- Email: [email protected]
Activating heat-treated nickel
they do not specifically address aluminum anodizing. Another source of information is a good text on Physical Metallurgy focusing on the lattice mismatch across the metal oxide interface. We are currently working with X-ray diffraction to determine the crystal structure of oxides. Aluminum oxide appears to be amorphous. David C. Fairboum, Chemi-Industrial Consultants, w3.one.net/=chemiind
ACTIVATING HEAT-TREATED NICKEL Does anyone have a suggestion on how to activate heattreated nickel to accept nickel sulfamate plate. Walt Bilous, AMP Inc., [email protected] Have you tried cathodic electroclean, rinse, rinse, 10% sulfuric acid, rinse, rinse, 5 oz/gal Wood’s nickel strike for 5 min (enough current to get some very light bubbling on the cathodic surface), rinse, rinse, plate? Tom Pullizzi, Team*Faraday, [email protected] The question is was the heat treatment in air or some other medium and is the nickel that has been heat treated the base material, an intermediate deposit, or otherwise free from impurities such as chromium, aluminum, titanium, etc.? If pure nickel is heat treated in air, an oxide a bit too tenacious for the above-mentioned treatment may result, and stronger surface preparations involving chlorides, fluorides, and/or even cyanide would be required (hot cyanide does it every time) followed by 30% hydrochloric acid (rinse before, of course!) then Wood’s strike. Dave Kinghom, Consultant, [email protected]
MECHANICAL POLISHING OF STAINLESS STEEL I am trying to gather information regarding mechanical polishing of stainless steel. We manufacture vessels and have a company standard set at 20 Ra. On occasion we get special customer requests for 15 Ra. Our shop typically goes overboard and finishes to 5 to 10 Ra (to get a pretty finish). That extra work is expensive. Marketing requires a pretty finish. I am trying to develop a method to get us to an affordable and acceptable finish. My plan is to machine or mechanically polish to set the finish then electropolish to clean and improve the appearance. I am trying to find a source of information that will cross reference industry standard finishes, i.e., #2B, #4, #6, buffed #7, etc., grit 150, 180, 240, 320, etc., IS0 designations, Ra microinch, and Ra micron. I have collected various pieces and have collated them into a spreadsheet but still have some holes and want to double check it against some reference as well as add to it. Do you have any suggestions where I can go to get this information? Claus Kinder, [email protected] You should be able to get approximately 50% reduction in Ra after electropolishing properly finished stainless steel sheet. In other words if you need a 15 Ra you should be able to get there from a 25 to 30 microinch finish. The process for mechanical finishing prior to electropolishing is substan-
36
tially different than the one used to produce the standard mill finishes though. Ed Bayha, Metal Coating Process Corp., mcp. [email protected] Mechanical polishing of stainless to Ra 5 does not need to be expensive. Some of our customers use mirror polished stainless steel, which is polished to Ra 0.9, in place of electropolishing because cost is competitive. Mike Taylor, Hwa Yang Stainless/Pacific Plus, [email protected]
PLATING OFF THE BEATEN PATH I have a couple of unusual applications. The first is rhenium plating and the other is tungsten/nickel intermetallit plating. I have been able to pick up some basic information on the chemical salts for making up solutions but I don’t know any operating conditions. Also, what type of anodes would I use-platinum/niobium, stainless steel, other insoluble? Any information on either of these strangers is very much appreciated. Bob Duvall, [email protected] On page 469 in “Modem Electroplating,” edited by Lowenheim, there are several references listed for rhenium plating. I am not sure of your meaning of “intermetallic” but the same book has numerous references listed for alloy plating with tungsten as one of the metals. James Watts, James Watts Inc., [email protected] One good place to start would be by running a cyclic voltammagram on your proposed solution. Almost any electrochemist can perform this test. You can also get information about the response of various potential anode materials from this test. This will tell you where the voltage should be. The results plot current versus potential so you can get the current range from here as well. You can estimate your current and voltage parameters from this curve. If rhenium traps hydrogen like platinum or palladium you need to know this and you’ll want to operate without a huge overpotential. Next determine the pH of your solution. The anodes are typically left in the solution so you need to have a feel for their corrosion resistance requirement. Next I’d start looking at Taguchi methods for screening trials to determine optimum pH, process times, and current densities within the previously determined window. Try X-ray fluorescence for a means of determining thickness. Good luck. Oh, you’d better find out what the environmental dangers from rhenium compounds are. Many of the precious metals are used in cancer drugs so they can be deadly. Also check out the Las Vegas metal reclaiming convention two years ago. You will find someone proposing a commercial process for reclaiming precious metals. You won’t want to lose any rhenium. David C. Fairboum, Chemi-Industrial Consultants, w3.one.net/=chemiind Ted Mooney is an independent consulting engineer based in
MF-
Kinnelon, N.J.
METAL FINISHING
l
AUGUST
1997
ACTIVATING HEAT-TREATED NICKEL Does anyone have a suggestion on how to activate heattreated nickel to accept nickel sulfamate plate. Walt Bilous, AMP Inc., [email protected] Have you tried cathodic electroclean, rinse, rinse, 10% sulfuric acid, rinse, rinse, 5 oz/gal Wood’s nickel strike for 5 min (enough current to get some very light bubbling on the cathodic surface), rinse, rinse, plate? Tom Pullizzi, Team*Faraday, [email protected] The question is was the heat treatment in air or some other medium and is the nickel that has been heat treated the base material, an intermediate deposit, or otherwise free from impurities such as chromium, aluminum, titanium, etc.? If pure nickel is heat treated in air, an oxide a bit too tenacious for the above-mentioned treatment may result, and stronger surface preparations involving chlorides, fluorides, and/or even cyanide would be required (hot cyanide does it every time) followed by 30% hydrochloric acid (rinse before, of course!) then Wood’s strike. Dave Kinghom, Consultant, [email protected]
MECHANICAL POLISHING OF STAINLESS STEEL I am trying to gather information regarding mechanical polishing of stainless steel. We manufacture vessels and have a company standard set at 20 Ra. On occasion we get special customer requests for 15 Ra. Our shop typically goes overboard and finishes to 5 to 10 Ra (to get a pretty finish). That extra work is expensive. Marketing requires a pretty finish. I am trying to develop a method to get us to an affordable and acceptable finish. My plan is to machine or mechanically polish to set the finish then electropolish to clean and improve the appearance. I am trying to find a source of information that will cross reference industry standard finishes, i.e., #2B, #4, #6, buffed #7, etc., grit 150, 180, 240, 320, etc., IS0 designations, Ra microinch, and Ra micron. I have collected various pieces and have collated them into a spreadsheet but still have some holes and want to double check it against some reference as well as add to it. Do you have any suggestions where I can go to get this information? Claus Kinder, [email protected] You should be able to get approximately 50% reduction in Ra after electropolishing properly finished stainless steel sheet. In other words if you need a 15 Ra you should be able to get there from a 25 to 30 microinch finish. The process for mechanical finishing prior to electropolishing is substan-
36
tially different than the one used to produce the standard mill finishes though. Ed Bayha, Metal Coating Process Corp., mcp. [email protected] Mechanical polishing of stainless to Ra 5 does not need to be expensive. Some of our customers use mirror polished stainless steel, which is polished to Ra 0.9, in place of electropolishing because cost is competitive. Mike Taylor, Hwa Yang Stainless/Pacific Plus, [email protected]
PLATING OFF THE BEATEN PATH I have a couple of unusual applications. The first is rhenium plating and the other is tungsten/nickel intermetallit plating. I have been able to pick up some basic information on the chemical salts for making up solutions but I don’t know any operating conditions. Also, what type of anodes would I use-platinum/niobium, stainless steel, other insoluble? Any information on either of these strangers is very much appreciated. Bob Duvall, [email protected] On page 469 in “Modem Electroplating,” edited by Lowenheim, there are several references listed for rhenium plating. I am not sure of your meaning of “intermetallic” but the same book has numerous references listed for alloy plating with tungsten as one of the metals. James Watts, James Watts Inc., [email protected] One good place to start would be by running a cyclic voltammagram on your proposed solution. Almost any electrochemist can perform this test. You can also get information about the response of various potential anode materials from this test. This will tell you where the voltage should be. The results plot current versus potential so you can get the current range from here as well. You can estimate your current and voltage parameters from this curve. If rhenium traps hydrogen like platinum or palladium you need to know this and you’ll want to operate without a huge overpotential. Next determine the pH of your solution. The anodes are typically left in the solution so you need to have a feel for their corrosion resistance requirement. Next I’d start looking at Taguchi methods for screening trials to determine optimum pH, process times, and current densities within the previously determined window. Try X-ray fluorescence for a means of determining thickness. Good luck. Oh, you’d better find out what the environmental dangers from rhenium compounds are. Many of the precious metals are used in cancer drugs so they can be deadly. Also check out the Las Vegas metal reclaiming convention two years ago. You will find someone proposing a commercial process for reclaiming precious metals. You won’t want to lose any rhenium. David C. Fairboum, Chemi-Industrial Consultants, w3.one.net/=chemiind Ted Mooney is an independent consulting engineer based in
MF-
Kinnelon, N.J.
METAL FINISHING
l
AUGUST
1997