Slide 1: AGA Tech Forum 99: What comes after Ni-Zn?
AGA TECH FORUM 99 “What comes after Ni-Zn?”
Slide 2: General Galvanizing R&D 1980-1999
General Galvanizing R&D 1980 - 1999 Ni-Zn Process New Alloy Development
Slide 3: The Ni-Zn Process: Advantages
The Ni-Zn Process Advantages: – Controls reactivity on steels up to about 0.2%Si or 0.2%SE SE (Silicon Equivalent Value) = %Si + 2.5X%P – Enhances coating appearance Smoother and shinier
Slide 4: The Ni-Zn Process: Shortcomings
The Ni-Zn Process Shortcomings: – Does not control very high Si steels – Does not control well steels with high P levels – Produces thin coatings on rimmed steels – Can produce floating dross – Can have high Ni usage
Slide 5: The Ni-Zn Process: Silicon Equivalent vs Coating Thickness
The Ni-Zn Process Silicon Equivalent (SE) Values vs Coating Thickness for Various Ni Bath Levels 5 Minutes Immersion at 455 °C 360 0.00% Ni 0.06% Ni Mean Average Coating Thickness (µm) 320 0.02% Ni 0.08% Ni 280 0.04% Ni 0.10% Ni 240 200 160 120 80 40 0 0.01 0.05 0.15 0.16 * 0.21 0.29 Si 0.15% Si 0.0
Slide 6: The Ni-Zn Process: Coating Thickness Reductions
The Ni-Zn Process Prime Western Ni-Zn Trials 5 minutes Immersion at 455°C 80 Coating Thickness Reductions (%) 0.02% Ni 0.08% Ni 60 0.04% Ni 0.10% Ni 0.06% Ni 40 20 0 < 0.01 0.05 0.15 0.16 0.21 0.29 Effective Silicon (%) Reductions in coating thickness with various bath nickel additions.
Slide 7: Ni-Zn Bath Operating Efficiency
Ni-Zn Bath Operating Efficiency Bath Ni Levels: >0.06%Ni – Ni consumption: 5X operating level Bath Ni Levels: <0.06%Ni – Ni consumption: 3X operating level
Slide 8: Ni-Zn Bath Operating Efficiency: Bath Chemistry
Ni-Zn Bath Operating Efficiency Bath Chemistry: – 0.06% - 0.09%Ni: Two drosses Zeta - 0.5%Ni+ Gamma - 3%Ni – <0.06%Ni: One dross Zeta - 0.5%Ni
Slide 9: Ni-Zn Bath Operating Efficiency: Nickel Additions
Ni-Zn Bath Operating Efficiency Maintain Ni operating level with minimum swings Add Ni in small amounts Add Ni when bath is not saturated in Fe
Slide 10: Ni-Zn Bath Operating Efficiency: Alloys
Ni-Zn Bath Operating Efficiency Master Alloy: Zn-2%Ni Make-Up Alloy: Zn-0.5%Ni Direct Alloying (DAP): Ni powder
Slide 11: In Search of the Successor to Ni-Zn
In Search of the Successor to Ni-Zn An alloy that would extend the limits: ~ 0.5%SE Consistent coating appearance Reduction of Zn pick-up
Slide 12: New Alloy R&D: The V-Ti Alloy
New Alloy R&D The V-Ti Alloy Zn-0.04V-0.05Ti-0.003Al Controlling Limit: 1%SE
Slide 13: The V-Ti Alloy: Coating Thickness
New Alloy R&D The V-Ti Alloy 400 PW 0.04V+0.02Ti 300 Coating Thickness (µ m) 0.02V+0.05Ti 200 0.04V+0.05Ti 100 Prime Western (PW) Zinc PW + 0.04% V + 0.02% Ti PW + 0.02% V + 0.05% Ti PW + 0.04% V + 0.05% Ti 0 0.0 0.2 0.4 0.6 0.8 1.0 Effective Silicon (wt%)
Slide 14: The V-Ti Alloy: Deficiencies
New Alloy R&D The V-Ti Alloy Alloy Deficiencies: – Ti incompatible with zinc-ammonium-chloride flux – High ash production – High Ti consumption: 5X to 7X bath level » to ash » to dross Possible Solution: – Develop a flux compatible with Ti
Slide 15: Co-operative R&D with Union Minière
New Alloy R&D Co-operative R&D with Union Minière (UM) UM R&D: Sn-Ni Alloy Exploratory R&D Combining Sn and V
Slide 16: New Alloy R&D: Zn-Sn-V
New Alloy R&D Zn-Sn-V Reduce Sn to 1% or lower Controlled up to 0.5%SE
Slide 17: Sn-V Alloy: Challenges and Concerns
New Alloy R&D Sn-V Alloy Challenges: – Cost of V – V slow to alloy Concerns: – Effect of Sn on: » Kettle steel attack » Coating composition » Coating embrittlement
Slide 18: Sn-V Alloy: Testing Program
New Alloy R&D Sn-V Alloy Lab-scale galvanizing trials Galvanizing trials in our pilot line Kettle corrosion tests Atmospheric exposure tests Coating adhesion tests Zn-V alloy development
Slide 19: Sn-V Alloy: Pilot Trials
New Alloy R&D Sn-V Alloy Pilot Trials: Zn-1Sn-0.05V-0.1Bi alloy – Processed 30,000 lb of structural steel: » Angle, tube, I-beams – Processed work from galvanizers: » Corrugated plate, mesh, square tubing
Slide 20: Sn-V Alloy: Pilot Trial Coating Thickness
New Alloy R&D Sn-V Alloy Pilot Trials: Coating Thickness: – 5 minute immersion, 450°C (850°F) » Range: 3 mils - 5 mils Steels: 0.07%SE - 0.35%SE Ash and Dross: Same as Zn control
Slide 21: Sn-V Alloy
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Slide 22: Sn-V Alloy
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Slide 23: Sn-V Alloy
“° New Alloy R&D Sn-V Alloy
Slide 24: Atmospheric Corrosion Test
Atmospheric Corrosion Test Kure Beach marine site 25m lot One year test results - December 1999
Slide 25: Kettle Steel Attack: Laboratory Tests
Kettle Steel Attack Laboratory Tests: – 1 X 2 X 5 in. kettle steel samples – Immersed in 15 kg Zn – Melt temperature: 450°C and 465°C – Alloys saturated with Fe – Test duration: 50 days – Alloys: SHG Zn and Zn-1Sn-0.05V-0.1Bi-0.003Al
Slide 26: Kettle Steel Attack: Weight Loss Results
Kettle Steel Attack % Weight Loss Results, 50 Days 450ºC 465ºC Zn-Pb 3.5 4.3 1Sn-0.05V 3.5 4.0
Slide 27: V-Master Alloy Development
V-Master Alloy Development Objective: – To reduce cost of alloy – To reduce difficulty of production
Slide 28: Effects of Ni-Zn and Sn-V Alloy on Coating Thickness
New Alloy R&D Effects of Ni-Zn and Sn-V Alloy on the Coating Thickness of Various Steels o 10 Minute Immersion at 450 C 450 SHG 400 0.055 Ni 350 1 Sn + 0.05 V + 0.1 Bi µ 300 250 200 150 100 50 0 0.07 0.14 0.15 0.16* 0.21 0.32 0.41* 0.46 0.51 0.99 Silicon Equivalent (%) * High phosphorous content
Slide 29: Sn-V Alloy: Advantages
New Alloy R&D Sn-V Alloy Advantages: – Controls reactivity up to 0.5%SE – Produces smooth, bright, spangled coatings – Can be used at normal bath temperature – Compatible with conventional galvanizing process
Slide 30: Plant Trial
Plant Trial Sn-V-Pb alloy Before year-end