Proposal for high performance corrosion resistance processes Dipsol Chemicals Co., Ltd Dipsol of America Inc. Toshiaki Murai May 2010
Content 1.Zinc plating system 1)Acid Zn Plating system ( barrel system) No Boric acid and Ammonium chloride addition better scratch and acceptability for tri-cr conversion 2)Alkaline Zn Plating system ( barrel system) better thickness distribution wide operation widow 2.Tri-Cr conversion system on Zn Clear and Black conversion coating better appearance,long bath life and easy maintenance 3. Next Generation of corrosion performance technology May 2010
1. Zinc Plating system 1) Acid Zinc plating system ( barrel system) 1-1) Future 1) No Boric and Ammonium Chloride additional system good waste treatment 2) Better ductility less scratch 3) Better tri-cr conversion acceptability high corrosion, no discoloration Bath composition item Zn g/l Chloride g/l range 20~40 150~170 5.5~6.3 40~60 0.2~0.6 Operation condition ph wetter ml/l brightener ml/l optimum 30 160 5.8 50 0.3 item Temp Cathode CD A/dm 2 optimum 35 0.6 4 range 25~45 0.2~1 3~8 Anode CD A/dm 2 Anode filtration Zinc 99.99% continuous 2~3 turnover
1-2) Waste treatment 100times dilution and just PH adjustment with addition of CA(OH)2 plating bath Zn N B New generation 0.0 <26 0 Potassium bath 0.2 0 52 Mix bath 0.4 100 0 1-3) Better tri-cr conversion acceptability. w/o baking With baking Tri-Cr Clear Tri-Cr Black May 2010
18 1-4 ) corrosion resistance NSS (hour) 0 72 144 240 New generation Potassium Mix
2) Alkaline Zinc plating system 2-1)Future: 1) Uniform thickness distribution 2) Lower running cost 3) wide operation widow Zn, Temperature 4) High plating speed Bath composition item Zn NaOH Make up replenishment conditioner (g/l) (g/l) (ml/l) (ml/l) (ml/l) optimum 10 140 8 4 15 Range 6~20 120~180 4~18 3~5 10~20 Operation condition item Temp ( ) Cathode Current density (A/dm 2 ) Anode current density (A/dm 2 ) optimum 35 1 4 Range 30~45 0.5~2 3~7 Anode Steel or Zn (99.99%) Filter Continuous 2~3 Turn over
2-2)better thickness distribution T.P=M10 150mmbolt Zn:12g NaOH:140g/L Current density:1.0a/dm time:50min. Current system 35 (NZ-100) New Generation 35 High uniformity 25 (NZ-200) thickness High end Middle High end Middle High end Middle 1 20.5 11.2 19.1 10.8 11.90 7.27 2 21.4 11.2 18.7 11.6 10.90 8.26 3 19.4 11 19.5 10.7 11.70 9.06 4 20.7 10.1 18.1 10.2 9.61 6.42 5 22.4 11 19.2 12.2 13.10 8.58 6 21.5 10.2 17.8 11.6 12.80 8.13 7 20.6 10.7 19.2 11.2 13.30 9.56 8 22.2 11.3 18.7 11.0 11.80 7.19 9 21.1 10.5 19.1 11.8 11.40 7.37 10 21.4 10.7 18.7 10.7 14.10 9.94 Ave 21.12 10.79(51%) 18.8 11.18(60%) 12.1 8.2(68%) Max 22.2 11.2 19.5 12.2 14.10 9.94 Mini 19.4 10.1 17.8 10.2 9.61 6.42
2-3)better tri-chromium conversion acceptability Appearance is stable even high plating bath temperature. conventional New generation
2. Tri-Cr conversion system on Zn 1) Clear conversion coating 1-1)Future 1.No discoloration 2.No hex-cr elution 3.Simple chemical 4.Low running cost 5.High corrosion performance 6.Easy modification for torque tension 7.Easy waste treatment May 2010
1-2) Corrosion performance make up concentration Make up(ml/l) 50 75 100 125 150 0 NSS(hours) 72 144 144h white rust(%) 5 0 0 0 0 Color tone Pink-Yellow Pink-Blue Yellow green-pink Yellow green-pink Yellow green discoloration No change No change No change No change No change Friction coefficient(μ) 0.351 0.338 0.345 0.355 0.345 Hex-Cr elution (μg/cm2) (80-95%) 72h ND ND ND ND ND 144h ND ND ND ND ND 2009.10.15 テクニカルセンター ( 研究開発 3 部 )
1-3) comparison with current system New Generation Current Clear 0 NSS (hours) 72 144 144h white rust(%) 0 0 Color tone Yellow green-pink Blue-Pink discoloration No change No change Friction coefficient Hex-Cr elution (μg/cm2) (80-95%) 0.345 (0.35±10% adjustable with additive ) 0.45 ( around) (Hex-Cr elution possibility after adjustment) 72h ND(0.01) ND(0.03~0.05) 144h ND(0.02) Above 0.05 I month ND(0.02) Above 0.05
2). Black conversion coating 2-1)Future 1. Uniform appearance, descent black Less scratch 2. Free of Cr6+ elution problems 3.Excellent corrosion resistance. Corrosion resistance at SST( 168Hr 5 % white rust), 4. Stable appearance no discoloration 5. Easy Control friction coefficient. 6.Easy control 7. Lower running cost 8. Long bath life 2-2) Cost comparison ( make up and running) Make up Running Total make up (ml/l) Total replenishment (ml/dm 2 ) New type 55 0.34 Existing type 206 1.01
2-3) corrosion resistance NSS(Hour) Age 0 72 120 168 192 216 Make Up 200dm 2 /L 600dm 2 /L
3.Next Generation of Corrosion Performance Technology May 2010
1.Future of Al Alloy Plating High corrosion performance with original deposit High galvanic corrosion performance Low hydrogen embrittlement Better Covering Power than Cadmium (Cd) Suitable for both rack and barrel applications May 2010
2. High Corrosion Performance with Original Deposit Amorphous structure Solid and stable oxidation film is deposited on its surface Coating has self healing properties. 3. Low Hydrogen Embrittlement No need of hydrogen embrittlement relief process Prevention of Hydrogen absorption May 2008
4. Applications Aircraft component ( replacement of Cd plating ) Connector box for power transmission wire Wind power/ Solar cell power station Replacement of Stainless steel Automotive component Component for motor Corrosion resisitance for magnet May 2008
5.Plating equipment for Ionic liquid Al Alloy Plating system Comparison between Zn and Al Alloy plating system Plating Bath Bath character Equipment Performance Low chemical cost Post treatment Zn Aqueous No problem with water and humidity Open Conventional plating system Hydrogen embrittlement relief process High covering High productivity Galvanic corrosion Al Special fluid (No solvent ) No toleration for water and humidity high absorbency of humidity Inert gas purge necessary Closed New equipment system is necessary High chemical cost No post treatment No baking Poor covering Low productivity Good galvanic corrosion
6. Process sequence of Al Plating *No use of acid pickling for its treatment Pretreatment degreasing shot blast alkaline electro clean Activation Spin Dry Plating (Nitrogen gas purge closed system) Activation Al Plating (Drain and Rinse) Post treatment WR (post treatment ) Spin Dry
7.Cyclic Corrosion Test Thickness and corrosion performance 1.5μm 4μm 6μm 40 cycle 80 cycle 100 cycle 120 cycle
8.Corrosion Performance of Al and Al Alloy Plating Barrel Al Plating Another system:m10 Bolt (Steel + Ni plating layer) Al Plating Al-Zr Plating Dipsol:M6Bolt Dipsol:M6Bolt CCT(cycle) 20 40 60 80 100 120 Another system w/o coating Another system With coating Dipsol Al Plating w/o coating Dipsol Al-ZrPlating w/o coating
9. CCT Comparison CCT(Cycle) Al plating Another process (8μm) thickness(μm) Zr % 20 cycle 40 4 17% 8 19% 2 36% 4 35% 8 35% A w/o coating A with coating B w/o coating B with coating 60 80 100 120
10.SVET measurement for Al alloy plating. Just after immersion Middle of immersion scratch Final stage of immersion Self healing mechanism By SVET (Scanning Vibrating Electrode Technique)corrosion voltage at scratch was observed to increase for first stage, however finally it decreases to zero (0). It means that this Al alloy has self healing function. May 2008
11.Al-Zr plating film formulation by GDS:Al- 27.8wt%Zr (Ration comes from SEM analysis result) 100 80 60 40 20 *Zr 360 *Al 396 *O 130 *Ni 341 *C 156 *Fe 372 *Cu 327 *N 149 *Mn 258 *Cl 134 0 0 2 4 6 8 10 μm
12. Crystal structure (XRD) Analysis of crystal structure of plating (XRD) Cu (substrate) Al Intensity (%) Al(111) Al(200) Al(311) Al(220) Mn up Zr up Al- 24.7%Zr- 5.8%Mn Al- 30.3%Zr- 1.0%Mn Al- 34.9%Zr Al- 32.8%Zr Al- 26.1%Zr Al- 18.0%Zr 30 40 50 60 70 80 90 100 2θ(deg) Al
13. Proof of passivation effect from Electro chemistry measurement method (Tafel plots) Corrosive electro potential shifts to high side Corrosive rate would be slower due to passivation. 1.E+00 1.E-01 Passivation film Plating layer Al-Zr/ Al-Zr-Mn Steel substrate Current density (A/cm 2 ) 1.E-02 1.E-03 1.E-04 1.E-05 Al Al-18.9Zr Al-35.9Zr Al-22.1Zr-4.0Mn Al-25.0Zr-2.9Mn Al-27.3Zr-3.0Mn 1.E-06 1.E-07 1.E-08 1.E-09 Al- 36%Zr Al- 19%Zr Al -2-1.5-1 -0.5 0 0.5 Electro potential (Potential, E / V vs. SCE) Al- 27%Zr- 3%Mn Al- 22%Zr- 4%Mn Al- 25%Zr- 3%Mn 溶出金属 Corrosive 10 0.001-1.6-1.4-1.2-1 -0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 1 1000 100 electro potential 1 0.1 0.01 0.0001 0.00001 Polarization curve 不動態金属
14.Future work Install mass production line Increase covering power Increase production capacity and capability May 2008