Plating Challenging Plating Challenging Substrates Substrates By: By: Frank Altmayer, MSF, AESF Fellow, Frank Altmayer, MSF, AESF Fellow, Technical Education Director, AESF Technical Education Director, AESF Foundation/NASF Foundation/NASF And: Relying heavily upon procedures And: Relying heavily upon procedures developed/investigated by Dr. Jack Dini, developed/investigated by Dr. Jack Dini, Consultant, Dr. Chris Marzano (deceased) and Consultant, Dr. Chris Marzano (deceased) and numerous others. numerous others.
And: Relying heavily upon procedures developed/investigated by And: Relying heavily upon procedures developed/investigated by Dr. Jack Dini, Consultant, Dr. Chris Marzano (deceased) Dr. Jack Dini, Consultant, Dr. Chris Marzano (deceased) and numerous others.and numerous others.
Note: Note: ““Troublemakers”* Troublemakers”* produce a stable oxide produce a stable oxide film that is difficult to film that is difficult to remove and can return remove and can return prior to platingprior to plating
*except non-conductors*except non-conductors
Plating AdhesionPlating Adhesion
• Oxide film is removed for a sufficient time to Oxide film is removed for a sufficient time to permit an initial electrodepositpermit an initial electrodeposit
• Oxide film is replaced by another film that Oxide film is replaced by another film that does not interfere with adhesiondoes not interfere with adhesion
• Oxide film is incorporated into the deposit in a Oxide film is incorporated into the deposit in a compatible mannercompatible manner
• Plated deposit is diffused into the substratePlated deposit is diffused into the substrate• Surface of basis metal is etched to produce a Surface of basis metal is etched to produce a
larger surface area with mechanical bonding larger surface area with mechanical bonding sitessites
Primary Schemes for Improving Adhesion:Primary Schemes for Improving Adhesion:
Adhesion Units: Adhesion Units: Pounds/inPounds/in22 (psi), MN or mega Pascals/m (psi), MN or mega Pascals/m22
Keys to Preparing AluminumKeys to Preparing AluminumUsing Correct Acid DipUsing Correct Acid Dip• Dissolves surface alloying elements, and residuals that may be left on the Dissolves surface alloying elements, and residuals that may be left on the
surface by cleaners (such as silicates). surface by cleaners (such as silicates). • Nitric acid needs to be fortified with fluorides to more adequately remove Nitric acid needs to be fortified with fluorides to more adequately remove
these metals from the surface, and to remove residual silicates from the these metals from the surface, and to remove residual silicates from the cleaner(s). cleaner(s).
Typical Acid Formulations:Typical Acid Formulations:• a. Nitric acid, 50% vol., containing 6lb./100 gal. (7 g/L) of ammonium a. Nitric acid, 50% vol., containing 6lb./100 gal. (7 g/L) of ammonium
bifluoride. This acid is used at 20-30°C. > 30°C, may cause localized bifluoride. This acid is used at 20-30°C. > 30°C, may cause localized etching or pitting. etching or pitting.
• b. Tri-acid, (50%vol. nitric, 25%vol. sulfuric, 60 g/L ammonium bifluoride or b. Tri-acid, (50%vol. nitric, 25%vol. sulfuric, 60 g/L ammonium bifluoride or 2% volume hydrofluoric acid). This acid is also used at 20-30°C. > 30°C, 2% volume hydrofluoric acid). This acid is also used at 20-30°C. > 30°C, may cause localized etching or pitting. may cause localized etching or pitting.
Acid for High Mg Alloys (example 5000 series):Acid for High Mg Alloys (example 5000 series):• Sulfuric acid, 25%vol., at 80-85°C (2-5 minutes) followed by a brief dip in Sulfuric acid, 25%vol., at 80-85°C (2-5 minutes) followed by a brief dip in
50% nitric acid at 20-30°C.50% nitric acid at 20-30°C.
• 70-75°F (20-25°C)70-75°F (20-25°C)• 30 seconds maximum immersion time30 seconds maximum immersion time
• Note: Alloying Elements such as Cu, Fe, Si can Note: Alloying Elements such as Cu, Fe, Si can retard the formation of a contiguous zinc film. retard the formation of a contiguous zinc film.
Keys to Preparing AluminumKeys to Preparing Aluminum
ZincateZincate•Time should be carefully controlled Time should be carefully controlled to within the suggested time frame to within the suggested time frame of the supplier of the zincate of the supplier of the zincate formulation, especially, the second formulation, especially, the second zincate film. zincate film.
•Typically between 30 seconds and Typically between 30 seconds and 2 minutes depending on 2 minutes depending on formulation. formulation.
•When double zincating, the second When double zincating, the second dip is normally much shorter in dip is normally much shorter in time than the first (typically 10-15 time than the first (typically 10-15 seconds). seconds).
•The use of a timer is important for The use of a timer is important for manually produced zincate films.manually produced zincate films.
Zincated Aluminum CastingsNon-uniform gray color indicates potential
problem with zincate
F. Altmayer
Keys to Preparing AluminumKeys to Preparing Aluminum
Zincate:Zincate:Temperature and quality of rinsing Temperature and quality of rinsing after zincating are also commonly after zincating are also commonly ignored variables ignored variables
The maximum temperature is typically The maximum temperature is typically 27°C (80°F). Zincating at too high a 27°C (80°F). Zincating at too high a temperature will compromise adhesiontemperature will compromise adhesion
The first rinse after zincating needs to The first rinse after zincating needs to flow at a high rate to avoid additional flow at a high rate to avoid additional zincate film(s)zincate film(s)
Uniform agitation in rinse is criticalUniform agitation in rinse is critical
Non-uniform air agitation yields non-uniform rinse quality
F. AltmayerF. Altmayer
Keys to Preparing AluminumKeys to Preparing Aluminum
50% vol.50% vol.• 150-175°F150-175°F• 1 minute after gassing 1 minute after gassing
startsstarts
Note: Note: Rinse time must beRinse time must beminimized or (if possible) minimized or (if possible) rinsing should be eliminated rinsing should be eliminated (if possible) to prevent(if possible) to preventoxide re-formationoxide re-formation
Adhesion Comparison Wood’s vs. Anodic Etch* on NiAdhesion Comparison Wood’s vs. Anodic Etch* on NiProcessProcess Adhesion, psiAdhesion, psi
Wood’s Ni Strike, 54ASF, 5 minutesWood’s Ni Strike, 54ASF, 5 minutes 103,000103,000
Option 1 (no Ni strike)Option 1 (no Ni strike) 110,000110,000
Option 2 (no Ni strike)Option 2 (no Ni strike) 110,000110,000
*Conical head tensile test of nickel plating over nickel substrate*Conical head tensile test of nickel plating over nickel substrate Data from Dr. Jack Dini, Lawrence Livermore Labs.Data from Dr. Jack Dini, Lawrence Livermore Labs.
Nickel StrikesNickel StrikesPurpose/Goal:Purpose/Goal:To de-oxidize the surface using hydrogen gas generation and To de-oxidize the surface using hydrogen gas generation and simultaneously deposit a thin layer of nickelsimultaneously deposit a thin layer of nickel
Note: Studies have shown that higher CCD in Woods Ni = Higher adhesionNote: Studies have shown that higher CCD in Woods Ni = Higher adhesion
Sulfate Based Nickel StrikesSulfate Based Nickel Strikes
Option-1:Option-1:
Nickel may be plated over an activated Nickel may be plated over an activated nickel alloy surface with a Watts nickel alloy surface with a Watts solution, if the pH of the Watts nickel solution, if the pH of the Watts nickel solution is at about 2solution is at about 2
Option-1:Option-1:Nickel SulfamateNickel Sulfamate 40 oz/gal40 oz/galSulfamic AcidSulfamic Acid 20 oz/gal20 oz/galTemperatureTemperature 70-120°F70-120°FCurrent DensityCurrent Density 50 ASF50 ASFTimeTime 5-10 min5-10 minNi Anodes (S is OK)Ni Anodes (S is OK)
Option-2Option-2Nickel SulfamateNickel Sulfamate 40 oz/gal40 oz/galpH (adj with Sulfamic Acid)pH (adj with Sulfamic Acid) 1.51.5Boric acidBoric acid 4 oz/gal4 oz/galTemperatureTemperature 70-120°F70-120°FCurrent DensityCurrent Density 20-100ASF20-100ASFTimeTime 5-10 min5-10 minNi Anodes (S is OK)Ni Anodes (S is OK)
Sulfamic Acid Based Nickel StrikesSulfamic Acid Based Nickel Strikes
Note: solution will not attack bare aluminum surfacesNote: solution will not attack bare aluminum surfaces
Stainless SteelStainless Steel
Rigorous Process for SS:Rigorous Process for SS:•Anodic cleaning in hot alkaline Anodic cleaning in hot alkaline solution at 30 A/ftsolution at 30 A/ft22,, 3minutes3minutes•Immersion in 20% vol. HCl at Immersion in 20% vol. HCl at room temperature for 1 minuteroom temperature for 1 minute•Anodic etch (optional) in 40% Anodic etch (optional) in 40% vol. sulfuric acid at 100 A/ftvol. sulfuric acid at 100 A/ft22 for 3 for 3 minutesminutes•Wood's strike at 25-50A/ftWood's strike at 25-50A/ft22 for 5 for 5 minutesminutes•Sulfamate nickel plateSulfamate nickel plate
Without Anodic EtchWithout Anodic Etch28,200psi28,200psi
With Anodic EtchWith Anodic Etch68,300psi68,300psi
Impact of Impact of Anodic Etch Anodic Etch on Ring Shear on Ring Shear
Adhesion on 17-4PH Adhesion on 17-4PH SS Substrate:SS Substrate:
Kovar/InvarKovar/InvarKovar*Kovar* (53% Fe, 29% Ni, 17% Co) (53% Fe, 29% Ni, 17% Co)•Developed to make vacuum seal to glassDeveloped to make vacuum seal to glass
Invar** Invar** (64%Fe, 36%Ni)(64%Fe, 36%Ni)•Has a very low coefficient of expansionHas a very low coefficient of expansion
Preparation Options:Preparation Options:•Cathodic CleanCathodic Clean-30-120 seconds30-120 seconds-140-180°F 140-180°F -Anodes: Stainless SteelAnodes: Stainless Steel-Current Density: 50 ASFCurrent Density: 50 ASF•Sulfuric Pickle orSulfuric Pickle or•Hydrochloric pickle orHydrochloric pickle or•Sulfuric or Hydrochloric pickle plus Wood’s StrikeSulfuric or Hydrochloric pickle plus Wood’s Strike
General Scheme:General Scheme:
•Porous parts must be covered in hard Porous parts must be covered in hard resin/many coats of lacquerresin/many coats of lacquer•Surface to be plated is roughened by tumbling Surface to be plated is roughened by tumbling in sandin sand•Plastics are further roughened by chemical Plastics are further roughened by chemical etchingetching•Roughened surface can be treated in palladium Roughened surface can be treated in palladium chloride solution-then EN platedchloride solution-then EN plated
*Excluding plastics that are commonly plated (eg ABS etc.)*Excluding plastics that are commonly plated (eg ABS etc.)
Unconventional Non-ConductorsUnconventional Non-ConductorsChess Pieces (“non-plateable” plastic)Chess Pieces (“non-plateable” plastic)•Etched in 50% sulfuric acid plus 2-5% peroxide for 10-12 hoursEtched in 50% sulfuric acid plus 2-5% peroxide for 10-12 hours
•1 minute soak in stannous chloride suspension 1 minute soak in stannous chloride suspension
•Prepare silvering solutions as follows:Prepare silvering solutions as follows:
-A. Dissolve 10 g silver nitrate in ~ 50 mL DI water. Add enough NHA. Dissolve 10 g silver nitrate in ~ 50 mL DI water. Add enough NH44OH to just OH to just
re-dissolve the formed precipitate and dilute to 100 mL final volume.re-dissolve the formed precipitate and dilute to 100 mL final volume.
-B. Prepare 75g/L KOH solution and 75 g/L Dextrose solution. B. Prepare 75g/L KOH solution and 75 g/L Dextrose solution.
-C. Mix equal volumes of each solution in B to create reducing solutionC. Mix equal volumes of each solution in B to create reducing solution
•One immersion coating is produced by diluting the silver nitrate One immersion coating is produced by diluting the silver nitrate solution 10: 1 , and adding approximately 10 mL reducing solution per solution 10: 1 , and adding approximately 10 mL reducing solution per liter of silver nitrate solution liter of silver nitrate solution
•Silver deposits on container and parts within the containerSilver deposits on container and parts within the container
•Repeat 6-8 more times to build up silver thicknessRepeat 6-8 more times to build up silver thickness
•Electroplate over the silver depositElectroplate over the silver deposit
Quiz Question:Quiz Question:
•How do you barrel silver plate the parts shown, when they How do you barrel silver plate the parts shown, when they float in water?float in water?
*ABS Eyelets used in manufacture of ECG electrodes*ABS Eyelets used in manufacture of ECG electrodes
Conventional Non-ConductorsConventional Non-ConductorsWith a TwistWith a Twist
Neodymium MagnetsNeodymium MagnetsNdNd22FeFe1414B B
•Discovered in 1982 (GM and Sumitomo)Discovered in 1982 (GM and Sumitomo)
•May be melt-spun (GM) or sintered (Sumitomo)May be melt-spun (GM) or sintered (Sumitomo)
•Nickel plated for corrosion protectionNickel plated for corrosion protection
European Patent: 0325-088*European Patent: 0325-088*•Prepare a combination of Oakite 195 and 90 as the primary cleaning Prepare a combination of Oakite 195 and 90 as the primary cleaning solution: 200 g/gal Oakite 195 + 140 g/gal Oakite 90solution: 200 g/gal Oakite 195 + 140 g/gal Oakite 90
•Cathodic for 5 seconds Cathodic for 5 seconds
•Anodic for 5-10 secondsAnodic for 5-10 seconds
•Cold water rinseCold water rinse
•Immerse for 5 seconds in 70 g/L sulfuric acidImmerse for 5 seconds in 70 g/L sulfuric acid
•Cold water rinse Cold water rinse
•Sulfamate nickel strikeSulfamate nickel strike*patent is primarily for phosphating Nd magnets *patent is primarily for phosphating Nd magnets
Magnesium AlloysMagnesium Alloys
• Quickly reacts with oxygen Quickly reacts with oxygen to produce oxide filmto produce oxide film
• Highly reactive metalHighly reactive metal– FiresFires– Dissolves in alcoholDissolves in alcohol– Cleaners must be below Cleaners must be below
pH 11pH 11• Used in cell phones, Used in cell phones,
laptops, cameras, solar laptops, cameras, solar collectors and other collectors and other electronic componentselectronic components
Magnesium has 66% the weight of Al, Magnesium has 66% the weight of Al, common alloying elements are Al, Zn, common alloying elements are Al, Zn,
Mn, ThMn, Th
Black chromium plated Black chromium plated magnesium casting used in magnesium casting used in
manufacture of solar collectormanufacture of solar collector
MagnesiumMagnesiumPreparation Process:Preparation Process:•Clean cathodically in an alkaline (<pH11) cleanerClean cathodically in an alkaline (<pH11) cleaner-Anodic cleaning is not suitableAnodic cleaning is not suitable•Pickle (30-120 seconds):Pickle (30-120 seconds):
Potassium fluoride (KF) ......................................... 3.5-7 ” Potassium fluoride (KF) ......................................... 3.5-7 ” Note: Use low KF for wrought products and high KF for castingsNote: Use low KF for wrought products and high KF for castings
Option 4 (no dimensional change) :Option 4 (no dimensional change) :Chromic Acid at 180 g/L, 2-10 minutesChromic Acid at 180 g/L, 2-10 minutes70-200°F depending on desired processing time70-200°F depending on desired processing time
Note: Note: •Chromic acid containing pickles need to be followed by hydrosulfite dip to eliminate CrChromic acid containing pickles need to be followed by hydrosulfite dip to eliminate Cr+6+6
Notes: Notes: •Double zincate required for M1660, M13120, Double zincate required for M1660, M13120, M13310, M13312 AlloysM13310, M13312 Alloys•Solubility of LiF is limited to the required Solubility of LiF is limited to the required concentrationconcentration•Fluoride controls the deposition rate. The Fluoride controls the deposition rate. The quality of the deposit is heavily dependent on quality of the deposit is heavily dependent on its concentrationits concentration
Zincates for Magnesium AlloysZincates for Magnesium Alloys
•0.75 oz/gal NaF 0.75 oz/gal NaF •or 0.3 oz/gal LiFor 0.3 oz/gal LiF•Immersion Time (minutes)Immersion Time (minutes)
- Al containing alloys 5-12Al containing alloys 5-12- Non-Al Alloys, 4-9Non-Al Alloys, 4-9- Pure Mg, 4-9Pure Mg, 4-9
•pH 10.2-10.4pH 10.2-10.4•Temp 160°FTemp 160°F
*Originally proposed by H. K. DeLong, *Originally proposed by H. K. DeLong, Dow Metal Products CoDow Metal Products Co
•Clean, Electroclean, pickle as described previously (use Clean, Electroclean, pickle as described previously (use chromic acid or 90% vol phosphoric solution)chromic acid or 90% vol phosphoric solution)•Etch 20-60 seconds:Etch 20-60 seconds:
- For Al containing alloys use 11% vol nitric acid containing 16 For Al containing alloys use 11% vol nitric acid containing 16 oz/gal chromic acidoz/gal chromic acid
- For others use 9% vol. nitric containing 8 oz/gal chromic acidFor others use 9% vol. nitric containing 8 oz/gal chromic acid
- 8-12 oz/gal NH8-12 oz/gal NH44HFHF22 may be substituted for HF may be substituted for HF
•EN plate in special formulation bathEN plate in special formulation bath
Plating Mg without Zincate*Plating Mg without Zincate*
Note: Only Ni from a fluoride based formulation has been found to produce Note: Only Ni from a fluoride based formulation has been found to produce successful adhesionsuccessful adhesion
*Originally proposed by H. K. DeLong, *Originally proposed by H. K. DeLong, Dow Metal Products CoDow Metal Products Co
•NHNH44OH…………………….. to pH 5.5-6.3OH…………………….. to pH 5.5-6.3
•Temperature………………… 170-180°FTemperature………………… 170-180°F•Applies very thin deposit - follow with regular Applies very thin deposit - follow with regular EN plateEN plate
Ni Electroplating SolutionNi Electroplating Solution
• Alloys use in aerospace include Alloys use in aerospace include Ti6Al4V, Ti2Cu, IMI 685 and Ti6Al4V, Ti2Cu, IMI 685 and Ti6Al12Sn4Zr2Mo Ti6Al12Sn4Zr2Mo
• Alloys typically contain Alloys typically contain
– Al (typically 3%)Al (typically 3%)
– V (typically 2.5%)V (typically 2.5%)
• High strength to weight ratio even High strength to weight ratio even @ elevated temperature@ elevated temperature
• Oxide formation upon air Oxide formation upon air exposureexposure
-Time:Time: 15-50 minutes15-50 minutes-Temperature:Temperature: 35° to 100° C35° to 100° C
•Sulfamate Ni, Acid Cu or EN PlateSulfamate Ni, Acid Cu or EN Plate
Ti6Al4V, after blast, 1000XTi6Al4V, after blast, 1000X
Ti6Al4V, after pickle, 1000XTi6Al4V, after pickle, 1000X
Ti6Al4V, after activation, 1000XTi6Al4V, after activation, 1000X
Plating Ti Alloys W/O Thermal Plating Ti Alloys W/O Thermal Treatment or “Weird” Treatment or “Weird” StrikesStrikes
US Pat. 4,414,039 Martin Thoma mtu Motoren- und Turbinen-Union Miinchen GmbH Miinchen, West Germany
Notes:Notes:•The adhesion values for nickel plating on titanium are on the The adhesion values for nickel plating on titanium are on the order of 14,000psiorder of 14,000psi•Heat treatment up to 400°C does not bring about any Heat treatment up to 400°C does not bring about any improvement in the adhesionimprovement in the adhesion•Heat treatment at 480°C for 2 hours increases the adhesion to Heat treatment at 480°C for 2 hours increases the adhesion to 40,000 psi with Ti6Al4V and to 20,000 psi with Ti2Cu40,000 psi with Ti6Al4V and to 20,000 psi with Ti2Cu•No hydrogen absorption occurs from plating with Ni, EN, acid No hydrogen absorption occurs from plating with Ni, EN, acid Cu Cu •Avoid chromium strike (excessive hydrogen absorption)Avoid chromium strike (excessive hydrogen absorption)
Plating Ti Alloys W/O Thermal Plating Ti Alloys W/O Thermal Treatment or “Weird” StrikesTreatment or “Weird” Strikes
Beryllium CopperBeryllium Copper
Alternate 1:Alternate 1:•DegreaseDegrease1.1.Caustic-soakCaustic-soak2.2.Pumice-scrubPumice-scrub3.3.Anodic-treat in Oakite 90 for 2 Anodic-treat in Oakite 90 for 2 minutes at 268 A/mminutes at 268 A/m2 2 (27ASF)(27ASF)4.4.1 minute in 18% (by wt) HCl1 minute in 18% (by wt) HCl5.5.Nickel sulfamate or electroless Nickel sulfamate or electroless nickel-plate to thicknessnickel-plate to thickness
Alternate 2:Alternate 2:•DegreaseDegrease•Caustic-soakCaustic-soak•Pumice-scrubPumice-scrub•Anodic-treat in alkaline cleaner for 2 Anodic-treat in alkaline cleaner for 2 minutes at 268 A/mminutes at 268 A/m22
•Fluoboric acid (48%) at 12% vol. 1 minute Fluoboric acid (48%) at 12% vol. 1 minute at 60°C; Hat 60°C; H22SOSO44 (66° Baume) 25% vol. 1 (66° Baume) 25% vol. 1
minute at 56°Cminute at 56°C•Bright-dip 515 ml HBright-dip 515 ml H33POPO44 24 ml acetic, 5.25 24 ml acetic, 5.25
ml HCl, 17.5 ml Hml HCl, 17.5 ml H22O for 20 s at 66°CO for 20 s at 66°C•Fluoboric acid for 30 s at 60°CFluoboric acid for 30 s at 60°C•Sulfamate or electroless nickel-plate to Sulfamate or electroless nickel-plate to thicknessthickness
Notes: Notes: •Adhesion levels: 100 to 400 MN/mAdhesion levels: 100 to 400 MN/m22 (~ 14,500-58,000psi) (~ 14,500-58,000psi)•Thermal diffusion treatments do not appear to improve adhesion on Be-CuThermal diffusion treatments do not appear to improve adhesion on Be-Cu•Tools made of Be-Cu do not produce sparksTools made of Be-Cu do not produce sparks
Berylco 10* and Berylco 25**Berylco 10* and Berylco 25**
• Pre-clean etc.Pre-clean etc.
• Chemical Dip (Chose one)Chemical Dip (Chose one)
Preparing Be for Plating:Preparing Be for Plating:•CleaningCleaning•Acid etch: 20 parts HNOAcid etch: 20 parts HNO33, 1 part HF, 20 parts , 1 part HF, 20 parts
water at 23°C for 5 minwater at 23°C for 5 min•Zincate in 30 g/L ZnO, 15 g/L KF and 25 ml/L Zincate in 30 g/L ZnO, 15 g/L KF and 25 ml/L HH22SOSO44 at 27°C for 10 seconds (pH 3.2) at 27°C for 10 seconds (pH 3.2)-Control of Zincate pH is critical to adhesionControl of Zincate pH is critical to adhesion•Cyanide copper strike 2-3 min at 16 A/ftCyanide copper strike 2-3 min at 16 A/ft22
•Sulfamate nickel plateSulfamate nickel plate
MolybdenumMolybdenumFeatures:Features:•Very high melting point (~5,000°F)Very high melting point (~5,000°F)•Forms hard, stable carbides in ferrous Forms hard, stable carbides in ferrous alloysalloys•Instantly produces oxide film (MoOInstantly produces oxide film (MoO22 and and
MoOMoO33) when exposed to air) when exposed to air•High corrosion resistanceHigh corrosion resistance•Ability to withstand high temperature Ability to withstand high temperature without softeningwithout softening−Used in military armor, aircraft parts, Used in military armor, aircraft parts, electrical contacts, industrial motors and electrical contacts, industrial motors and filamentsfilaments
Tungsten/(W) AlloysTungsten/(W) AlloysPreparation of W/Alloys*:Preparation of W/Alloys*:•CleanClean
•Etch in 3 parts HF, 1 part HNOEtch in 3 parts HF, 1 part HNO33, 4 parts H, 4 parts H22O for 5 minutes O for 5 minutes
at RTat RT
•Options:Options:
•(alternate patented etching process used successfully on (alternate patented etching process used successfully on WC) Anodic etch, 1.5 ASI, 68-140°F, 10-30 minutes 100-WC) Anodic etch, 1.5 ASI, 68-140°F, 10-30 minutes 100-250g/L Na250g/L Na22PP22OO77
•Etch anodically in 300g/L KOH @50C, 100ASF, 5 minutes Etch anodically in 300g/L KOH @50C, 100ASF, 5 minutes plus chromium strikeplus chromium strike-Better matches coefficient of expansionBetter matches coefficient of expansion
•Sulfamate Ni PlateSulfamate Ni Plate
*Procedure from Dr. Chris Marzano (deceased), IIT Metallurgy Dept.*Procedure from Dr. Chris Marzano (deceased), IIT Metallurgy Dept.Adhesion level is only marginal ~3,000psi (ring shear)Adhesion level is only marginal ~3,000psi (ring shear)
W: Highest W: Highest melting point of melting point of
Time:Time: 3 min.3 min.TemperatureTemperature 22°C22°C•Sulfamate Ni plateSulfamate Ni plate
Note: Note: Adhesion is very low (~3,000psi) Adhesion is very low (~3,000psi) unless the deposit is diffusion treated unless the deposit is diffusion treated @ 700°C in a constrained condition @ 700°C in a constrained condition using TMZ (Tungsten-Molybdenum-using TMZ (Tungsten-Molybdenum-Zirconium) containment (25 micron Zirconium) containment (25 micron clearance). The adhesion increases clearance). The adhesion increases X10X10
Source: Dr. Jack DiniSource: Dr. Jack Dini
Pickling solution for Zirconium, Zircaloys and Hafnium:Pickling solution for Zirconium, Zircaloys and Hafnium:HNOHNO33 25 to 50%25 to 50%
HFHF 2 to 5% 2 to 5%
Pickling solution for Zirconium-Niobium alloysPickling solution for Zirconium-Niobium alloysHH22SOSO44 28 to 32% 28 to 32%
HNOHNO33 28-32% 28-32%
HFHF 5-10%5-10%
Notes:Notes:•Both metals are very sensitive to traces of hydrogen, which lowers their fracture Both metals are very sensitive to traces of hydrogen, which lowers their fracture toughnesstoughness•Pickle temperatures should not exceed 65°C (150°F), to prevent excessive pickup Pickle temperatures should not exceed 65°C (150°F), to prevent excessive pickup of hydrogenof hydrogen•To help prevent formation of insoluble fluoride surface stain, a stop bath consisting To help prevent formation of insoluble fluoride surface stain, a stop bath consisting of 70% HNOof 70% HNO33, and 30% H, and 30% H22O can be usedO can be used•HF attacks Zr/Hf, and HNOHF attacks Zr/Hf, and HNO3 3 oxidizes the hydrogen formed by the reaction and oxidizes the hydrogen formed by the reaction and
prevents its absorption by the metal. prevents its absorption by the metal. •HNOHNO3 3 /HF should not be less than 10 to 1 in normality/HF should not be less than 10 to 1 in normality
Source: R. Terrence Webster, Metallurgical Consultant, Surface Engineering Handbook
Zirconium AlloysZirconium Alloys
Plating Process Sequence 1:Plating Process Sequence 1:•Degrease,Degrease,
•Diffusion Treat Ni plated part @ 1300 °F in vacuum for 1 hr or Cu plated part @350F Diffusion Treat Ni plated part @ 1300 °F in vacuum for 1 hr or Cu plated part @350F for 3 hr with the plated article placed in a molybdenum alloy, TZM ring, or constrained for 3 hr with the plated article placed in a molybdenum alloy, TZM ring, or constrained casecase-Coefficient of thermal expansion for molybdenum is lower than that of zirconium and nickel, it provides a Coefficient of thermal expansion for molybdenum is lower than that of zirconium and nickel, it provides a stress on the plating as the assembly is heatedstress on the plating as the assembly is heated
•““Load” activating solution by immersion of pickled zirconium for 10 min@ Load” activating solution by immersion of pickled zirconium for 10 min@ 22°C in:22°C in:
-Ammonium bifluoride 10 to 20 g/L plusAmmonium bifluoride 10 to 20 g/L plus
-Sulfuric Acid 0.75 to 2.0 g/LSulfuric Acid 0.75 to 2.0 g/L
•Etch in Activating Solution for 1 minute @ 22°C Etch in Activating Solution for 1 minute @ 22°C
•Remove any loosely adhering film or smutRemove any loosely adhering film or smut
-Use ultrasonics orUse ultrasonics or
-Use 2-10% vol HBFUse 2-10% vol HBF44
•Same Thermal Treatment as procedure 1 is requiredSame Thermal Treatment as procedure 1 is required
