number of systems that utilize fuel cells as part of a mission to reduce power costs aboard Navy vessels. The challenge related to fuel cells for the Navy, especially in low acoustic and thermal signature applications, is not only their ability to provide power cost effectively, but to endure in the marine and littoral environments in which the Navy operates. Cost, durability, size, weight, thermal, and water management are major challenges to the commercialization of fuel cell technology in both commercial and military applications. There are many manufacturing issues that need to be solved in order to bring fuel cells to the mass market for Navy applications. Significant manufacturing and acquisition costs can be reduced by reducing or eliminating the use of precious metal catalysts, such as platinum and rare earth metals, to reform fuels.</p> <p>In light of these challenges, the Center for Advanced Mineral and Metallurgical Processing (CAMP) at Montana Tech is developing fuel cell manufacturing and materials technology for the Office of Naval Research ManTech Program to investigate electroless plating of palladium and palladium alloys on stainless steel substrates. This research includes laboratory work (discussed on page three of this newsletter) and an extensive literature search of electroless and other methods that have been used to form palladium and palladium alloy membranes. This article summarizes the findings.</p> <p align="center"><img src="images/fig1-1.gif"></p> <p><b>Electroless Plating</b></p> <p>Electroless plating is a chemical process which catalytically reduces metal ions in an aqueous solution and deposits that metal on a substrate without the use of electrical energy. The process is similar to electroplating except that no outside current is needed. A controlled pretreatment sequence and plating process are critical to produce good adhesion of the metal to the substrate.</p> <p>In the electroless plating process, the driving force for the reduction of metal ions and their deposition is supplied by a chemical reducing agent in solution. In the case of palladium and palladium alloys, the reductant is typically hydrazine. This driving potential is essentially constant at all points of the surface of the component, provided solution agitation is sufficient to ensure a uniform concentration of metal ions and reducing agents. Electroless deposits, in theory, have a very uniform thickness all over the part. The electroless process has definite advantages when plating irregularly shaped objects, especially those which are difficult to plate by conventional means. </p> <p><b>Hydrogen Flux Calculations</b></p> <p>A unique property of palladium is that hydrogen gas diffuses through the metal. This characteristic is commonly used to produce very pure hydrogen using a palladium membrane. The flux of hydrogen gas through a palladium membrane is dependent on temperature, hydrogen partial pressure, and membrane thickness. From both a metal cost and flux standpoint, it is desirable to make the palladium membrane as thin as possible. Therefore, instead of using pure palladium foil membranes, many researchers have investigated plating palladium onto porous metallic and non-metallic substrates. </p> <p>There has been a substantial amount of research performed with respect to hydrogen flux measurements through palladium and palladium alloy membranes. Hydrogen flux is the rate of hydrogen passing through the membrane per unit area. Flux is typically denoted by the formula: </p> <p align="center"><img src="images/table1-1.gif"></p> <p>Where:</p> <p style="margin-left: 50px">N<sub>H2</sub> = hydrogen flux in moles per second per square meter<br /> K = permeability [moles per meter per second per pascal]<br /> P<sub>H2, ret</sub> , P<sub>H2, perm</sub> = the partial pressures of hydrogen on the retentate and permeate sides of the membrane, respectively [pascals]<br /> X<sub>M</sub> = membrane thickness [meters]</p> <p>According to Morreale (2003), the exponent (n) in the above formula is equal to 0.5 if the rate-limiting step in the hydrogen transport mechanism is diffusion and that transport is unidirectional. However, the assumption that diffusion is the rate-limiting step may not be accurate. Morreale found that the optimum value for the exponent, was greater than 0.5 in experiments as the hydrogen pressure on the retentate (upstream) side of the membrane increased. The optimum exponent value was determined to be 0.62 at retentate pressures up to 9,000 pascals and temperatures up to 1173 K. For this study, hydrogen flux values varied from 0.002 to 0.062 mol/s/m2, with greater values associated with higher pressure differential and higher temperatures. Experiments described in this study were conducted with relatively thick palladium membranes (XH ~ 1 mm). </p> <p><b>Data Review and Statistical Analysis</b></p> <p>Data from a large number of hydrogen purification studies were tabulated in 2004 by Rothenberger. These data were imported into Stat-Ease statistical software and response curves were created. The following figures show the effect of several variables on the trend for a particular response. These figures are for those sets of data where the plating was by electroless deposition and the permeate side pressure was atmospheric using a sweep gas. The membranes were plated onto either aluminum oxide or porous stainless steel. The variables examined were palladium membrane thickness (µm), reciprocal temperature (1000/T K), and electroless versus other plating techniques. The responses were flux (mol/s/m2), permeance (mol H2/(m2" sec" Pan) " 1012 (not shown), and permeability (mol H2/(m" sec" Pan) " 105. The noted factors of 10 were used to make the axis numbers easy to read. </p> <p align="center"><img src="images/fig1-2.gif"></p> <p align="center"><img src="images/fig1-3.gif"></p> <p>Figures 1-2 and 1-3 show the response of hydrogen flux with respect to changing temperature and palladium thickness. As the temperature is increased the hydrogen flux goes up; flux is poor at lower temperatures, but is much greater the thinner the membrane and the higher the temperature. The flux, of course, at a membrane thickness of zero is only a mathematical projection. The lowest temperature shown is 300ºC since palladium membranes must be operated above 300ºC to ensure a defect free membrane. The usual operating temperature is in the range of 450ºC to 500ºC and the desired membrane thickness is less than 5 micrometers (µm). The problem at operating palladium membranes below 300ºC is that a mixture of body-centered-cubic and face-centered cubic hydride solid solution phases is formed. Above 300ºC only a single solid solution phase exists. This problem is two-fold, i.e., if the membrane is cycled above 300ºC and then back to ambient temperature several times, stresses are formed because of the different thermal expansion coefficients of the phases. The resulting stresses can cause defects in the membrane. One way to minimize the cycling problem is to treat the membrane at elevated temperature in a vacuum to remove dissolved hydrogen. In addition, the flux of hydrogen at ambient temperatures through palladium is very small, whereas it is much higher at elevated temperatures (300ºC to 600ºC). </p> <p align="center"><img src="images/fig1-4.gif"></p> <p align="center"><img src="images/fig1-5.gif"></p> <p>Figures 1-4 and 1-5 show the response of the membrane permeability to hydrogen with respect to changing temperature and palladium thickness. As expected, this follows the same trend as shown for hydrogen flux.</p> <p>The fact that hydrogen flux increases with increasing temperature and decreasing palladium thickness is not surprising. The data appears to indicate that there is still room for improvement  higher temperatures and thinner membranes should result in even greater fluxes. However, there are practical limits to both of these parameters in terms of material limitations. For example, it may be possible to deposit even thinner palladium membranes on substrates, but the integrity of these membranes will be compromised, especially when subjected to extreme temperature cycling. The same holds true for the higher temperatures needed for increased flux  many of the materials currently being used in purification systems are at their practical temperature limits.</p> <p>In conclusion, significant improvements in hydrogen purification technology will likely require a radical departure in the current way of thinking by incorporating completely different materials and methods. ONR will continue to pursue cost effective manufacturing processes to make Navy power utilization less expensive and more efficient.</p> <p>References</p> <p>1. Morreale, B. D., M. V. Ciocco, R. M. Enick, B. I. Morsi, B. H. Howard, A. V. Cugini, and K. S. Rothenberger. "The Permeability of Hydrogen in Bulk Palladium at Elevated Temperatures and Pressures." Journal of Membrane Science 212.1-2 (2003): 87-97. Print.</p> <p>2. Rothenberger, K., A. Cugini, B. Howard, R. Killmeyer, M. Ciocco, B. Morreale, R. Enick, F. Bustamante, I. Mardilovich, and Y. Ma. "High Pressure Hydrogen Permeance of Porous Stainless Steel Coated with a Thin Palladium Film via Electroless Plating." Journal of Membrane Science 244.1-2 (2004): 55-68. Print.</p> <p class="body_text"><img src="../../archive/updated/ltwidwell.gif"></p> </div> </td> <!-- InstanceEndEditable --> </tr> <tr> </tr> </table> <br> <table width="100%" border="0"> <tr> <td colspan="2"><div align="center"> <p><em>The EMPF is a U.S. Navy-sponsored National Electronics Manufacturing Center of Excellence focused on the development,<br> application, and transfer of new electronics manufacturing technology by partnering with industry,<br> academia, and government centers and laboratories in the U.S</em></p> </div></td> </tr> <tr> <td class="footer">ACI Technologies, Inc. - - <a href="http://www.aciusa.org">www.aciusa.org</a> - - (610)362-1200</td> <td><div align="right"><a href="http://www.onr.navy.mil/Science-Technology/Directorates/Transition/Manufacturing-ManTech.aspx"><img src="http://www.empf.org/empfasis/archive/images/mantech.gif" width="144" height="42" border="0"></a></div></td> </tr> </table> <div align="right"> <!-- Start of StatCounter Code --> <script type="text/javascript" language="javascript"> var sc_project=350643; var sc_partition=1; </script> <script type="text/javascript" language="javascript" src="http://www.statcounter.com/counter/counter.js"></script> <noscript> <a href="http://www.statcounter.com/free_hit_counter.html" target="_blank"><img src="http://c2.statcounter.com/counter.php?sc_project=350643&amp;amp;java=0" alt="hit counter" border="0"></a> </noscript> <a href="http://www.empf.org/sitemap.htm"><em>[site map] </em></a> <!-- End of StatCounter Code --> <!-- Start of StatCounter Code --> <script type="text/javascript" language="javascript"> var sc_project=1902214; var sc_invisible=1; var sc_partition=17; var sc_security="759b802c"; </script> <script type="text/javascript" language="javascript" src="http://www.statcounter.com/counter/counter.js"></script><noscript><a href="http://www.statcounter.com/" target="_blank"><img src="http://c18.statcounter.com/counter.php?sc_project=1902214&java=0&security=759b802c&invisible=1" alt="website statistics" border="0"></a> </noscript> <!-- End of StatCounter Code --> </div> </body> <!-- InstanceEnd --></html>