Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 239 of 707

Ammonium chloride, 30 g/L Hydrochloric acid to pH 0.1-0.5 Temperature, 40-50° C Current density, 0.1-1.0 A/dm2 Anodes, pure palladium Deposits from the acid chloride system are dull to semibright. Current effi- ciency is 97 to 100%. The plating solution itself is notably sensitive to contami- nation by copper, which can displace palladium from solution. Work to be plat- ed in this solution should thus be struck with palladium or with gold. PALLADIUM-NICKEL PLATING Palladium readily forms alloys with other metals and has been plated in numer- ous alloy formulations. Of these, the most important commercially has been palladium-nickel, which can be deposited as a homogeneous alloy over a com- position range from approximately 30% to over 90% palladium by weight. Current practice favors an alloy composition from approximately 75 to 85% wt. palladium. A formulation suitable for alloys in this range is as follows: Palladium as Pd(NH3 )4 Cl2 , 18-28 g/L (palladium metal, 8-12 g/L), Ammonium chloride, 60 g/L Nickel chloride concentrate, 45-70 ml/L (nickel metal 8-12 g/L) Ammonium hydroxide to pH 7.5-9.0 Temperature, 30-45° C Current density, 0.1-2.5 A/dm2 Anodes, platinized Palladium-nickel alloy electrodeposits are notably less sensitive to hydrogen- induced cracking than are pure palladium deposits. They are, how- ever, somewhat more susceptible than pure palladium to stress cracking upon deformation. As with pure palladium plating sys- tems, various proprietary additives are available for brightening and stress control. 0(73$/ ,,, 3' 1, 6(5,(6 W R] R] 3G $X $X 3 G 3G 1L WKH DOWHUQDWLYH IRU HOHFWURQLF DQG FRQQHFWRU DSSOLFDWLRQV DFKLHYLQJ FRVW UHGXFWLRQV RI PRUH WKDQ 3 G 1L WK H 7KH 21/ DFKLHYLQJ FRVW UHGXFWLRQV RI PRUH WKD Q FRPSDUHG WR JRO G 7KH 21/< SURGXFWLRQ YHUL¿H G SDWHQWH G /< SURGXFWLRQ YHUL¿HG SDWHQWHG FRPPHUFLDOO\ DYDLODEOH DPPRQLD IUHH 3G 1L SURFHVV 1R DPPRQLD 1R DPPRQLD 1R FKORULGH 1R FKORULGH 0HWDORU 7H HO O :LGH FXUUHQW GHQVLW\ UDQJHLGH FXUUHQW GHQVLW\ UDQJ H 0HWDORU 7HFKQRORJLHV 86$ &RUSRU WLRQ 7H ZZZ PHWDORU FRP DGYDQFHGBFRDWLQJV XV#PHWDORU FRP ZZ ZPHWDOR U FR P DGYDQFHGBFRDWLQJ V XV#PHWDOR U )D [ HFKQRORJLHV 86$ &RUSRUDWLRQ [ )D[ FRP www.metalfinishing/advertisers 238 FRPPHUFLDOO\ DYDLODEOH DPPRQL D IUHH 3 G 1L SURFHVV 6WDEOH DOOR\ FRPSRVLWLRQ S+ )XOO\ DQDO\]DEOH )XOO\ DQDO\]DEO H S + 6WDEOH DOOR\ FRPSRVLWLRQ DOWHUQDWLYH IRU HOHFWURQLF DQG FRQQHFWRU DSSOLFDWLRQ V FRPSDUHG WR JROG

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